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Minutes of the 51st PCSC Meeting held on 25-02-2016 Page 1

SOUTHERN REGIONAL POWER COMMITTEE BENGALURU

Minutes of the 51st Meeting of Protection Coordination Sub-Committee

(PCSC – 51) of SRPC held on 25.02.2016

1. Introduction The 51st meeting of Protection Coordination Sub-Committee (PCSC-51) was held on 25th February, 2016 in the Conference Hall of Southern Regional Power Committee (SRPC), Bangalore. The list of participants is enclosed at Annexure-I.

Sh. S.R. Bhat, Member Secretary (MS), SRPC welcomed the Members and Participants to the meeting and briefed them on the following:

Informed members that Protection Audit Review of Stations (15 in number) under Task-2 by the Consultant was under progress. Audit of 10 Stations has already been completed. The remaining five Stations, viz., 220 kV Kothagudem TPS (14-16 March, 2016), 220 kV Kaiga APS (4-6 April, 2016), 400/ 220 kV Guttur SS, 400/220 kV Raichur TPS, and 220 kV Nagjheri Station, would also be audited shortly. He requested Constituents’ active cooperation in completing Task-2 activities to the satisfaction of all parties involved.

Reminded members of completion of dead-lines of time-extensions given to various SR-Constituents by Hon’ble CERC for completion of their respective Protection Audit Remarks (PAR), and requested them to approach the Commission for obtaining further time-extension. The PAR-Timelines of various SR-Constituents are given at Annexure-II.

Informed members of the joint study that was conducted on 03.02.2016 with KSEB, SRPC & SRLDC for designing SPS of N-1 & N-2 of 400kV Udumalpet- Palakkad D/C. The minutes of the study are enclosed at Annexure-III.

Apprised members of the special meeting held on 23.02.2016 to discuss the scheduling request of CEPL. The record notes of the meeting are enclosed at Annexure-IV.

22. Confirmation of the Minutes of the 50th PCSC meeting held on 27.01.2016

SE (Protection), SRPC stated that the Minutes of the 50th meeting of the PCSC had been circulated vide SRPC letter No. SRPC/SE-III/ PCSC-49/ 2015/ 1016-48 dated 11.02.2016. As no observations had been received from any of the Constituents, the Minutes of the 50th meeting of PCSC were confirmed.

3. Details of Grid Disturbances (GD’s), Grid Incidents (GI’s), Line Trippings due to Auto-Reclose non-operation and PLCC mal- operation.

The trippings due to GD’s, GI’s, Auto-Reclosure failure/ non-operation, and PLCC mal-operation

that had occurred during the period December, 2015 - January, 2016 were discussed in the Meeting. The deliberations and recommendations of the PCSC-forum are enclosed at Annexure–V.


4. Status of pending PCSC recommendations The status of implementation of pending PCSC recommendations was discussed in the meeting.

The Constituents had been requested to kindly submit the status of their compliance latest by 25-03-2016. The updated status of the same as on 15-03-2016 is enclosed at Annexure–VI.

5. Remedial measures/ Action taken for the tripping incidents of the transmission elements

under forced outage The tripping incidents of the transmission elements under forced outage for which the remedial

measures/ actions taken still awaited were discussed in the meeting. The Constituents had been requested to kindly furnish the remedial measures/ action taken in time so as to forward the same to Central Electricity Authority. The updated list of the same as on 15.03.2016 is enclosed at Annexure-VII.

6. Certificate for Healthiness of Batteries

As per the MoP/ CEA direction given in pursuant to recommendations of the Enquiry Committee (NEW grid disturbance on 30th & 31st July, 2012), RPC’s are required to obtain from their respective Constituents the monthly certificate for healthiness of batteries, installed at 220 KV and above voltage level Substations (for power supply to Relays, RTUs and PLCC equipment) and furnish the same to CEA/ MoP. With reference to above, the Constituents have been requested to submit the certificate on healthiness of batteries on monthly basis (i.e. status for a month may be sent by the 7th day of the following month) to SRPC. The sought status for the month of January, 2015 has not been received from the following SR-Constituents:

APTRANSCO, PED, CEPL, TPCIL

7. Review of Islanding Schemes for Southern Region With the addition of new generators & transmission elements in the Southern Region (SR), the

existing islanding schemes of SR have been reviewed, and the modified Islands incorporating these new elements as enclosed at Annexure-VIII were discussed in the meeting.

It was highlighted that as per the current scenario (January, 2016), Load Generation Balance of

Hyderabad and Chennai Islands had not been achieved. In this regard, the Constituents were requested to kindly furnish the details of (i) load relief from df/dt and AUFR relays, (ii) participating generators, and (iii) participating loads to be considered in various Islanding Schemes latest by 25.03.2016 so as to finalize the revised Islanding Schemes in the next PCSC meeting.

8. Load Impedance Encroachment and Over current protection settings.

The issue of model settings to be adopted for Load Impedance Encroachment and Over Current Protection were discussed in the meeting. A presentation showing the guidelines given by the


Ramakrishna Committee in this regard is enclosed at Annexure-IX. The IEEE document on “Transmission line Protective Systems loadability” is also enclosed at Annexure-X for kind reference.

All Constituents are requested to ensure Load Impedance Encroachment and Over current

protection settings of their respective systems are generally in line with the above guidelines. 9. Review of implementation of certain Protection Audit Recommendations (PAR) of SR

Constituents In the meeting, change in scope of certain PAR of SR-Constituents had been discussed. The

responsibility of complying with those PAR was discussed and fixed as given at Annexure-XI. 10. Status report on implementation of protection audit recommendations by SR-Constituents In compliance of CERC Order dated 18.08.2015 w.r.t Petition Nos. 86/MP/2014 and

374/MP/2014, SRPC had been directed to submit a bi-annual report regarding implementation of protection audit recommendations by SR-Constituents. In this regard, based on the updates received from SR-Constituents, a status report has been submitted to Hon’ble CERC vide SRPC letter no: SRPC/ PAR/ SE-III/ 2015/ 1375-76 dated 02.03.2016. A copy of the same is enclosed at Annexure-XII for ready reference.

11. Network configuration changes

As per the information furnished by SR-Constituents to the OCC forum in their 116th meeting

(held on 10.02.2015; Minutes circulated on 26.02.2016), the following network configuration changes (additions/ deletions/ modifications of transmission elements) took place in the southern grid during the period December, 2015 - February, 2016.

Hinduja NPCL Unit-1 (520 MW) in AP declared on COD from 11.01.2016. Coastal Energen Unit II (600 MW) declared COD from 0000 hrs of 15.01.2016. 220KV LILO from 220KV Kalkiri – Chinkampalli line to 220KV Thimmapuram SS in Chittoor

District of Ckt km 2.228 was Commissioned on 16.12.2015 by APTRANSCO. 220/132/33kV LIS Substation Thimmapuram of capacity (MVA) 131.5 was commissioned

on 16.12.2015. Consequent to the successful Trial Operation, following assets under “Transmission

System associated with Phase-I, Generation Projects in Odisha, Part-A, Eastern Region” have been put under Commercial Operation w.e.f 0.00 Hrs of 27.01.2016 in terms of clause 4 of CERC (Terms and Conditions of Tariff) Regulations, 2014.

765 KV S/C Angul – Jharsuguda (Sundargarh) line –I along with 765KV Bays i.e. 709L & 709R at Angul pooling Station and 710,711,& 712 at Sundargarh Pooling Station, and 1 no 3x80MVAR Switchable Line Reactor at Angul Pooling Station and associated Bays, under Phase –I, Generation Projects in Odisha, part –A, in Eastern Region.

Consequent to the successful Trial Operation, following assets under “Transmission System associated with Phase-I, Generation Projects in Odisha, Part-A, Eastern Region” have been put under Commercial Operation w.e.f 0.00 Hrs of 25.01.2016 in terms of


clause 4 of CERC (Terms and Conditions of Tariff) Regulations, 2014. One set of 765/400 kV, 3x500 MVA Transformer ICT III at Angul Pooling Station and

associated bays(710T, 710,711,413 T,413 & 414) under Transmission System associated with Phase-I, Generation Projects in Odisha, Part-A, Eastern Region”

Narasaraopet 220KV SS in Guttur District of 2x100 MVA Capacity was augmented to 3x100 MVA capacity and was commissioned on 01.01.2016 by APTRANSCO.

220kV LILO line from RSS – Warangal DC line to 220kV /132 SS Manthani of Ckt Km 59 was commissioned on 06.01.2016 by TSTRANSCO.

1x100 MVA Transformer of Manthani 220/132kV SS (2x100 MVA Capacity) in Karimnagar District was commissioned on 06.02.2016 by TSTRANSCO.

KKNPP Unit I which was under outage for Annual Maintenance Work from 11:30 hrs of 24.06.2015 was revived at 07:12 hrs of 30th January 2016.

12. Instances of SPS Operation

Based on the information furnished by SRLDC, it is informed that the following instances of SPS operation took place in SR during the period 27.01.2016 – 24.02.2016.

Sl No

Date Time (hrs)

Reason Load relief obtained (MW)

AP KAR KEL TN Total

1 28-Jan-16 19:52 SPS S3-800 operated 150 84 150 253 637

2 09-Feb-16 7:59 Wardha-Parli SPS operated due

to tripping of Aurangabad-Sholapur line

230 155 120 170 675

3 09-Feb-16 8:34 Wardha-Parli SPS operated 230 140 80 156 606

4 20-Feb-16 18:22 Talcher-Kolar SPS operated as

pole-1 tripped 0 500 0 592 1092

5 21-Feb-16 16:46 Talcher-Kolar SPS operated as

pole-1 tripped 300 450 0 334 1084

6 22-Feb-16 12:25 Suspected Overdrawl by SR

constituents 138 100 0 92 330

13. Compliance of Hon’ble CERC Orders

13.1 Petition No. 146/MP/2013 with I.A. 36/2013: Order dated 20.02.2014

Compliance of Regulations 5.2 I of the Grid Code: Issue regarding non-furnishing of FIR / Trip Analysis Report, EL, DR, etc. was also highlighted. It is pointed out that the above reports are to be submitted / uploaded on SRLDC web application within 24 hours as mandated under IEGC / CEA Regulations.


Implementation of Phase-I and Phase-II of Protection Audit Recommendations: All the constituents are requested to submit the updated status of the compliance (those who have not completed recommendations mentioned in the Phase I and Phase II) to SRPC Secretariat at the earliest.

Compliance of Regulations 5.2 (e) & 5.2 (l) of the Grid Code and Regulation 3(1)(e) of CEA Grid Standards: The constituents are requested to strictly comply with these provisions by ensuring standard protections systems having the reliability, selectivity, speed and sensitivity to isolate the faulty equipment and protect all components from any type of faults, within the specified fault clearance time and providing protection coordination

Ensuring proper maintenance of transmission lines and adopting best O&M practices: The constituents are requested to conduct line patrolling regularly as per the SRPC transmission line patrolling guidelines (available under the menu item “All Uploads Operation Miscellaneous Transmission Line Patrolling Protocol / Guidelines for Southern Region” on SRPC website). (http://www.srpc.kar.nic.in/website/2014/operation/patrolling.pdf).

13.2 Petition No. 167/Suo- Motu/2012: Order dated 22.02.2014

The Constituents are requested to follow approved protection philosophy

ISTS licensees are requested to submit details of updated distance protection relay setting of all inter-regional lines to POSOCO & RPCs.

All SLDCs are requested to install/activate sound recording system in their control rooms within three months from the date of issue of this order.

The Constituents are requested to submit the progress of implementation to SRPC and SRLDC as specified in the Hon’ble CERC Order.

13.3 Petition No. 263/MP/2012: Order dated 19.12.2013

Constituents are requested to implement the quantum of relief by AUFR and df/dt relays by identifying additional feeders and keep them functional within one month of issuing this order.

SLDCs are also requested to map these relays on their respective SCADA system within three months of issuance of this order.

The Constituents are requested to submit the progress of implementation to SRPC and SRLDC as specified in the Hon’ble CERC Order.

13.4 APTRANSCO’s Petition No.95/MP/2015: Date of hearing 09-04-2015

It was noted in the Analysis and Decision part of the Order that:

“8. Noting the submissions of the petitioner, SRPC and SRLDC and activities initiated by the petitioner for procurement of materials required for implementation of the remarks of protecting audit, we allow time to the petitioner till 31.12.2015 for completion of our directions in Order dated 19.12.2013 in Petition No. 146/MP/2013.”

“9. SRPC is directed to monitor the status of completion of works relating to protection

http://www.srpc.kar.nic.in/website/2014/operation/patrolling.pdf


audit remarks in respect of 7 nos 400 kV sub-stations and 11 nos 220 kV sub-stations of APTRANSCO, protection audit remarks in Protection Coordination Sub-Committee (PCSC) meetings and coordinate the periodic protection audit to be carried out in Southern Region after deliberation in SRPC and submit bi-monthly report to the Commission.”

13.5 TSTRANSCO’s Petition No.83/MP/2015: Order dated 14-05-2015

It was noted in the Order that:

“12. Noting the submission of the petitioner, SRLDC and SRPC and considering the actions already initiated by the petitioner for implementation of works relating to protection audit, we allow time till 31.10.2015 and 31.8.2016 for implementation of Phase-I and Phase -II works respectively. The petitioner is directed to submit affidavit confirming the completion of Phase I of protection audit remarks by 31.10.2015 and Phase-II of protection audit remarks by 31.8.2016.

13. SRPC is directed to monitor the status of completion of remarks in these substations vis-à-vis protection audit remarks in Protection Coordination Sub Committee (PCSC) meetings. SRPC is further directed to coordinate the periodic protection audit to be carried out in Southern Region after deliberation in SRPC.”

13.6 Order in Petition No. 86/MP/2014 and 374/MP/2014: Order dated 18-08-2015

The time-lines given to the various SR-Constituents for completion of Phase-I and Phase-II activities of Protection Audit Recommendations vide above Order are given below:

(A) KSEBL:

18. Noting the submission of KSEBL, SRLDC and SRPC and considering the actions already initiated by KSEBL for implementation of remarks of protection audit, we allow time till 31.12.2015 and 31.3.2016 for implementation of Phase-II works and R&M works at Idduki HEP respectively.

(B) TANTRANSCO:

21. After considering the submissions of TANTRANSCO, SRLDC and SRPC, it is noted that TANTRANSCO`s request for time till 31.5.2015 for implementation of Phase–I activities of providing numerical relays for feeder protection and Auto transformer protection is already over. We allow time till 30.6.2016 for other Phase-I activities such as provision of line VT, 5 core CT, Time synchronizing with GPS, Disturbance recorder & event logger and Phase-II activities. According to SRLDC, total implementation period is 15 to 16 months for items which involve major procurement, design changes with major site modification/civil activities. Accordingly, we allow 16 months time i.e up to 30.11.2016, for Renovation and Modernization of Singarpet, Singaperumalkoil, Salem and Tondiarpet 230 kV sub-stations from the issue of the order.

(C) NLC:

22. NLC has sought time upto 31.12.2014 and 31.3.2015 for completion of Phase-I work of Numerical Relay Retrofitting and for Phase-II works of providing second battery bank of PLCC respectively. It is noted that the completion dates for Phase-I and Phase-II of protection audit remarks as requested by NLC are already over. Therefore, no direction is required in this regard. However, we direct NLC to file a confirmation report regarding completion of protection audit works for Phase-I and Phase-II.


(D) KPTCL:

23. …

…

Considering the submission of KPTCL and SRLDC, we allow time to KPTCL time till 15.01.2016 for completion of Phase-I and Phase-II of protection audit remarks. No further extension shall be granted in this regard.

(E) KPCL:

24. …

…

Considering the submission of KPCL and SRLDC, we allow time to KPCL till 31.10.2015 and 31.12.2015 for completion of Phase-I for Phase-II of protection audit remarks respectively. No further extension shall be granted in this regard.

26. We direct SRPC to (a) submit status of protection audit remarks in respect of APGENCO, NTPC (SR), Talcher, Puducherry, PGCIL (SRTS I & II), MAPS and TANGEDCO, (b) monitor the status of completion of remarks of protection audit in respect of all constituents of Southern Region in Protection Coordination Sub-Committee (PCSC) meetings, and (c) to coordinate periodic protection audit to be carried out in Southern Region after deliberation in SRPC. All the constituents of Southern Region are directed to file their status with SRPC on regular basis to facilitate proper monitoring in PCSC meetings. SRPC is directed to submit bi-annually status report to the Commission confirming the completion of Phase-I, Phase-II and R&M works of protection audit remarks of the constituents of Southern Region.

14. Nomenclature for naming various files uploaded in Web based Tripping Monitoring System of

SRLDC Portal

The nomenclature to be followed by the Constituents in naming various files (FIR, DR, EL, TR) corresponding to a tripping incident was brought out in the SRPC letter No. SRPC/ SE-III/ PCSC-45/ 4609 – 649 dated 26.06.2015 and in the minutes of PCSC-45 issued vide SRPC letter No. SRPC/SE-III/ PCSC-45/ 2015/ 5422-455 dated 21.07.2015. As illustrated therein, the format to be followed for the user entered part-name is given below:

Transmission Element File name to be given by the user

Transmission line SSN_DSN_line#_FT

Inter-connecting Transformer SSN_ICT#_FT

Generating Transformer SSN_GT#_FT

Generating Unit SSN_Unit#_FT

Where, SSN = Source Station Name/ From end Station Name/ Sending end Station Name

DSN = Destination Station Name/ To end Station Name/ Receiving end Station Name


FT = File Type (FIR/ DR/ EL/ TR)

All SR-Constituents are requested to kindly intimate the above file naming nomenclature to all the concerned and ensure that it is followed at all stations in their control area so that tripping analysis can be done systematically.

15. Date & Venue of the next Meeting

It is informed that the 52nd PCSC meeting will be held on 30.03.2015 (Wednesday) at 10:30 hrs in the Conference Hall of SRPC, Bengaluru.

*****

Annexure-I

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Annexure-I

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Annexure-I

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Annexure-I

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Annexure-I

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Annexure-I

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PAR – Timelines of SR-Constituents

The timelines given by Hon’ble CERC to various SR-Constituents for the completion of their respective Phase-I and

Phase-II works of Protection Audit recommendations are given below:

Sl.

No

Constituent CERC

Petition No.

/Date of

Order

Date for

completio

n of

Phase-I

activities

Date for

completion

Phase-II

activities

Remarks

1 APGENCO 146/MP/2013

Date of Order

: 20.02.2014

Affidavits dt:06.09.2014 &

17.09.2014 were filed on

behalf of APGENCO in

CERC duly stating that the

implementation of Phase-l &

Phase-II activities of

Thermal & Hydel Stations

would be completed by 31-

05-2015 & 31-12-2015

respectively, pursuant to

CERC order dated

20.02.2014 against the

Petition No.146/MP/ 2013.

APGENCO informed vide

their letter dated 17.02.2016

that the process of filing

single Affidavit on behalf of

APGENCO Thermal &

Hydel stations in CERC is

under process to consider

for extension of time up to

30.07.2016 & 31.12.2017

respectively for

implementation of all the

identified

activities of APGENCO

Thermal & Hydel

Substations.

2 APTRANSCO 95/MP/2015

Date of Order

: 27.4.2015

31.12.2015 31.12.2015 APTRANSCO informed

that they would be filing an

application before CERC

within one month for

obtaining further time

extension.

(Ref: PCSC-51 held on

25.02.2016)

3 TSGENCO 146/MP/2013

Date of Order

: 20.02.2014

TSGENCO made Affidavit

dt: 16.12.2014 on status of

implementation of Phase-I

and Phase-II activities

pursuant to CERC order

dated 20.02.2014 (Petition

No. 146/MP/2013) and

informed to

complete the above subject

work on 31.08.2015.

TSGENCO informed that

their management is in the

process of filing an


for obtaining further time

extension.


25.02.2016)

Annexure- II

Page 1 of 3

4 TSTRANSCO 83/MP/2015

Date of Order

: 14.5.2015

31.10.2015 31.08.2016 TSTRANSCO informed

that Phase-I activities are

under advanced stage of

completion as Erection &

commissioning of the same

are in progress.


25.02.2016)

5 KPCL 374/MP/2014

Date of Order

: 18.8.2015

31.10.2015 31.12.2015 KPCL informed that they

had filed a Petition (No.

265/MP/2015) dated

29.10.2015 before Hon’ble

CERC praying to grant an

extension of time up to

30.12.2016 for completing

the Phases I and II

activities.

The Commission in its

ROP dated 26.11.2015 for

the Petition No.

265/MP/2015 has directed

the KPCL to file additional

submission, if any, by

22.12.2015.

However, as no additional

submission has been made

by KPCL, order of Hon’ble

CERC for the petition is

awaited.

6 KPTCL 374/MP/2014

Date of Order

: 18.8.2015

15.1.2016 15.1.2016 KPTCL filed a separate

application before CERC on

07.01.2016 seeking time

extension up to 31.05.2017,

and the same is under

consideration by CERC.

7 KSEB 86/MP/2014

Date of Order

: 18.8.2015

31.12.2015

31.12.2015

(excepting

for R&M

works at

Idduki HEP

for which

time

extension is

up to

31.3.2016)

KSEB informed that they

would be filing an


within one month for

obtaining further time

extension up to 31.12.2017.


25.02.2016)

Annexure- II

Page 2 of 3

8 TANTRANSCO 374/MP/2014

Date of Order :

18.8.2015

30.6.2016 30.11.2016

9 NLC 146/MP/2013

Date of Order

: 20.02.2014

374/MP/2014

Date of Order

: 18.8.2015

As per the affidavit

submitted to CERC

regarding completion of

Phase-I & Phase-II audit

works against the CERC

Order dated 20.02.2014 for

the Petition 146/MP/2013,

NLC has sought time up to

31-12-2014 for completion

of Phase-I and up to 31-03-

2015 for completion of

Phase-II activities.

NLC has been directed to file

a confirmation report before

CERC regarding completion

of protection audit works for

Phase-I and Phase-II in

compliance with CERC

Order dated 18.08.2015

against the Petition

374/MP/2014.

NLC informed that their

Phase-I works had been

completed before

31.12.2014. And their

pending Phase-II works (2

no.) had also been

completed by the third week

of February, 2016.


25.02.2016)

10 NPCIL 146/MP/2015

Date of Order

: 20.02.2014

01.05.2014 01.09.2014 As per the status furnished

to SRPC, out of the total 9

recommendations given

covering KAPS and MAPS,

two no. of recommendations

pertaining to MAPS are yet

to be complied with.

Note: PGCIL (SR-I & SR-II) and NTPC (excluding Talcher), and majority of the IPP’s have completed

implementation of their respective Protection Audit Works.

Annexure- II

Page 3 of 3

Annexure- III

Page 1 of 8

Annexure- III

Page 2 of 8

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Annexure- III

Page 3 of 8

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0.9201.6

116.6

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0.9208.9

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0.9203.9

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0.9206.2

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452010KAYMKLM

1.0210.5

-25.4

-1.6

25.4

-4.5

-26.9

-17.2

27.0

11.5

-25.6

25.6

22.1

0.0

0.0

452024TRIVDRM4

1.0212.4

-105.4

-16.0

105.4

13.8

-105.4

-16.0

105.4

13.8

-105.4

-16.0

105.4

13.8

-105.4

-16.0

105.4

13.8

-140.6

-18.4

1

1

141.0

27.0

-140.6

-18.4

1

1

141.0

27.0

-140.6

-18.4

1

1

141.0

27.0

-182.9

0.5

1

1

183.7

14.0

-182.9

0.5

1

1

183.7

14.0

46.7

-93.8

-45.0

91.1

1

0.0

-75.0

-41.1

-25.0

81.7

31.8

-80.3

-36.0

149.8

28.0

-144.2

-11.7

52.6

-20.0

-52.2

14.9

452037KOZHIKODE

0.9199.4

-215.4

-14.4

219.1

29.6

-215.4

-14.4

219.1

29.6

1

0.0

-13.8

454004COCHIN

1.0387.1

454002TRIVNDRM

1.0391.0

454005PALAKD

1.0385.8

444004MYWADI

1.0386.8

454001TRICHUR

1.0385.7

458.6

-30.0

-454.9

25.4

458.6

-30.0

-454.9

25.4

-269.9

7.8

271.2

-39.4

-269.9

7.8

271.2

-39.4

R1

71.0

-57.0

-71.0

3.8

71.0

-57.0

-71.0

3.8

442006THENI2

0.9218.2

442004ABISEK42

1.0225.1

442005UDMLPT2

0.9216.1

1

Annexure- III

Page 4 of 8

Sharath

Typewriter

BASECASE

Sharath

Typewriter

452001KANYAMPT

0.9190.8

452034AREACODE-B

0.9197.4

432004KADAKOLA

0.9200.4

121.7

15.5

-117.8

-10.8

452035KNHRD-SPL

0.8181.2

452005AREACODE-A

0.9191.3

452013MADKTARA

0.9206.9

452014MALPRMBA

0.9201.6

452016NALLALAM

0.9191.0

452021SHORNUR

0.9204.0

452023VADAKARA

0.8184.2

100.9

-15.3

-100.315.6

100.9

-15.3

-100.3

15.6

145.6

20.9

-142.0

-10.7

88.7

33.3

-87.8

-35.0

129.9

24.4

-128.9

-23.1

100.2

18.8

-99.3

-17.8

452009KANHIROD

0.8178.7

452018PALAKAD

0.9208.2

452025COCHIN2

1.0212.1

452026PALAKD2

0.9208.4

452012LOPERIAR

1.0216.5

-29.2

-6.8

29.3

-2.7

-29.2

-6.8

29.3

-2.7

-32.0

-6.9

32.2

-3.2

82.3

29.8

-80.9

-35.7

82.3

29.8

-80.9

-35.7

-101.2

-1.7

101.3

1.6

-101.2

-1.7

101.3

1.6

-101.2

-1.7

101.3

1.6

105.0

41.0

452002IDUKKI2

1.0220.0

452006BRAHMPRM

1.0212.0

110.1

31.1

-109.3

-32.0

110.1

31.1

-109.3

-32.0

-78.7

-26.9

79.5

22.8

-78.7

-26.9

79.5

22.8

-10.0

-2.6

10.0

1.9

-10.0

-2.6

10.0

1.9

598.0

298.5

452008KLMSSERY

1.0212.2

-39.4

11.5

1

1

39.5

-10.8

-39.4

11.5

1

1

39.5

-10.8

-29.4

11.7

29.5

-13.4

-29.4

11.7

29.5

-13.4

129.3

34.9

-127.2

-33.6

129.3

34.9

-127.2

-33.6

452019PALOM

1.0212.0

452003SABRGRI

1.0216.0

3.6

-4.2

-3.6

-3.6

63.2

-2.4

-62.3

-9.9

122.8

7.0

-120.9

-7.0

1

304.0

131.2

452004EDAMAN2

1.0212.2

29.2

29.2

-29.0

-35.2

29.8

29.9

-29.6

-35.8

29.8

29.9

-29.6

-35.8

35.1

-49.7

-34.4

39.2

1

98.8

28.9

452007EDAPAN

1.0209.4

452011KUNDARA

1.0210.2 452020

POTHNCOD1.0211.8

154.5

17.5

-153.6

-16.0

195.6

19.1

-194.7

-14.2

-32.1

7.8

32.2

-13.5

-32.1

7.8

32.2

-13.5

206.7

8.1

-204.4

4.3

206.7

8.1

-204.4

4.3

452017PALMNEW

1.0212.07

4.9

11.7

-74.9

-12.5

172.5

54.3

-169.7

452010KAYMKLM

1.0210.2

-36.7

0.5

36.8

-6.3

-14.2

-19.8

14.2

14.1

-15.9

15.9

24.0

0.0

0.0

452024TRIVDRM4

1.0211.9

-111.6

-14.0

111.6

11.8

-111.6

-14.0

111.6

11.8

-111.6

-14.0

111.6

11.8

-111.6

-14.0

111.6

11.8

-148.8

-15.7

1

1

149.3

25.3

-148.8

-15.7

1

1

149.3

25.3

-148.8

-15.7

1

1

149.3

25.3

-168.0

-0.8

1

1

168.6

13.2

-168.0

-0.8

1

1

168.6

13.2

87.7

-102.4

-84.9 10

5.4

1

0.0

-74.5

-47.2

-26.9

81.8

32.4

-80.3

-36.2

151.3

31.9

-145.4

-13.4

57.4

-17.3

-56.8

12.8

452037KOZHIKODE

0.9196.9

-221.0

-17.5

225.0

34.5

-221.0

-17.5

225.0

34.5

1

0.0

-13.2

454004COCHIN

1.0384.1

454002TRIVNDRM

1.0389.8

454005PALAKD

1.0381.5

444004MYWADI

1.0384.9

454001TRICHUR

1.0382.3

801.4

15.1

-789.8

68.8

-225.3

12.8

226.3

-47.6

-225.3

12.8

226.3

-47.6

R1

39.5

-63.5

-39.5

10.8

39.5

-63.5

-39.5

10.8

442006THENI2

0.9217.8

442004ABISEK42

1.0224.6

442005UDMLPT2

0.9215.5

1

Annexure- III

Page 5 of 8

Sharath

Typewriter

CASE 1: BASECASE + N-1 OF 400KV UDUMALPET- PALLAKAD-1

Sharath

Typewriter

452001KANYAMPT

0.9197.2

452034AREACODE-B

0.9205.1

432004KADAKOLA

0.9203.4

112.4

1.9

-109.2

-1.3

452035KNHRD-SPL

0.9191.2

452005AREACODE-A

0.9199.1

452013MADKTARA

1.0214.1

452014MALPRMBA

1.0209.9

452016NALLALAM

0.9199.2

452021SHORNUR

1.0212.4

452023VADAKARA

0.9193.6

91.2

-20.5

-90.7

19.8

91.2

-20.5

-90.7

19.8

142.3

11.4

-139.2

-4.2

82.8

24.2

-82.1

-27.4

108.6

6.6

-108.0

-7.3

99.3

12.5

-98.5

-12.4

452009KANHIROD

0.9189.2

452018PALAKAD

1.0216.4

452025COCHIN2

1.0214.5

452026PALAKD2

1.0216.4

452012LOPERIAR

1.0218.5

-35.1

-12.8

35.3

2.8

-35.1

-12.8

35.3

2.8

-35.9

-11.5

36.1

0.9

64.5

5.3

-63.7

-15.3

64.5

5.3

-63.7

-15.3

-75.9

13.2

76.0

-13.7

-75.9

13.2

76.0

-13.7

-75.9

13.2

76.0

-13.7

105.0

41.0

452002IDUKKI2

1.0220.0

452006BRAHMPRM

1.0214.3

95.5

2.6

-95.0

-4.7

95.5

2.6

-95.0

-4.7

-82.2

-24.1

83.0

19.9

-82.2

-24.1

83.0

19.9

-20.3

-17.4

20.3

16.6

-20.3

-17.4

20.3

16.6

598.0

185.3

452008KLMSSERY

1.0214.4

-48.9

-16.0

1

1

49.0

17.1

-48.9

-16.0

1

1

49.0

17.1

-28.6

-1.1

28.6

-0.7

-28.6

-1.1

28.6

-0.7

123.2

18.9

-121.3

-19.2

123.2

18.9

-121.3

-19.2

452019PALOM

1.0212.7

452003SABRGRI

1.0216.0

18.2

6.6

-18.2

-14.3

50.5

-10.1

-49.9

-4.1

111.2

3.0

-109.8

-4.7

1

304.0

84.3

452004EDAMAN2

1.0212.8

37.5

22.1

-37.3

-28.1

38.3

22.7

-38.1

-28.6

38.3

22.7

-38.1

-28.6

23.3

-45.0

-22.8

33.4

1

98.8

28.9

452007EDAPAN

1.0210.0

452011KUNDARA

1.0210.8 452020

POTHNCOD1.0212.7

143.9

17.0

-143.1

-17.0

185.5

18.4

-184.6

-14.6

-23.5

2.9

23.6

-8.9

-23.5

2.9

23.6

-8.9

191.5

9.3

-189.6

-0.8

191.5

9.3

-189.6

-0.8

452017PALMNEW

1.0212.77

0.8

4.2

-70.8

-5.0

183.1

45.5

-180.0

452010KAYMKLM

1.0210.8

-26.5

-0.6

26.5

-5.5

-25.3

-18.4

25.4

12.7

-24.6

24.6

23.2

0.0

0.0

452024TRIVDRM4

1.0212.7

-106.7

-16.4

106.7

14.2

-106.7

-16.4

106.7

14.2

-106.7

-16.4

106.7

14.2

-106.7

-16.4

106.7

14.2

-142.2

-18.9

1

1

142.7

27.7

-142.2

-18.9

1

1

142.7

27.7

-142.2

-18.9

1

1

142.7

27.7

-132.0

20.1

1

1

132.4

-12.7

-132.0

20.1

1

1

132.4

-12.7

55.8

-92.3

-54.0

90.0

1

0.0

-76.0

-37.3

-26.0

81.6

30.5

-80.3

-35.7

148.4

20.7

-143.3

-7.3

48.9

-26.2

-48.4

20.6

452037KOZHIKODE

0.9203.3

-212.3

-5.8

215.7

19.2

-212.3

-5.8

215.7

19.2

1

0.0

-14.8

454004COCHIN

1.0393.1

454002TRIVNDRM

1.0391.7

454005PALAKD

1.0391.9

444004MYWADI

1.0388.6

454001TRICHUR

1.0392.8

680.7

-80.1

-672.4

124.9

-203.1

9.9

203.8

-49.7

-203.1

9.9

203.8

-49.7

R1

49.0

-38.4

-49.0

-17.1

49.0

-38.4

-49.0

-17.1

442006THENI2

0.9218.4

442004ABISEK42

1.0225.4

442005UDMLPT2

0.9216.6

1

Annexure- III

Page 6 of 8

Sharath

Typewriter

CASE 2: CASE 1 + 215 MW LOAD SHEDDING AT PALAKKAD & MADAKTHARA

Sharath

Typewriter

452001KANYAMPT

0.9192.3

452034AREACODE-B

1.0209.2

432004KADAKOLA

0.9202.2

114.2

17.5

-110.8

-15.2

452035KNHRD-SPL

0.8181.7

452005AREACODE-A

0.9192.3

452013MADKTARA

1.0217.9

452014MALPRMBA

1.0220.0

452016NALLALAM

0.9191.6

452021SHORNUR

1.0220.0

452023VADAKARA

0.8184.7

88.1

-7.2

-87.6

6.7

88.1

-7.2

-87.6

6.7

143.2

24.0

-139.7

-14.5

99.9

19.1

-99.0

-18.1

452009KANHIROD

0.8179.2

452018PALAKAD

1.0220.0

452025COCHIN2

1.0215.5

452026PALAKD2

1.0220.0

452012LOPERIAR

1.0219.31

02.5

-15.7

-100.7

10.8

102.5

-15.7

-100.7

10.8

105.0

41.0

452002IDUKKI2

1.0220.0

452006BRAHMPRM

1.0215.1

139.8

-16.6

-138.6

17.5

139.8

-16.6

-138.6

17.5

-87.7

-22.5

88.6

18.7

-87.7

-22.5

88.6

18.7

54.8

-43.4

-54.8

42.9

54.8

-43.4

-54.8

42.9

598.0

167.6

452008KLMSSERY

1.0215.1

55.3

-55.4

1

1

-55.2

57.9

55.3

-55.4

1

1

-55.2

57.9

0.5

-14.4

-0.5

12.5

0.5

-14.4

-0.5

12.5

150.8

9.7

-148.1

-5.9

150.8

9.7

-148.1

-5.9

452019PALOM

1.0212.8

452003SABRGRI

1.0216.0

-34.9

23.8

35.1

-30.7

93.4

-18.5

-91.4

11.3

142.9

-2.0

-140.5

5.0

1

304.0

103.7

452004EDAMAN2

1.0212.3

9.9

32.0

-9.8

-38.4

10.1

32.8

-10.0

-39.0

10.1

32.8

-10.0

-39.0

58.1

-52.2

-56.9

44.0

1

98.8

28.9

452007EDAPAN

1.0209.8

452011KUNDARA

1.0210.5 452020

POTHNCOD1.0212.1

174.8

13.6

-173.6

-9.3

214.6

15.3

-213.5

-8.4

-54.3

11.2

54.6

-16.0

-54.3

11.2

54.6

-16.0

234.3

9.5

-231.3

9.9

234.3

9.5

-231.3

9.9

452017PALMNEW

1.0212.88

8.1

-0.9

-88.0

0.1

151.9

48.4

-149.7

452010KAYMKLM

1.0210.8

-56.7

6.8

56.8

-12.1

8.9

-27.4

-8.8

21.7

1.3

-1.3

29.9

0.0

0.0

452024TRIVDRM4

1.0212.1

-124.2

-12.2

124.2

10.0

-124.2

-12.2

124.2

10.0

-124.2

-12.2

124.2

10.0

-124.2

-12.2

124.2

10.0

-165.6

-13.4

1

1

166.2

25.2

-165.6

-13.4

1

1

166.2

25.2

-165.6

-13.4

1

1

166.2

25.2

1

1

1

1

173.3

-105.2

-166.6

126.3

1

0.0

-76.5

-44.4

-32.8

81.6

29.5

-80.3

-35.4

149.3

33.9

-143.6

-16.4

50.4

-12.7

-50.0

7.4

452037KOZHIKODE

0.9198.2

-209.3

-25.5

212.9

40.2

-209.3

-25.5

212.9

40.2

1

0.0

-13.3

454004COCHIN

1.0400.4

454002TRIVNDRM

1.0390.2

454005PALAKD

1.0403.5

444004MYWADI

1.0388.5

454001TRICHUR

1.0401.70

.0

-50.5

0.0

0.0

0.0

-50.5

0.0

0.0

R1

-55.1

0.3

55.2

-57.9

-55.1

0.3

55.2

-57.9

442006THENI2

0.9218.1

442004ABISEK42

1.0224.7

442005UDMLPT2

0.9216.5

1

Annexure- III

Page 7 of 8

Sharath

Typewriter

CASE 3: CASE 2 + N-1-1/N-2 OF 400KV UDUMALPET - PALAKKAD DC + 430 MW LOAD SHEDDING IN SHORNUR, MALAPARAMBA & PALAKKAD AREA

Sharath

Typewriter

Sharath

Typewriter

Sharath

Typewriter

Sharath

Typewriter

452001KANYAMPT

0.9192.6

452034AREACODE-B

1.0211.2

432004KADAKOLA

0.9202.4

114.1

16.9

-110.6

-14.8

452035KNHRD-SPL

0.8182.2

452005AREACODE-A

0.9192.7

452013MADKTARA

1.0219.8

452014MALPRMBA

1.0220.0

452016NALLALAM

0.9192.1

452021SHORNUR

1.0220.0

452023VADAKARA

0.8185.2

88.1

-7.5

-87.6

6.9

88.1

-7.5

-87.6

6.9

143.1

23.5

-139.7

-14.1

99.9

18.7

-99.0

-17.8

452009KANHIROD

0.8179.8

452018PALAKAD

1.0220.0

452025COCHIN2

1.0216.2

452026PALAKD2

1.0220.0

452012LOPERIAR

1.0219.99

2.5

-21.5

-90.9

14.9

92.5

-21.5

-90.9

14.9

105.0

41.0

452002IDUKKI2

1.0220.0

452006BRAHMPRM

1.0215.8

130.7

-24.1

-129.6

24.4

130.7

-24.1

-129.6

24.4

-88.8

-21.4

89.7

17.6

-88.8

-21.4

89.7

17.6

45.7

-46.6

-45.7

46.0

45.7

-46.6

-45.7

46.0

598.0

132.3

452008KLMSSERY

1.0215.7

44.8

-62.3

1

1

-44.6

64.7

44.8

-62.3

1

1

-44.6

64.7

-0.9

-18.1

0.9

16.3

-0.9

-18.1

0.9

16.3

146.4

5.3

-143.8

-2.3

146.4

5.3

-143.8

-2.3

452019PALOM

1.0213.0

452003SABRGRI

1.0216.0

-25.3

25.8

25.5

-32.9

85.2

-20.5

-83.5

11.6

136.1

-2.9

-133.8

4.8

1

304.0

86.8

452004EDAMAN2

1.0212.5

15.2

29.0

-15.1

-35.4

15.5

29.8

-15.4

-36.0

15.5

29.8

-15.4

-36.0

50.8

-50.4

-49.8

41.3

1

98.8

28.9

452007EDAPAN

1.0210.0

452011KUNDARA

1.0210.7 452020

POTHNCOD1.0212.3

168.3

13.5

-167.2

-10.2

208.5

15.1

-207.5

-8.9

-48.6

9.3

48.8

-14.4

-48.6

9.3

48.8

-14.4

225.2

9.4

-222.5

7.5

225.2

9.4

-222.5

7.5

452017PALMNEW

1.0213.08

5.3

-3.1

-85.3

2.4

158.4

45.1

-156.1

452010KAYMKLM

1.0211.0

-50.5

5.9

50.5

-11.4

2.0

-26.3

-2.0

20.4

-4.0

4.0

29.1

0.0

0.0

452024TRIVDRM4

1.0212.4

-120.9

-13.1

120.9

10.9

-120.9

-13.1

120.9

10.9

-120.9

-13.1

120.9

10.9

-120.9

-13.1

120.9

10.9

-161.3

-14.5

1

1

161.8

25.7

-161.3

-14.5

1

1

161.8

25.7

-161.3

-14.5

1

1

161.8

25.7

1

1

1

1

151.5

-103.0

-146.1

118.0

1

0.0

-76.9

-40.4

-32.0

81.5

29.1

-80.3

-35.3

149.3

33.3

-143.6

-16.0

50.3

-13.2

-49.9

7.9

452037KOZHIKODE

0.9198.5

-209.3

-24.8

212.9

39.4

-209.3

-24.8

212.9

39.4

1

0.0

-13.4

454004COCHIN

1.0402.9

454002TRIVNDRM

1.0390.7

454005PALAKD

1.0406.4

444004MYWADI

1.0388.8

454001TRICHUR

1.0404.50

.0

-51.2

0.0

0.0

0.0

-51.2

0.0

0.0

R1

-44.6

6.2

44.6

-64.7

-44.6

6.2

44.6

-64.7

442006THENI2

0.9218.2

442004ABISEK42

1.0225.0

442005UDMLPT2

0.9216.7

1

Annexure- III

Page 8 of 8

Sharath

Typewriter

Sharath

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CASE 4: CASE 3 + 50 MW LOAD SHEDDING TO CONTROL 220KV IDUKKI - UDUMALPET S/C LINE

Sharath

Typewriter

Sharath

Typewriter

Annexure- IV

Page 1 of 10

Record Notes of the Special Meeting on scheduling of Coastal Energen Units I & II Page 1

RECORD NOTES OF THE SPECIAL MEETING HELD ON 23.02.2016 TO DISCUSS

SCHEDULING REQUEST OF COASTAL ENERGEN UNITS I & II.

A Special Meeting on the subject was conducted on 23rd

February 2016 in SRPC Conference

Hall, Bengaluru. The list of participants is enclosed at Annexure- I.

Shri S.R.Bhat, Member Secretary (SRPC) welcomed all the participants to the Meeting. As per

the prevailing grid scenario in SR, the power demand had picked up. The grid had been further

affected on account of the unfortunate fire incident in the control room of Sharavathy Generating

Station of KPCL. Sharavathy was a vital hydro station and as learnt it could take quite some time

before it gets restored. In view of this, the endeavor should be to maximize generation in the

Region to meet demand without compromising grid security.

M/s Coastal Energen (CEPL) had requested to schedule generation of both units (600 MW each)

in the Tuticorin-Pooling Complex. Earlier in the Meeting held on 11.12.2015 in CEA, it had

been decided to limit total generation quantum of NTPL and CEPL to 1,350 MW keeping in

view rating of bus-bar and isolator at NTPL station. CEPL had been asked to limit generation up

to the margin available after allowing full generation at NTPL.

Subsequently, CEPL had proposed a Special Protection Scheme (SPS) in Tuticorin PS -CEPL-

NTPL Complex for running both Units of CEPL till June, 2016, by which time both CEPL and

PGCIL were likely to complete their respective lines. This issue had been discussed in the 50th

Protection Coordination Sub Committee Meeting held on 27.01.2016 at Trivandrum. In that

Meeting, SRLDC had stated the following:

i. With proposed SPS operation, Generation would get reduced but without

commensurate load shedding. In order to achieve LG balance, demand would be met

through higher power flow on 765 kV Raichur-Sholapur lines, which could trigger

operation of inter-regional SPS.

Annexure- IV

Page 2 of 10


ii. In case of non-operation of SPS, there was a chance that end-equipment at NTPL

switchyard would get damaged due to the limitation imposed by its bus-bar rating.

TANTRANSCO had opined that since loads were yet to be identified for the proposed SPS, the

issue be discussed in detail in the forthcoming Meeting of OCC.

In this regard, it was proposed to have three level protection in the event of tripping of 400 kV

Quad Moose D/C CEPL – Tuticorin Pooling Station line.

Scenario of likely power flow that could happen across the Coastal- NTPL Pooling Station

Complex is shown below:

1. With one Unit Operation at CEPL:

Annexure- IV

Page 3 of 10


AND

OR

AND

OR

2. With two Unit Operation at CEPL:

A. Primary protection scheme to be implemented in the Main-1 and Main-2 protection relay of

the 400 kV CEPL- Tuticorin line is shown below:

I. Main – 1:

II. Main - 2:

Annexure- IV

Page 4 of 10


AND

OR

Logic to be implemented is whenever said feeder goes for a 3 phase tripping OR the

power flow on 400 kV CEPL- Tuticorin Pooling Station is less than 15 MW AND both

units are in service; it will trip Unit-2 and bring down Unit-1 generation to 450 MW. The

output contact is taken from the Distance Protection relay and logic is assigned inside the

DCS, such that output will be initiated, in case of 3 phase tripping only. Main I and II

protection relay will have the configuration as said above and hence the chances of

failure are remote. The tripping output is also taken separately from both the relays and

wired up separately for turbine tripping.

B. The secondary protection (as a backup) for the SPS Scheme is given below:

I. Backup -1: The line breaker contacts of 400kV CEPL- Tuticorin line are also wired

up to DCS to execute the scheme as shown below:

Backup – 1:

II. Backup-2: In order to restrict the power flow of 450 MW from CEPL station to NTPL

station, Directional over current relay of 400kV CEPL- NTPL line will also be

configured to protect NTPL system. Setting of the Over current relay is 650 A with

definite time delay of 1.2 sec.

Annexure- IV

Page 5 of 10


Backup – 2:

III. Backup – 3: The Third level of backup protection is envisaged at 400 kV NTPL SS. It

is proposed to have over-current protection on 400 kV NTPL – Tuticorin PS , if the

line current is greater than 2,200 A, then it would trip the 400kV NTPL – Coastal

Energen S/C.

Backup – 3:

Deliberations:

TANTRANSCO:

In order to envisage SPS Scheme with Load shedding, it is difficult to provide

required load specifically for this scheme since numbers of loads had already been

identified for various schemes. Besides, that area had strong renewable injection

which was also to be absorbed.

SRPC:

According to the Backup- 2 SPS scheme, when the line current of 400kV CEPL-

NTPL line is greater than 650 A, one unit would trip while other unit would need to

ramp down to 450 MW within 1.2 sec (as ramping down may take time this could

Annexure- IV

Page 6 of 10


lead to triggering of Backup-3). This could lead to complete station blackout at

Coastal Energen. Thus it would get reflected on flows on Raichur-Sholapur link and

possibly trigger SPS. Since thermal unit takes time to ramp down, as a precautionary

measure maintain one of the Unit at 450 MW and other unit at 550 MW.

NTPL:

NTPL expressed concern regarding the security of bus bar in the event of failure of

SPS operation. They stated that they should be adequately compensated by CEPL in

case any equipment damage occurred at NTPL station on account of non-operation of

SPS and also for any incidental damages. NTPL agreed for Backup-3 SPS. It was

also stated that there should not be any Deviation liability and DC should be protected

during any mal operation of SPS and subsequent complete loss of evacuation.

SRLDC:

SRLDC stated that insulation from deviation liability and DC protection during

maloperation of SPS was not acceptable. SRLDC also pointed out that in case of non

operation of SPS, there could be a loss of both stations (NTPL&CEPL) totaling about

2000MW. This would cause major problems on inter regional Corridor's. Hence the

reliability of operation of SPS should be ensured.

CEPL:

Dedicated line CEPL-Tuticorin PS would come up by June 2016. Tower erection

would start by first week of March 2016. Regarding equivalent load shedding, it

stated that the same was at par with any other generating in SR. Thus, tripping of any

unit would have similar impact on Inter Regional corridor.

Conclusions:

It was decided to proceed with implementation of SPS at CEPL & NTPL.

Total schedule of 450 + 550 MW could be allowed for CEPL. This is subject

to SRLDC approval, keeping in view grid conditions. Unit to be saved should

be maintained at 450 MW ex-bus generation.

Annexure- IV

Page 7 of 10


Compliance report of SPS implemented with inbuilt logic to be furnished to

SRLDC/SRPC.

SRLDC informed that CEPL has to conduct the mock test on SPS and submit

report to them.

Special Protection Scheme implemented at CEPL can be vetted by NTPL

preferably with the help of PGCIL.

CEPL was requested to assist in implementing the SPS at NTPL.

During any prolonged/planned outage at NTPL, NTPL would communicate

the details to SRLDC. Revised set points, if required could be worked out in

consultation with CEPL/NTPL/SRPC. CEPL would not modify the logic by

itself.

Onus would be on CEPL to factor in safety of its equipments before

implementing logic.

SPS can be reviewed/ disabled at any point of time, whenever Grid condition

demand or during non operation of SPS (though logic is getting satisfied)

SPS would be considered as a special case keeping in view the grid condition

(loads picking up & Sharavathy station outage) and would not be cited as

precedence for acceptance of other SPS on similar lines.

***************

Annexure- IV

Page 8 of 10

Annexure- IV

Page 9 of 10

Annexure- IV

Page 10 of 10

Grid Occurrences discussed in 51st PCSC (25-02-2016) 1/ 29

Grid Occurrences - 51

1. Details of Grid Disturbances:

1 Complete outage of 230kV Madurai S/s (Chekanaurani) of TANTRANSCO

(i) Date and Time of Event 19-01-2016 at 11:56 hrs

(ii) Location 230kV Madurai (Chekanaurani) Substation

(iii) Reported Disturbance /

Fault

Fault had occurred in 230kV Madurai-Sembatty line. Trip from

distance relay was not extended to breaker due to protection DC

fail. LBB protection got operated resulting in a busbar trip at

230kV Madurai substation. All elements got tripped as there is a

single bus operation at 230kV Madurai S/s

(iv) Generation Loss Nil

(v) Category GD-1

SLD

Single line diagram of 230 kV Checkanurani SS as provided by TANTRANSCO is attached at the end. 230 kV Madurai – Semabatty S/C line tripping: Madurai (TANTRANSCO) end:

As per FIR/DR/EL/TR, the line tripped at 11:37:43.829 hrs on R-E fault due to operation of DPR, Z1 protection (30.8 km).

From DR, it was seen that only R-ph current became zero (all phase voltages and the other phase currents remained intact). Finally Y & B phase poles got opened after 250 msec due to operation of Relays 1, 4, 7, 10 & 11. It was stated in TR that at 11.56 hrs during line fault in 230KV SEMBATTY #, LBB Initation of R-Phase CMR relay latched resulting the LBB Protection Operation. However, explicit Events relating to LBB operation were not found in the furnished DR and EL.

Time sync between 230 kV side of TANTRANSCO and 400 kV side of PGCIL-SR2 needs to be ensured. Sembatty (TANTRANSCO) end:

DR & EL not furnished. In the Report dated 25.01.2016, it was stated that the line successfully auto-reclosed from Sembatty end. But

this could not be verified as the respective DR & EL were not furnished. ICT- 1&2 tripping:

As per FIR/DR/EL/TR, 230 kV side of ICT- 1&2 tripped at 11:56:51.318 hrs due to BBP operation on 230 kV Bus of Chekanaurani.

As per Report of TANTRANSCO dated 25.01.2016:

Annexure- V


TANTRANSCO: At Madurai, LBB scheme is being extended through Contact Multiplier Relay (CMR). Also, for 230 kV Madurai –

Sembatty S/C line, A/R has been kept disabled at Madurai end due to Breaker problem. The breaker is a very

old one (of more than 25 years), and has been planned to be replaced.

Now at Madurai end for the above fault on 230 kV Madurai – Sembatty S/C line, 3-ph trip, which should have

occurred, had not occurred due to fuse failure in the A/R lockout relay circuit. Therefore, with current present

in Y & B phases, LBB relay got initiated.

However, due to the welding of R-ph contacts of CMR, LBB initiation persisted, and did not get reset even after

auto-reclosing of the line from Sembatty end.

Due to this, LBB protection acted; and as the station is under single-bus operation, all 230 kV breakers tripped.

SRLDC:

Till the breaker is replaced and A/R put into service at Madurai end, 3-ph trip may be given at both ends for faults on the 230 kV Madurai – Sembatty S/C line.

As the Substation is included under R&M works, TANTRANSCO may provide Re-Trip feature for the LBB protection.

Recommendations:

TANTRANSCO to provide split-bus operation with bus sectionalizer CB for their 230 kV Madurai (Chekanurani) SS.

TANTRANSCO to provide two main-zone operation for the numerical BBP that is being commissioned. TANTRANSCO to examine the feasibility of providing Re-Trip feature for the LBB protection, and accordingly

take steps for implementing the same.

2 Complete outage of 220kV Peenya Substation of KPTCL

(i) Date and Time of Event 20-01-2016 at 16:33hrs

(ii) Location 220kV Peenya Substation of KPTCL


Fault

Bus coupler tripped while changing Nelamangala line-3 from south bus

to North bus. This led to the multiple tripping at Peenya S/s.

(iv) Load Loss

(v) Category GD-1

Annexure- V


SLD: The Single Line Diagram of 220 kV Peenya SS as provided by KPTCL is attached at the end.

As per FIR/ TR of KPTCL:

During scanning of 220 kV Bus at SRS Peenya station, a red hot spot of 125 degree centigrade was observed at South Bus isolator of 220 kV Nelamangala-Peenya line-3.

To reduce the hot-spot temperature at isolator point, TL & SS Peenya Division decided to parallel the south and north bus by closing the North bus selector isolator of above line through 220 kV Bus coupler.

However, during the process one of the isolator blades did not close due to alignment problem. As a result, heavy arc (heavy unbalance current) was drawn into the 220KV Bus, and caused tripping of bus

coupler at Peenya end and also simultaneously tripping of 220 kV Hoody, Peenya-2, Peenya-3 & Peenya-4 lines at 400/220 kV Nelamangala SS in distance relay Zone-2 indication.

Nelamangala (KPTCL) end:

From DR/EL of Peenya line-2, the line tripped at 16:33:10.165 hrs due to DPR, Z2 operation.

From DR/EL of Peenya line-3, the line tripped at 16:33:10.165 hrs due to DPR, Z2 operation.

From DR/EL of Peenya line-4, the line tripped at 16:33:10.165 hrs due to DPR, Z2 operation. From DR/EL of Hoody (Nelamangala-Hebbal-Peenya) line, the line tripped at 16:33:09.850 hrs due to DPR, Z1

operation. KPTCL:

BBP is not present at Peenya. Prefault bus-configuration: South Bus: 220kV lines Nelamangala 1,2 and 3, Hebbal, Subramanyapura and 220kV class Transformers (3x150MVA + 1x 67.5MVA). North Bus: 220kV NRS line. Also, Bus-Coupler (BC) was in charged condition.

On 20-01-2016, while scanning of 220kV south bus for hot spots through thermo vision camera, red hot spot of 125 degree was observed in 220 KV Nelamangala – Peenya 3 line bay in South Bus Isolator point. Hence it was intended to parallel both the buses by closing the North Bus isolator of 220 KV Nelamangala – Peenya line-3. However, due to improper closing of one of the blades (suspected due to alignment problem), Earth fault protection of bus coupler acted to open it.

During bus changeover events such as above, it is a general practice to keep only BC Over current protection in service (Earth fault protection is kept out of service to prevent unwarranted trippings of BC due to unbalance currents). However, in the instant case, by mistake the earth fault protection for bus coupler was not kept out of service during bus changeover.

Subsequently, when the concerned shift personnel tried to open north bus isolator, heavy arc was drawn into it. As a result, the 220 kV feeders (other than Peenya-Hebbal-Nelamangala feeder) tripped from remote end (Nelamangala) due to operation of DPR, Zone-2.

Annexure- V


Peenya-Hebbal-Nelamangala feeder tripped from Nelamangala end in Zone-1 as the line DPR settings had been kept for the final intended line, 220 kV Nelamangala-Yelahanka line, which would get commissioned in two months.

Following 220kV stations got affected due to this tripping: NRS, A station and EDC (Due to EDC-HAL cable fault, EDC was fed from A station)

Load loss as per the information received from SLDC: 571MW Energy unserved approximated to be 0.133 MU. KSEB:

Instead of keeping the Earth fault protection of Bus-Coupler out of service during bus changeover, it would do well to increase its setting to maximum pick up value.

To this, KPTCL agreed to look into it.

3 Complete outage of 220kV Nagjheri power station and 220kV Ambewadi substation of KPTCL

(i) Date and Time of Event 22-02-2016 at 12:36 hrs

(ii) Location 220kV Nagjheri power station and 220kV Ambewadi substation


Fault

220kV lines from Nagjheri power house started tripping from

11:00 hrs due to fault in lines. The sequence of tripping is shown

in SOE list. At 12:33 hrs, 220kV Narendra-Ambewadi lines-1&2

got tripped which resulted in loss of evacuation path to Nagjheri

station resulting in tripping of running Units and complete

outage at Nagjhheri power station. 220kV Ambewadi station also

got de-energized due to tripping of source feeders i.e. 220kV

Narendra-Ambewadi-1&2 and 220kV Nagjheri-Ambewadi-1&2.

(iv) Load Loss 99 MW

(v) Generation Loss 500 MW

(vi) Category GD-1

SLD:

Annexure- V


As per Tripping Report of KPTCL:

Annexure- V


Line maintenance issues:

SRLDC stated that as most of the lines tripped on transient single phase to earth fault, regular line patrolling &

clearing the trees/ branches in the ROW of the lines warrants urgent attention by KPCL & KPTCL.

Remedial Action: To this, KPTCL informed that the matter had been taken up with concerned Line Operation

and Maintenance wing to carry out corridor clearance and maintenance as per schedule to avoid frequent line

faults in this corridor.

Provision of A/R on 220 kV lines in Kali Complex:

SRLDC stated that the issue was deliberated in earlier PCSC meetings also. Since most of these faults are

transient single phase to ground faults, the outages such as the current one could be easily avoided by

providing A/R on the 220 kV lines of Kali Complex. KPCL/ KPTCL should take steps to implement the same.

To this, KPTCL informed that there is a need to check the integrity of the Earth mat before a decision to put

A/R into service can be taken, and assured that they would examine and revert on this issue soon.

Review of Nagjheri SPS:

SRLDC informed that the existing SPS at Nagjhari is as given below:

Annexure- V


If one of evacuation lines at Nagjheri Power house trips and Loading on other out going circuits is more than 620 Amps

Trip one 150 MW unit.

However, as Ambewadi-Narendra lines (the last set of lines to be tripped from NPH), tripped on Over Current

protection without prior tripping of any of the NPH Units implies that the above SPS had not operated. As such,

the healthiness and/ or operation of NPH SPS needs to be reviewed.

Taking 220 kV Nagjheri – Kodasalli D/C lines into service:

KPCL informed they have kept these lines idle-charged from Kodasalli end as per SLDC, Karnataka instructions.

It was reasoned that by doing so, over-loading of various 220 kV lines can be avoided.

On this, SRLDC replied that Over-loading issue will crop up if only generation from Kali complex (Kadra +

Kodasalli+Nagjheri) is very less. However, in view of normal to full generation from Kali Complex (esp. NPH

generation), it would do well to examine the option of taking Nagjheri-Kodasalli D/C lines into service by KPCL/

KPTCL.

It was also decided to conduct a study to examine this issue. Accordingly, the following study had been done:

Nagjheri – Kodasalli lines Study

With closing of Nagjheri-Kodasalli D/C lines, the constraining elements in the network under consideration

(Kali complex including KAPS) can be easily seen as (i) 220 kV Kaiga - Kodasally S/C line [K-K], and (ii) 220 kV

Kodasalli - Nagjheri D/C line [K-N]. Since generations at Kadra, Kodasalli & Nagjheri act as sources of opposing

e.m.f’s to the generation at Kaiga, it is but natural to expect over-loading of these constraining elements as the

generation from Kali complex is reduced. To find out the limiting factors with 220 kV Nagjheri-Kodasalli D/C

lines in service, various scenarios have been considered and the results in each case are tabulated below:

A. All Units in service at Kadra and Kodasalli Stations:

Case No. Element Power flow (MW)

1 NPH Generation: 550 MW

220 kV Kaiga – Kodasalli S/C line 76.3

220 kV Kodasalli - Nagjheri D/C line 113.1 each



220 kV Kodasalli - Nagjheri D/C line 155 each













Annexure- V


B. One Unit each in service at Kadra and Kodasalli Stations: Case No. Element Power flow MW)










C. No Generation at Kadra and Kodasalli Stations:

Case No. Element Power flow (MW)










From above, it can be seen that as long as reasonable level of generation is maintained at Kadra, Kodasalli,

and Nagjheri, no over-loading occurs on any of these lines. However, as we decrease Kali complex

generation (Kadra+Kodasalli+Nagjheri) to less than 200 MW (with Nagjheri contributing less than 50 MW),

over-loading of the lines K-K or K-N or both occurs as brought out under Cases A.5, A.6, B3 & C.3. It is

therefore concluded that 220 kV Kodasalli - Nagjheri D/C lines can be put into service if at least 200 MW

generation from Kali Complex (with Nagheri Contribution not less than 50 MW) is ensured. However, it may

noted that with closing of 220 kV Kodasalli – Nagjheri D/C lines, ‘ n-1’ may not be there for these lines and

220 kV Kaiga – Kodasalli S/C line, which points to the need for system strengthening of these lines.

SPS Operation:

It was informed by SRLDC that SPS of 765kV Solapur-Raichur got operated at 12:25 hrs due to its flow crossing

2500MW. This SPS operation, which had occurred prior to trippings at Nagjheri station, was due to over drawl

by SR constituents (Telangana, AP), and gave a load relief of 330 MW as given below:

1. AP – 138 MW

2. T.N - 92 MW

3. Karnataka - 100 MW

4. Kerala - 0 MW

Recommendations:

Annexure- V


To avoid tripping of transmission lines on transient faults, KPCL/ KPTCL is recommended to carry out periodic

patrolling of lines, and ensure their proper maintenance by carrying out jungle/ bushing clearance and

trimming of tree branches within the RoW of transmission lines as per the SRPC transmission line patrolling

guidelines (available under the menu item "All Uploads Operation Miscellaneous Transmission Line

Patrolling Protocol / Guidelines for Southern Region" on SRPC website).

KPCL/ KPTCL to review operation of SPS at NPH for functionality (reduction of generation with tripping of

evacuating lines) and healthiness.

KPCL to put 220 kV Kodasalli - Nagjheri D/C lines into service if more than 200 MW generation from Kali

Complex (with Nagheri Contribution not less than 50 MW) is ensured on sustained basis.

2. Details of Grid Incidents:

Sl. No.

कर.स. घटनाकावििरण / Details

of Event

तारीख/ Date &

समय /Time कारण / Reason

शरणी/

Category

1 Tripping of 400kV lines and ICT-2 at 400kV Kalpakka station

10.12.2015 at 15:20 hrs

400kV Kalpakka-Vemagiri line-2, 400kV Kalpakka-Simhadiri line-4 anf ICT-2 at Kalpakka got tripped at Kalpaka end only on operation of Busbar Protection. While testing new 400kV Hinduja Power co ltd feeder bay in the yard, trip pulse got extended to Bus-2 of Busbar protection and all connected feeders/ICT to Bus-2 got tripped.

GI-2

*** The tripping event had already been discussed in PCSC-50 meeting held on 27.01.2016 ***

2 Tripping of 400kV Trivandrum-Tirunelveli line-1

11-12-2015 at 4:56 hrs

B-phase to earth fault had occurred and line tripped due to persistent fault. From DR of Tirunelveli end it was observed that the voltage was persistent in Y & B phases for nearly 2.5 seconds

GI-2

Tirunelveli (PGCIL-SR2) end:

As per FIR/DR/EL/TR, the line tripped at 04:56:28.243 hrs on B-E fault and reclosed after 1 sec due to A/R operation. But due to persistent fault, the line tripped again on SOTF/TOR.

From DR, the R & Y phase voltages persisted for about 2.6 sec from the start of A/R operation.

Remedial action(as informed by PGCIL-SR2):

It was informed that A/R scheme would be tested at Trivandrum End in Feb end.

Trivendrum (PGCIL-SR2) end:

As per TR, TVM Line-1 tripped at 04:56:27 am & at 04:56:28 am on B-E fault (2.60 kA, 128 km from Trivandrum) on persisting fault.

From FIR, Tie-CB got opened on PDR operation. From DR the line tripped at 04:56:27.368 hrs on B-E fault due to A/R operation; From EL, the line was observed to be tripped in 3-ph at 04:56:28.270 hrs.

Annexure- V


Events relating to complete A/R operation and further tripping of Tie-CB on PDR operation were not shown either in DR or EL.

PGCIL (SR-II):

400kV Trivandrum- Tirunelveli line-1 tripped on B phase to earth fault. At Tirunelveli end, Line Auto reclosed

successfully. At Trivandrum end, Tie-CB auto-reclosed successfully but Main-CB did not auto reclose. The

reason for its failure was later traced to the problem in CB’s spring mechanism. As a result, the Main CB

opened after a delay of 2.5 seconds due to PDR operation.

Remedial action:

The problem with CB was proposed to be attended during the next approved shutdown on 8th March.

3 Tripping of 400/220 kV, 315 MVA ICT-2 at Chittoor

11-12-2015 at 7:12 hrs

ICT-2 tripped on OLTC oil surge relay trip at 400 kV Chittoor Substation. There was no fault in ICT

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As per FIR, ICT-2 tripped at 07:26 hrs on OLTC Oil Surge Relay trip.

As per DR, ICT-2 tripped at 07:22:53.995 on OLTC Buccholtz trip.

In EL, the events prior to 07:26:21.651 hrs were not recorded, by which time ICT-2 HV and LV CB’s were observed to be in OPEN condition.

Remedial action: APTRANSCO informed that the ICT tripped due to mal-operation of ABB-make OLTC oil surge relay. The

low-burden relay was replaced with high burden oil surge relay of AREVA make.

On this, SRLDC requested APTRANSCO to check for OLTC oil surge relays of other ICTs also.

4

Tripping of 400kV Alamathy-Tiruvalam line-1 and 400kV Alamathy-Vallur line-2

13-12-2015 at 22:42 hrs

400kV Vallur-Alamathy Line-2 got tripped from Vallur end during failure of Y-phase LA in 400kV Alamathy-Tiruvalam line. Protection at Vallur end tried for an auto-reclose and gave a 3 phase trip.

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*** At Alamathy SS, Tiruvalam – 1 & 2 are in same dia; Vallur 1 & 2 are in same dia. 400 kV Alamathy – Tiruvalam line-1: Alamathy (TANTRANSCO) end:

As per FIR/DR/EL/TR, the line tripped at 22:45:00.720 hrs on Y-E fault (failure of Y-ph LA), and then auto-reclosed after 1 sec due to A/R operation, but again tripped on SOTF/ TOR due to persistent fault.

Tiruvalam (TANTRANSCO) end:

As per FIR/DR/EL/TR, the line tripped at 22:42:32.496 hrs on Y-E fault due to A/R (CAT) operation. Around the time when the A/R relay PCS921 was about to give closing pulse, DT was received from the remote end causing the line trip in all 3-phases.

Time sync between Alamathy and Tiruvalam needs to be ensured.

400 kV Alamathy – Vallur line-2: Alamathy (TANTRANSCO) end:

As per FIR/DR/EL/TR, the line tripped in 3-ph at 22:39:59.286 hrs due to A/R lock-out and BAR (DR observations).

In TR, it was mentioned that line tripped in 3-ph due to DT receipt from Vallur end. Vallur (NTECL) end:

As per FIR/DR/EL/TR, the line tripped at 22:42:32.509 hrs on Y-E fault due to A/R operation. The line auto-reclosed after 1 sec, but again tripped on TOR due to persistent fault. (But from DR, A/R operation dead-time was observed to be 50 msec)

It was stated in FIR/TR that while Main-1 detected the fault in Zone-2, Main-2 detected the fault in Zone-1. Reasons for this line tripping? Why the other lines did not tripping during the event? SRPC:

It was noted that no representative from NTECL, Vallur came to attend the meeting.

Annexure- V


Prima facie, it appears that the Vallur end relay on Vallur-Alamathy line-2 over-reached for the fault on Alamathy – Tiruvalam line-1. However, the fact that Vallur end relay on Vallur-Alamathy line-1 had not operated during the tripping event indicates the need to review relay settings at Vallur end for Vallur-Alamathy D/C line.

Recommendations: NTECL, Vallur to furnish a report detailing the reasons for mal-operation of Vallur end relays for a fault on

Alamathy-Tiruvalam line-1, and remedial measures taken to PCSC forum. In the report, their preparedness for implementing line differential protection on Vallur-Alamathy lines may also be indicated.

5 Tripping of 400kV Jeypore-Gajuwaka line-2

24-12-2015 at 13:46 hrs

Y-B phase to earth fault had occurred in line and line auto-reclose successfully from Gazuwaka end. 9 minutes after occurrence of fault, breaker at Gajuwaka end tripped on direct trip receive from Jeypore end

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Gajuwaka (PGCIL-SR1) end:

As per FIR/TR, the line tripped at 13:46 hrs on Y-B fault, and auto-reclosed successfully. And then again tripped at 13:55 hrs due to DT receipt from Jeypore end.

As per DR/EL, the line tripped in three-phase at 13:46:07.492 hrs on Y-B fault, and auto-reclosed after 0.9 sec due to A/R operation.

DR & EL pertaining to DT receipt event at 13:55 hrs not furnished. Jeypore (PGCIL-ER1) end:

No FIR/DR/EL/TR furnished.

Remedial action: When enquired by SRLDC regarding operation of A/R for L-L-E fault, PGCIL (SR-I) informed that they would

check up the three-phase A/R scheme with the help of the Manufacturer during the next shut down process.

SRPC:

Like WRTS-I, SRLDC may provide User Id and Password to ERTS-I also to enable them to upload various tripping files in SRLDC’s web portal (TMS). PGCIL (SR-I) may also help in this regard.

6 Tripping of 400kV Sattenapalli-Vijayawada line

25-12-2015 at 3:01 hrs

Line tripped due to operation of over voltage protection at Vijayawada end and Direct Trip was received at Sattenapalli end

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Sattenapalli (APTRANSCO) end: As per FIR/Dr/EL, the line tripped at 03:00:50.848 hrs due to DT receipt from Nunna end.

From DR, it was however observed that only Y-phase voltage dipped to zero, and the remaining phase voltages were healthy. This means that the other end (Vijayawada) opened in single phase only.

Vijayawada (Nunna)(PGCIL-SR1) end:

As per FIR/TR, the line tripped at 3:01 hrs due to OVR, Stage-I operation. It was stated that (i) EL was not in working condition, and (ii) DR had not triggered. PGCIL (SR-I):

There is a problem with CB due to which all poles did not open upon receiving 3-ph trip command. So, PD relay had acted to open the CB ( R & B ph- poles).

Event Logger was defective, and its replacement was in the scope of APTRANSCO. To this, APTRANSCO informed that they would check up and revert soon.

Recommendations: PGCIL (SR-I), in co-ordination with APTRANSCO, to address the problem with CB at the earliest opportune time. APTRANSCO to take steps to replace the faulty Event Logger at Vijayawada (Nunna) SS.

7 Tripping of 400 kV Vemagiri-Gauthami-2

26-12-2015 at 00:01 hrs

Line tripped on operation of over voltage protection at Gauthami end and direct trip was

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Annexure- V


received at Vemagiri. FIR, DR and EL of Gouthami end was not available to validate the over voltage tripping.

Vemagiri (APTRANSCO) end:

As per FIR/DR/EL, the line tripped at 23:59:35.544 hrs due to DT receipt from Gautami end. Gautami end:

No FIR/DR/EL/TR furnished. SRPC:

When enquired about this tripping and the reasons for non-uploading of various tripping files, GVK Gautami personnel replied that they were not aware of such obligation.

Since, the same can also be expected to be the state of affairs with other IPP’s in the region, SRLDC may kindly arrange to provide User Id and Password all IPP’s in SR, so that they may directly upload various tripping files in SRLDC web portal in cases of trippings involving their stations.

Subsequently, tripping files (DR & EL) were received from GVK Gautami vide their e-mail dated 25.02.2016.

From DR/EL, the line tripped in 3-ph at 00:08:16.884 hrs. However, no over voltage condition was observed.

Recommendations:

GVK Gautami to adjust drop-off to pick-up ratio to > 98% for the Over Voltage relays at Gautami end on 400 kV Gautami – Vemagiri lines.

GVK Gautami to ensure time-sync of all DR’s & EL’s at Gautami Station with GPS

8 Tripping of HVDC Bhadrawati Pole-1

27-12-2015 at 4:38 hrs

Pole-1 tripped on DC differential protection;

Annexure- V


Annexure- V


9

Tripping of HVDC Bhadrawati Pole-1 & Pole-2

28-12-2015 at 4:48 hrs and 28-12-2015at 4:19 hrs

Pole-1 tripped on DC differential protection. Pole-2 tripped on Buchholtz surge trip.

Annexure- V


Remedial action: PGCIL (SR-I) informed that the Converter transformer was replaced in the first week of January, 2016.

Tripping on 28.12.2015 at 4:19 hrs:

As per FIR/TR, On 28.12.2015, at 04:19hrs, Pole-1 & 2 were carrying 100MW from W-->S direction. Pole-2 tripped on "28-12-2015 04:19:58.140 CWT22K198T T2W.BUCHOLZ SURGE - TRIP" alarm. From the

relay indications, it was found that the Buccholtz Surge - Trip was initiated from P2WY Converter Transformer.

Remedial action: After physical inspection, gas accumulated in the Transformer was released through air vents. Pole-2 was taken into service on 28.12.2015 at 05:10 Hrs.

10

Tripping of 400/220kV ICT-3 at N’Sagar

28-12-2015 at 9:04 hrs

Main CB (42852) of lCT-3 was out of service for Bus-1 shutdown. Tie CB (42952) tripped due to tripping of Bus Reactor at 09:14 Hrs (on Back up Impedance protection) causing isolation of ICT-3

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*** CB’s -428 (ICT’s Main-CB), 429, 430 (LR’s Main-CB) are in same dia. SLD:

Prior to tripping event, Main-CB (42852) was out of service for Bus-1 S/D.

As per FIR/EL/TR, Tie-CB (42952) tripped due to tripping of Bus Reactor at 09:14:18 hrs (on Back up Impedance protection) causing isolation of ICT-3.

From EL, Main-CBB (43052) LBB operated event was there along with Bus Reactor Impedance protection. From DR, ICT-3 tripped at 09:14:17 hrs due to HV side Tie-CB LBB operation. DR & EL were not configured to show events at msec level. PGCIL (SR-I): After availing Bus-1 shutdown, Bus CVT did not change from Bus-1 to Bus-2 due to problem in Change-over

contact relay. Due to this loss of Bus Voltage, the Backup Impedance protection of the Bus Reactor (BR) acted to trip CB-429

and CB-430.

Remedial action: The faulty Changeover contact relay was replaced with a spare one.

NLC:

Since backup impedance (BuI) protection of BR is supposed to act as back-up protection only in the event of actual fault occurrence, its operation merely on loss of voltage is not desirable. A suitable logic that allows operation of BuI protection only in cases of fault occurrence should be built in back-up impedance protection relay.

KPTCL:

Such a logic can probably check for the presence of negative and zero sequence currents. This will ensure presence of fault and allows the BuI protection to clear the fault.

However, it is important to see whether the relay supports building such extra logic. TANTRANSCO:

Annexure- V


The blocking logic can make use of 75 A and 75 B NC contacts for its operation.

Finally, it has been suggested to PGCIL (SR-I) to examine the feasibility of incorporating such a logic for Reactor’s backup impedance protection, and verify its efficacy on experimental basis by providing the same to any of its reactors.

SRPC:

When enquired about LBB-operation of Main-CB and Tie-CB events as recorded in EL, PGCIL (SR-I) replied that it was a legend problem, assured that it would be rectified.

11 Tripping of HVDC Gazuwaka Pole-2

31-12-2015 at 9:06 hrs

HVDC pole-2 tripped on operation of ‘High harmonic trip’. All filters of Pole-2 got tripped on ‘resistive thermal overload trip’

As per FIR/DR/EL/TR:

At 09:06 hrs, Pole-2 tripped on operation of "High Harmonic trip". At the same time "Ferro Resonance" was also detected on East side. It was observed that all the filters of Pole-2 tripped on "Resistive thermal overload Trip".

The in-service filters of Pole-I also tripped on 3 can failure trip. However, due to coming into service of the available 01-filter of HVDC Pole-I, it remained in Service.

PGCIL (SR-I):

Remedial action: The pole tripping due to harmonic inrush phenomenon (predominantly 3rd and 5th harmonics) was had

been referred to ALSTOM for suitable action.

12 Tripping of 400/220kV ICT-3 at Sriperambadur

31-12-2015 at 17:18 hrs

ICT tripped due to suspected mal-operation of pressure relief device

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As per FIR/TR, ICT-3 tripped at 17:18 hrs due to mal-operation of B-phase unit OLTC PRV. Wrong operation was attributed to PRV flag mechanical sluggishness. HV-3(1652) breaker, 1752- TIE breaker and LV-3(1852) breaker go tripped.

Remedial action: ICT-3(400/230KV) put back into service after rectifying the mechanical sluggishness of the B-ph unit of

OLTC PRV flag by charging the HV-3 Breaker (1652) at about 18.49, LV-3 Breaker (1852) 18.50 hrs, and TIE Breaker (1752) at 18.51hrs.

13

Tripping of 220 kV Ambewadi-Ponda line-1

01-01-2016 at 13:30 hrs

line tripped on a transient fault in B-phase and DEFR had operated and cleared the fault. Not much dip in voltage was observed in DR, hence it is suspected that a high resistance fault had occurred in line

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As per FIR/TR, the line tripped at 13:17 hrs on B-E fault due to DEFR operation. As per DR/EL, the line tripped at 13:17:38.020 hrs due to DEFR operation. From DR, no appreciable dip in any of the phase voltages was noticed. Also R & Y phase currents got

reduced 50 msec after DEFR start before finally tripping of all three poles after 900 msec (from DEFR Start). As this kind of pattern was observed in the past trippings also, this owes explanation from KPTCL.

Remedial action: KPTCL informed that 220kV Ambewadi-Ponda lines are passing through dense forest area and subjected to

very high resistive faults. Resistive reaches in distance relays are revised in order to enable primary protection to clear the faults. Revised settings adopted during January 2016.

14

Tripping of 400kV Vijayawada-Gajuwaka line-1

02-01-2016 at 07:09 hrs

Line tripped on a B-phase to earth fault. Line auto-reclosed at Gajuwaka end and tripped from Vijayawada end. A/R lockout and pole discrepancy trip was observed from EL of

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Annexure- V


Vijayawada substation


As per FIR/DR/TR, the line tripped at 07:09:11 hrs on B-E fault due to A/R operation and auto-reclosed successfully after 1 sec.

It was stated that EL had not been triggered for the event. Vijayawada (PGCIL-SR1) end:

As per FIR/TR/DR, the line tripped at 07:09:15.223 hrs on B-E fault due to A/R operation, but failed to auto-reclose successfully.

From EL, the line tripped at 07:10:27.311 hrs on B-E fault due to A/R operation. However, the line failed to reclose, so PD relay acted to open the other two phases at 07:10:29.940 hrs.

Complete A/R operation and PDR operation were not shown in DR.

Time-sync between DR and EL at Vijayawada needs to be ensured. PGCIL (SR-I):

This line was connected through CB-2252 (BHEL-make) and CB-2252 (CGL make). However, only the CB-2352 was in healthy condition.

It was noticed that prior to this tripping event, the line had tripped multiple times with successful A/R operation. This could have brought CB-2352 on to verge of proper operation, and might have resulted in A/R loc-out in the instant case.

Remedial action: PGCIL (SR-I) informed that the line tripped on B-E fault. A/R attempted but un-successful due to persistent

fault. Thorough patrolling of line carried out and no abnormality found. Heavy fog and mist observed on the day of tripping may be the reason for fault.

15

Tripping of Gajuwaka Pole-1

03-01-2016 at 15:51 hrs and at 18:10 hrs

At 15:51 hrs, HVDC Pole-1 tripped due to “line side Ac O/V fault’’ and “valve winding AC O/V fault”. At 18:10 hrs Pole-1 tripped on GUPS redundancy exceeded

Tripping at 15:51 hrs:

Tripping at 18:10 hrs:

Annexure- V


16

Tripping of 400kV VTPS-Sattenapalli line-1 and 400kV Srisailam-Sattenapalli line

03-01-2016 at 23:58 hrs

400kV Satenapalli-Srisailam line tripped on R-phase to earth fault in zone-1.line did not auto reclose. 400kV VTPS-Satenapalli line-1 tripped on operation of over-voltage protection at Satenapalli end during fault in 400kV Srisailam-Satenapalli line

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400 kV Srisailam – Sattenapalli line-1: Sattenapalli (APTRANSCO) end:

As per FIR/DR/EL, the line tripped (in 3-ph) at 23:58:00.845 hrs on R-E fault due to DPR, Z1 operation. Srisailam (TSGENCO) end:

As per FIR/DR/EL, the line tripped at 23:57:04.841 hrs on R-E fault due to DPR, Z1 operation. 400 kV VTPS – Sattenapalli line-1: Sattenapalli (APTRANSCO) end: As per FIR/EL, the line tripped at 23:58:10.092 due to OVR operation.

From DR, the line tripped in 3-ph at 23:58:00.890 hrs due to Group-B 3-ph trip. SRLDC suggested APTRNASCO to ensure Drop-off to Pick-up ratio of OV relay above 98%. VTPS (APGENCO) end:

It was noted that no APGENCO representative came to attend the meeting. Also no tripping files (FIR, DR, EL, TR) had been furnished even after elapse of two months, which

constitutes an inexcusable violation of Regulation 5.2 (r) of IEGC. TSGENCO:

As 400 kV Srisailam LB is an underground generating station, a UG Cable of length around 1 km has been laid from Power House to the Switchyard to transmit power. From Switchyard, various transmission lines ensue. As the effective lines are a combination of UG cable and Overhead Transmission line, A/R feature has not been envisaged on any of these lines as it may create problem for the cable in case of permanent fault.

On this, it has been decided to seek the views of NLDC and examine the practices adopted by the Utilities transmitting power from their plants in similar way.

In this context, the general logic to be adopted for providing A/R on the transmission lines (220 kV & above) emanating from a generating station (Hydro/ Thermal/ Nuclear) has been deliberated. And after thorough discussion, PCSC forum has agreed to adopt the master-slave single-phase auto-reclosure logic for implementing A/R on the lines emanating from a generating station as explained below:

“In this, after a line got opened from both ends (generator end & remote end) on A/R operation, the remote end will be auto-reclosed as usual after the elapse of its dead-time (say, 1 sec). However, the generator end relay will check for the line voltage after elapse of an elongated dead time (say 1.3 sec; here the additional 0.3 sec has been included as a safety time margin). If

Annexure- V


the line voltage so sensed is healthy & normal (which implies that the fault has already been cleared), then generator end will be auto-reclosed; else 3-ph trip will be given at generator end to open the other two phases.”

17 Tripping of HVDC Bhadrawati pole-1

09-01-2016 at 5:08 hrs

Pole tripped on Thyristor redundancy lost and GUPS redundancy exceeded

As per FIR/TR of Gajuwaka (PGCIL-SR1): On 09.01.2016, at 05:08hrs, Pole-1 & 2 were carrying 1000MW,W-->S direction. Pole-1 tripped on

"VBE1W.VALVE POWER SUPPLY UNIT- LOW" & "VBE1W.VBE OPERATING STATE - TRIP". From the MPM, it was found that "Thyristor Redundancy Lost" & "GUPS redundancy Exceeded" alarms were

appearing in P1WB-YDLV valve.

Remedial action: During investigation of TPB alarms, 03 Nos of Thyristors found faulty in P1WB-YDLV valve. The redundancy

lost alarm was attended by replacing Two Nos faulty Thyristors in P1WB-YDLV-T4-L1 & P1WB-YDLV-T4- L8. Pole-1 was taken into service on 09.12.2015 at 11:08 Hrs.

18 Tripping of ICT-2 at Kayathar

09-01-2016 at 15:52 hrs

ICT tripped due to mal-operation of oil surge relay (OSR)

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As per FIR furnished by Kayathar (TANTRANSCO), ICT-2 tripped at 15:52 hrs due to OSR operation. It was stated that water droplets and consequent formation of Copper Oxide found inside the OSR of R & B phases resulted in shorting of the contacts, and caused OSR operation.

Remedial action: Water droplets entry path to OSR Relay was arrested and properly covered.

19 Tripping of 400/220kV ICT-2 at Gooty substation

12-01-2016 at 16:27 hrs

ICT tripped due to mal-operation of differential protection

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As per FIR/TR, ICT-2 tripped at due to operation of Differential protection. From DR, the tripping occurred at 16:20:29.639 hrs due to operation of Differential protection. From EL, the tripping occurred at 16:24:05.620 hrs due to operation of Differential protection. Time-sync between DR and EL needs to be ensured.

Remedial action: PGCIL (SR-I) has informed that ICT-2 tripped on mal-operation of differential protection (P643). As it has

got something to do with internal problem of the relay, the issue has been referred to its OEM, M/s Alstom.

20

Tripping of 400kV Gazuwaka pole-1 and 400kV Jeypore-Gazuwaka line-2

12-01-2016 at 21:28 hrs

Pole-1 blocked due to Low DC current during tripping of 400kV Jeypore-Gazuwaka line-2 due to a permanent fault.

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Tripping of 400 kV Gajuwaka-Jeypore line-2: Gajuwaka (PGCIL-SR1) end:

As per FIR/DR/EL/TR, the line tripped at 21:28:01.918 hrs on B-E fault due to 3-ph A/R operation. The line auto-reclosed successfully after about 1 sec, but tripped again on TOR due to persistent fault.

Remedial action PGCIL (SR-I) informed that the line tripped on Y-N fault. A/R attempted but un-successful due to persistent

fault. Thorough patrolling of line carried out and no abnormality found. Heavy fog and mist observed on the day of tripping may be the reason for fault.

Jeypore (PGCIL-ER1) end:

No Files (FIR/DR/EL/TR) furnished. Tripping of Pole-1:

Annexure- V


PGCIL (SR-I):

Remedial action: The issue of pole block on low DC current has been taken up with its OEM, M/s Alstom. A thorough maintenance check has been proposed in next shutdown during which various contact

resistances will also be checked for correctness.

21 Multiple tripping at 400kV Guttur sub-station

17-01-2016 at 18:53 hrs

Failure of Lightning Arrestor of Y-phase Line Reactor of 400kV Guttur-Hiriyur line-1 and line tripped on distance protection Zone-1. Bus-bar protection of 400kV Bus-2 at Guttur substation also got operated during the event sensing this through fault. 400/220 kV ICT-1 & 2 at Guttur, 400kV Kaiga-Guttur-2, 400kV Guttur-Narendra-2, 400kV Guttur-Hiriyur-2 and 400kV Guttur-Munirabad which are on 400kV Bus-2 got tripped during the incident. 400kV Guttur-Narendra-1 which was on Bus-1 also tripped at the same time.

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Bus configuration of 400 kV Guttur Substation of KPTCL is Double Main & Transfer Bus scheme. Kaiga – 1&2, Hiriyur_PG – 1&2, Narendra_PG – 1&2, Munirabad-1, and Jindal-1 are the 400 kV feeders

emanating from 400 kV Guttur SS. SLD:

400 kV Guttur – Hiriyur_PG line-1: Guttur (KPTCL) end:

400 kV Bus -2

JSW

220kV bus

Hiriyur PGCIL 2 X 180MW

390MW

311MW

***Fault was failure of Y phase LA of

Hiriyur line-1 reactor

2 X 315

MVA

Munirabad

41MW

Narendra

2 X 37MW

Kaiga

400kV Bus-1

1

2

1

2

1

2

2X162MW

Annexure- V


As per FIR/EL/TR, the line tripped at 18:39:28.771 hrs on Y-E fault due to A/R operation. The line tried to auto-reclose after 1 sec but tripped again due to persistent fault. It was stated that the failure of line reactor’s Y-ph lightning arrestor had caused the line tripping.

From the DR furnished, operation of A/R was not clear. Hiriyur (PGCIL-SR1) end:

As per FIR/EL/TR, the line tripped at 18:53:25.354 hrs on Y-E fault due to A/R operation. The line tried to auto-reclose after 1 sec but tripped again due to persistent fault & DT receipt from Guttur end.

400 kV Guttur – Hiriyur_PG line-2: Guttur (KPTCL) end:

As per FIR, the line tripped at 17:39:29 hrs due to BBP operation. DR & EL not furnished. Hiriyur (PGCIL-SR1) end:

As per FIR/DR/EL/TR, the line tripped at 18:53:26.036 hrs due to DT receipt from Guttur end. 400 kV Guttur – Narendra_PG line-1: Guttur (KPTCL) end:

As per FIR, the line tripped at 18:47:54 hrs due to BBP operation. DR & EL not furnished. Narendra (PGCIL-SR1) end:

As per FIR/DR/EL/TR, the line tripped at 18:53:26.812 hrs due to DT receipt from Guttur end. 400 kV Guttur – Narendra_PG line-1: Guttur (KPTCL) end:

As per FIR, the line tripped at 19:16:55 hrs due to BBP operation. DR & EL not furnished. Narendra_PG end:

As per FIR/DR/EL/TR, the line tripped at 18:53:26.812 hrs due to DT receipt from Guttur end. Tripping of ICT-1:

As per FIR, ICT-1 tripped at 19:01:00 hrs due to BBP operation. DR & EL not furnished. Tripping of ICT-2:

As per FIR, ICT-2 tripped at 19:35:36 hrs due to BBP operation. DR & EL not furnished. 400 kV Guttur – Munirabad (Guddadahalli) line: Guttur (KPTCL) end:

As per FIR, the line tripped at 19:01 hrs due to DPR, Z4 operation. Munirabad (PGCIL-SR1) end:

As per FIR/TR, the line tripped at 18:53 hrs on Y-E fault due to DPR operation.

It was stated that DR & EL data were not available. KPTCL:

Bay arrangement prior to fault was as follows: Bus-1: Kaiga-1, JSWEL, Narendra-1

Bus-2: Kaiga-2, Narendra-2, Munirabad, Hiriyur 1 &2, ICT-1 &2

400kV Hiriyur-1 tripped on M-I&II, Zone-1, YN, 148.5meters, 14.24kA. A/R operated but unsuccessful due to persistent fault (fault current of 21.5kA).

Reason: Y phase LA of Hiriyur -1 line reactor failed during the instance.

Annexure- V


Analysis: Single phase to Earth fault was sensed in Hiriyur -1 line. Y pole was opened and close command issued

after dead time. As per the scheme 3-phase trip would have been issued as the fault is persisting due to line reactor LA failure. However bus bar protection operated and lines and ICTs connected to bus-1 got tripped during the instance.

Tripping of 400kV Guttur-Narendra-1 connected to bus-1 during the instance was analysed due to wrong selection of trip bus (trip bus 2 was selected in CRP).

Remedial action: Several tests were done to analyze the root cause for operation of bus bar protection. But no specific

reason could be identified. Hence it is suspected that momentary arcing in some weak insulator strings in the bus might have

triggered bus differential protection. Action will be taken to test insulators strings in the bus. KSEB:

Here, BBP relay (RADHA) is a high impedance differential relay. Sometimes, the relay may mal-operate due to the presence of magnetizing current. If primary current pick-up, I(op), is set low, then it may so happen that the sum of the magnetizing currents from each core may exceed this value for heavy fault currents, and result in unnecessary BBP operation.

As CT supervision also cannot detect such differential magnetizing currents, it is necessary to check online the currents flowing through the relay terminals during normal operation; and based on that decision to replace the relay or putting additional external resistors may be taken.

NLC:

Generally mal-operation of high-impedance based BBP relays can be avoided by suitably revising voltage threshold (bia) settings.

APTRANSCO:

For fault analysis, first BBP relay indication should be checked to determine for which phase it had picked up. If it is also of Y-ph (same as the faulty phase), then no need to suspect insulator strings integrity; instead revising voltage threshold (bias) settings would do well to prevent such mal-operations.

For this, stabilizing resistor values to be used are to be determined based on maximum through-fault levels. SRPC:

Even though all 400 kV transmission elements (other than Guttur-Hiriyur line-1) have tripped almost at same time at Guttur end due to same cause, viz., BBP operation, the FIR’s submitted for these elements indicate a time-spread of two hours from 17:39 hrs to 19:35 hrs giving an impression that these have tripped at different times due to different causes, which is not correct.

Recommendations:

KPTCL to configure all DR’s and EL’s at 400 kV Guttur SS so that they will also get triggered for BBP operation. KPTCL to ensure time-synchronization of all DR’s and EL’s with GPS at their 400 kV Guttur SS.

22 Tripping of 400/220kV ICT-1 at Munirabad

18-01-2016 at 12:46 hrs

ICT-1 tripped during operation of tie bay breaker

GI-2

As per FIR/DR/EL/TR, ICT-1 tripped at 12:44:55.214 hrs due to 3-ph Group-A trip relay. [Main-CB (41052); Tie-CB (41152).]

From EL, Tie-CB Lock-out happened at 12:19:43 hrs. Then R & Y poles of the Tie-CB were observed to be in OPEN condition at 12:22.46 hrs. Then at 12:44:57 hrs both Tie-CB and Main-CB, “CB Manual OPEN” event was observed. Finally Main-CB got opened at 12:44:57 hrs due to 86A Trip relay operation.

EL was not configured to record events at msec level. PGCIL (SR-I):

It was a case of mal-operation. Around the tripping time, some works were being carried out. While attempting to isolate the DC earth fault, Master trip relay had generated a spurious signal to trip the breakers.

Recommendations:

Annexure- V


PGCIL (SR-I) to configure Event Logger (s) at Munirabad to record event at msec level. PGCIL (SR-I) to set right Time and Field Time values being shown in EL to proper values.

23 Tripping of ICT-2 at Hoody substation

20-01-2016 at 6:14 hrs

ICT-2 tripped without any relay indication GI-2

As per FIR, ICT-2 tripped without any relay indication. KPTCL informed that the tripping was suspected due to momentary DC grounding.

KPTCL: Prior to the tripping event, a fault occurred on 11 kV feeder. Due to this, PT neutral earth potential had risen

up and resulted in blowing out of PT fuses in ICT-2 CRP. Due to this, Over Current relay on 220 kV side picked up and tripped the ICT.

Remedial action: One more neutral was added to PT. IV side OCR setting was revised to from 0.5 A to 1A.

24 Tripping of 400kV Raichur-YTPS line

20-01-2016 at 12:20 hrs

line tripped on operation of pole discrepancy due to trip initiation from C-Pole tripping relay. line was holding from YTPS end.

GI-2

YTPS (KPCL) end:

As per FIR, the line was kept holding. Raichur TPS (KPCL) end:

As per FIR/TR, the Line tripped at 12:20:36 hrs on operation of Pole discrepancy due to trip initiation from C-Pole tripping relay (186C). Main Breaker (252-3) was under work permit.

It was stated that DR was not available. KPCL:

On detailed inspection, arc spots were observed in the C-pole auxiliary tripping relay (186C) casing. Remedial action The relay casing was replaced with new one and the line was charged at 14:51:50Hrs.

25 Tripping of 400kV Neelamangala-Hoody line-2

20-01-2016 at 15:14 hrs

line-2 tripped at Hoody end on Pole discrepancy and line was in charged condition from Nelamangala end

GI-2

Nelamangala (KPTCL) end:

As per FIR, line kept holding at Nelamangala end. Hoody (KPTCL) end:

As per FIR, the line tripped at 15:13 hrs on breaker DC supply fail and PDR operation. DR & EL not furnished. KPTCL:

The line tripped due to operation of RXMS auxiliary relay which is very sensitive. While closing the relay panel doors, its contacts got touched and initiated the trip command.

Remedial action: A suitable resistor was added in series in the relay circuit to reduce RXMS relay sensitivity.

26 Tripping of ICT-1 at Chittoor substation

24-01-2016 at 19:15 hrs

ICT tripped due to operation of differential and Buccholtz protection.

GI-2

As per FIR, ICT-1 tripped at 9:30 hrs due to operation of differential and Buccholtz protections. As per DR, ICT-1 tripped at 9:30:14.538 hrs due to operation of differential protection. As per EL, ICT-1 tripped at 9:30:09.283 hrs due to operation of differential protection. Time-sync between DR and EL with GPS needs to be ensured. Remedial action:

Annexure- V


APTRANSCO informed that ICT-1 tripped on differential protection due to internal problem in it. ICT was kept out of service.

3. Details of trippings due to Auto-Reclosure non-operation

Sl. No.

कर.स. घटनाकावििरण / Details

of Event



शरणी/

Category

1

Tripping of 400kV Vijayawada-Nellore line-2

31-12-2015 at 12:02 hrs

Line tripped on Y phase to earth fault. Attempt for auto-reclose / Un-successful auto-reclose could not be established from the furnished DR/ EL.

GI-2

Nellore (PGCIL-SR1) end:

As per FIR/DR/EL/TR, the line tripped in 3-ph at 12:02:57.890 hrs on Y-N fault due to operation of Main-1 & Main-2 protections.

Vijayawada (PGCIL-SR1) end:

As per FIR/DR/TR, the line tripped in 3-ph at 12:03:30.300 hrs on Y-N fault due to DPR, Z1 operation (200 km). As per EL, the line tripped in 3-ph at 11:59:19.772 hrs on Y-N fault due to operation of Main-1 & Main-2

protections. PGCIL:

At Nellore end, A/R blocking command was persisting. This may be due to some problem in A/R relay contacts. Hence, it failed to reclose successfully.

Remedial action PGCIL (SR-I) informed that the line tripped on Y-N fault. Thorough patrolling of line carried out and no

abnormality found. Heavy fog and mist observed on the day of tripping may be the reason for fault. Recommendations:

PGCIL (SR-I) to furnish a report bringing out the reasons for non-operation of A/R during the tripping event, along with remedial taken, to PCSC forum.

2 Tripping of 400kV Vijayawada-Gajuwaka line-1

05-01-2016 at 04:18 hrs

line tripped on a R-phase to earth fault. Line auto-reclosed at Gajuwaka end and tripped from Vijayawada end.

GI-2


As per FIR/DR/TR, the line tripped at 04:17:57 hrs on R-N fault, and successfully auto-reclosed after 1 sec due to A/R operation. (In DR, time-stamp down to msec, was not shown)

It was stated that EL had been not triggered during the event. Vijayawada (PGCIL-SR1) end:

As per FIR/DR/EL/TR, the line tripped at 04:17:59.637 hrs on R-N fault due to A/R operation. But the line failed to auto-reclose.

From EL, it was observed that the line tripped sat 04:19:15.034 hrs on R-N fault due to A/R operation. But Tie-CB (2352) A/R locked-out within 100 msec, and Main-CB (2452) locked-out within 900 msec. Subsequently the other poles of Main-CB got opened at 4:19:17.650 hrs on PDR operation, and that of Tie-CB got opened at 4:19:18.883 hrs on PDR operation.

PGCIL (SR-I):

Remedial action The line tripped on R-N fault. Thorough patrolling of line carried out and no abnormality found. Heavy fog

and mist observed on the day of tripping may be the reason for fault. They were planning to replace the existing insulators with CLR type insulators.

Recommendations:

PGCIL (SR-I) to furnish a report bringing out the reasons for non-operation of A/R during the tripping event,

Annexure- V


along with remedial taken, to PCSC forum.

3

Tripping of 400kV Jeypore-Gajuwaka line-1

12-01-2016 at 4:24 hrs

Line tripped on a R-phase to earth fault and A/R was under lockout. Line-1 had previously tripped at 3:24 hrs due to persistent fault during which it had attempted for an auto-reclose.

GI-2

Jeypore (PGCIL-ER1) end:

No files (FIR/DR/EL/TR) furnished. (The uploaded files were same as that of Gajuwaka). Gajuwaka (PGCIL-SR1) end:

As per DR, the line tripped at 04:24:55 hrs on R-E fault due to DPR operation. From EL, it was observed that the Main-CB (CWD Q51) A/R was under lock-out since 04:18:28.000 hrs; and

the Tie-CB (CWD Q50) was under lock-out since 04:24:48.397 hrs. As a result, when R-N fault occurred at 04:24:56.137 hrs due to the line did not auto-reclose, instead tripped in 3-ph due to DPR operation.

Time-sync between DR and EL needs to be ensured. PGCIL (SR-I):

Prior to this event, a fault occurred at 3:24 hrs during which time A/R operation occurred multiple times, due to which A/R contacts got stuck.

Remedial action PGCIL (SR-I) informed that the line tripped on R-N fault. The thorough patrolling of line carried out and no

abnormality found. Heavy fog and mist observed on the day of tripping may be the reason for fault. A/R relay has been replaced.

4 Tripping of 400kV IL&FS-Nagapattianam line-1

26-01-2016 at 13:03 hrs

Line tripped on R-phase to earth fault. Line auto-reclosed at IL&FS and failed to auto recloses at Nagapatinam.

GI-2

Is this line-1 or line-2?(Because as per ILFS, this is line-1; as per PGCIL-SR2, this is line-2) ILFS end:

As per FIR/DR/EL/TR, the line tripped at 13:03:49.150 hrs on R-E fault, and successfully reclosed after 1 sec due to A/R operation.

Nagapattinam (PGCIL-SR2) end:

As per FIR/DR/EL/TR, the line tripped in 3-ph at 13:03:49.201 hrs on R-E fault due to DPR, Z1 operation. From EL, “A/R lock-out from BCU” event was observed at 13:03:50.176 hrs. PGCIL (SR-I): A/R momentarily went into non-auto mode during updation of SCADA database. As the fault occurred during

this time, A/R failed to operate from Nagapattinam end.

For all the above cases of A/R non-operation, the time scale for the DR should be properly configured, say two sec, post triggering to capture complete A/R operation.

4. Details of trippings due to PLCC mal-operation

Sl. No.

कर.स.

घटनाकावििरण / Details

of Event



शरणी/

Category

1 Tripping of 400kV Gajwel-Hyderabad

29-12-2015 at 6:11 hrs and 7:11 hrs

Line tripped at Gajwel end only due to suspected PLCC mal-operation at Gajwel end

GI-2

Tripping at 6.11 hrs: Hyderabad (PGCIL-SR1) end:

As per FIR, line kept holding from Hyderabad end.

Annexure- V


Gajwel (TSTRANSCO) end:

As per FIR, line tripped at 6.11 hrs due DT receipt from Hyderabad end. DR & EL not furnished. Tripping at 7.11 hrs: Hyderabad (PGCIL-SR1) end:

As per FIR, line kept holding from Hyderabad end. Gajwel (TSTRANSCO) end:

As per FIR, line tripped at 7.20 hrs due DT receipt from Hyderabad end. DR & EL not furnished. TSTRANSCO

The line tripped at Gajwel end only due to DT receipt. PLCC coupling device might have mal-operated, and they have proposed to carry out PLCC end-to-end

testing in co-ordination with PGCIL (SR-I). To this PGCIL (SR-I) also agreed.

DR and EL had not been triggered due to communication error. SRPC:

DR’s and EL’s of Gajwel SS had also not been submitted for the past trippings dated 02.11.2015. If that was also attributed to communication errors, there is an urgent need to check the integrity of all DR’s & EL’s at Gajwel SS.

Recommendations:

TSTRANSCO to check the integrity of all DR’s and EL’s, and sort out communication related issues at 400 kV Gajwel SS.

2 Tripping of 400kV Thrissur-Palakkad line - 1

04-01-2016 at 18:28 hrs

Line tripped at Thrissur end and was holding from Pallakad due to suspected PLCC mal-operation

GI-2

Palakkad (PGCIL-SR2) end:

As per FIR, line kept holding from Palakkad end. Thrissur (PGCIL-SR2) end:

As per FIR/DR/EL/TR, line tripped at 06:28:20.500 hrs due to DT receipt. Remedial action: PGCIL (SR-II) informed that the line tripped at Thrissur end only due to PLCC mal-operation. The faulty

P4LD Card (ABB make) had been replaced.

3 Tripping of 400kV Ramagundam-N’Sagar line-2

07-01-2016 at 21:07 hrs

Line tripped at Ramagundam end on direct trip receive and was holding from N’sagar end.

GI-2

N’Sagar (PGCIL-SR1) end: As per FIR, the line was kept holding from N’Sagar end. NTPC-Ramagundam end: As per FIR/EL, the line tripped at 21:07:10.980 hrs on receipt of Carrier Lockout Signal. It was observed that

85 L/O relay& Auto Reclose L/O relays operated.

From DR, line tripping occurred at 21:02:02.300 hrs. Time sync of DR & EL needs to be ensured

PGCIL (SR-I) informed that there was no counter increment at Nagarjunasagar.

Remedial action: NTPC-Ramagundam informed that the line tripped due to DT receipt and lockout relay had acted. PLCC

levels were checked and found ok.

It was agreed that NTPC and PGCIL (SR-I) would carry out PLCC end-to –end testing to check signal

Annexure- V


reception integrity.

4 Tripping of 400kV Neelamangala-Hoody line-2

20-01-2016 at 15:14 hrs

line-2 tripped at Hoody end on Pole discrepancy and line was in charged condition from Nelamangala end

GI-2

Same as 2.25

For all the above cases of PLCC mal-operation, the following shall be carried out by the concerned Constituents in co-ordination.

Healthiness of PLCC system components (hardware and software) at both ends shall be checked and faulty components shall be repaired/ replaced.

End-to-end communication for DT/ permissive & other signals may be ensured by testing at both the ends.

*****

Annexure- V


SLD of 230 kV CHECKANURANI SS of TANTRANSCO

Annexure- V


SLD of 220 kV PEENYA SS of KPTCL

Annexure- V

Meet

ing

No /

Index

Details of

Event

Date Reason PCSC Recommendations Utility

Responsible

for

implementa

tion

Status of Recommendations

as on 15-03-2016

Remarks

49/II/1

3

Tripping of

running Units 1

& 3 at

Rayalaseema

TPS of

APGENCO

31-10-2015

at 03:30 hrs

While synchronizing Unit-5 with grid, Bus bar

protection of 220kV Bus-1 operated which

resulted in de-energization of 220kV Bus-1.

This resulted in tripping of running Unit-

1&Unit-3, 220kV lines Pulivedula-1,

Yeralaguntla-1, Chinakampalli-1, Timmapura

In view of the availability of 25AX, APGENCO shall keep

synchronizing facility in auto-mode after getting it’s

operation verified by its OEM, M/s BHEL.

APGENCO Yet to be informed Pending

49/III/

4

Tripping of

400kV

Krishnapatnam-

Chittoor line-1

19-10-2015

at 07:49 hrs

R-phase to earth fault had occurred in line.

Chittoor end tried for auto-reclose. However,

due to persistent fault, breaker at Chittoor end

tripped. Krishnapatnam end relay did not try

for auto-reclose and gave a 3 phase trip as

observed from D.R

• APGENCO to make A/R functional on all lines emanating

from Krishnapatnam TPS by 10th December, 2015.

APGENCO Yet to be informed Pending

44/III/

2

Tripping of

400kV

Ghanapur-

Mamidapalli

line

15-04-2015

at 2:03 hrs

Line tripped at Mamidapalli end only and was

holding at Ghanapur. Overvoltage protection

had operated at Mamidapalli

TSTRANSCO to make DR

functional at Mamidipalli

TSTRANSCO TSTRANSCO informed vide their mail dated 24.06.15 that the existing relays

would be replaced with numerical relays in DPR works.

Pending

During testing of DC earth leakage, DC got

extended to bus bar protection relay. Hence bus

bar protection operated and tripped the 220KV

BUS connected transformers and feeders.

18-11-2015

at 11:20 hrs

Tripping of

220kV

Chittoor-

Tiruvalam

50/II/1

4

Pending Implementation of PCSC Recommendations (30th to 51st)

Andhra Pradesh42/II/3 Outage at

Regulapadu

station of

APTRANSCO

21-02-2015

at

00:49 hrs

Y-Ph Metering PT failed at 220KV

Ragulapadu Substation. Fault got cleared

by tripping of lines from remote ends.

APTRANSCO to furnish the remedial measures taken in

consequent to the tripping

incident along with the status of bus bar protection and bus

coupler at Regulapadu S/s.

A/R feature to be enabled on Regulapadu – Alipuira 220

kV inter-state line.

APTRANSC

O

Mail recieved on 22-08-2015:

APTRANSCOhas planned to commission ABB make ETL-41 type PLCC

terminal along with NSD-50 type protection coupler at Ragulapadu end towards

Alipura. vide our Ltr Dt 23-07-2015, it is requested KPTCL to arrange ABB

make ETL-41 cabinet with NSD-50 type protection coupler for establishing PLC

communication between Alipura- Ragulapadu.

KPTCL Mail recieved on 23-01-2016:

KPTCL is ready with ETL-41 cabinet with NSD-50 type protection coupler at

Alipur end.

APTRANSCO mail received on 24-02-2016:

Protection coupler equipment is ready at Ragulapadu end. Wave trap errection is

pending at Ragulapadu end. To maintain the ground clearenace structural

modification works are going on for errection of wave trap.

Pending

Telangana

PendingAPTRANSCO mail received on 24-02-2016:

220KV chittoor substation is a old 220KV substation with single bus operation.

Bus bar protection has both main & checkzone are in service.

APTRANSC

O

1.APTRANSCO to furnish SLD of 220/132 kV Chittoor

SS,

2. APTRANSCO to confirm whether 220 kV side is on

single-bus operation with only one main-zone. If so,

APTRANSCO shall examine the feasibility of providing

split-bus operation or multiple main-zones for bus bar

protection, and take necessary steps to implement it.

Annexure- VI

Page 1 of 20

48/II/5 Tripping of

400kV

Nagarjunsagar-

Mahboobnagar

line

07-09-2015

at 2:58 hrs

Line tripped on operation of over-voltage

protection at Mahboobnagar and direct trip

received at N’sagar station. DT receive was

observed in DR and EL of N’sagar station.

D.R/EL of Mahboobnagar was not furnished to

validate the overvoltage tripping

TSTRANSCO to furnish a detailed report on the tripping

event along with remedial measures taken to PCSC forum.

TSTRANSCO Yet to be informed Pending

48/III/

4

Tripping of

220kV Gajwel-

Shankarapally

line

20-09-2015

at 2:24 hrs

line tripped at Gajwel end on R-Phase to

ground fault. Reason for non-auto reclose

could be established as DR and EL of both

ends were not furnished

• TSTRANSCO to furnish a detailed report on the tripping

event along with remedial measures taken to PCSC forum.


51/IV/

1

Tripping of

400kV Gajwel-

Hyderabad

29-12-2015

at 6:11 hrs

and 7:11 hrs

Line tripped at Gajwel end only due to

suspected PLCC mal-operation at Gajwel end

TSTRANSCO to check the integrity of all DR’s and EL’s,

and sort out communication related issues at 400 kV Gajwel

SS.


Karnataka30/I/A RTPS

Tripping

incidents and

the Spl meeting

held

at RTPS on

13th and 14th

March 2014

Mar-14 Spl meeting held at RTPS on 13th

and 14th

March 2014

The PCSC forum recommended for replacement of

existing electromechanical relays with Numerical relays.

KPCL Mail recieved on 21-10-2015 and 23-11-2015:

1) Replacement of Old electromagnetic relays with Numerical relays has been

completed for RTPS-BTPS line & commissioned on 18.03.2014.

Raichur-PG1 & Raichur-PG2 lines have already retrofitted with numerical

relays.

The retrofitting of electromechanical relays with Numerical version for the

following lines/ICTs have been completed/commissioned as follows:

a) ICT-2 –Commissioned on 01-08-2015

b) ICT-1 ---Commissioned on 08-08-2015

c) Munirabad line--- Commissioned on 16-08-2015.

d) Mehaboobnagar line-- Commissioned on 09-09-2015.

2. Job order placed on 26.06.2015 on M/s Alstom T&D India Ltd. Chennai for

retrofitting of relays for all 220kV lines at RTPS.

3. Retrofit of existing bus bar(CAG-34) with numerical version– Budgetary

offers obtained and is under process.

Pending

47/II/6 Tripping of

400kV

Khammam-

KTPS line-2

30-07-2015

at 6:08 hrs

Y-phase to earth fault had occurred in line.

From Khammam end DR it was

observed that the relay after dead time tried for

auto-reclose. The fault was

persisting and relay gave a single phase trip

instead of a 3 phase trip after 1.25sec. R& B

pole voltage dip after 2 sec

possibly due to operation of pole discrepancy.

Auto-reclose close command observed after

2.5 seconds and all poles got closed.

1. TSGENCO to check the reclaim time of A/R and set it at

25 sec at KTPS.

2. TSGENCO to carry out PLCC end-to-end testing in

coordination with PGCIL (SR-I) for KTPS – Khammam

line-2; retrofitting of Protection Coupler may be carried out

based on the test results.

TSGENCO Yet to be informed Pending

Annexure- VI

Page 2 of 20

38/G

D/3.2

GD-1 at Guttur

Substation of

KPTCL

05-11-2014

at 11:42 hrs

Circuit breaker of 400kV Guttur-Hiriyur

line-1 failed at Guttur end while availing

shutdown for replacement of CVT. The

failure of breaker caused bus fault at Guttur.

KPTCL was requested to expedite the early implementation

of pending recommendations of:

1. Protection Audit (Phase-I & Phase-II)

2. PSAG-4, PSAG-5, and PSAG-8

KPTCL KPTCL mail received on 23-01-2016:

'The following works are attended at 400kV Guttur SS :

1. Replacement of Hiriyur-1 line, Bus Coupler, Tie Bus coupler breakers by new

Alstom make breakers (3 new CBs commissioned) recently.

2. New CVTs provided for 400kV Hiriyur line-1 and commissioned on

21.01.2016

Pending

39/I/5 Tripping of

400/220kV

ICT-2 at

Hoody

substation of

KPTCL

01-12-2014 Suspected mal-operation of 220kV side

Rphase

over current relay

1. PCSC forum recommended KPTCL to replace the relay

with a different make.

2. KPTCL was also requested to train the O&M personnel

adequately before performing any maintenance works to

avoid such unwanted trippings.

KPTCL Mail received on 27-05-2015 & 29-07-2015:

C&R panels of 500MVA ICT 1&2 will be replaced under scheduled R&M

works. O&M personnel are instructed to take sufficient care in order to avoid

unwarrented trippings.

KPTCL mail received on 23-01-2016:

New C&R panels(with numerical relays) erected for 500MVA ICT-1 &2 under

R&M work, which will be commissioned shortly.

Pending

16-07-2014 As reported directional over current relay of

ICT’s operated due to snapping of line

jumper in 220kV Lingapur line.

1. Bus bar protection shall be provided by asset owner (

i.e KPTCL).

2. Settings for main distance protection & Overcurrent

protection shall be examined and reviewed.

3. Time synchronization of the Substation shall be

ensured.

4. Correct DR shall be submitted to the SRLDC for trip

analysis.

KPTCL

38/G

D/3.5

GD-1 at Kadra

and Kodasalli

hydro power

station

13-11-2014

at 19:31hrs

A fault had occurred in 220 kV Kadra and

Kodasalli. As A result, de-energization of

220kV bus occurred at Kadra and

Kodasalli.

1. The PCSC forum requested KPCL to speed up the

installation of Numerical Distance Protection relay in

Kadra –Kaiga and Kodasalli –Kaiga.

2. The PCSC forum requested KPCL to submit the

implementation status of PSAG-10 recommendations within

a week’s time.

KPCL Mail recieved on 21-10-2015:

NIT floated on 5.5.15 through e-portal. Bid evaluation completed. LOA's issued

to M/s Schneider Electric Infrastructure Ltd. on 08.10.2015.


LOA's issued to M/s Schneider Electric Infrastructure Ltd. on 08.10.2015.

Engineering work is in progress.

Pending

34/III/

1

400kV

Raichur-BTPS

line

26-06-2014 Transient fault in R-phase.

Line did not auto reclose

A/R at BTPS end to be made operational within one

month

KPCL 1. A/R for 220kV lines enabled already.

2. Shut down of lines availed to commission the auto reclosing schme for 400

kV line at BTPS.


Timer relays have been received at site. A letter has been addressed to M/s

Alstom to complete the work on priority basis.


Commissioning of Autorecloser planned on 14, 15 & 16th of Dec-2015 subject

to availability of LC.

Pending

Mail recieved on 27-05-2015 (KPTCL):

1. KPTCL has taken action to provide bus bar protection to 220kV buses.

2. Over current relay Settings of ICTs to be reviewed by PGCIL.

Mail received on 29-07-2015 (KPTCL):

Initial Tendering stage


Detailed estimate prepared for taking up the work. CEE, Transmission Zone,

Gulbarga will take up necessary procurement and further execution.

Pending

38/G

D/3.1

GD-1 at

Mahalingapura

Substation of

KPTCL

25-10-2014 Fault had occurred in 220kV

Mahalingapura-Narendra line-2. Due to the

failure of relay operation at Mahalingapura,

breakers at remote end tripped which

resulted in bus dead condition.

1. PCSC forum recommended KPTCL to replace the old

static distance protection relays with numerical relays.

2. PCSC forum also requested KPTCL to provide a broken

conductor alarm indication in Control Room.

3. Standing instruction needed to be given to the all

substation personnel for not changing the relay settings

without approval of RT/MRT wing.

KPTCL Mail received on 27-05-2015 (KPTCL) & 29-07-2015:

1.Existing Back up relays will be replaced by numerical type distance

relays.Procurement is in tendering stage. Remaining observations were

attended.


Existing back up relays will be replaced by Main-2 protection. LOI issued M/s

Alstom for taking up the works.Remaining observations were attended.

Pending

34/I/6 400/220 kV

ICT-1 & 2 at

MUNIRABA

D

Annexure- VI

Page 3 of 20

40/IV/

1

220kV Sedam-

Tandur line

20-12-2014

at 22:20 hrs

Line tripped on Yphase to earth fault from both

the ends

KPTCL was requested to explore the possibility of

providing A/R feature to this line and submit the remedial

measures to the PCSC forum.

KPTCL KPTCL mail recieved on 23-01-2016:

Carrier protection is being restored for 220kV Sedam-Tandoor line at Sedam

end. After restoring the carrier protection , AR will be enabled.

Pending

42/I/1

(GD)

Complete

outage of

220kV Sedam

substation of

KPTCL

15-02-2015

at 14:24 hrs

Fault occurred in 220kV Sedam-Shahpur line 1. KPTCL to provide Bus Bar protection and LBB

protection at Sedam S/s and furnish

the status of their implementation to PCSC forum.

2. KPTCL to implement A/R feature on 220 kV Sedam-

Tandur inter-state line.

KPTCL Mail received on 29-07-2015:

1. Procurement of Bus bar and LBB protection is in the final tendering stage.

2. Action is being taken to restore the carrier protection for 220kV Sedam-

Tandoor line. AR will be enabled after restoration of PLCC.

Pending

42/I/2

(GD)

Complete

outage of

220kV

Ambewadi

substation of

KPTCL

12-03-2015

at 7:51 hrs

Fault in 220kV Ambewadi-Nagjheri line-2 1. KPTCL shall provide A/R feature on Ambewadi – Ponda

220 kV D/C inter-state line.

2. Till the completion of R&M works for bus bar and LBB

protection, KPTCL shall explore

the possibility of having split bus operation at Ambewadi

and submit the details of the

same to PCSC forum.

KPTCL Mail received on 29-07-2015:

1. Procurement of Bus bar and LBB protection is in the final tendering stage.



Pending

41/I/1 GD-1 at 220kV

Kadra power

Station of

KPCL

16-02-2015

at 12:56 hrs

Triggering incident was B-phase to earth fault

had occurred in 220kV Kadra-Kodasalli line.

Line tripped from Kodasalli end only. 220kV

Kaiga-Kadra tripped in Zone-3 from Kaiga

end. Tripping of evacuating lines caused bus

shut down at Kadra hydro station.

1. KPCL to make functional the Main2 (EPAC) relay

with the help of KPTCL at the earliest.

2. KPCL to investigate the reason for DC fuse fail

during transient fault in 220kV Kadra-Kodasalli line

including the testing/ checking of DC supply cables, breaker

control cables, and trip coils.

3. KPCL to ensure supply for Main-1& Main-2

protections, Trip Coils (TC1, TC2) from separate battery

banks.

KPCL

40/I/1 GD-1 at 220kV

Ambewadi

Station of

KPTCL

22-12-2014

at 21:22 hrs

Triggering incident was B-phase to earth fault

in 220kV Ambewadi- Nagzari line-1. B-pole

of breaker did not open at Ambewadi end.

LBB protection not available at Ambewadi

end. All elements tripped on Zone-2 from

remote ends.

1. Till the completion of R&M works for bus bar and LBB

protection, KPTCL shall explore the possibility of having

split bus operation at Ambewadi and submit the details of

the same to PCSC forum.

2. KPTCL shall provide the details of the tripping of Supa

hydro station connected downstream from 110 kV bus.


Action is being taken by KPTCL for operating Ambewadi in split bus mode.

Problem in bus coupler breaker is attended.Isolator overhaulling work is

completed.PTs are already provided to 220kV Bus-II. After commissioning of

Bus-II PTs, Ambewadi can be operated in split bus mode. Pending works will

be completed within a months time.

KPTCL mail recieved on 23-01-2016:

Bus-II PTs yet to be commissioned.Planned to complete before end of April-

2016.

Pending

Mail received on 28-05-2015:

1. Main-2 relays already installed and commissioned.

2. DC fuses are intact. Till date no such incidence occurred.

3. Possibility of DC-1 & DC-2 arrangement and splitting of DC will be

reviewed.

Mail received on 07-07-2015 , 21-10-2015 and 23-11-2015:

1. Completed.

2. Completed.

3. Possibility of DC-1 & DC-2 arrangement and splitting of DC will be

reviewed.

Pending


1. Bus bar protection panels pocured and erected at Sedam. Wiring , testing

,commissioning is being taken up.Planned to complete by April 2016.



Pending41/I/4 Complete

outage at

220kV Sedam

Substation of

KPTCL (GD-

1)

27-01-2015

at 8.00 hrs

R-Phase to ground fault occurred on 220kV

Sedam-Shahpur line. Fault not cleared from

Sedam end due to stuck-breaker condition.

While the Sedam- Sahapur line tripped from

Shahapur end in Zone-1, the other 220 kv lines

from Sedam tripped at remote ends in Zone-2.

This caused complete outage of 220kV Sedam

substation.

1. KPTCL to provide Bus bar and LBB protections for

220 kV bus at Sedam S/s.

2. KPTCL to implement A/R feature on 220 kV Sedam-

Tandur inter-state line.

KPTCL

Annexure- VI

Page 4 of 20

43/II/1

4

Tripping of

400/220kV

ICT-1 at

BTPS

14-01-2015

at 1:09

hrs

ICT tripped due to operation of Over current

and Earth fault relay

KPCL to check the possibility of providing line differential

protection between RTPS and Yermarus stations.

KPCL Mail received on 07-09-2015 , 21-10-2015 and 23-11-2015:

Revised relay settings are awaited from KPTCL.

Revised relay settings furnished by KPTCL will be incorporated in co-ordination

with KPTCL shortly.

Pending

45/III/

12

Tripping of

400kV Raichur-

BTPS line

01-06-2015

at 01:02 hrs

line tripped on R-phase to earth fault. Line did

not auto-reclose

KPCL to make A/R operational on 400 kV RTPS – BTPS

S/C line at both ends.


Completed at RTPS end.

Pending at

BTPS end.

42/II/2 Tripping of

220kV

Chikodi-

Talandage and

220kV Chikodi-

Mudshingi line

20-02-2015

at

06:40 hrs

Lines tripped during test charging 220kV

Chikodi-Belgaum line-2 from Chikodi

end.

1. KPTCL to provide A/R feature on the 220 kV Chikkodi –

Talandage, and 220 kV Chikkodi –Mudashinge inter-state

lines.

2. KPTCL to carry out E/F relay coordination for Chikkodi -

Talandage and Chikkodi –

Mudashinge lines in coordination with Maharashtra.


1) Replaced existing VXL by ABB make C&R panel for both interstate lines on

21.04.2015. The ABB Engineer visited 220KV Chikodi on 05.11.2015 for

enabling AR system to existing ABB make REL511 relay for both interstate

line, but AR system not enable due to internal cards faulty. Hence action is being

taken to replace the ABB,REL511 distance relays within a months time.

Pending

46/II/2

1

Trippings at

220kV Raichur

TPS

07-06-2015

at 01:35 hrs

1. KPCL to check the operation of anti-pumping relay on

220 kV side and keep it in healthy condition.

2. KPCL to provide manual reset to the 220 kV side master

trip relay.

3. KPCL to use both the 220 kV buses as main buses under

normal operation, and should go for single bus operation

only during emergencies.


1) Completed

2) Completed.

3) Two bus operation for 220kV buses : In place of existing CT switching relays,

High speed manual heavy duty change over switch of sufficient current capacity

will be retrofitted to all feeders at 220kV station and same will be operated

manually during changeover of feeder by one bus to the other and this

arrangement may facilitate to put both buses in service. Time required for this

retrofit is around 90days . However, this work will be taken up only after

retrofitting of electromagnetic relays with numerical relays for Main-2 protection

of all 220kV lines, for which work is in progress.

Pending

44/II/3 Tripping of

220kV

Kaiga-

Kodasalli

and 220kV

Kodasalli-

Nagjheri line- 1

22-04-2015

at

20:28 hrs

220kV Kodasalli-Nagjheri line-1 tripped from

Kodasalli end on operation of

distance protection, zone-2.

220kV Kodasalli-Nagjheri line-1&2 is kept

opened from Nagjheri end, hence fault

could not be cleared with carrier aided

protection. Backup earth fault relay at

Kaiga end got operated during the event and

resulted in tripping of 220kV Kaiga-

Kodasalli line from Kaiga end.

1. KPCL to check the possibility of implementing

Permissive Over Reach (POR) with Echo feature at

Kodasally end.

2. If the above is not possible, KPCL shall check the

possibility of keeping the 220kV

Kodasalli-Nagjheri lines OPEN at Kodasalli end and idle-

charged at Nagjheri end, and

implement the same.

KPCL Mail received on 07.07.2015:

The matter had been discussed with KPTCL. KPTCL recommended to keep

Zone-2 time lever to zero. If this is acceptable, then the same shall be

incorporated immediately.

Mail received on 07-09-2015 , 21-10-2015 and 23-11-2015:

The matter has been discussed with KPTCL. KPTCL recommended to keep

Zone-2 time lever to zero.

If this is acceptable to SRLDC, then the same shall be incorporated

immediately.Reply from SRLDC is awaited.

Pending

Annexure- VI

Page 5 of 20

47/III/

8

Tripping of

220kV

Ambewadi-

Ponda line-2

02-08-2015

at 13:20 hrs

Line tripped on a transient fault in B-phase.

There is no

provision for auto reclose.

47/III/

10

Tripping of

220kV

Ambewadi-

Ponda line-1

08-08-2015

at 10:51

hrs and 09-08-

2015 at

11:15 hrs

Line tripped on a B-phase to earth fault. Line

tripped as there is no provision for auto-reclose

47/III/

12

Tripping of

220kV

Ambewadi-

Ponda line-1

17-08-2015

at 13:20 hrs

Line tripped on a transient fault . There is no

provision for Auto reclose.

Till A/R is put into service on Ambewadi-Ponda line-1,

KPTCL to reduce Zone-2 time setting to zero sec. at

Ambewadi end.

KPTCL Yet to be informed Pending

PendingYet to be informedKPTCL KPTCL to revise distance relay settings at Nelamangala

end for 220 kV Nelamangala – Hebbal - Peenya line – 1 for

the effective line length of 17 km. These new settings can be

appropriately reviewed as and when the tie-arrangement at

Hebbal is done away with.

All connected 220kV lines and transformers

were taken on 220kV North bus as South bus

was under shut down for conversion of strung

bus to rigid bus and isolator replacement under

R&M works. Failure of HV side Y phase CT

of 150MVA Transformer-3 occurred at Peenya

Substation which resulted in operation of

Differential and HV REF protection. The

failure of CT also resulted in a 220kV bus fault

in North Bus.

27-09-2015

at 4:23:17 hrs

Complete

outage of

220kV Peenya

Substation in

Karnataka

48/I/2

(GD)

PendingYet to be informedKPTCLKPTCL to activate non-directional Over Current protection

with a time delay of 600-800 msec for Fuse

failure condition at Lingasugur.

220kV RTPS-Lingasugur line-2 tripped at

TPS end on operation of distance

protection zone-1. 400/220kV ICT-2 got

tripped on operation of earth fault

protection. 220kV RTPS-Lingasugur line-

1&3 tripped on distance protection

zone-2 and zone-3 respectively. Due to

tripping of ICT-2, the running units got

overloaded and it was mentioned that

under frequency occurred as units are

on load control. The Units got tripped

on under frequency.

06-08-2015

at 4:51 hrs

47/II/1

3

Tripping of

Unit-1&2

along with

400/220kV

ICT-2 at

Raichur TPS

Annexure- VI

Page 6 of 20

48/I/3

(GD)

Outage of

220kV

Ambewadi

station in

Karnataka

30-09-2015

at 10:41 hrs

220kV Ambewadi-Nagjheri line-2 tripped on B-

phase to earth fault. This resulted in loss of

supply to 220kV Ambewadi bus. 220kV

Ambewadi-Ponda line-1&2 were hand tripped

after deenergization of bus at Ambewadi.

KPTCL to fast-track providing A/R on all 220 kV lines

emanating from Ambewadi SS to prevent Station shut-down

on temporary faults.


Will be complied in a months time.

Pending

48/I/4

(GD)

Complete

outage of 220

kV HSR

substation of

Karnataka

06-10-2015

at 16:32 hrs

All connected 220kV lines at 220kV HSR

substation i.e. Somanahalli, EPIP, Hoody and

Nagnathapura tripped during the incident.

Triggering incident was fault in 220kV HSR-

EPIP line

KPTCL to review distance relay settings at Naganathpura

SS in view of LILO arrangement at HSR Lay-out.


ABB make REL 670 type distance relays provided to Somanahalli and hoody

lines. Planned to commission within 10 days.

Pending

49/II/1

5

Trippings at

Raichur TPS

12-11-2015

at 00:30 hrs

Running Unit-4, 5 and Unit-8 and 400kV

RTPS-Yeramaras TPS feeder got tripped due

to de-energization of both 400kV Bus-1&2 at

Raichur TPS

1. KPCL to carry out hot-line washing of RTPS-connected

lines regularly to avoid trippings due to fog and dust.

2. KPCL may see the feasibility of providing breaker

flashover protection at RTPS, and implement the same if

possible.

KPCL Yet to be informed Pending

220kV Nagjheri-Ambewadi line-1 tripped at

13:33 hrs due to B phase to earth fault.

Ambewadi was radially fed from Nagjheri

power station through 220kV Nagjheri-

Ambewadi line-2. Tripping of this line caused

220kV Bus shut down at Ambewadi and

remaining lines and transformers were hand

tripped

49/I/1.

3

(GD)

Complete

outage of

220kV

Ambewadi

Substation of

KPTCL

29.10.2015 at

14:34 hrs

PendingYet to be informedKPTCL1. KPCL to provide A/R on all 220 kV lines emanating from

Nagjheri PH.

2. KPTCL to provide A/R on all 220 kV lines emanating

from Ambewadi SS.

Annexure- VI

Page 7 of 20

17-01-2016

at 18:53 hrs

Multiple

tripping at

400kV Guttur

sub-station

51/II/2

1

PendingYet to be informedKPCL/

KPTCL

1. To avoid tripping of transmission lines on transient faults,

KPCL/ KPTCL is recommended to carry out periodic

patrolling of lines, and ensure their proper maintenance by

carrying out jungle/ bushing clearance and trimming of tree

branches within the RoW of transmission lines as per the

SRPC transmission line patrolling guidelines (available

under the menu item "All Uploads Operation

Miscellaneous Transmission Line Patrolling Protocol /

Guidelines for Southern Region" on SRPC website).

2. KPCL/ KPTCL to review operation of SPS at NPH for

functionality (reduction of generation with tripping of

evacuating lines) and healthiness.

3. KPCL to put 220 kV Kodasalli - Nagjheri D/C lines into

service if more than 200 MW generation from Kali Complex

(with Nagheri Contribution not less than 50 MW) is ensured

on sustained basis.

220kV lines from Nagjheri power house started

tripping from 11:00 hrs due to fault in lines.

The sequence of tripping is shown in SOE list.

At 12:33 hrs, 220kV Narendra-Ambewadi

lines-1&2 got tripped which resulted in loss of

evacuation path to Nagjheri station resulting in

tripping of running Units and complete outage

at Nagjhheri power station. 220kV Ambewadi

station also got de-energized due to tripping of

source feeders i.e. 220kV Narendra-Ambewadi-

1&2 and 220kV Nagjheri-Ambewadi-1&2.

22-02-2016

at 12:36 hrs

Complete

outage of

220kV

Nagjheri power

station and

220kV

Ambewadi

substation of

KPTCL

51/I/3

(GD)

PendingYet to be informedKPTCL 1. KPTCL to configure all DR’s and EL’s at 400 kV Guttur

SS so that they will also get triggered for BBP operation.

2. KPTCL to ensure time-synchronization of all DR’s and

EL’s with GPS at their 400 kV Guttur SS.

Failure of Lightning Arrestor of Y-phase Line

Reactor of 400kV Guttur-Hiriyur line-1 and

line tripped on distance protection Zone-1. Bus-

bar protection of 400kV Bus-2 at Guttur

substation also got operated during the event

sensing this through fault. 400/220 kV ICT-1

& 2 at Guttur, 400kV Kaiga-Guttur-2, 400kV

Guttur-Narendra-2, 400kV Guttur-Hiriyur-2

and 400kV Guttur-Munirabad which are on

400kV Bus-2 got tripped during the incident.

400kV Guttur-Narendra-1 which was on Bus-1

also tripped at the same time.

Annexure- VI

Page 8 of 20

48/I/1

(GD)

Disturbance in

220kV

Tamilnadu

system

05-09-2015

at 14:04 hrs

Complete outage of 230kV Palladam, 230 kV

Othakalmandapam S/s, 230 kV Coimbatore

S/s, 230 kV Thudialur and 230 kV

Sadayapalayam S/s

TANTRANSCO to take suitable measures like installing

more stub-towers along 230 kV OK Mandapam – Myvady

line to avoid excessive sag due to over-loading.

TANTRANS

CO

TANTRANSCO Mail received on 19-02-2016:

230kV Othakalmandapam - Myvadi feeder will be made LILO at Kongal Nagar.

Line restringing will be carried out along with the above proposal.

Pending

43/II/5 Tripping of

400kV

Alamathy-

SVChatram

line-1&2

and 400/230kV

ICT

at S.V.Chatram

29-03-2015

at

15:29 hrs

Tamil NaduLine-2 tripped on R-phase to earth fault.

Line autoreclosed at SVChatram end and failed

to reclose at Alamathy end. Bphase to earth

fault in line-1. Line tried for A/r but due to

permanent fault line did not reclose. ICT

tripped on operation of over flux protection.

PendingTANTRANSCO vide their mail dated 24.06.15 informed that different relays in

Main-I & Main-II would be ensured at the earliest.


Different relays in Main-I & Main-II will be ensured.

TANTRANS

CO

TANTRANSCO was requested to swap the relays between

two stations, so that

Main-1 and Main-2 will be of different make at each station.

Annexure- VI

Page 9 of 20

50/II/2 Tripping of

400kV

Alamathy-

S.V.Chatram

line-2

08-11-2015

at 10:48 hrs

Line tripped on D.T. receive on CHANNEL-2

at SV.Chatram end when the operator at

ALAMATHY S/S end tried to close Alamathy-

SVChatram-1&2 Feeder Tie Breaker.

Suspected DC earth fault had caused the

initiation of direct trip.

TANTRANSCO to provide A/R for 400 kV bay Tie-CB’s

at Alamathy SS and SV Chatram SS.

TANTRANS

CO


Instruction has been issued to enable Auto Reclosure feature in 400kV Tie

Breakers. The same will be informed to SRPC after completion.

Pending

49/I/1.

5

(GD)

Complete

outage of

S.P.Koil

station of

TANTRANSC

O and

generation loss

at MAPS

09-11-2015at

09:33 hrs

Fault had occurred in 230kV MAPS-S.P.Koil

feeder-1. LBB protection got operated as

breaker of this feeder was under lockout and

resulted in tripping of 230kV bus at S.P.Koil.

Unit-1&2 at MAPS due to loss of evacuating

feeders i.e. 230kV MAPS-S.P.Koil feeder-1&2

1. TANTRANSCO to ensure correctness of operation of

LBB relays at SP Koil.

2. TANTRANSCO & MAPS to furnish their respective

compliance report of the recommendations of to-be-

conducted PSAG-14 meeting at MAPS, Kalapakkam.

TANTRANS

CO


LBB scheme will be checked to ensure correctness of operation while availing

Line Clear.

TANTRANSCO and MAPS mail received on 25-01-2016:

Complaince report was submitted with respect to the recommendations given in

the Minutes of PSAG-14 Meeting.

Pending

50/I/3

(GD)

Complete

outage of

230kV

Mywadi station

of

TANTRANSC

O

21-12-2015

at 6:28 hrs

Busbar protection got operated for a fault in

230kV Mywadi-Anaikadavu line

1. TANTRANSCO to examine the feasibility of providing

two main-zone operation for bus bar protection by exploring

various alternatives like replacing existing bus-coupler CB

with a hybrid bus-coupler CB that comes with inbuilt CT,

replacing existing BBP relay with another suitable relay that

supports two main-zone operation, and implement the same.

TANTRANS

CO


Revision of Bus Bar Protection setting was carried out. The stabilizing voltage

setting was raised from 410 to 450 volts. After completing the necessary test, the

bus bar protection put in to service on 29.12.2015.

Pending

Annexure- VI

Page 10 of 20

50/II/1

7

Tripping of

400/230kV

Myvadi ICT-3

27-11-2015

at 17:26 hrs

400/230kV Myvadi ICT-3 tripped due to the

operation of 230 kV CB LBB protection at 230

KV bus (TNEB) of Myvadi station.

TANTRANSCO to check the LBB scheme for LV-3, and

furnish the remedial measures taken to PCSC forum.

TANTRANS

CO


LBB scheme will be tested while availing Line Clear.

Pending

PendingYet to be informedTANGEDCO NTECL, Vallur to furnish a report detailing the reasons for

mal-operation of Vallur end relays for a fault on Alamathy-

Tiruvalam line-1, and remedial measures taken to PCSC

forum. In the report, their preparedness for implementing

line differential protection on Vallur-Alamathy lines may

also be indicated.

400kV Vallur-Alamathy Line-2 got tripped

from Vallur end during failure of Y-phase LA

in 400kV Alamathy-Tiruvalam line. Protection

at Vallur end tried for an auto-reclose and gave

a 3 phase trip.

13-12-2015

at 22:42 hrs

Tripping of

400kV

Alamathy-

Tiruvalam line-

1 and 400kV

Alamathy-

Vallur line-2

51/II/4

PendingYet to be informedTANTRANS

CO

1. TANTRANSCO to provide split-bus operation with bus

sectionalizer CB for their 230 kV Madurai (Chekanurani)

SS.

2. TANTRANSCO to provide two main-zone operation for

the numerical BBP that is being commissioned.

3. TANTRANSCO to examine the feasibility of providing

Re-Trip feature for the LBB protection, and accordingly take

steps for implementing the same.

Fault had occurred in 230kV Madurai-

Sembatty line. Trip from distance relay was not

extended to breaker due to protection DC fail.

LBB protection got operated resulting in a

busbar trip at 230kV Madurai substation. All

elements got tripped as there is a single bus

operation at 230kV Madurai S/s

19-01-2016

at 11:56 hrs

Complete

outage of

230kV

Madurai S/s

(Chekanaurani)

of

TANTRANSC

O

51/I/1

(GD)

50/II/1

6

Kerala44/I/1

(GD)

Complete

outage of

Idukki Hydro

Power Station

(GD-1)

28-04-2015

at 12:30 Hrs

220 kV breaker of unit-3 at Idukki Power

house flashed and bus differential protection

acted. All Generators (6Nos.) along with all

220 kV feeders tripped during the incident.

1. KSEB to reduce sensitivity of REF protection

appropriately at Idukki PH.

2. KSEB to replace/ repair the faulty breaker.

3. KSEB to check the PLCC equipment at New Pallam and

inform the remedial measures taken to PCSC forum.

KSEB Mail recieved on 30-10-2015:

1. Purchase procedures is still in progress.

2. Replaced.

3. PLCC equipment Tested and found OK.


1. Even though repeated plans to have a joint inspection with M/s.ABB who is

the OEM of the relay panel for replacing the relays with numerical ones, the

same could not become successful. Finally, the inspection has been fixed on

15.03.2016. It has been planned to replace existing REF protection with low

impedance ones after retrofitting the numerical ones of OEM.

Pending

(Recomme

ndation

No.1)

PendingTANTRANSCO Mail received on 19-02-2016:

400kV S.V.Chatram - Alamathy -1 feeder 'C' phase jumper cut at Loc.No.178

from Alamathy end and created temporary fault with 400kV S.V.Chatram -

Alamathy -2 feeder 'A' phase jumper. Both feeders runs on the same tower.

PUTT Trip and AR successful at S.V.Chatram end. AR lockout at Alamathy

end. Direct Trip received at S.V.Chatram end due to wrong operation of TNC

switch at Alamathy end.

TANTRANS

CO

TANTRANSCO to check and ensure the healthiness of

A/R scheme at Alamathy end on 400 kV Alamathy – SV

Chatram line – 2.

400KV Aalmathy-S.V.Chatram line-1 tripped

on B-phase to earth fault. Line auto reclosed

and at both end subsequently A/R locked out

due to permanent fault.

400KV Alamathy-S.V.Chatram line-2 Line

tripped on R-phase to earth fault. Line

autoreclosed at S.V.Chatram and failed to auto-

reclose at S.V.Chatram end.

27-11-2015

at 15:35 hrs

Tripping of

400kV

Alamathy-

S.V.Chatram

lines - 1&2

Annexure- VI

Page 11 of 20

42/II/2

3

Tripping of

HVDC

Bhadravathi

Pole-1

18-03-2015

at

13:55 hrs

Pole tripped due to failure of auxiliary supply PGCIL (SR-I) to submit the compliance report on PSAG-11

recommendations to PCSC

forum.

PGCIL Reply received during 46th PCSC meeting:

Tertiary Transformer charged and auxiliary power for HVDC is being availed

from tertiary widings of ICT.

Pending

Yet to be informed Pending42/II/7 Tripping of

400kV

Jeypore-

Gazuwaka line-

1&2 and

tripping of

HVDC back to

back pole-

1&2 at

Gazuwaka

23-02-2015

at

13:34 hrs

HVDC pole-1 got tripped due to failure

of 4 no. power supply card. HVDC

pole-2 tripped on DC low voltage trip.

400kV Jeypore-Gazuwaka line-1&2

tripped due to operation of Over voltage

protection at Gazuwaka end.

PGCIL (SR-II) to submit the report of M/s ABB’s on

preventing supply card failures.

PGCIL

PGCIL34/I/7 HVDC

BHADRAVA

THI POLE 2

18-07-2014 As reported pole-2 tripped due on 5th

harmonic alarm.

1. Complete analysis of the faults and rectification/remedial

action taken to avert similar occurrence in the HVDC Back

to Back station shall be submitted.

2. The PCSC forum recommended PGCIL, SRTS-I take up

the issue with WRTS to submit the report as per IEGC

guidelines.

3. SRLDC is also requested to send a letter to WRLDC to

submit the reports to SR also.

4. Based on the SRTS/SRLDC correspondences, SRPC

would take it up with WR and PGCIL if the issue is not

getting resolved.

PGCIL Reply received during 46th PCSC meeting:

Being pursued with POWERGRID, WR-1

Pending

PGCIL Mail received on 02-09-2015:

The scheme was tested thoroughly found normal.

Pending to

check the

possibility

of re-trip

feature

PendingReply received during 46th PCSC meeting:

Operation is in-order as per OEM manual (ABB HVDC)

PGCILPGCIL (SR-I) to furnish the reasons for Converter

Transformer differential protection

operation for Pole-2 along with the remedial measures taken.

HVDC Pole-1 at Gazuwaka tripped due to

tripping of filter banks and Pole-2 tripped

due to operation of differential protection.

400kV Jeypore-Gazuwaka line-1 tripped

on over-voltage from Gazuwaka end.

14-03-2015

at

17:12 hrs

Tripping of

HVDC pole-

1&2

at Gazuwaka

and

400kV 400kV

Jeypore

Gajuwaka

line -1

42/II/2

2

43/II/2 Multiple

tripping

at 400/230kV

Hosur

substation

of Powergrid

26-03-2015

at 15:40 hrs

230kV Bus-2 at Hosur (PG) got

tripped as spurious initiation got

extended to LBB relay of 230kV

Hosur-Hosur(PG) line at Hosur(PG)

end due to shorting of contacts in

lockout relay. 400/230kV ICT-2, ICT-

3, 230kV Hosur-Vinnamangalam,

230kV Hosur(PG)-Hosur which were

connected to Bus-2 got tripped along

with bus coupler breaker

PGCIL (SR-II) to check the possibility of providing re-trip

feature in LBB relay.

Annexure- VI

Page 12 of 20

44/I/3

(GD)

765 kV

Raichur-

Sholapur line 1

&

2 tripped

24-05-2015

at 19:19 hrs

Tripped on Overload. 1. PGCIL to provide the status of healthiness of SPS contact

logic in SRLDC’s SCADA.

2. PGCIL to furnish the details of the implemented SPS-7

scheme including logic diagram to PCSC forum.

PGCIL Yet to be informed Pending

44/II/4 Tripping of

400kV

Ramagundam-

Hyderabad line-

3,

400kV

Hyderabad-

Malkaram line-

1 and 400kV

Bus-1

at Hyderabad

23-04-2015

at

15:11 hrs

400kV Ramagundam-Hyderabad line-3 at

ramagundam end only due to DT receive.

400kV Hyderabad-Malkaram line-1

tripped at Hyderbad end only and was

holding from Malkaram end. 400kV Bus-1 at

Hyderabad due to operation of bus

bar protection.

PendingYet to be informedPGCILPGCIL (SR-I) to check healthiness of PLCC panels at

Hyderabad SS, and repair/ replace

them, if necessary.

Annexure- VI

Page 13 of 20

44/II/6 Multiple

tripping at

Vemagiri

substation of

APTRANSCO

25-04-2015

at 10:04

hrs

400kV Vemagiri-Vijayawada line-1&3, 400kV

Vemagiri-Goutami line-2, 400kV Vemagiri-

Konaseema line-2 and 400/220kV ICT-2 at

Vemagiri tripped

during the incident. Triggering incident

was failure of B-phase L.A in 400kV

Vijayawada-Vemagiri line-1 at Vemagiri.

1. PGCIL (SR-I) to enable Auto reclosure feature at

Vijayawada end.

2. PGCIL (SR-I) to check distance relay settings for

Vijayawada – Vemagiri line 3, and

furnish a compliance report to PCSC forum.


44/II/8 Tripping of

400kV

Gooty-NPS

line-2

26-04-2015

at 13:16

hrs

R-phase to earth fault had occurred in

line. Lines auto-reclosed at gooty end

and later tripped due to DT receive from

NPS end.

PGCIL (SR-I) to coordinate STUB protection settings with

the distance protection time

settings at NPS.


45/II/2

1

Tripping of

400/220kV

ICT-1 at Gooty

Substation

03-06-2015

at 12:30 hrs

ICT tripped due to mal-operation of

differential relay

1. PGCIL to follow IS and CEA regulations while carrying

out maintenance work.

2. PGCIL to furnish a report on what caused the ICT-1

tripping including remedial measures.


46/II/1 Tripping of

400/220kV

ICT-2 at

Nagarjunsagar

Station

16-06-2015

at 18:12 hrs&

19:18 hrs

ICT-2 tripped due to mal-operation of 86B

relay due to suspected DC earth fault.

PGCIL (SR-I) to furnish a detailed report on ICT-2& Bus II

outage at 19.18 hrs on 16.06.2015 along with the remedial

measures taken.


46/II/4 Tripping of

400/220kV

ICT-2 at Gooty

substation

22-06-2015

at 13:06 hrs

At 220kV Gooty Switching Station, 220KV

Gooty Receiving Station feeder line side Y-

Phase jumper connected between line isolator

to boom resulting in a 220kV Bus fault. This

resulted in tripping of ICT-2 and 220kV

feeders connected to 220KV BUS-II.

PGCIL (SR-I) to furnish a detailed report as to what caused

LBB operation at 400 kV Gooty SS along with the remedial

measures taken.


45/II/1

5

Tripping of

765kV Raichur-

Solapur line-

1&2

03-05-2015

at 4:13 hrs

Lines tripped on transient fault. Auto reclose

was un-successful. SR &NEW grid separated

due to tripping of 765kV lines

To avoid tripping of transmission lines on transient faults,

PGCIL is recommended to carry out periodic patrolling of

lines, and ensure their proper maintenance by carrying out

jungle/ bushing clearance and trimming of tree branches

within the RoW of transmission lines as per the SRPC

transmission line patrolling guidelines (available under the

menu item "All Uploads Operation Miscellaneous

Transmission Line Patrolling Protocol / Guidelines for

Southern Region" on SRPC website).


PendingYet to be informedPGCIL1. PGCIL (SR-I) to submit the action taken report on the

measures suggested by their OEM.

2. PGCIL (SR-I) to check for the availability of Chatter

Disable feature in P141 and

configure it appropriately to block operation of REF

protection on DC fluctuations.

REF protection of Line reactor of

Nellore-1&2 and Tiruvalam line-1 maloperated

due to DC earth fault

25-04-2015

at

18:10 hrs

Tripping of

765kV

Kurnool-

Tiruvalam line-

1

and 765kV

Kurnool-

NPS-1

44/II/7

Annexure- VI

Page 14 of 20

47/II/1

1

Tripping of

HVDC

Bhadrawati

Pole-1

05-08-2015

at 10:53 hrs

Main pump-2 of valve cooling got

tripped during dip in 33kV auxiliary bus

voltage. Valve cooling flow got reduced

due to tripping of pump and resulting in

tripping of pole-1

PGCIL (SR-I) to furnish compliance report on PSAG-11

recommendations without further delay to PCSC

forum.


765 kV

RAICHUR -

SHOLAPUR 1

and 2

04-09-2015

at

19:25 hrs

Sholapur -1 and 2 Feeder got tripped at

Raichur end on operation of over current

protection in Main-1 distance relay and

holding from Solapur end on 04.09.2015 at

19:24:42 Hrs

765 KV

RAICHUR –

KURNOOL 2

04-09-2015

at

19:25 hrs

Kurnool -II Feeder got tripped on B-N fault

and holding from Kurnool end (successfully

auto-reclosed at Kurnool end) subsequently

tripped at other end on operation of Over

Voltage stg-1 protection at Raichur end on

04.09.2015 at 19:24 Hrs

49/II/4 Tripping of

400kV Gooty-

NPS line-1

13-10-2015at

10:15 hrs

Direct Trip was sent to NPS end of line-1

during opening of Main CB of Gooty-NPS line-

2 at Gooty end. This resulted in tripping of line-

1 at NPS and line was holding from Gooty.

Over voltage protection got operated at NPS

end and resulted in tripping of line

1. PGCIL (SR-I) to configure time scale resolution in Event

Logger to msec. at Nelllore PS (NPS) and furnish DR

corresponding to OVR, Stag-I operation at NPS end during

the tripping event.

2. PGCIL (SR-I) to ensure time-sync of DR’s and EL’s with

GPS at Gooty and NPS.


1. PGCIL (SR-I) to furnish a report detailing the sequence of

events including the remedial measures taken to PCSC

forum.

2. PGCIL (SR-I) to verify and ensure time-synchronizationof

DR& EL with GPS at both Gooty and NPS.

3. PGCIL (SR-I) to check and resolve,in co-ordination with

APTRANSCO, the professed Phase-Discrepancy that is

found to be occurring between 400 kV Gooty (PG) SS and

the surrounding 220 kV network of APTRANSCO in the

event of a fault.

Breaker at NPS end tripped on Direct Trip

receipt from NPS end. After 4 seconds, over

voltage protection operated at NPS end as

observed from EL, and direct trip was sent to

Gooty.

01-07-2015

at 09:59 hrs

Tripping of

400kV Gooty-

NPS line-1

46/II/1

3

28-07-2015

at 11.52.22

hrs.

Separation of

SR-grid and

NEW-grid

46/II/2

2

47/II/1

8

1. PGCIL (SR-I) to check the A/R scheme implemented

through BCU’s at all its GIS/ SAS substations for correct

operation.

2. PGCIL (SR-I) to ensure time-synchronization of DR &

EL of 765 kV Kurnool SS with GPS.

3. PGCIL (SR-I) to sort out the LEGEND ISSUE related to

tripping of the lines in the Event Logger of Raichur.

4. PGCIL (SR-I) to check & ensure the functionality &

healthiness of synchronization facility at Raichur end at the

earliest opportune time.


PendingYet to be informedPGCIL

PendingYet to be informedPGCIL1. PGCIL (SR-I) to obtain from PGCIL (WR-l) the reasons

for DT receipt from Sholapur end and furnish thesame along

with the remedial measures taken to PCSC forum.

2. PGClL (SR-I) to verify the logic implemented of SPS-1

and SPS-7 for the 76S kV Raichur - Sholapur link

byavailing the line shutdown at the earliest opportune time.

3. PGCIL (SR-I) to furnishthe details of the implemented

SPS-1 and SPS-7 schemes including their logicdiagrams to

PCSC forum.

Annexure- VI

Page 15 of 20

51/II/2

2

Tripping of

400/220kV

ICT-1 at

Munirabad

18-01-2016

at 12:46 hrs

ICT-1 tripped during operation of tie bay

breaker

1. PGCIL (SR-I) to configure Event Logger (s) at

Munirabad to record event at msec level.

2. PGCIL (SR-I) to set right Time and Field Time values

being shown in EL to proper values.


51/III/

1

Tripping of

400kV

Vijayawada-

Nellore line-2

31-12-2015

at 12:02 hrs

Line tripped on Y phase to earth fault. Attempt

for auto-reclose / Un-successful auto-reclose

could not be established from the furnished

DR/ EL.

PGCIL (SR-I) to furnish a report bringing out the reasons

for non-operation of A/R during the tripping event, along

with remedial taken, to PCSC forum.


51/III/

2

Tripping of

400kV

Vijayawada-

Gajuwaka line-

1

05-01-2016

at 04:18 hrs

line tripped on a R-phase to earth fault. Line

auto-reclosed at Gajuwaka end and tripped

from Vijayawada end.

PGCIL (SR-I) to furnish a report bringing out the reasons

for non-operation of A/R during the tripping event, along

with remedial taken, to PCSC forum.


41/II/1

2

Tripping of

400KV Coastal-

NTPL line

13-02-2015

at 22:54 hrs

Line tripped B-phase to earth fault and later

tripped on R-Y phase fault. From Coastal end

D.R, Y & B poles of breaker opened first and

R-pole appears to be opened on Pole

discrepancy.

CEPL to check A/R scheme at their end. CEPL Yet to be informed Pending

41/IV/

2

400kV

Tuticorin PS-

NTPL line

09-02-2015

at 03:17 hrs

Y-phase to earth fault had occurred in line.

Line auto reclosed at Tuticorin PS end and

failed to reclose at NTPL end.

NTPL to check A/R scheme at their end. NTPL Yet to be informed Pending

44/III/

4

Tripping of

400kV

Coastal

(CEPL)-

Tuticorin

pooling

station

20-04-2015

at 12:35 hrs

Line tripped at Coastal energen end only and

was holding from TTRNPS

CEPL to furnish a detailed report on this trip event to PCSC

forum.

CEPL Yet to be informed Pending

Others

50/I/2

(GD)

Complete

outage of

TPCIL power

station

30-12-2015

at 06:02hrs

Running units at Thermal Powertech power

Station tripped due to tripping of 400kV

Nellore pooling station (NPS)-TPCIL line and

400kV Nellore pooling station (NPS)-ECC line

1.PGCIL (SR-I) to furnish Action Taken Report on the

findings of OEM on relay mal-operation at NPS end on 400

kV NPS – NCCK line to PCSC forum.

2. PGCIL (SR-I) to appropriately configure Station Event

Logger at NPS to record events at msec interval.

3. PGCIL (SR-I) to carry out PLCC end-to-end testing in

coordination with TPCIL for 400 kV NPS –TPCIL line.

4.PGCIL (SR-I), MEPL, SEL, TPCIL & NCC to take steps

to provide line differential protection at their respective ends

on all 400 kV lines (except Gooty line) emanating from

Nellore Pooling Station, and furnish an action plan to

implement the same.


Annexure- VI

Page 16 of 20

46/II/3 Tripping of

400kV

Ramagundam-

Dichipalli line

21-06-2015

at 03:27 hrs

Line tripped on operation of overvoltage

protection at Ramagundam end and direct trip

was received at Dichipalli. Over-voltage

operation could not be established with D.R &

E.L submitted by Ramagundam station.

1. NTPC, Ramagundam to investigate the reasons for Over

Voltage alongside checking the drop off- to- pick-up ratio of

the OV relay.

2. The tripping is not as per the grading adopted for

Overvoltage, Stage-I protection (Grading is C2: 110% and 6

sec time delay) at Ramagundam. NTPC, Ramagundam to

check up the same.

NTPC Yet to be informed Pending

47/III/

2

Tripping of

400kV

Vemagiri –

GVK (JPD)

line-2

16-07-2015

at 17:02 hrs

R-phase to earth fault had occurred in line.

Line auto reclosed at Vemagiri end and failed

to reclose at GVK end.

GVK to put A/R into service at GVK Jegurupadu end on

400 kV GVK (Jegurupadu) – Vemagiri line-2.

GVK Yet to be informed Pending

48/II/1

6

Tripping of

400 kV Hassan

-Udupi line-1

05-10-2015

at 13:33

Line tripped due to B-E fault in Z2. Main 1

relay tripped in Z2. Three phase trip operated

at Hassan. Auto-reclose successful at other end

and line was charging from other end. Then

OV stage 1 picked up in Main2 relay and

operated in OV after the time delay

UPCL to furnish reasons for delayed operation of distance

relay in Zone-1 at their end, and the remedial measures

taken, if any.

UPCL Mail recieved on 19-11-2015 (UPCL):

The fault was of resistive nature, was sensed from Hassan end in Zone-2 reach.

The DR from UPCL indicates resistive high current prior to operation of Zone-1

in C Phase. This is seen as development of Zero sequence voltage and current

prior to Zone -1 operation.

The operation of single phase Z1 from UPCL end was correct followed by

successful AR operation.

Pending

51/II/7 Tripping of

400 kV

Vemagiri-

Gauthami-2

26-12-2015

at 00:01 hrs

Line tripped on operation of over voltage

protection at Gauthami end and direct trip was

received at Vemagiri. FIR, DR and EL of

Gouthami end was not available to validate the

over voltage tripping.

1. GVK Gautami to adjust drop-off to pick-up ratio to >

98% for the Over Voltage relays at Gautami end on 400 kV

Gautami – Vemagiri lines.

2. GVK Gautami to ensure time-sync of all DR’s & EL’s at

Gautami Station with GPS

GVK

Gautami

Yet to be informed Pending

PendingYet to be informedUPCL 1. UPCL to provide different make relays for Main-1 &

Main-2 at UPCL end on 400 kV UPCL – Hassan lines – 1 &

2.

2. UPCL to make GPS functional at their Station and ensure

time-sync of various DR’s and EL’s with GPS.

400kV Hassan-Udupi line-2 tripped on

Directional earth fault protection with Y-E

fault and direct trip was sent to Udupi end.

Directional Earth fault feature of Main-2 relay

at Hassan gave 3-ph trip after 2.6 seconds and

fault current in Y-phase was 1.1 kA. The

distance as well as DEF protection for 400kV

UPCL-Hassan line-2 at UPCL end did not

sense the fault. The generator transformer

backup earth fault protection (51N) had sensed

the fault and tripped both the running units at

UPCL leading to generation loss at UPCL

power station. Back up directional earth fault

protection at 220kV side of 400/220kV ICT’s

at UPCL did not sense the high resistance fault

in line-2

30-11-2015

at 17:22 hrs

Tripping of

400kV UPCL-

Hassan line-2

and running

Units-1&2 at

Udupi power

station

50/II/1

8

Annexure- VI

Page 17 of 20

36/II/8 400kV

Raichur-

Munirabad line

07-09-2014 B-phase to earth fault had occurred in line.

Line auto reclosed at Munirabad end and failed

to reclose at Raichur end.

KPTCL:

PD (pole discrepancy) time delay would be changed.

PGCIL /

KPTCL


38/II/5 400kV

Ramagundam-

Hyderabad line-

4

27-10-2014 Line tripped on Bphase

to earth fault.

Line did not auto

reclose at Hyderabad

end due to

PLCCmal-operation.

Planned to replace the PLCC system within a week's time at

both the ends during the shutdown.

NTPC/

PGCIL

Yet to be informed. Pending

40/II/3 Tripping of

400

kV

TALAGUPPA

– HASSAN

line

01-01-2015

at

13:38 hrs

On account of R-phase to earth fault, line

tripped at Hassan end due to operation of

distance Zone-2 and non-receipt of

carrier. From D.R of Talaguppa end it is

observed that fault had occurred in Yphase.

1. PGCIL and KPTCL to ascertain the reason for the

phase discrepancy in the relay operation and take suitable

remedial measures.

2. KPTCL to check the PLCC operation at Talaguppa

end and submit the report to the PCSC forum.

PGCIL/

KPTCL

Mail received on 27-05-2015 (KPTCL) & 29-07-2015:

End to end testing of PLCC has been done and problem in the PLCC is

atttended. Phase discripancy in the relay operation is to be checked jointly.


Problem is in identification of phases at Talguppa end. To be rectified by M/s

KPTCL.

Pending

42/II/1 Tripping of

400kV Coastal-

Tuticorin PS

line

19-02-2015

at

16:37 hrs

Line tripped at Coastal end only

due to suspected PLCC maloperation

and was holding from

Tuticorin PS end. Running Unit at

Coastal energen also got tripped

during the event.

PLCC end-to-end testing shall be carried out by CEPL and

Tuticorin PS (PGCIL-SR II) by

06.04.2015.

CEPL/

PGCIL(SR-II)

Mail received on 02-09-2015 and 25-11-2015:

On 11.06.2015 PLCC testing carried out by M/s ABB Engineer. ABB suspects

that the problem is with frequency interference related issue, and suggested to

change to new frequecies.

Pending

with CEPL

Miscellaneous

39/I/2 Tripping of

400Kv

Ghanapur-

Mamidipally

line

22-12-14

at 10:52 hrs,

24-12-14 at

11:32

hrs,

24-12-14 at

16:16 hrs

Due to PLCC Mal-operation at HYD S/S end,

DT received at MMPLY end and line got

tripped.

PGCIL is requested check up with the manufacturer to

resolve the issue and submit remedial measures to PCSC

forum.

PGCIL/

TSTRANSCO

Mail received on 26-05-2015 from TSTRANSCO:

On 27-12-2014 PGCIL requested to arrange services of OEM(Manufacturer)for

identifying the problem. TSTRANSCO arranged the same on 06-01-2015 and

the manufacturer testing and concluded that the problem in not in the newly

erected digital protection coupler at both ends and the issue is related to relay

panel at Ghanapur. [OEM minutes enclosed]

Pending

42/II/1

8

Multiple

tripping at

Raichur

thermal

power station

of

KPCL

09-03-2015

at

06:36 hrs

400kV Raichur TPS-Raichur(PG) line-

1&2, 400kV Raichur-Mahboobnagar,

Unit#7 and ICT-2 at RTPS tripped

during the incident. B phase to earth

fault had occurred in 400kV Raichur

TPS-Raichur line-1

1. KPCL to review REF setting (DMT or IDMTL) for unit-7

by first week of April, 2015 and

inform the same to PCSC forum.

2. TSTRANSCO to furnish Mehaboobnagar’s DR and EL

and the reasons for distance relay

operation at their end within a week’s time.

3. PGCIL (SR-I) to rectify the issues relating to A/R

operation, relay reach (Z2), reverse reach

(Z4) and SOTF auxiliary contacts within a week’s time, and

submit the actions taken to

PCSC forum.

KPCL/TSTR

ANSCO/PGC

IL (SR-I)

Mail received on 26-05-2015 from TSTRANSCO:

It is found that the main-2 ABB make REL316 type distance relay was

defective and same was replaced with MICOM P444 by M/s.PGCIL on 23.04-

2015. After replacement of main-II, DR can be extracted from this relay. For EL

in to service, some field winding is pending which is being taken up in this

month.

Pending

Annexure- VI

Page 18 of 20

43/II/1

2

Multiple

tripping at

400kV

Raichur(PG)

and RTPS of

KPCL

11-04-2015at

18:04 hrs

400kV Raichur(PG)-Gooty line-2,

400kV Raichur TPS-Raichur(PG)

line-1&2, 400kV Raichur-

Mahboobnagar, Unit#5 at RTPS

tripped during the incident

KPCL, KPTCL and PGCIL (SR-I) to furnish the action

taken report on the

recommendations given by PSAG members held at Raichur

on 22-04-2015 and

23-04-2015.

KPCL/KPTC

L/ PGCIL(SR-

I)


Tripping of

Unit 1 at

NCTPS

24-05-2015

at 19:13 hrs

ID Fan trip

Tripping of

Unit 1 at

MEPL

24-05-2015

at 19:13 hrs

Coal Mill tripped

Tripping of

Unit 1 at

Krishnapatnam

24-05-2015

at 19:17 hrs

Generator Protection operated

Tripping of

Unit-8 at RTPS

24-05-2015

at 19:19 hrs

Tripped on Overvoltage.

Complete

outage of

MEPL power

station

45/I/2

(GD)

PendingYet to be informedAPGENCO/

PGCIL (SR-I)

1. APGENCO to furnish to PCSC forum (i) A3-size Single

Line Diagram of SDSTPS, and (ii) the sequence of

events with time stamp showing the protection that opened

Tie-CB (405) at SDSTPS.

2. APGENCO to review STUB/TEED protection in all dias

at SDSTPS and ensure that they are configured

for instantaneous operation.

3. APGENCO to properly configure the STATE of the

tripping events so that they get recorded

appropriately like TRIP/ OPERATED in their corresponding

Event Loggers.

4. APGENCO to ensure time sync of all DR’s and EL’s at

SDSTPS.

5. PGCIL (SR-I) to provide line differential protection for

400 kV NPS –Nellore-PG lines 1 & 2.

44/I/3

(GD)

1. All Tripped units, viz., Krishnapatinam, MEPL, Raichur,

NCTPS to submit a detailed report

on this event including the remedial measures taken to PCSC

forum.

2. KPCL to check the excitation system of Unit 8 of RTPS,

and submit the remedial measures

taken to PCSC forum.

KPCL/

MEPL/

APGENCO/

TNEB

TANGEDCO vide their mail dated 07.07.2015 informed that as per the

discussion and recommendation of 44th meeting of PCSC held on 28.05.2015, a

time delay of 2 Sec had been introduced for the above tripping for all the ID

fans at NCTPS-II.

MEPL vide their mail dated 14.09.2015 informed that they have implemented 2

seconds delay for under voltage tripping of all Drag Chain Feeder Conveyors.

And this has been done for both the Units.

Pending

with

KPCL,

APGENC

O

PendingMEPL vide their mail dated 14.09.2015: informed the following

1. Tan Delta Testing of winding and DGA of Insulating Oil for all CTs was

carried out and normal.

2. Could not find any problem during internal checks hence we are in touch with

ABB for rectification work. Will be done by the end of 15th Oct'15

3. End to end testing of Carrier signals was carried out and found them healthy.

MEPL/

PGCIL(SR-I)/

SEL

1. MEPL to ensure healthiness of all CT’s by carrying out

Tan Delta and DGA tests wherever necessary.

2. MEPL to take suitable action to correct the operation of

tie-CB Bay Control Unit that caused LBB/ BBP operation.

3. PGCIL (SR-1) to carry out end-to-end PLCC testing in

coordination with MEPL and ensure that carrier-aided

protection on MEPL – NPS line is in healthy condition.

4. SEL to properly time-coordinate their Over Current

phase and Earth fault relays in consultation with MEPL.

Y phase CT failure at MEPL led to tripping of

400kV NPS-MEPL, 400kV SEPL-MEPL line

and Unit-2 at MEPL. Uni-1 was not in service

at the time of tripping

20-05-2015

at 20:38 hrs

As per FIR submitted, CT damage observed in

Chitoor-Main bay (404). Main breakers

connected to bus-1 (401, 404, 407, 410) got

tripped on operation of bus bar protection. Unit-

1 tripped on operation of MFT. Unit-2 was not

in service

08-09-2015

at 18:20 hrs

Complete

outage of

Krishnapatnam

TPS

47/I/2

(GD)

Annexure- VI

Page 19 of 20

47/II/9 Tripping of

400kV Coastal-

NTPL line and

running units

at NTPL

03-08-2015

at

15:43 hrs

R-phase to earth fault had occurred in 400 kV

Coastal NTPL line. Line autoreclosed at NTPL

end and failed to reclose at Coatal end. Auto

reclose block was persisting due to PLCC

channel fail. Also running Units-1&2 at NTPL

tripped on operation of GT differential

protection.

1. NTPL to ensure (i) proper DATE settings, and (ii) time-

sync with GPS for DR and EL at NTPL.

2. CEPL to furnish remedial measures taken regarding

PLCC channel failure.

NTPL/ CEPL Yet to be informed Pending

50/II/1

1

Tripping of

400kV Neyveli

TS2-Pugalur

line

14-11-2015

at 4:01 hrs

Line tripped on operation of over voltage

protection at Pugalur end. However from DR it

was observed that the voltages were below the

O/v stg-1 threshold limits

NLC to configure DT receipt event from Pugalur for

triggering DR and EL at NLC TPS II.

PGCIL (SR-II) to check drop-off to pick-up ratio of OVR

relay at Pugalur and configure its operation as per SRPC

provided OVR gradings.

NLC / PGCIL

(SR-II)


51/II/6 Tripping of

400kV

Sattenapalli-

Vijayawada

line

25-12-2015

at 3:01 hrs

Line tripped due to operation of over voltage

protection at Vijayawada end and Direct Trip

was received at Sattenapalli end

1. PGCIL (SR-I), in co-ordination with APTRANSCO, to

address the problem with CB at the earliest opportune time.

2. APTRANSCO to take steps to replace the faulty Event

Logger at Vijayawada (Nunna) SS.

PGCIL (SR-

I)/

APTRANSC

O


PendingYet to be informedKPTCL/

KPCL/

NPCIL

1. KPTCL/ KPCL to see the possibility of implementing

Weak Infeed logic with Echo feature enabled by Under

Voltage (27) element on Kadra-Karwar lines 1 &2, and

implement the same if feasible.

2. NPCIL to time-coordinate Kaiga’s DEFR settings with (i)

Zone-2 settings at Kaiga, and (ii) primary protections of the

lines emanating from Kadra and Kodasalli.

3. KPCL to ensure time-sync of EL’s, and healthiness of the

Fault Locators at Kadra.

220kV KAdra-Karwar lines-1&2 tripped

on earth fault in B-phase in zone-2.

Kaiga-Kadra line tripped at Kaiga end

only on operation of directional eath

fault protection.

31-07-2015

at

11:44 hrs

Tripping of

220kV Kadra-

Karwar line-

1&2 and

220kV

Kaiga-Kadra

line

47/II/7

Yet to be informedPGCIL (SR-I)

/ KPTCL

1. For Gooty –Nelamangala line, PGCIL (SR-I) and

KPTCL to provide 3-ph trip logic at their respective ends

upon detection of PLCC link failure during dead-time of

A/R operation.

2. PGCIL (SR-I) to make GPS functional at Gooty SS, and

ensure time-sync of various DR’s and EL’s with it (GPS).

3. PGCIL (SR-I) /KPTCL to furnish reason for the operation

of Backup impedance protection of the line reactor at

Nelamangala end and the remedial measures taken to PCSC

forum.

R-phase to earth fault had occurred in Line.

Line did not auto-reclose from both ends. It

was mentioned that Y&B pole breakers at

Neelamangala tripped on operation of pole

discrepancy and backup impedence protection

for line reactor got operated.

12-11-2015

at 00:20 hrs

Tripping of

400kV Gooty-

Nelamangala

line

50/II/8 Pending

49/II/1

1

Tripping of

400/220 kV

ICT-2 at

Kurnool

Substation and

400kV

Kurnool-

Srisailam line

26-10-2015

at 14:31 hrs

400kV Kurnool-Srisailam line - distance

protection zone-2 had operated at Srisailam

end. However from DR, R-phase to earth fault

and zone-2 start were observed. Breakers at

Kurnool end tripped on direct trip receive from

Srisailam end.

ICT-2 Main-CB tripped due to operation of

bus bar protection, and Tie-CB tripped due to

DT receipt from Srisailam

1.TSGENCO in coordination with APTRANSCO to carry

out end-to-end testing of PLCC channels by 15.12.2015 on

400 kV Srisailam – Kurnool S/C line and 400 kV Srisailam

– Sattenapalli D/C line.

2. TSGENCO and APTRANSCO to make A/R functional

on 400 kV Srisailam – Kurnool line.

3. TSGENCO to resolve configuration problems with the

newly commissioned relays at Srisailam LB so that

unwarranted DT sending to remote ends is addressed.

TSGENCO/

APTRANSC

O


Annexure- VI

Page 20 of 20

Sl.No. Element NameOutage

date/time

Revival

date/time

Reason for

OutageSender/ Receiver Remedial Measures/ Actions taken

1400 Kv GAJWEL -

SHANKARPALLY 1

02-11-

2015/12:22:

00

02-11-

2015/14:40:

00

R - N FAULT TSTRANSCO To-be-discussed

2400 Kv GAJWEL -

SHANKARPALLY 1

02-11-

2015/11:33:

00

02-11-

2015/11:59:

00

R-N FAULT TSTRANSCO To-be-discussed

3765 KV RAICHUR -

SHOLAPUR 2

02-01-

2016/10:46:

00

CONDUCTER

SNAPPING

PGCIL (SR-I) / PGCIL

(WR-I)To-be-discussed

4400 Kv SHANKARPALLY-

MAMIDIPALLY

25-01-

2016/13:56:

00

25-01-

2016/16:00:

00

DT RECEIVED

TRIPPED AT

SKPLY END

TSTRANSCO To-be-discussed

5400 kV MYSORE -

KOZHIKODE 1

28-01-

2016/12:53:

00

28-01-

2016/13:18:

00

B - N FAULT PGCIL (SR-II)

PGCIL(SR-II): Tripped on B-N fault

during liveline OPGW stringing

works.

6220 kV AMBEWADI -

PONDA 2

28-01-

2016/14:01:

00

28-01-

2016/19:20:

00

DISTANCE

PROTECTIONKPTCL / GOA To-be-discussed

7400 Kv VTPS - MALKARAM

2

31-01-

2016/14:23:

00

R-N FAULTAPGENCO /

TSTRANSCOTo-be-discussed

Pending Remedial Measures/ Actions taken

for the Critical Tripping Incidents (as on 15-03-2016)

Annexure- VII

Page 1 of 8

8 400 kV CHITTOOR - SPDR

01-02-

2016/09:55:

00

01-02-

2016/10:40:

00

L/R

PROTECTION

OPERATED

APTRANSCO / PGCIL

(SR-II)

PGCIL (SR-II): Tripped on operation

of L/R Buchholz protection.

APTRANSCO: Tripped at chittoor end

on receipt of direct trip signal from

SPDR. Protection is in order at

APTRANSCO.

9400 kV VIJAYAWADA -

NELLORE 1

01-02-

2016/12:57:

00

01-02-

2016/18:49:

00

TRIPPED ON

Y_N FAULT 257

KM FROM VJA

PGCIL (SR-I) To-be-discussed

10400 kV VIJAYAWADA -

NELLORE 2

01-02-

2016/06:30:

00

01-02-

2016/06:32:

00

TRANSIENT

FAULTPGCIL (SR-I) To-be-discussed

Annexure- VII

Page 2 of 8

11220 kV IDUKKI -

UDUMALPET

03-02-

2016/11:54:

00

03-02-

2016/12:19:

00

TRIPPED ON B-

PH FAULTKSEB / TANTRANSCO

TANTRANSCO: AR successful at

Udumalpet end. Feeder tied at Idukki

end on 03.02.2016 at 12:19 hrs.

KSEB: IDUD feeder tripped on zone 1

at Udumal pet end and carrier was sent

from that end. But the carrier was not

received at Moolamattom end due to

the problems with wiring to the relay.

Therefore, the relay at Moolamattom

end tripped in Zone 2. This happened

when wiring modifications were made

for new numerical relay in place of old

L3WYAS electro mechanical relay.

The rectification work is pending

which will be resolved soon.

12400 kV MYSORE -

KOZHIKODE 2

04-02-

2016/12:24:

00

04-02-

2016/13:07:

00

TRIPPED WHILE

CARRYING

OPGW WORKS

PGCIL (SR-II)

PGCIL(SR-II): Tripped on B-N fault

during liveline OPGW stringing

works. Construction Staff/Gangs has

been adviced to take all precautions

while OPGW stringing.

13400/220 kV ICT-3 AT

RAICHUR

05-02-

2016/03:01:

00

05-02-

2016/05:24:

00

TRIPPED DUE

TO TRIPPING OF

RCR-SEDAM

LINE

KPCL To-be-discussed

Annexure- VII

Page 3 of 8

14 400 Kv NTPL - TTRNPS

05-02-

2016/11:47:

00

05-02-

2016/13:05:

00

HOT SPOT @

NTPL ENDNTPL / PGCIL (SR-II) To-be-discussed

15765 KV KURNOOL -

THIRUVALLM 1

11-02-

2016/14:30:

00

11-02-

2016/19:56:

00

D/T RECIEVED

AT KURNOOL

END

PGCIL (SR-I) / PGCIL

(SR-II)To-be-discussed

16 GOOTY-SOMANAHALLI

18-02-

2016/14:16:

00

18-02-

2016/15:03:

00

BY PASSED DUE

TO FAULT ON

LIE SIDE

KPTCL / PGCIL (SR-II) To-be-discussed

17 400 Kv HASSAN - UPCL 1

18-02-

2016/11:30:

00

18-02-

2016/11:45:

00

B-N FAULT PGCIL (SR-II) / UPCL To-be-discussed

18HVDC TALCHER - KOLAR

POLE

20-02-

2016/18:22:

00

20-02-

2016/19:15:

00

VALVE

COOLING

PROBLEM

PGCIL (SR-II) To-be-discussed


POLE

21-02-

2016/16:46:

00

21-02-

2016/21:36:

00

VALVE

COOLING

PROBLEM


20 400 kV CUDDAPPA - KOLAR

22-02-

2016/08:39:

00

22-02-

2016/10:32:

00

B - N FAULTPGCIL (SR-I) / PGCIL


21400 kV HYDERABAD -

KURNOOL

22-02-

2016/06:48:

00

22-02-

2016/07:18:

00

TRIPPED ON R-N

FAULT

PGCIL (SR-I) /

APTRANSCOTo-be-discussed

22400 kV PUGALUR -

KALAIVANTHAPATTU 2

22-02-

2016/13:53:

00

Y PHASE FAULT PGCIL (SR-II) To-be-discussed

23 400 kV CUDDAPPA - KOLAR

25-02-

2016/14:23:

00

25-02-

2016/17:05:

00

B-N FAULTPGCIL (SR-I) / PGCIL


24400/220 kV ICT-2 AT

CUDDAPAH

25-02-

2016/14:23:

00

25-02-

2016/14:36:

00

OVERCURRENT

TRIPPGCIL (SR-II) To-be-discussed

Annexure- VII

Page 4 of 8

25220 Kv CHIKKODI -

TALANDGE

25-02-

2016/17:44:

00

25-02-

2016/18:22:

00

OVERCURRENT

TRIPKPTCL To-be-discussed

26220 Kv CHIKKODI -

TALANDGE

26-02-

2016/19:24:

00

26-02-

2016/20:23:

00

TRIPPED AT

TALANDGEKPTCL To-be-discussed

27400/220 kV ICT-3 AT

TALAGUPPA

27-02-

2016/17:33:

00

27-02-

2016/18:11:

00

RELAY

MALOPERATIO

N

KPTCL To-be-discussed

28220 kV IDUKKI -

UDUMALPET

28-02-

2016/13:40:

00

28-02-

2016/14:17:

00

PHASE TO

PHASE FAULTKSEB/ TANTRANSCO

KSEB: On 28.02.2016, IDUD feeder

tripped on zone 1 at both end. At

Idukki end tripped, reclosed and

tripped. The tripping was normal. The

carrier receive at Idukki end was not

functional due to the wiring problem

of the relay. The relay is new, hence

the DR to be fine-tuned for getting

clarity for the wave form. The problem

will be solved as early as possible.

TANTRANSCO: Temporary fault. AR

lock out at Udumalpet end. Feeder

charged from Udumalpet end and tied

at Idukki end on 28.02.2016 at 14:17

hrs.

29 400/220 kV ICT-1 AT HOODY

29-02-

2016/17:43:

00

29-02-

2016/17:49:

00

TRIPPED AT 220

KV SIDEKPTCL To-be-discussed

Annexure- VII

Page 5 of 8

30400 kV NEYVELI TS2-

NEYVELI TS-2

29-02-

2016/12:08:

00

29-02-

2016/12:34:

00

PLCC

MALOPERATIO

N

NLC To-be-discussed

31 220 kV SEDAM - TANDUR

29-02-

2016/18:14:

00

29-02-

2016/22:23:

00

DISTANCE

PROTECTION

OPERATED

KPTCL/ TSTRANSCO To-be-discussed

32400 kV KHAMMAM -

KALPAKKA 1

01-03-

2016/05:35:

00

R-N FAULTPGCIL (SR-I) /

APTRANSCOTo-be-discussed

33400 Kv KUDGI- KOLHAPUR-

2

04-03-

2016/07:18:

00

04-03-

2016/07:38:

00

DT RECEIVED

AT KUDGI END.

PGCIL (SR-II) / PGCIL

(WR-I)To-be-discussed

34400 kV NEYVELI TS 2 -

NEYVELI TS2

04-03-

2016/11:22:

00

04-03-

2016/17:07:

00

TRIPPED AT

NLCTS2 ENDNLC To-be-discussed

35220 kV AMBEWADI -

PONDA 1

05-03-

2016/14:32:

00

05-03-

2016/17:50:

00

DISTANCE

PROTECTIONKPTCL / GOA To-be-discussed

36220 kV KANIAMPET -

KADAKOLA

05-03-

2016/13:29:

00

05-03-

2016/14:02:

00

DISTANCE

PROTECTIONKSEB / KPTCL To-be-discussed

37220 kV IDUKKI -

UDUMALPET

06-03-

2016/04:28:

00

06-03-2016/TRIPPED ON B-N

FAULTKSEB/ TANTRANSCO

TANTRANSCO: Temporary fault. AR

successful at Udumalpet end. Tx

incremented by 1. Feeder tied at

Idukki end on 06.03.2016 at 05:32 hrs.

38400 kV HASSAN -

NEELAMANGALA

07-03-

2016/14:55:

00

07-03-

2016/16:17:

00

B - N FAULT KPTCL To-be-discussed

39400 kV RAMAGUNDAM -

CHANDRAPUR 2

07-03-

2016/19:39:

00

07-03-

2016/20:50:

00

R - B FAULTNTPC / PGCIL (WR-I) /

PGCIL (SR-I)To-be-discussed

40400 kV RAMAGUNDAM -

CHANDRAPUR 2

08-03-

2016/23:55:

00

09-03-

2016/01:01:

00

TRIPPED ON R-B

FAULT

NTPC / PGCIL (WR-I) /

PGCIL (SR-I)To-be-discussed

Annexure- VII

Page 6 of 8


POLE

08-03-

2016/01:29:

00

08-03-

2016/02:12:

00

VALVE

COOLING

PROBLEM


42 400 Kv NELLORE - SPDR 2

09-03-

2016/17:20:

00

09-03-

2016/19:34:

00

ISO. PROBLEMAPTRANSCO /

TANTRANSCOTo-be-discussed

43220 kV IDUKKI -

UDUMALPET

12-03-

2016/02:32:

00

12-03-

2016/15:44:

00

R -N FAULT KSEB/ TANTRANSCO To-be-discussed

44 220 kV SABARGIRI - THENI

12-03-

2016/13:55:

00

12-03-

2016/14:35:

00

R-N FAULT KSEB/ TANTRANSCO To-be-discussed

45400 kV N'SAGAR -

CUDDAPPA 1

12-03-

2016/12:13:

00

12-03-

2016/13:23:

00

Y-N FAULT PGCIL (SR-I) To-be-discussed

46 400 Kv COASTAL - NTPL

14-03-

2016/01:36:

00

14-03-

2016/02:36:

00

TRIPPED

REASON

AWAITED

CEPL / NTPL To-be-discussed


14-03-

2016/02:59:

00

14-03-

2016/08:57:

00

TRIPPED ON Y-N

FAULTNTPL / PGCIL (SR-II) To-be-discussed

48220 kV AMBEWADI -

PONDA 1

14-03-

2016/03:44:

00

14-03-

2016/10:50:

00

B-N FAULT KPTCL / GOA To-be-discussed


14-03-

2016/01:36:

00

14-03-

2016/02:21:

00

TRIPPED

REASON

AWAITED

NTPL / PGCIL (SR-II) To-be-discussed


14-03-

2016/01:12:

00

14-03-

2016/01:36:

00

TRIPPED ON

R_N FAULT AT

NTPL END

ONLY HOLDING

AT TTCRN


51 400 Kv COASTAL - TTRNPS

14-03-

2016/01:36:

00

14-03-

2016/03:04:

00

TRIPPED

REASON

AWAITED

CEPL / PGCIL (SR-II) To-be-discussed

Annexure- VII

Page 7 of 8


14-03-

2016/03:04:

00

14-03-

2016/20:28:

00

TRIPPED

REASON

AWAITED


53220 kV AMBEWADI -

PONDA 1

14-03-

2016/03:44:

00

B-N FAULT KPTCL / GOA To-be-discussed


14-03-

2016/02:59:

00

TRIPPED ON Y-N

FAULTNTPL / PGCIL (SR-II) To-be-discussed


14-03-

2016/03:04:

00

TRIPPED

REASON

AWAITED



14-03-

2016/01:36:

00

14-03-

2016/02:21:

00

TRIPPED

REASON

AWAITED



14-03-

2016/01:12:

00

14-03-

2016/01:36:

00

TRIPPED ON

R_N FAULT AT

NTPL END

ONLY HOLDING

AT TTCRN



14-03-

2016/01:36:

00

14-03-

2016/02:36:

00

TRIPPED

REASON

AWAITED


59 400 Kv COASTAL - TTRNPS

14-03-

2016/01:36:

00

14-03-

2016/03:04:

00

TRIPPED

REASON

AWAITED

CEPL / PGCIL (SR-II) To-be-discussed


15-03-

2016/02:02:

00

15-03-

2016/03:51:

00

R -N FAULT NTPL / PGCIL (SR-II) To-be-discussed

61220 kV IDUKKI -

UDUMALPET

15-03-

2016/02:09:

00

15-03-

2016/02:51:

00

R-N FAULT KSEB/ TANTRANSCO To-be-discussed

Annexure- VII

Page 8 of 8

Islanding Schemes in Southern Region

Load Relief from AUFR and df/dt

Sl. No

AUFR and df/dt

stages

AP TS KAR KER T N PED

Reco

mm

end

ed

Implem

ented

Reco

mm

end

ed

Implem

ented

Reco

mm

end

ed

Implem

ented

Reco

mm

end

ed

Implem

ented

Reco

mm

end

ed

Implem

ented

Reco

mm

end

ed

Implem

ented

AUFR Average MW

1 Stage-I (49.2 Hz) 392 392 417 419 576 578 204 214 740 804 21 21

2 Stage-I (49.0 Hz) 393 393 419 420 578 578 205 217 744 808 21 22

3 Stage-I (48.8 Hz) 398 398 424 426 586 593 208 212 753 867 21 25

4 Stage-I (48.6 Hz) 399 399 426 431 588 593 209 211 756 867 22 24

AUFR Total 1582 1582 1686 1696 2328 2342 826 854 2993 3346 85 92

1 df/dt stage-I (at 49.5

Hz & 0.2 Hz/sec fall

of frequency) 345 345 367 368 474 483 172 178 624 626 18 12

2 df/dt stage-II (at 49.3

Hz & 0.3 Hz/sec fall

of frequency) 855 855 912 914 737 734 175 175 559 572 0 6

df/dt Total 1200 1200 1279 1282 1211 1217 347 353 1183 1198 18 18

Feeder Tripping Frequency for Islanding: 47.9 Hz

Methodology:

Anticipated Generation = G

Total Loads participating = Dp

Combined Load Relief

from AUFR and df/dt relays = Dr Anticipated load (D) = Dp - Dr

As per guidelines, Islanded Electrical System should have

20% more generation than load. Accordingly Constituents are

requested to provide details for Anticipated Generation and

Anticipated load for the following Islands of SR.

Annexure- VIII

Page 1 of 10

SRPC Secretariat| As on January, 2016 1

1. Hyderabad Islanding Scheme

Anticipated Generation 2896 MW

Total Loads Participating 3332.245 MW

AUFR+df/dt Load relief 200 MW

Anticipated Load 3132.2 MW

a) Generators Participating

S.No. Generator Entity

Anticipated MW

Supplying

1 ORIENT CEM 220.00 IPP 45

2 RGM-NTPC 400.00 RGM-TPS 187







9 KKTYATPS 400.00 TSGENCO 421

Anticipated Generation Total 2896

b) Loads Participating

Bus Number Load Entity Pload (MW)

422002 CHADRTTA 220.00 TS_STU 403.7675

422017 GACIBWLI 220.00 TS_STU 343.3528

422020 MOULALI 220.00 TS_STU 318.0552

422021 DURSHED 220.00 TS_STU 162.24

422024 MALKARAM 220.00 TS_STU 29.8391

422029 MEDCHAL 220.00 TS_STU 266.5906

422037 HIAL 220.00 TS_STU 54.466

422039 SIVRALLY 220.00 TS_STU 212.3238

422041 GAJWEL 220.00 TS_STU 177.0771

422044 PULKUTHY 220.00 TS_STU 15.1105

422053 SALIVAGU 220.00 TS_STU 6.9313

422055 BLMPLLI 220.00 TS_STU 138.4262

422063 SADASIVPET 220.00 TS_STU 129.8335

424002 RGM-NTPC 400.00 NTPC_SR 387.6287

422011 SHAURGAR 220.00 TS_STU 324.5029

Annexure- VIII

Page 2 of 10


422003 GHANAPUR 220.00 PGCIL_CTU 307.6458

422009 MALALLLI 220.00 TS_STU 54.4536

Total Loads participating 3332.245

AUFR Relief 200

df/dt Relief

Anticipated Load 3132.2

c) Feeders Tripping Sl.No Voltage

level

No. of

Circuit

From Bus Name To Bus Name

1 400 kV D/C Ramagundam Nagarjunasagar (Talapalli)

2 400 kV D/C Khammam Mamidapalli

3 400 kV D/C Malkaram VTPS- Stage-IV

4 400 kV D/C Ramagundam Bhadrawati

5 400 kV S/C Ghanapur Nagarjunasagar (Talapalli)

6 400 kV S/C Ghanapur Kurnool

7 400 kV S/C Shankarapalli Srisailam Left Bank

8 400 kV S/C Mamidapalli Srisailam Left Bank

9 400 kV S/C Ramagundam Dichipaly

10 400 kV S/C Khammam Warangal

11 220 kV S/C Kotagudem Shapurnagar

12 220 kV D/C Narketpalli Malkaram

13 220 kV D/C Dindi Chandrayengutta

14 220 kV S/C Malayalapalli Jagtiyal

15 220 kV D/C Malayalapalli Nagaram

16 220 kV D/C Warangal Nagaram

17 220 kV S/C Malayalapalli Bhimgal

18 220 kV S/C Malayalapalli Vemanoor

19 220 kV S/C Malayalapalli Medaram

20 220 kV S/C Shankarapalli Tandur

21 220 kV S/C Mamidapalli Shamshabad

22 220 kV S/C Mamidapalli Shadnagar

23 220 kV D/C Durshed Siddipet

24 220 kV D/C Gajwel Minipur

25 220 kV D/C Gajwel Kamareddy

26 220 kV D/C Yeddumailaram Shankarapalli

Annexure- VIII

Page 3 of 10


2. Chennai Islanding Scheme







Anticipated

MW

Supplying

1 ETPS2 230.00 TN 30

2 MAPS2 230.00 MADRAS-APS 304

3 NCTPS-I 230.00 TN 594

4 SDEV 230.00 TN 10

5 OPG_ALM 230.00 TN 0

6 SUZLON 230.00 TN 0

7 KAMACHI 230.00 TN 5

8 KAVERI 230.00 TN 3

9 ARS 230.00 TN 3

10 VALLUR 400.00

NTECL-

VALLUR 1425

11 NCTPS-II 400.00 TN 1110

Anticipated Generation 3484

b) Load Participating


442001 TVALAM2 230.00 TN_STU 155.0332

442002 GUMDIP2 230.00 TN_STU 32.2072

442007 ACHARAP2 230.00 TN_STU 39.3613

442014 ARNI2 230.00 TN_STU 194.2737

442015 BASINBR2 230.00 TN_STU 87.9435

442021 ETPS2 230.00 TN_THERMAL 111.0315

442024 HYNDAI2 230.00 TN_STU 54.457

442027 KADAPEI2 230.00 TN_STU 202.5802

442034 KILPAWW2 230.00 TN_STU 133.2734

442037 KORATUR2 230.00 TN_STU 210.8154

442038 KOYMBDU2 230.00 TN_STU 239.1693

442043 MANALI2 230.00 TN_STU 135.3065

Annexure- VIII

Page 4 of 10


442046 MOSUR2 230.00 TN_STU 248.8731

442049 MYLAPOR2 230.00 TN_STU 343.0261

442055 NOKIA2 230.00 TN_STU 23.175

442056 ORAGADM2 230.00 TN_STU 118.4877

442074 SIRSERI2 230.00 TN_STU 103.7713

442075 MAMBAKM 230.00 TN_STU 89.7883

442078 SPKOIL2 230.00 TN_STU 235.5069

442082 TARMANI2 230.00 TN_STU 189.2855

442083 TONPET2 230.00 TN_STU 140.0097

442094 VEERPRM2 230.00 TN_STU 112.0652

442099 KITSPARK 230.00 TN_STU 49.7665

442119 CMRL 230.00 TN_STU 20.186

442128 ALDRCMRL 230.00 TN_STU 20.1861

442129 GUINDY 230.00 TN_STU 146.5847

444001 SRPRMBDR 400.00 PGCIL_CTU 443.1275

444002 ALAMATTY 400.00 TN_STU 229.9846

444018 SVCHTRM 400.00 TN_STU 124.8129

Total Loads Participating 4234.089

AUFR Relief 620

df/dt Relief Anticipated Load 3614.089

c) Feeders Tripping

Sl.No Voltage

level

No. of

Circuit


400 kV D/C Sriperumbudur Nellore- PG

400 kV D/C Kalavindapattu Pugalur

400 kV D/C Chitoor Thiruvallam

400 kV D/C Thiruvalam- TN Mettur-Stage-III

400 kV D/C Thiruvalam Nellore- PG

400 kV S/C Chitoor Sriperumbudur

400 kV S/C Thiruvallam Kolar- PG

400 kV S/C SV Chatram Pondicherry

400 kV S/C Sriperumbudur Chitoor

230 kV S/C Arani Singarapettai

230 kV S/C Acharapakkam Villupuram

230 kV S/C Singarapettai Thiruvalam- TN

230 kV S/C Chitoor Thiruvallam- TN-2

230 kV S/C Gummdipondi Sulurpet

Annexure- VIII

Page 5 of 10


d) ICT Tripping Sl.No High Voltage (HV)

level

HV side- Bus Name Low Voltage (LV)

level

LV side- Bus

Name

1 765 kV Thiruvalam 400 kV Thiruvalam

2 765 kV Thiruvalam 400 kV Thiruvalam

3. Neyveli Islanding Scheme




Anticipated Load 3994.285MW



Anticipated

MW Supplying

1 Kadmparai TN 300

2 Kundah 2 TN 30.4

3 Kundah 3 TN 150

4 Kundah 4 TN 100

5 MTPS Stage-2 TN 792

6 MTRPH TN 0

7 STCMS TN 250

8 NLCTS12 230.00 TN 251.1

9 NLC22 230.00 NEYVELI-ALL 567

10 PP Nalur TN 0

11 PUSHEP TN 150

12 Suzlon TN 0

13 NLC1EXP 400.00 NEYVELI-ALL 384

14 NLC2 400.00 NEYVELI-ALL 756

15 NLC2EXP 400.00 NEYVELI-ALL 450

16 METR-III 400.00 TN 565

17 ILFS 400.00 ILFS 540

Anticipated Generation 5285.5

Annexure- VIII

Page 6 of 10




442005 UDMLPT2 230.00 TN_STU 150.1811

442010 ALUNDR42 230.00 PGCIL_CTU 142.6378

442013 ARASUR2 230.00 TN_STU 389.5652

442017 CUDALRE2 230.00 TN_STU 165.7051

442018 DEVKRCY2 230.00 TN_STU 192.4078

442019 EACHNGA2 230.00 TN_STU 56.7152

442022 GOBI2 230.00 TN_STU 321.009

442025 INGUR2 230.00 TN_STU 401.9839

442026 KADALAN2 230.00 TN_STU 34.9428

442042 MTRAUTO 230.00 TN_STU 166.3279

442045 OKMNTPM 230.00 TN_STU 273.1627

442053 NLC22 230.00 TN_STU 125.49

442057 PALADAM2 230.00 TN_STU 260.6523

442060 PERMBLR2 230.00 TN_STU 241.6082

442061 PONPRM2 230.00 TN_STU 356.9801

442069 SALEM2 230.00 TN_STU 393.6232

442071 SAMAYPM2 230.00 TN_STU 129.861

442081 TANJORE2 230.00 TN_STU 180.993

442084 TRICHY2 230.00 TN_STU 280.4979

442088 TUDIYLR2 230.00 TN_STU 65.5438

442089 TVARUR2 230.00 TN_STU 40.98

442090 TVMALAI2 230.00 TN_STU 166.6578

442092 UNJANAI2 230.00 TN_STU 158.9933

442096 VILUPRM2 230.00 TN_STU 69.1459

442102 SDYPLYM 230.00 TN_STU 32.7086

442106 ANIKADVU 230.00 TN_STU 18.69

442107 ALIYAR 230.00 TN_STU 31.203

442126

PALKAPALYAM

230.00 TN_STU 90.8307

442127 ANTHIYUR 230.00 TN_STU 96.6601

444008 SALEM-TN 400.00 TN_STU 284.5355

452018 PALAKAD 220.00 KL_STU 272.6201

462002 VLIYANR2 230.00 PONDY_STU 204.5312

462003 BHAHUR2 230.00 PONDY_STU 196.8412


AUF Relief 2000

df/dt Relief Anticipated Load 3994.285

Annexure- VIII

Page 7 of 10


c) Feeders Tripping Sl.No Voltage

level

No. of

Circuit


1 400 kV D/C Pugalur Kalavindapattu

2 400 kV D/C Myvadi Tirunelveli

3 400 kV D/C Salem Hosur

4 400 kV D/C Thiruvalam- TN Mettur-Stage-III

5 400 kV D/C Palakkad Thrissur

6 400 kV S/C Myvadi Checkanurani (Madurai)

7 400 kV S/C Alandur (Trichy) Checkanurani (Madurai)

8 400 kV S/C Alandur (Trichy) Karaikudi New

9 400 kV S/C Pugalur NLC Expansion 2

10 400 kV S/C Pugalur NLC TPS 2

11 400 kV S/C SV Chatram Pondicherry

12 230 kV S/C Acharapakkam Villupuram

13 230 kV S/C Alandur (Trichy) Alagarkoil

14 230 kV S/C Hosur Mettur Auto

15 230 kV S/C Karimangalam Mettur Auto

16 230kV S/C Pudanchandai Deviakurchi

17 230 kV S/C Pugalur Alandur (Trichy)

18 230 kV S/C Alandur (Trichy) Pudukottai

19 230 kV S/C Pugalur Myvadi

20 230 kV S/C Myvadi Sembatti

21 230 kV S/C Mettur TPS- 2 Singarapettai

22 230 kV S/C Singarapettai Salem

23 230 kV S/C Singarapettai TV Malai

24 230kV S/C Unjani Pudanchandai

25 230 kV S/C Thiruvarur Karambayam

26 230 kV S/C Udumalpet Idukki

27 230 kV D/C Palakkad (400 kVside) Madakathara

28 230 kV S/C Palakkad Madakathara

Annexure- VIII

Page 8 of 10


4. Koodankulam Islanding Scheme






S.No. Generators Entity PGen (MW)

1 INDARCPP 230.00 TN 0

2 TTPS2 230.00 TN 990

3 UDAYATR2 230.00 TN 0.4

4 STERLITE2 230.00 TN 6

5 IBPTL 2 230.00 TN 20

6 KKNPP 400.00 KKNPP 950

7 TUTCRNJV 400.00 NTPL 950

8 CENERGY 400.00 COASTL-ENERG 400

9 SABRGRI 220.00 KL 304

10 KAYMKLM 220.00 KL 0

Anticipated Generation 3620.4



442006 THENI2 230.00 TN_STU 143.2453

442008 ALAGARK2 230.00 TN_STU 131.4524

442011 AMADPRM2 230.00 TN_STU 3.7718

442012 ANUPANG2 230.00 TN_STU 273.3405

442032 KARAIKD2 230.00 TN_STU 115.0001

442033 KAYTHAR2 230.00 TN_STU 45.7007

442036 KODIKUR2 230.00 TN_STU 75.8534

442058 PARMKDY2 230.00 TN_STU 96.864

442059 PASUMAL2 230.00 TN_STU 264.121

442063 PUDANS2 230.00 TN_STU 205.5551

442064 PUDUKOT2 230.00 TN_STU 160.8576

442066 PUGALUR2 230.00 TN_STU 249.8756

442068 RENGPRM2 230.00 TN_STU 145.601

442072 SANKNRI2 230.00 TN_STU 13.0247

442073 SEMBATY2 230.00 TN_STU 207.1181

442079 SRPUDUR2 230.00 TN_STU 129.2502

Annexure- VIII

Page 9 of 10


442085 TSIPCOT2 230.00 TN_STU 189.6917

442086 TTPAUTO2 230.00 TN_STU 128.5702

442093 VALTHUR2 230.00 TN_STU 75.167

442095 VERANAM2 230.00 TN_STU 3.7374

442108 KRMBYAM 230.00 TN_STU 24.9647

442130 TUTCRNJV 230.00 NTPL 20

444030 KAYATHAR 400.00 TN_STU 63.7883

452003 SABRGRI 220.00 KL_STU 0.382

452004 EDAMAN2 220.00 KL_STU 102.258

452004 EDAMAN2 220.00 KL_STU 114.0903

452007 EDAPAN 220.00 KL_STU 167.1125

452011 KUNDARA 220.00 KL_STU 160.4111

452020 POTHNCOD 220.00 KL_STU 399.0273

452033 PUNPRA 220.00 KL_STU 115.1144


AUFR relief 800

df/dt relief Anticipated Load 3024.946

c) Feeders Tripping Sl.No Voltage level No. of

Circuit


1 400 kV D/C Pugalur Kalavindapattu

2 400 kV S/C Pugalur NLC Expansion 2

3 400 kV S/C Pugalur NLC TPS 2

4 400 kV S/C Alandur (Trichy) Checkanurani (Madurai)

5 400 kV S/C Alandur (Trichy) Karaikudi New

6 400 kV S/C Myvadi Checkanurani (Madurai)

7 400 kV D/C Myvadi Tirunelveli

8 230 kV S/C Pugalur Alandur (Trichy)

9 230 kV S/C Pugalur Myvadi

10 230 kV S/C Myvadi Sembatti

11 230 kV S/C Alandur (Trichy) Alagarkoil

12 230 kV S/C Alandur (Trichy) Pudukottai

13 230 kV S/C Thiruvarur Karambayam

14 230kV S/C Unjani Pudanchandai

15 230kV S/C Pudanchandai Deviakurchi

16 220 kV S/C Idukki New Pallom

17 220 kV S/C Sabarigiri Pallom

18 220 kV S/C Sabarigiri Ambalamugal

19 220 kV S/C Pallom New Pallom

Annexure- VIII

Page 10 of 10

Load Impedance

Encroachment

&

Over Current Protection

Settings

Annexure- IX

Page 1 of 15

2

Power flow on a Transmission line

Annexure- IX

Page 2 of 15

3

Annexure- IX

Page 3 of 15

4

Distance Relay characteristics modified for Load Encroachment

Annexure- IX

Page 4 of 15

5

Ideal solution to tackle load encroachment may

be based on the use of blinders or by suitably

setting the resistive reach of specially shaped

impedance elements or by use of polygon type

impedance elements.

It is recommended that all the distance relays

should have quadrilateral / polygon characteristic.

For relays having Mho characteristics, it is

desirable to have load encroachment prevention

characteristics or a blinder.

Annexure- IX

Page 5 of 15

6

In the absence of credible data regarding minimum voltage and maximum load expected for a feeder during emergency system condition, following criteria may be considered for deciding resistive reach / blinder setting to prevent load point encroachment: Maximum load current (Imax) may be considered as

1.5 times the thermal rating of the line or 1.5 times the associated bay equipment current rating ( the minimum of the bay equipment individual rating) whichever is lower. (Note: The rating considered is approximately 15 minutes rating of the transmission facility). Minimum Voltage (Vmin) to be considered as 0.85pu

(85%). For setting angle for load blinder, a value of 30 degree

may be adequate in most cases.

Annexure- IX

Page 6 of 15

7

For high resistive earth fault where impedance locus

lies in the Blinder zone, fault clearance shall be

provided by the back-up directional earth fault relay.

Load encroachment feature is to be enabled in

distance relays where the zone-3 resistive reach is

more than the load resistance.

Annexure- IX

Page 7 of 15

8

Annexure- IX

Page 8 of 15

9

Directional Phase Over Current Protection (TL):

Directional phase over current relays are still being

used as back-up protection for 220kV transmission

lines by many utilities. However, in view of time

coordination issues and increased fault clearance time

in the event of failure of main distance protection, it

is recommended that for all 220kV lines also main-1

and main-2 protections similar to 400kV lines be

provided.

In these relays, it is desirable to set the pickup value

around ~ 120 % I(base) [based on the Emergency

rating of conductor].

Annexure- IX

Page 9 of 15

10

Directional Ground Over Current Protection (TL) The ground over current threshold should be set to

ensure detection of all ground faults, but above any continuous residual current under normal system operation. Continuous residual current may arise because of following: Unbalanced series impedances of untransposed

transmission circuits

Unbalanced shunt capacitance of transmission circuits.

Third harmonic current circulation.

In these relays, it is desirable to set the pickup value around 20 % I(base).

Annexure- IX

Page 10 of 15

11

Phase Over Current Protection (ICTs):

The phase over current threshold should be set to

ensure detection of all phase faults, but above any

continuous phase current under normal system

operation. The timing should be coordinated with the

phase over current protection of downstream network.

The non-directional Instantaneous high set over

current element shall be set to a value which is 1.3

times the transformer through fault current or transformer inrush current, whichever is higher.

Annexure- IX

Page 11 of 15

12

Model Setting Calculations: • I1>: This parameter is set to 150% of base current.

• k1 (TMS): Model value is 0.26.

• I2>: This parameter is set to 800% of base current.

• t2: This parameter is set to 0.05s.

Over Load Protection:

Overload relay shall be set at 105% of rated current with

delay of 5 seconds. This shall be connected to give only

alarm and not for tripping. The Alarm is used to alert the

operator to take necessary steps to reduce loading.

In the event of sudden increase in load current, the

mechanical protections like Oil temperature high and

Winding temperature high should take care of this.

Annexure- IX

Page 12 of 15

13

Directional Ground Over Current Protection (ICTs):

The ground over current threshold should be set to

ensure detection of all ground faults, but above any

continuous residual current under normal system

operation. The timing should be coordinated with the

downstream backup protection including Zone-3

timing for a remote end 220kV bus fault.

Setting Calculations:

• IN1>: This parameter is set to 20% of base current.

• k1 (TMS): Model value is 0.58.

• IN2>: This parameter is set to 800% of base current.

• t2: This parameter is set to 0.05s.

Annexure- IX

Page 13 of 15

14

Report of the Task Force on Power System under Contingencies (August, 2013)

Model Setting Calculations for Typical IEDs, Line Protection Setting Guidelines, Protection System Audit Check-list, Recommendations for Protection Management. (March, 2014)

CBIP Publication no 274: Manual on Protection of Generators, Generator Transformers and 220kV and 400kV Networks

CBIP Publication no 296: Manual on Reliable Fault Clearance and Back-Up Protection of EHV and UHV Transmission Networks

CIGRE WG B5.10, 411: Protection, Control and Monitoring Of Series Compensated Networks

CIGRE WG 34.04 ; Application Guide on Protection Of Complex Transmission Network Configurations

Annexure- IX

Page 14 of 15

15

Annexure- IX

Page 15 of 15

This is a special report of the IEEE – Power System Relay Committee.

March 2001

TRANSMISSION LINE

PROTECTIVE SYSTEMS LOADABILITY

A report to the

Power System Relay Committee of

the IEEE Power Engineering Society

prepared by working group D6

Abstract

This paper is about the effects of protective relaying on the loadability of transmission lines. The calculation of

relaying load limits for use in comparing to transmission line load limits or other limits is discussed. The identification

of problems associated with the application of relay protection that result in the interference of line loading capabilities

is covered. This is followed by the discussion of methods available that are aimed at increasing the loadability of relay

schemes while also maintaining required levels of relay coverage and security.

Members of the working group

Tony Seegers - chair Ed Krizauskas - vice-chair

Mike Agudo Larry Budler

Doug Dawson Tom Domin

Daniel Hamai Charlie Henville

Bob Holmgren Dave Jamison

Bogdan Kasztenny Peter Kotos

Bill Lowe Bernard Matta

Mike McDonald Dean Miller

George Moskos Brad Nelson

Don Sevcik Tarlochan Sidhu

Skip Williams Karl Zimmerman

John Zipp

Annexure- X

Page 1 of 30

This is a special report of the IEEE – Power System Relay Committee.

Page i March 2001

Contents

1. Introduction …………………………………………………………………………. 1

2. Fundamental Concepts of Loadability …………………………………………….. 1

2.1 Definition of Relay Load Limit …………………………………………….. 1

2.2 Calculation of Load Limits …………………………………………….. 1

2.2.1 Overcurrent Relays …………………………………………….. 1

2.2.2 Distance Relays …………………………………………….. 2

2.2.3 Current Differential Relays …………………………………… 3

2.2.4 Phase Comparison Relays …………………………………… 4

3. Factors Affecting Line Loadability …………………………………………….. 4

3.1 Protective Equipment …………..………………………………………….. 4

3.1.1 Relays ………..…………………………………………….. 4

3.1.2 Pilot Systems ………..…………………………………………….. 7

3.1.3 Current Transformers …………………………………………..… 7

3.2 System Factors ……………………………………………………… 7

3.2.1 Transmission Line Ratings ……………………………………………. 7

3.2.2 Transmission System Power Factor …………………………. 10

3.2.3 Unbalanced Currents …………………………………………….. 11

3.2.4 Multi-Terminal Lines …………………………………………….. 11

3.2.5 Power Swings …………………………………………….. 12

3.2.6 Faults and Fault Angles …………………………………………….. 13

4. Solutions ………………………………………………………………………... 14

4.1 Relay Settings ………..…………………………………………….. 14

4.1.1 Line Coverage …………………………………………….. 14

4.1.2 Backup Coverage …………………………………………….. 15

4.1.3 Breaker Failure …………………………………………..… 16

4.2 Dealing with Transients ……………………………………………. 16

4.2.1 Voltage ………..……………………………………………. 16

4.2.2 Thermal Load ………..……………………………………………. 17

4.2.3 Load Angle ………..……………………………………………. 17

4.2.4 Outages ………..……………………………………………. 18

4.3 Protective Equipment ………..……………………………………………. 18

4.3.1 Distance Relay Characteristic Shape …………………………. 18

4.3.2 Use of blinders ……………………………………………. 18

4.3.3 Power Swing Blocking ……………………………………………. 19

4.3.4 Adaptive techniques ……………………………………………. 20

4.4 Systems ……………………………………………………………. 20

4.4.1 Planning ………..………….……………………………….… 20

4.4.2 Controlled Flows on Lines …………………………………... 20

4.4.3 Load Shedding ……………………………………………. 20

4.4.4 Series-Compensated Lines …………………………………... 20

5. Summary ………………………………………………………………………… 22

6. Appendix ………………………………………………………………………… 23

Appendix A: Overcurrent Relay Loadability Calculation Example. ……… 23

Mho Distance Relay Loadability Calculation Examples ……… 23

Appendix B: Fundamentals of Distance Relays …………………………. 24

7. References ………………………………………………………………………… 29

8. Bibliography ………………………………………………………………………… 29

Annexure- X

Page 2 of 30

This is a special report of the IEEE – Power System Relay Committee

Page 1 March 2001

February 2001

1. Introduction

As transmission lines are loaded to higher and higher levels, and as the concept of open transmission access becomes

a reality, the subject of load-carrying capabilities of transmission lines is becoming increasingly important. Short term

ratings of lines are being applied for system operations, and conflicts with load limitations and the protection system

settings are becoming more prevalent.

Generally, the characteristics of the line itself should determine the limits of line loading. The level to which the

protection system permits a transmission line to be loaded is based on transmission line protection design and setting

philosophies, system characteristics, and protective equipment thermal ratings. A line relay load limit is established

for the purpose of comparing with the line load limit to determine if steps must be taken to prevent undesirable relay

operation.

This paper discusses the various factors to consider concerning relays in the determination of transmission line

loadability; considerations for protection design and relay setting philosophies to prevent limitations on line

loadability; and utility practices for settings, equipment ratings, and methods to mitigate related problems.

2. Fundamental Concepts of Loadability

2.1 Definition of Relay Load Limit

For the purposes of this document, the line relay load limit will be defined to be the loading permitted by the relay

including a security margin. The direction of power flow may or may not be a factor depending on the relay

2.2 Calculation of Load Limits

Protective relay load limits are often conservative, with some room provided for equipment errors and some

fluctuation in the loading. The amount of these margins is dependent upon the amount of risk of load induced

protection trips the user is willing to accept. Therefore when calculating load limits, it is wise to recognize the role that

margins play, and to clearly state whether or not the calculated limits include any margins. The following discussion

on calculation will include consideration of margins.

2.2.1 Overcurrent Relays

These relays respond to a specific value of current which can be converted to a specific load by multiplying by the

operating voltage. However, since current magnitude is sometimes available to operators, it is better to state the load

limit in terms of current. The current load limit is the magnitude of current at which the relay is expected to start

timing towards its trip condition. When considering this limit, it is important to be aware of two factors:

a) The overcurrent relays, line current monitors, and the interposing transducers exhibit finite accuracy.

Therefore it is possible that the relay may operate at a current lower than the set current or the monitored current.

b) The load current may sometimes remain considerably above the steady state level for an amount of time

in excess of the relay operating time. The usual cause of sustained high load currents is cold load pickup, when load

currents may remain at 50% to 100% higher than the steady state value. Overcurrent relays are typically applied on

subtransmission lines that are more susceptible to cold load pickup conditions than transmission lines.

When the above two factors are considered it is clear that the load current limit should include a safety margin. A

margin of 10 to 20 percent is typical if cold load pickup is not a factor. A higher margin is more appropriate if cold

load pickup is a possibility. The trip point load limit (without margin) of an overcurrent relay set to trip at a current I

Annexure- X

Page 3 of 30

SRPC

Highlight


Page 2 March 2001

February 2001

(in amperes), can be expressed in terms of “Trip Point Amps” or as “Trip Point MVA” at a given line to line voltage

VLL (in volts). These values can be calculated by:

Smax = √3 * VLL * I where all values are physical units (1)

Appendix A gives an example of a loadability calculation for a transmission line overcurrent relay.

2.2.2 Distance Relays

These relays respond to an impedance of varying magnitude which depends on the power factor of the load

impedance. Their load limit is normally quoted in MVA, at nominal operating voltage at some specified power factor.

This point is chosen to be conservative enough to exceed expectations of actual line load levels and power factors. The

distance relay definite time delays are usually much faster than those of overcurrent relays; so margins have to allow

for larger transient conditions (with shorter duration) than is the case with overcurrent relays. On the positive side,

since these relays are usually applied on transmission lines which are not exposed to the cold load pickup

phenomenon, such load pickup is not usually a concern.

The most commonly encountered distance characteristic is the mho. Other distance relay characteristics will exhibit

different responses to loading and may be more or less appropriate for use in situations where loading is a problem.

(See Appendix B)

Figure 1 shows the apparent impedance of the load with respect to a distance relay with a forward reaching mho

characteristic.

R

NO TRIP

OUTSIDE

OF CIRCLE

X

q

ZR

ZL

Steady State

Loadability Limit

A pparent steady state

load impedance

in this region

X

f

Figure 1: Loadability calculation for mho characteristic

Annexure- X

Page 4 of 30


Page 3 March 2001

February 2001

When calculating the margin, it is important to consider the effect of the full range of load power factor. (as shown in

the gray area) The impedance reach at the steady state loadability limit ZL (without margin) of a mho characteristic of

known reach ZR, with a maximum torque angle of θ and at a power factor of Cos(φ) is determined by the geometry of

the mho circle as

ZL = ZR *Cos(θ-φ) As shown in Figure 1 (2)

To calculate the power Smax at a given voltage VLL at the positive sequence impedance Z (ohms) at the loadability

limit, the applicable formula is

Smax = VLL2/ Z (3)

When using the above calculated loadability limits for planning or operating purposes, it is important that the user be

advised whether the limits include any margins.

Appendix A gives examples of a loadability calculation for two transmission line mho relays. The above calculations

can be adopted for forward or reverse reaching mho relays as depicted in figure 4.

2.2.3 Current Differential Relays

Current differential relays respond to the differential current formed in the relays using the measurements from all the

line terminals transmitted over a fast communications channel. The differential signal formed internally by the relay to

reflect an internal fault current is compared to a restraint signal. The comparison is made using a multi-slope

percentage characteristic.

Current differential relays are almost completely immune to increased load on a protected line. As the load current

increases, the spurious differential current caused by finite CT accuracy will increase, but at the same time, the

restraining current will increase as well. The percentage characteristic ensures relay stability for any amount of

overload. This scheme is affected by tapped loads on the line. The presence of tapped loads may prevent this scheme

from being utilized on the given line.

Generally, as a rule, the current differential relays are backed-up by overcurrent and/or distance relays (primarily to

back-up against loss of communication channel). Consequently, the lines protected by current differential relays may

face similar loadability problems as those protected by overcurrent relays, stepped distance relays or distance pilot

schemes because of the presence of these backup relays.

2.2.4 Phase Comparison Relays

These relays respond to phase relation between the currents at all the terminals of a protected line. The relation

between the phase angles of the currents is typically checked by monitoring the time alignment between the rectified

currents. In order to reduce the required bandwidth of the communication channel, a single operating signal is often

formed out of three phase currents and the correlation is checked once a cycle (single-comparison relay) or twice a

cycle (dual-comparison relay).

Phase comparison relays have a current level detector which starts the comparison of the local and received pulses.

Due to the potential for misoperation caused by noisy communication, the comparison is normally not activated.

Increasing the starter level detector for increased load will decrease low magnitude fault detection. As the load current

increases, the relationship of the phase angles of the currents at the line terminals remains consistent thereby

preventing false tripping. This scheme is affected by tapped loads on the line. The presence of tapped loads may

prevent this scheme from being utilized on the given line.

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Like the current differential relays, the phase comparison relays are often backed-up by overcurrent and/or distance

relays (to cover loss of communication channel). As a consequence, the lines protected by phase comparison relays

may face certain loadability problems because of the presence of these backup relays.

3. Factors Affecting Line Loadability

3.1 Protective Equipment

When determining the loadability of a transmission line, the limitations due to the protective equipment must be

considered.

3.1.1 Relays

Published relay characteristics are based on the operation of relays within specified limits of environmental conditions

and electrical inputs. The accuracy and sensitivity of relays change (generally decrease) when the relays are operated

outside of the specified limits.

3.1.1.1 Relay Ratings

The ANSI/IEEE C37.90 standard [1] specifies standard service conditions, standard ratings, performance

requirements, and requirements for testing of relays and relay systems used to protect and control power apparatus.

With regard to loadability, the following pertinent ratings should be considered: the standard current and voltage

ratings, maximum design current and voltage at which the relay is designed to be energized continuously, and the total

temperature of relay coils which is the sum of the temperature rise of coils and the ambient temperature.

The effect of higher currents, voltages, and ambient temperature is to increase the total temperature inside the relay.

Higher relay temperatures reduce relay insulation life. Also, the sensitivity and accuracy of the relay most likely will

be decreased. Therefore, from a thermal point of view, if the sensitivity, accuracy, and service life of the relay is to be

preserved, the continuous load current should not exceed the maximum design current at which the relay can be

energized continuously.

If the average ambient temperature in a given installation exceeds the rated ambient temperature, then the continuous

currents and voltages applied to the relay need to be derated to avoid the thermal consequences mentioned above.

3.1.1.2 Overcurrent Relays

The aforementioned standard [1] specifies the standard current ratings, but does not specify the highest current at

which the relay can be energized continuously. Through the years, relays have been designed to meet or exceed the

standard current ratings. Consequently, the margin by which the maximum continuous current exceeds the standard

current rating varies from relay to relay and manufacturer to manufacturer. Typical values of maximum continuous

currents for overcurrent relays are usually 2-3 times nominal tap current. If overcurrent relays are connected to trip,

they usually cannot be subjected to steady state currents greater than their pickup tap setting (because the relay will trip

the circuit shortly after the current exceeds the pickup tap setting). Thus their maximum continuous rating is not

usually a factor in limiting line loadability, unless their tripping function has been disabled to allow more load carrying

capability.

3.1.1.3 Distance Relays

Distance relays are energized by VT voltages and CT currents. The standard voltage ratings, maximum continuous

voltages, and standard current ratings for the relays are specified by the above standard. The maximum continuous

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current is not specified and it varies from relay to relay. Typical values of maximum continuous currents for distance

relays are usually 2-3 times rated nominal current.

The load limit for distance relays is covered in clause 2 “Fundamental Concepts of Loadability”.

3.1.1.4 Directional Power

Directional power relays can be applied on intertie lines between utilities, or between a utility and non-utility

generation. These relays measure voltage and current and then calculate real power (watts), usually to limit power

transfer due to line thermal limitations or commercial purposes. The basis for the setting of the relay becomes the load

limit for the line.

3.1.1.5 Thermal Replica

Thermal replica relays emulate as closely as possible thermal processes in a protected system element. Practically,

they are implemented exclusively as microprocessor-based relays utilizing currents, a temperature probe input, and a

thermal and physical model of the transmission line aimed at calculating the hottest spot temperature based on

available data in order to cause alarms or to trip. This type of relay uses current magnitude, and may also use other

parameters such as the physical properties of the conductor, the effects of solar heating, the estimated wind speed

across the conductor, geographical location (longitude and latitude), ambient temperature (measured), date, and time

of day. Since the velocity and the direction of the air flow in the proximity of the line has a significant effect on the

temperature of the conductors and due to the potential for variation of these factors along the line; several critically

located sensors would be needed. In the absence of these sensors and the communication system needed to

consolidate that data from the sensors, assumptions must be made and margins used to allow for the errors in those

assumptions.

3.1.1.6 Fault Detectors

Fault detectors refer to instantaneous overcurrent relays (usually non-directional) that supervise the operation of

distance relays. In electromechanical schemes, the pick up of the fault detectors should be set above load to prevent

contact wear due to chatter when the current is near pickup. Fault detectors can be set below load for multifunction

microprocessor relay applications.

Some complex relays use the trip-supervising fault detectors to also serve as the fault detectors for the

switch-onto-fault (SOTF) protection. When closing a breaker into heavy line loads, this can cause false (SOTF) trips

if the fault detectors were set low enough to pick up. In this case, SOTF should be supervised by additional logic, such

as undervoltage, to prevent false operation upon picking up load.

Some fault detectors used in microprocessor-based relays utilize the zero- and negative-sequence currents, sense the

incremental positive sequence current (increase with respect to certain historical values), as well as adjust the

threshold for the absolute current levels using an adaptive slow-acting control loop. Such improved fault detectors

used to supervise the distance elements may prevent some false operations due to heavy loading.

3.1.1.7 Remote Breaker Failure Backup

At times, the protective relays on a line may be set to provide backup protection to lines leaving the remote bus. The

increased relay reach required to provide this coverage will reduce the loading permitted by the relays. The

installation of breaker failure and secondary relaying on those remote line terminals may reduce the need for remote

backup allowing for shortened relay reaches and greater load capability on the line.

3.1.1.8 Local Backup Relaying

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Local backup may be viewed as a secondary relaying system that provides backup for a failure of the primary relaying

system. This secondary system typically is set identical to the primary so load limits are not affected unless the

secondary relay has a characteristic that is more susceptible to tripping on load. This system does not cover the failure

of a local interrupting device.

Another form of local backup is the protection for a failure of the local breaker or for a failure of the complete relay

system. Also, as mentioned in the previous clause, local breaker failure relaying provides a means to isolate the fault

„locally‟ thereby reducing the need for a long reaching (and possibly load limiting) remote backup relaying settings.

The fault-detecting relay that is used in the local breaker failure scheme is normally not the load limiting device.

3.1.1.9 Overload Protection of Tie Lines

Unscheduled outages can be a problem with major intertie transmission lines. When such a line is removed from

service by fault or otherwise, the power flow through the rest of the system will likely persist. It is at such a time that

overload conditions on other tie lines and internal lines could occur.

Occasionally overcurrent relays are used to protect tie lines from overloading. When power flows increase drastically,

overload relays can help prevent damage to transmission lines and other equipment. The overcurrent relay

characteristics have to be based on both time and current to prevent false tripping due to short term transient load

excursions. The overload relays must carry maximum load during short time or emergency conditions, without

tripping.

It is not always the line on which the overload relays are installed that could be damaged. Shedding tie line load may

prevent overloading of other transmission lines and equipment in the system. Occasionally the overload sensing of a

transmission tie line is used to transfer trip a transmission line or other equipment in some other part of a system, and

vice versa.

3.1.2 Pilot Systems

Line loading can cause a problem for a specific case of blocking carrier. In a directional comparison blocking scheme

on a three-terminal line, outgoing load can pick up the reverse zone relay on one terminal, thereby sending carrier to

block the other two terminals. If that terminal with outgoing load is a weak fault current source, a fault on the

protected line may not drop out the picked-up blocking. In that case, the other two terminals of the line would remain

blocked and will not pilot trip for the fault.

In phase comparison blocking schemes, current-based fault detectors key carrier at one current level and arm the

comparison tripping logic at a higher current level. Sufficient load to key carrier, but not arm tripping, will not present

a tripping risk, but will operate the carrier and may bring in alarms for sustained carrier keying. Load through the line

(appearing like an external fault) above the comparison tripping level presents a risk of false trip if the blocking carrier

function does not perform correctly each half cycle. This applies to two or three-terminal lines.

3.1.3 Current Transformers

3.1.3.1 Thermal Limits

The CT ratio should be selected so that, for maximum primary load current the secondary current produced does not

exceed the continuous thermal current rating of any part of the CT overall secondary circuit. Most CTs have a nominal

continuous current rating of 1- or 5- secondary amperes, but higher ratings can be specified. These ratings are

specified by the standard rating factor. Values of the standard rating factor are 1.0, 1.33, 1.5, 2.0, 3.0 and 4.0 [2].

Cables and wire leads will usually have a greater ampacity than the CT secondary because other considerations

determine cable and wire size.

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3.1.3.2 Error

Maximum CT ratio error occurs during fault current, not load current, so CT ratio error is not a significant issue in

affecting loadability. However, some low ratio protection CTs may have errors of a few percent even at load currents.

CT accuracy will not be an issue if load limiting relays and meters are connected to the same CTs. However, if the

relays are connected to high accuracy CTs and the meters are connected to low accuracy CTs, the relays may "see"

currents a few percent higher than the meters. In such cases, lines operating close to load limits of relays may actually

be operating somewhat closer to the relay limits than indicated by the meters. The effects of such CT errors along with

other metering errors should be accommodated in the margins discussed in Clause 2.2 of this paper.

3.2 System Factors

3.2.1 Transmission Line Ratings

In the current market environment, utilities are pressured to use the capability of their transmission lines to the fullest

extent by taking advantage of short term ratings, less conservative assumptions, and dynamic ratings. Relays and their

associated settings should be applied with both objectives of protecting the transmission line and making available the

full capacity of the line.

Ratings of overhead transmission lines depend on the maximum temperature which the associated conductors may

reach without exceeding clearance or conductor thermal damage limits. When an increase in current flow occurs on a

conductor, its temperature change follows a time curve determined by the amount of current change, ambient

conditions, and properties of the conductor. Ambient conditions include wind speed, air temperature, amount of cloud

cover, angle of sun in the sky, and various other parameters of the surrounding air.

3.2.1.1 Continuous Rating

In Figure 2, I1 and Temp 1 represent less than critical flow, with a dynamic change to I2 and Temp 2 at critical flow. If

Temp 2 represents the limiting or „critical‟ temperature for which a line is designed, then I2 would represent the

continuous rating of the line and could flow indefinitely. This rating is sometimes referred to as the „normal‟ or „24

hour‟ rating. Line ratings are typically expressed in amperes or MVA.

T ime

Tem

pera

ture

Curr

ent

I1

I2

T ime

Temp 1

Temp 2

Time1

Time2

Time1

Time2

Figure 2: Critical temperature rise for the continuous rating of a line

3.2.1.2 Short Term Rating

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When the current increases are of short duration, a higher current level can exist without exceeding the critical

temperature limit. A typical „short-term‟ temperature rise characteristic is illustrated in Figure 3. Short term or

„emergency‟ ratings of lines are established to identify the level of overload that can be carried by transmission lines

during short time frames which typically vary from several minutes to several hours.

Time

Te

mp

era

ture

Curr

ent

I1

I2

Time

Temp 1

Temp 2

Time1

Time2

Time1

Time2

Figure 3: Typical temperature rise for determining short term ratings

3.2.1.3 Seasonal Ratings

Since the conductor temperature rise is dependent on ambient temperature, different ratings can be established from a

seasonal standpoint on the basis of expected ambient temperatures using probabilistic historic data. Summer and

winter ratings are typically established. In the same way, day and night ratings can also be developed.

3.2.1.4 Dynamic Ratings

The above rating methods are static in nature and are embedded with conservative assumptions to allow for „worst

case‟ conditions. Dynamic ratings are based on actual prevailing conditions as they exist at a given time and, as such,

are typically higher than related static ratings. Determination of line ratings on a dynamic basis requires real time

continuous monitoring of parameters such as conductor temperature or line tension.

It is possible that static ratings of other equipment connected in series with a line such as circuit breakers, switches and

line traps may be less than that of the line itself. In such cases, the facility with the lowest rating will determine the

maximum load that can be applied to the line.

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R

high load

low load

X q

f

trip point

POWER FLOWS OUT

POWER FLOWS OUTPOWER FLOWS IN

POWER FLOWS IN

VARS FLOW OUTVARS FLOW OUT

VARS FLOW INVARS FLOW IN

Q-II Q-I

Q-III Q-IV

Figure 4: Load vs. trip point on R-X diagram

3.2.2 Transmission System Power Factor

Load is practically viewed as MW and Mvars, which can be converted to impedance and plotted as a point on an R-X

diagram as shown in Figure 4. The shaded areas show typical load regions. Lines can be operated with the apparent

load impedance in any of the four quadrants of the R-X plane. (e.g. Quadrant I: REAL POWER FLOWS OUT, VARS

FLOW OUT) As load increases, the apparent impedance decreases, thereby moving the load impedance point toward

the origin, and closer to the mho circle trip characteristic.

The angle of the load current (power factor angle) determines the angular location of the load impedance point and at

what angle φ it would contact the mho trip circle. Power factor (PF) angles typically range from zero degrees to +/- 40

degrees, compared to the relay characteristic impedance angle θ which typically ranges from 60 to 80 degrees. As

shown in Figure 4, the power factor angle affects the loadability. For example, in Quadrant I (POWER FLOWS OUT,

VARS FLOW OUT), as the PF angle increases, the load which can be transferred decreases. One must also be aware

of load in the reverse direction (Quadrants II and III).

For long reaching mho settings, some utilities assume the worst case of the load angle equal to the relay angle. Others

take advantage of a more reasonable assumption such as 32°, 30° or 26° lagging load. For example, this can provide as

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much as 37%, 41% or 52% increased loadability, respectively, compared to using a relay angle of 75 degrees as the

load angle.

3.2.3 Unbalanced Currents

Unbalanced load currents present additional challenges to transmission line protection systems. If one phase is more

heavily loaded than the others, the relay load limit on that phase (due to overcurrent, impedance or mho relay limits)

will result in a lower three phase load than could have been transmitted if all three phases were balanced. Unbalanced

load current also results in zero sequence or negative sequence currents that may appear as faults to sensitive

protection that responds to such quantities. It should be noted that even though the load presented to a transmission

system may be balanced, unbalances in the system impedances may result in unbalanced load currents. Unbalanced

system impedances are most often caused by untransposed transmission lines. The unbalanced currents resulting from

such unbalanced impedances generally become more of a problem as loads become very heavy or if unbalanced

settings are too sensitive.

Most conventional fault study and power flow analysis computer programs usually assume the power system is

completely balanced. Special analytical tools are required to represent the system on a phase by phase basis to

examine the effect of load and system unbalances. Such tools include electromagnetic transients programs (that

perform steady state analysis on a phase by phase basis), and specially written analytical routines on commercial

graphic analysis/mathematical programs. These special tools are not normally used on conventional protective relay

applications. Therefore the first indicator of a load balance problem affecting line loadability is usually undesirable

line tripping during heavy loads. Digital relay event records that include pre-trip recordings will assist in the

identification of such unbalances. Multifunction digital relays may also have spare unbalance current level detectors

that could be used to generate an alarm if sustained unbalanced load current approach the limits of unbalance

protection. These alarms may be used to identify approaching load limits due to unbalance before the limit is found by

line tripping.

One solution to the potential misoperation of neutral and negative-sequence overcurrent relays under overload

unbalanced conditions is to use positive sequence restraint. A portion (from a few percent up to about 15%) of the

positive sequence current magnitude is used to compliment the negative- and zero-sequence operating currents. As the

load increases, the zero- and negative-sequence currents caused by line asymmetry increase, but at the same time, the

positive-sequence current increases as well providing restraint to prevent false tripping.

3.2.4 Multi-Terminal Lines

Transmission line loadability creates additional challenges to adequately protect all terminals of a multi-terminal line

with standard relay reach and time settings. The transmission line protection system must allow maximum load to flow

during short time or emergency conditions without tripping.

The apparent line impedance, as seen by the protective relay can drastically increase due to infeed currents. It is the

effect of the apparent impedance that necessitates the need for high impedance settings, which in turn infringes on

loadability of the multi-terminal line.

Typically Zone 2 elements are set to protect all terminals of a multi-terminal line with the worst infeed conditions.

This means sensing a fault at any terminal and tripping in a definite amount of time. When the load-carrying level has

to be preserved and the distance relay settings cannot be set to protect to the end of each terminal in a reasonable time,

other means must be taken to ensure adequate protection. Sequential tripping or pilot systems can usually solve these

problems. With sequential tripping, tripping speed is sacrificed. This slower tripping has to be weighed against all

other factors. The use of a pilot system can usually solve the problem, but is often the most expensive solution.

3.2.5 Power Swings

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The apparent power flow of a typical transmission line, whose impedance is predominately inductive, is determined

by its reactance and the magnitude and angle of its terminal voltages.

PVs Vr

X

sin (4)

where,

Vs, Vr are the magnitudes of the sending and receiving end voltages.

X is the line reactance.

is the angle by which Vs leads Vr.

Any disturbance to the power system, such as a fault, a load change, or line switching, causes the relative angular

positions of the power generators to change. Because of the inertia of the generators, these changes are oscillatory; the

angles overshoot and swing around before settling down to their new positions. These generator angle swings cause

changes in the angles of the line terminal voltages and result in power flow swings on the lines.

For lines subject to significant power swings, loadability studies must be concerned not only with the maximum

steady-state power flow, but also with the magnitude and duration of power swings. Protective relays must refrain

from operating during stable swings, otherwise unnecessary tripping of sound lines will aggravate the disturbance.

For example, in Figure 5, the line current swings above the pickup level of an overcurrent protective function three

times before settling to a new operating level below the overcurrent setting. If the integrated time above the pickup

level exceeds the relay setting, an unwanted trip will result.

New line load

disturbance

time

cu

rre

nt

pu

Figure 5: Line current swings

In transmission systems, distance relays are more common than overcurrent types and swings can be plotted on an R-X

diagram to determine their proximity to relay characteristics.

If a line is near the electrical center of the swinging system, the apparent impedance seen by the line‟s distance relays

may enter the relay characteristic during power swings. (Figure 6) If the apparent impedance remains within the

characteristic longer than the time delay setting of the zone, an unwanted trip will occur. A transient stability study of

the system is usually necessary to determine the locus of apparent impedance during such disturbances.

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Distance relay

characteristic

Apparent impedance

locus

X

R

Figure 6: Apparent impedance for power swing

Long and heavily loaded transmission lines between load and generation centers are generally much more vulnerable

to such problems than short, metropolitan-area lines between load stations. When there is a risk of unwanted tripping

during stable power swings, auxiliary protective devices providing power-swing blocking (also known as out-of-step

blocking) may be used to ensure security of the distance relaying.

3.2.6 Faults and Fault Angles

In addition to power swings discussed in the previous clause, other factors may affect a relay's performance during

certain load flow conditions. Depending on the type of relay characteristic, load flow combined with fault resistance

may result in incorrect operations for remote end faults and for reverse faults.

For the representative system shown in Figure 7, assume the load flow is from left to right. Then, Figure 8 shows that

the sending end voltage (VS) progressively leads the left bus voltage (VBL), the right bus voltage (VBR), and the

receiving end voltage (VL). Now, consider relay R1 at the left bus and assume that a fault occurs just beyond the right

bus as shown in Figure 7. The fault current from the left end of the line will be derived from the voltage of the sending

end source and the impedance to the fault. The angle of the pre-fault voltage at the left bus and the sending end source

voltage will be different by the load flow angle. Thus, the angle between the left bus voltage and the current will be

different from the true fault angle during the time that the pre-fault voltage is maintained by memory action.

sending

endreceiving

end

fault

R2R1

IL

VBR

VL

VBLV

S

Figure 7: Representative system

The condition described above may have a substantial impact on the apparent impedance of a distance relay. With

pre-fault loading and non-zero fault resistance, the apparent impedance will be different from the actual positive

sequence impedance to the fault. Depending on the type of relay characteristic (mho, reactance, quadrilateral), the

type of fault, and the direction and magnitude of the load flow, the effect could create an underreach condition or an

overreach condition.

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Another condition that could create an incorrect operation is a close-in reverse fault. Consider relay R2 at the right bus

and assume a single-line-to-ground fault with fault impedance at the right bus as shown in Figure 7. Figure 8 shows

the resulting pre-fault voltages with the assumed left to right load flow. In this case, the source voltage (VS) driving

the fault current will lead the initial polarizing voltage of the relay. Although the dynamic coincidence angle

calculated by the relay results in a non-trip condition, the steady-state angle between the relay operating voltage and

polarizing voltage will be less than 900. For some relay designs, this polarizing angle error can cause incorrect

operation on reverse faults.

VBL

VBR

VS

VL

Figure 8: Prefault voltages

In any case, the possibility of operating for an external fault during heavy load flow is extremely undesirable. This

operation could remove unfaulted equipment from service when the system is already stressed to its limit. Certain

relay designs have found ways to reduce the undesirable effects of load flow on relay performance. the protection

engineer should look for cautions in the relay manufacturer documentation related to load flow and settings. To

independently determine the amount and extent of the overreaching on particular relay designs, dynamic testing may

be necessary. This testing may be needed to determine if the steady-state margins generally applied to load

encroachment on protective relays are adequate for a particular zone of protection.

4. Solutions

4.1 Relay Settings

One significant solution to relay loadability issues is the selection of relay settings. The pickup of the relay as well as

the characteristic shape of the affected element can, in most cases, be varied by changing the settings of the relay. The

following is a discussion of how the relay settings can be varied to deal with loadability issues.

4.1.1 Line Coverage

Desired line coverage by distance elements is influenced by many factors including the protection scheme being used,

the measuring characteristics of the relay elements and system configuration. The chosen protection schemes using

distance elements can include non-pilot stepped zone schemes as well as any of several underreaching and

overreaching directional comparison pilot schemes. The characteristic of the distance elements in use can be one of

several different types including impedance, mho, offset mho, reactance, quadrilateral and lenticular. Due to the

varying shapes of these elements, a setting to obtain the desired reach at the line impedance angle can result in varying

sensitivities to load encroachment. System configuration has a large effect on the settings required in these schemes to

get effective coverage. Line length, number of line terminals, distribution transformer line taps and infeeds can all

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require overreaching elements to be set quite long. Obviously, the longer the required relay reach, the more likely a

loading problem can occur.

Using the equation:

Smax = V LL 2 / Z (where Z is the relay reach) (5)

gives a conservative estimate of whether the relay settings will pose a problem or not.

A typical transmission line may employ up to three or more zones of protection for multi-phase faults. These zones

may be employed in a high-speed pilot type protection scheme or in a stand-alone back-up scheme or in portions of

both schemes.

4.1.1.1 Forward Zones

Underreaching elements such as zone 1 rarely encounter a problem from load. If a loading problem were found to

exist for zone 1, the reach can usually be shortened to eliminate it. If zone 1 is used in an underreaching pilot scheme,

an overlap of the opposite zone 1 settings must be maintained. A zone 2 element is always required to reach the

remote bus with a least a 20-30% margin. Setting zone 2 at this minimum reach will not exceed the load limits in most

cases of two terminal lines. Other overreaching zones require much longer settings and are therefore susceptable to

loading problems. They generally exist to provide remote backup protection and tripping sensitivity. These zones

along with multiterminal zone 2 settings must accommodate infeed conditions which cause an increase in the required

reach. If loading is a problem for the overreaching zones they may be eliminated if their role of backup relaying is not

considered crucial. Otherwise, the loading problem must be handled using a selection of relay characteristic shapes,

blinders, load encroachment settings, or other solution.

4.1.1.2 Reverse Blocking Zones

In a directional comparison blocking scheme a reverse looking distance element is used to send block to the remote

terminal. It is set to reach behind its terminal and overreach the remote tripping relay by an adequate margin. Because

of the element‟s reach, it can be susceptible to load encroachment. If this element is only used to send a blocking

signal to the remote terminal it will not directly cause the line to trip due to load. The element could delay or prevent

tripping for internal line faults that would have other adverse consequences. In some schemes the reverse blocking

element also trips through a timer for backup protection. For these schemes, tripping would occur as a result of load

encroachment.

4.1.2 Backup Coverage

For lines with three terminals or lines with taps for distribution transformers, the effects of infeed and apparent

impedance cause overreaching Zone 2 and Zone 3 impedance settings to be increased. This also causes reverse

blocking impedance settings to be increased. As a result, these elements are the most susceptible to load

encroachment.

4.1.3 Breaker Failure

In order for the breaker failure overcurrent fault detection to be sensitive enough to cover at least the protected line, it

is often necessary to operate with the detector picked up constantly at times of heavy load. This is not usually a

problem as long as the breaker failure relay time delay is initiated by protective relay tripping and adequate time is

provided to allow overcurrent fault detector to reset after the breaker interrupts the fault. The specifications for the

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fault detector relay should be checked to make sure that the level of load current does not exceed the continuous rating

of the relay.

4.2 Dealing with Transients

By definition, transients are short time phenomena. If the transients result in measured parameters that enter the

operating characteristics of an instantaneous relay, it will trip. If the parameters enter the operating characteristic of a

time delayed relay it will trip only if no other protection or control action is taken to move the system conditions

outside the characteristic. The dual approach for line protection dealing with transients is to ensure that:

1. Measured parameters do not enter the operating characteristic of instantaneous protection

2. Time delayed protection is coordinated with other protection and control systems which are intended to

relieve the transient condition to an extent where the measured parameters do not enter the relay‟s operating

characteristics.

The following will consider the various measured parameters that may affect line protection systems.

4.2.1 Voltage

Transient voltage depressions usually have more significant effect on line protection systems than transient

overvoltages. Voltage depressions are often an indicator of a stressed or faulted system. If they are caused by a

faulted system, proper time coordination of the main and backup protection systems will ensure satisfactory operation.

However, if the voltage depression is caused by severe overloads, special protection systems, or operator action will

normally be required to deal with the problem. The line protection system will:

a.) either have to coordinate with special protection systems (if they exist),

b.) or be applied, and set, such that the maximum voltage depression during transient overload conditions will

not cause the measured parameters to enter the operating characteristics of the line protection system.

This second requirement means that protection systems should be applied and set such that the steady state operating

characteristic will not respond to voltage depressions during heavy overloads for which no automatic remedial action

is expected. It should be noted that low voltages on transmission systems are often accompanied by high reactive

power consumption that may cause the power factor of the load impedance to take on an unusually low value. Figure

9 from [6] shows the change in apparent impedance in two different types of load ((a) and (b)) as the voltage is varied

from 1.1 p.u. to 0.8 p.u..

Annexure- X

Page 17 of 30

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February 2001

(a)

(b)

R

X

0.8

0.8

1.1 1.1

Figure 9 - Change in apparent impedances due to voltage changes.

It can be seen from Figure 9 that the change in apparent impedance is very dependent on the relationship of load

impedance to voltage. One phenomenon that can cause significant voltage depression is that of stalling motor loads.

Motors may stall due to slowly cleared faults [4] or slow voltage recovery following fault clearing. The increased

reactive power drawn by stalled motor loads can depress transmission voltages and cause load impedances to enter the

characteristics of long reaching distance relays.

The use of a lower than normal voltage (1.0 to 0.8 p.u.) to calculate the load limit of the distance relays; Smax =

VLL2/Z, clause 2.2.2; will compensate for the undervoltage condition that could occur with an overload condition.

4.2.2 Thermal Load

Thermal overload conditions may or may not result in voltage depressions, but are the result of unusually high

currents. Transmission lines are often able to withstand moderate overloads for several seconds, or even minutes.

Although short circuit protection is sometimes set to protect a line from overload, it is not the best way to provide such

protection. Short circuit protection (such as Zone 3 elements of distance relays) can never be expected to coordinate

with the thermal overload capability of transmission lines. If lines are expected to be able to sustain temporary

overloads, either adequate operator control should be ensured, or specifically designed thermal overload protection

should be applied (see clause 3.1.1.5). The thermal overload protection should be able to coordinate as much as

possible with the temporary overload capability of the protected line.

4.2.3 Load Angle

Very heavy loads resulting in high load angle across a transmission line may cause certain types of distance relays to

become blind to remote phase to phase short circuits[3]. In this situation, the security of the line protection is not

threatened as much as the dependability to sense all faults in the protected zone. For this reason, transient conditions

that result in a high load angle, without associated voltage depression or thermal overload can usually be tolerated until

operator action can reduce the load angle.

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4.2.4 Outages – Three Phase and Single Phase

Transmission line outages due to temporary faults are usually restored to normal by automatic reclosing. Tripping

may be single phase or three phase.

In the case of three phase tripping, parallel circuits may be temporarily overloaded, or may be subjected to reduced

voltages or high load angles or swings. In such cases, the comments noted above regarding those transient conditions

become applicable.

In the case of single phase tripping, the faulted line is still able to carry a portion of load, and possibility of problems

due to high (balanced) load in parallel circuits is reduced. However, while the single phase is open, the surrounding

power system is subject to a certain amount of unbalance, and line protection in adjacent or parallel circuits (such as

negative or zero sequence overcurrent protection) may misoperate due to the unbalance resulting from load flow

through the faulted line [5].

In such cases, the sensitive unbalance protection must be time delayed to coordinate with the reclosing and maximum

expected pole discordance time of the line with single phase tripping.

4.3 Protective Equipment

There are several features and options that may be available in protective equipment which can allow a protective

device to be less sensitive to load current while still providing the desired fault protection settings.

4.3.1 Distance Relay Characteristic Shape

A lenticular, rectangular, or even more sophisticated characteristic enables a relay to protect the line, provide

maximum resistive fault coverage, and still avoid overlapping with the load regions on the impedance plane. This

applies to underreaching zone 1, as well as to overreaching zones 2 and 3, and the reverse zone used by distance

blocking pilot schemes and for remote breaker failure. Appendix B discusses the different characteristic shapes in

more detail.

4.3.2 Use of blinders

A blinder is an element of a distance relay that can be used to restrict the operating characteristic of the relay. One

common blinder is a straight line characteristic on the R-X diagram and generally at an angle from 60 to 90 degrees

positive from the R axis. The straight line is positioned to limit the resistive reach of the distance relay. Another type

of blinder has a more complex characteristic that restricts the operation of the distance relay in an area near the R axis.

Both types of blinders are typically used in combination with a mho characteristic. The combination of the mho

characteristic and a blinder is set to protect the line and limit the area of tripping for steady state conditions in the

region of load and therefore reducing the limitation the distance relay would have on line loading. Figure 10 shows

both types of blinders applied with a mho relay. Typically only one type of blinder would be used in a given

application.

Annexure- X

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February 2001

R

X

Blinder No. 1

Blinder No. 2

Figure 10: Blinder characteristics

If the mho and the blinder characteristics are produced by two different relay functions the combination may have

different reaction times to changing fault and load conditions. The transient reaction of the combination may lead to

greater difficulties with transient overreach for a fault just beyond the length of the line with previous heavy load flow.

Care must also be taken that a stable fault swing after heavy load flow does not activate a mho relay implementing

blinder characteristic. Creating both the mho and blinder characteristics with algorithms in a single microprocessor

relay removes this concern.

4.3.3 Power Swing Blocking

Transmission line distance relays are susceptible to tripping on stable and unstable swings where the apparent

impedance presented to the relay enters the operating characteristic. Where operation of the line protection due to

swings could cause undesirable consequences, the protection may be supplemented by additional protection

(out-of-step protection) to detect the swing condition. The out-of-step protection is usually set to detect the swing

before the short circuit protection would operate. The out-of-step protection may be used to block the distance

protection and/or to trip the line at an optimum line angle. When out-of-step protection blocks a line trip, it should be

ensured that the out-of-step condition will be eliminated by some other means of separating the two asynchronous

sources. Thus out-of-step blocking is often only applied in association with out-of-step tripping at some other

preferable separation point. (see clause 3.2.5)

Transmission line protection systems that depend on a phase comparison or differential protection technique will not

sense swings that are centered in the protected line. Out-of-step tripping protection may be used to supplement

differential or phase comparison protection where line opening on an out-of-step condition is required.

A typical out-of-step blocking scheme uses two separate regions on the impedance plane and monitors the timing of

the apparent impedance entering the two regions (outer and inner). Fast movements indicate a fault, slow transitions

indicate a power swing. The problem is that the two zones must have finite size difference. The outer region may

overlap with the region of increased load. A distance relay with out-of-step blocking will require more room to keep its

out-of-step outer zone between the regions of increased load and inner line impedance.

Annexure- X

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February 2001

4.3.4 Adaptive techniques

In many microprocessor-based relays, settings can be changed using setting groups to accommodate system

conditions (e.g. load level, generators or lines in/out of service). At the present time, adaptive techniques that

automatically modify settings according to measured system conditions have not been widely used.

4.4 Systems

Loadability must be considered when designing an overall system. All aspects of the design, the operations, the

automatic systems, and the protection system must coexist and work together to fulfill the overall design criteria. The

intent of the transmission planners, the purpose of the operating constraints, and the protection system limits all have

to be considered when trying to satisfy a loadability limit.

4.4.1 Planning

With respect to transmission line loadability, it is prudent for the design of a protection system to be closely

coordinated with the planning of transmission facilities. If additional terminals to the surrounding transmission

network were proposed to be added to a transmission line, the proposed terminals will introduce short circuit current

infeeds to the line. If a transmission line is protected by a directional comparison pilot protection system supervised

by impedance elements, the new terminals will necessitate an extension of the reaches of these impedance elements. If

this extension of impedance relay reach results in an undesirable decrease in line loadability, then another type of

protection system (i.e. phase comparison instead of directional comparison) must be considered.

4.4.2 Controlled Flows on Lines

Reconfiguring the power system can often control load flows to reduce an overload condition on a transmission line.

Phase shifting transformers or other modern flexible ac transmission technology techniques may also be used to

control the load flows on transmission lines.

4.4.3 Load Shedding

When transmission lines become severely overloaded, it may be necessary to shed load in order to maintain integrity

of the power grid. Load shedding can be accomplished by manual load shedding, automatic load shedding (e.g.

undervoltage load shedding), or via SCADA.

4.4.4 Series-Compensated Lines

Series Capacitors (SCs) have become an important element in economical long distance power transmission. The main

purpose for using SCs is to decrease the effective inductive reactance of a power line. The following benefits can be

achieved:

increased power transfer capability (Figure 11).

improved power system stability,

reduced system losses,

improved voltage control,

better power regulation.

Annexure- X

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Page 20 March 2001

February 2001

series compensated line

00 22.50 450 900 112.5 0 1350 1800

POWER ANGLE

P1

XL - line reactance

67.50 157.5 0

PO

WE

R

P2

plain line

XC - capacitor reactance

- power angle

LX

sVrVP max

CXLX

sVrVP

max

Figure 11: Comparison of the loadability of uncompensated and series compensated lines

The cost of increasing line loadability by installing SCs, compared to constructing a new equivalent line, is usually in

the order of 15-30%. The amount of series compensation is typically limited to 60-70% of the line reactance in order to

avoid undesirable subsynchronous oscillations. The series capacitance can be installed entirely in one location, either

in the substation or someplace along the line (typically mid-line). Otherwise, the series capacitance is split between

several (typically two) banks of capacitors installed at both ends of the line.

Series capacitors are normally equipped with both automatic and manually operated bypass facilities to protect the

capacitors from overvoltage during faults and to enable operation of the line while the capacitors are out of service.

Protective relaying for series compensated lines must be capable of accommodating the maximum power transfer with

the capacitors in service, yet also be able to detect faults at the remote end of the line with the capacitors bypassed.

Since series compensated lines are usually long lines, special attention is needed to be sure that the selected line

protection will not limit the load transfer capability of the line.

Annexure- X

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5. Summary

The essential goal of relay system design with respect to loading is to ensure that no unintended relay operations occur

during conditions created by system load. The fundamental definitions of relay load limits are discussed. Calculations

of limits are covered for the most common relay types. Examples of calculations for overcurrent and mho impedance

type relays are provided in Appendix A. These calculations are made to assure that the relays will not trip under

maximum load conditions.

Beyond the fundamental issues, many factors that have the potential to limit loading need to be considered. Some of

these factors are directly related to the relays. These include not only the settings, but also the choices of relays and

relay schemes. Many system factors will also affect the application and performance of relaying systems. Included are

line ratings, loading, power factors, load balance, and multiterminal connections. The effects of swings and faults are

also included.

Once the problems related to loading are outlined and discussed, the next step is to begin to address them. The

solutions discussed are accomplished through relay settings, selection of equipment, and design of schemes applied to

prevent load problems on relaying systems. Many times, careful planning and control of the system operating issues

can help prevent load problems from occurring.

Annexure- X

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February 2001

6. Appendix

Appendix A: Overcurrent Relay Loadability Calculation Example.

The following is an example calculation of the loadability limit for a 60 kV line with a tapped maximum distribution

load of 40 MVA plus transmission load through a remote terminal and with a phase overcurrent relay set to start at 800

A primary. It is assumed that the 800 A setting of the overcurrent relay cannot be increased due to the need to provide

dependable protection for short circuits under all contingencies.

If a 50% margin is required to ensure the ability to pick up cold distribution load tapped onto the line simultaneously

with the ability to carry transmission load (through the remote terminal of the line), and a 20% margin is required for

the transmission load, the following loadability results are obtained.

The maximum distribution load current is

AI d 3853*60

000,40

The required allowance for distribution load current with 50% margin gives a need to allow 1.5*385 = 577 A for

distribution load.

Remaining allowance for through load = 800-577 = 223 A

and allowing a 20% margin for through load, additional loadability for through load is

AI t 1862.1

223

And the total loadability for the line including margins for tapped 40 MVA distribution load and through load is then

given as Id+It = 385 + 186 = 571 A

A current of 571 A corresponds to approximately 59 MVA at 60 kV.

Thus the loadability of the line protection system could be stated as “571 A, or 59 MVA at 60 kV, including margins”.

The loadability of the protection system could be of concern if it was lower than the rated loadability of the line.

Mho Distance Relay Loadability Calculation Examples

Example 1 Consider a mho distance relay with a maximum torque angle of 75° set with a reach of 100 ohms

primary protecting a 230 kV transmission line. Assume it is not possible to reduce the reach setting of the relay, and

no special load blinding characteristics are applied. Also assume that it is desired to calculate the loadability at the

nominal voltage of 230 kV assuming a worst case load power factor of 0.866 (30° lagging) and with a safety margin of

80%. That is, the relay is not expected to reach greater than 80% of the minimum impedance presented by the load

with a power factor of 0.866. If planning studies indicate that the overload condition could be associated with an

undervoltage condition, a voltage lower than nominal should be used for the calculation.

Reach of relay at an impedance angle of 30° Zr = 100 * Cos (75-30) = 70.7 ohms.

Minimum allowable load impedance is therefore 70.7 / 0.8 = 88.4 ohms.

Maximum allowable loading with margin, is 2302 / 88.4 = 600 MVA (approximately).

Annexure- X

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February 2001

Example 2 A certain 138 kV line has recently been rated for 346 MVA under emergency or peak conditions.

The company requires a 5% margin for relay pickup at 30 degree power factor. One end of the line has a relay with a

forward looking mho setting of 90 ohms at 82 degrees. The setting is checked as follows:

Zr = 90 * COS (82-30) = 55.4 ohms

1382 / 55.4 = 344 MVA (approximately)

This value is below the desired rating of 346 MVA. Working backward using the 5% margin:

346 * 1.05 = 363 MVA

1382 / 363 = 52.46 ohms

Zr = 52.46 * COS(82-30) = 85 ohms

The setting is being used as remote back up. A reduction in the pickup from 90 to 85 ohms can be accommodated

without any serious problems.

Appendix B: Fundamentals of Distance Relays

Distance relays are a family of relays that determine whether or not the impedance from a relay location to a fault is

within the operating characteristic of the relay. The relays accomplish this by using the magnitude of voltage and

current, and the phase angle between the two. The characteristic of this relay type can be described using a

resistance-reactance (R-X) diagram. Some of the distance relays are better at handling heavy line loads than others.

Since the first type of distance relays used were impedance relays, the terms distance relay and impedance relay are

sometimes incorrectly used interchangeably. The basic impedance relay‟s characteristic when plotted on an R-X

diagram is a circle around the origin. The relay is non-directional, so it was most often used with a directional unit.

The combination of the impedance unit and the directional unit produces a tripping area inside the circle of the

impedance unit that occupies all angles within the first quadrant and parts of those within the second and fourth

quadrants. (Figure 12) This type of distance relay is more sensitive to heavy loads than other distance relays. The

relay‟s sensitivity to faults on the protected line and its sensitivity to load in the forward direction are equal. (Note

that the forward direction is here defined by current flowing from the substation where the relay is located.)

Annexure- X

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February 2001

X

R

low load

high load

trip pointq = 750

f

Figure 12: R-X diagram for directional impedance relay showing load vs. trip point

The offset impedance relay is a modification of the basic impedance relay. The characteristic of the offset impedance

relay is a circle with the center offset into the first quadrant. (Figure 13) The chord of the circle that passes through the

origin and the center of the circle is at the angle of maximum reach for the relay. This angle is set at or near the line

impedance angle. If the line impedance is R + jX, the line angle is the arctangent of X/R. The higher the voltage of the

line and the larger the line conductor, the larger the line angle.

jX

R

Figure 13: Offset impedance characteristic

Although the offset impedance relay is more sensitive in the forward direction than in the reverse, it still has some

reverse sensitivity so it must be used with a directional unit or be time delayed. The decreased sensitivity of the offset

impedance relay in the forward load area makes it better that the impedance relay for line loadability.

The mho relay reach characteristic is similar to that of a completely offset impedance relay. Its steady state

characteristic is a circle that passes through the origin. (Figure 14) The maximum reach of the relay is set at or near

the angle of the line impedance. No additional directional unit is required because the mho relay is inherently

directional.. The reduced reach of the mho relay along the R axis allows greater loadability of the protected line than

an impedance relay does.

Annexure- X

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February 2001

jX

R

Figure 14: Mho characteristic

A reverse offset mho relay is a mho relay with the center of the circle offset in the direction of the origin. The offset

mho relay, like the offset impedance relay, has a zone of sensitivity to faults in the reverse direction. The offset mho

relay is applied in cases where it is important to include the origin in the trip zone and the unit is time delayed.

A forward offset mho relay is a mho relay with the center of the circle offset away from the origin. A forward offset

mho characteristic can provide good backup protection for remote forward resistive faults, without the load

encroachment problems of a mho element with no forward offset. Figure 15 shows a forward offset mho relay used in

conjunction with a mho element.

R

X

Forward

Offset Mho

Mho

Figure 15: Mho and forward offset mho characteristics

For shorter lines the impedance and the offset impedance relays provide limited fault resistance coverage. For short

line applications the type of distance relay called a reactance relay is used. The characteristic on a R-X diagram is a

line drawn parallel to the R axis in the first and second quadrant. The distance the line is away from the R axis is

determined by the setting reach of the relay. The reactance relay is directional but its reach in the resistive direction is

Annexure- X

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February 2001

only limited by the energy requirements of the unit. This makes the reactance relay very sensitive to load. To correct

for this limitation, the relay is used in conjunction with a mho or an offset impedance relay to limit the resistive reach.

(Figure 16)

jX

R

ZONE 3

ZONE 2

ZONE 1

Figure 16: Self-polarized Mho and reactance characteristic

A variation to the reactance relay is a quadrilateral relay. With the quadrilateral relay the limit of its reach in the

resistive directions are straight lines on a R-X diagram instead of using a mho element. (Figure 17) The reach in the

area of forward load flow is limited by a discrete setting on the relay.

jX

R

ZONE 1

ZONE 3

ZONE 2

Figure 17: Quadrilateral characteristic

The mho relay characteristic can be described by measuring the angle between the operating phasor of (IZ - V) and the

phasor (Vpol). Where I is the line current, Z is the reach of the relay at the maximum reach angle, V is the voltage at the

relay location, and Vpol is the polarizing voltage. When the characteristic is defined by the angle being 90 degrees,

then the characteristic is a circle. If the characteristic is defined by an angle between the phasors being greater than 90

degrees, the characteristic has a lenticular (lens) shape. (Figure 18) The lenticular characteristic allows increased

loading on the line compared to the true mho relay but also has less sensitivity to faults with fault resistance.

R

jX

Figure 18: Lenticular characteristic

Annexure- X

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February 2001

7. References

[1] IEEE C37.90-1989 (R1994) IEEE Standard for Relays and Relay Systems Associated with Electric Power

Apparatus

[2] IEEE C57.13-1993 IEEE Standard Requirements for Instrument Transformers

[3] R.J. Marttila, “Effect of Transmission Line Loading on the Performance Characteristics of Polyphase Distance

Relay Elements”, IEEE Trans. on Power Delivery, Vol. 3, No. 4, Oct. 1988, p 1466-74.

[4] B.R. Williams, W.R. Schmus, D.C. Dawson, “Transmission Voltage Recovery Delayed by Stalled Air Conditioner

Compressors,” IEEE Trans. On Power Systems, Vol.7, No.3, Aug. 1992, pp. 1173-78.

[5] Estergalyos, J. –chairman, “Single Phase Tripping and Auto Reclosing of Transmission Lines-- IEEE Committee

Report”, IEEE Trans. on Power Delivery, Vol. 7, No. 1, Jan. 1992 p 182-192.

[6] IEEE Power System Relaying Committee Working Group, "Summary of System Protection and Voltage

Stability," IEEE Transactions on PowerDelivery, Vol 10, No 2, April 1995, p 631-638.

8. Bibliography

M. Mir, “Adaptive vs. Conventional Reach Setting of Digital Distance Relays,” Electric Power Systems Research,

Vol. 43, 1997, p 105-11.

S. Pickering, “Application Benefits of Numerical Distance Protection,” 49th Annual Texas A&M Protective Relay

Conference Apr 15-17, 1996.

J. Roberts, E.O. Schweitzer, R. Arora, E. Poggi, “Limits to the Sensitivity of Ground Directional and Distance

Protection,” 49th Annual Texas A&M Protective Relay Conference Apr 15-17, 1996.

T. Yanagihashi, S. Kumano, T. Nomura, T. Kubo, M. Hatata, E. Ibaragi, I. Mitani, “Improved Protection Relays to

Cope With Changes in Power Transmission Networks and Their Operating Conditions,” CIGRE, Paris, Aug 28-Sep 3,

1994, Paper No. 34-201.

G. Sweezy, G. Swift, R. Coish, “A Delta-Current Admittance Relay For Line Loadability Enhancement,” 21st Annual

Western Protective Relay Conference, Oct 18 - 20, 1994.

G.E. Alexander, J.G. Andrichak, W.Z. Tyska, “Relaying Short Lines,” Texas A&M Protective Relaying Conference,

Apr. 15-17, 1991.

A.T. Giuliante, J. Gosalia, G.K. Clough, “A Multi-Processor Approach to Distance Protection,” Western Protective

Relay Conference, Spokane, WA, Oct. 22-5, 1990.

J. Crockett , W.A. Elmore, “Performance of Phase-to-Phase Distance Units,” Texas A&M Relay Conference, Apr.

1987.

A. T Johns, A. A. El-Alaily, “New Distance Protective Relay With Improved Coverage for High-Resistance Earth

Faults,” Proceedings of the Institution of Electrical Engineers. (Great Britain), Vol. 124, No. 4, April 1977, p 349-55

Annexure- X

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February 2001

W. D. Humpage, J. Rushton, “Power-System Studies for the Determination of Distance-Protection Performance,”

Proceedings of the Institution of Electrical Engineers (Great Britain), June 1972, Vol. 119, No. 6, pp. 677-688

G.E. Alexander, J.G. Andrichak, W.Z. Tyska, S.B. Wilkinson, “Effects of Load Flow on Relay Performance,” Texas

A&M Relay Conference, April 1986.

Gary C. Bullock, “Cascading Voltage Collapse in West Tennessee – August 22, 1987”, 17th

Annual Western

Protective Relay Conference October 25, 1990

Annexure- X

Page 30 of 30

S.

No

Name of

Substation Details of work Status of Implementation of Protection Audit Recommendations Remarks

S.

N

Name of


PLCC protection panels for Srisailam and Chalakurthy are not

available. Provision for the same to be done

Shall be provided.

Latest Update vide mail on 01-02-2016:

PLCC Protection panels Erection is under the Scope of TSTRANSCO.

The issue was discussed in PCSC-51 held on 25-02-2016 and it was made clear that the responsibility of complying

with this recommendations lies with TSGENCO.

Pending

PLCC panel is erected but not commissioned

It will be reviewed.


Procurement is in advance stage (Order is going to be placed by TSTRANSCO)



Pending

S.

N

Name of

SubstationDetails of work Status of Implementation of Protection Audit Recommendations Remarks

S.

N

Name of


Phase-II

1 220 KV

Srisailam

Project SS

Review of certain Protection Audit Recommendations of SR-Constituents

APGENCO (HYDEL)

PLCC: No carrier protection coupler is available in 220 kV

station feeders

Provided for Tallapally-1&2 feeders and will be procured and commissioned for remaining feeders by 31-08-2015.

APGENCO Mail received on 09-02-2016:

Provided for Tallapally-1&2 feeders and will be procured and commissioned for remaining feeders (under

APTRANSCO scope).


with this recommendations lies with APGENCO.

Pending

5 220 kV Jurala

Generating

Station

3 220 kV N'Sagar

TSGENCO

Phase I

Phase I

Phase I & Phase-II

1 400 kV

Srisailam LB

S/S (Gen)

TSTRANSCO

PlCC 48 V DC single battery set is available. No redundant

battery set with charger. Failure may affect carrier protection

and real time data loss to the system operator due to

communication Equipment power loss


Will be reviewed at site and procurement action will be initiated accordingly.



Pending

Annexure- XI

Page 1 of 3

10 400kV side of

400/ 220 kV

Gajwel

SubstationReplacement of PLCC panels of 400 kV Ramagundam line to be

done


Under PGCIL Scope. PGCIL authories have informed that the panels will be replaced soon as their indent for

material is under process.


with this recommendations lies with TSTRANSCO.

Pending

S.

No

Name of


2 400 kV

Palakkad SS

[PGCIL (SR-

II)]

Outsource supply supplied from 11 kV Para feeder is having

low reliability and hence alternate arrangements to be made for

reliable supply.

Latest Update as on 24-08-2015:

The tertiary supply from ICT#2 erection completed. Request for availing aux supply is being processed by KSEB.

The issue was discussed in PCSC-51 held on 25-02-2016 when PGCIL (SR-II) informed that they had started

availing supply from the tertiary of ICT # 2 from 3rd week of Jan, 2016.

Complied

S.

No

Name of


1 400 kV NTPC

Ramagundam

S/S (Gen)

Distrubance Recorders (ABB, INDACTIC) not having GPS

time synchronisation (for 400 kV Warangal Line, 400 kV

Gajwel Line, 400 kV Malkaram Line, 400 kV Hyderabad Line #

3, 400 kV Hyderabad Line # 4), 400 kV Dichipalli Numerical

relay (DR) not having GPS time synchronisatiion.

a) These disturbance recorders are connected to a PC. The PC has now been time synchronized through GPS. The PC

synchronizes the DRs with the batch process (WINCOM) on regular basis. - Complied

b) 400 kV Dichipalli Numerical relay (DR): Time synch problem has been taken up with APTRANSCO, the owner

of the equipment. - Taken up with APTRANSCO : Dec-15

The issue with regard to time synchronisation of Dichipally feeders numerical relay was discussed in PCSC-51 held

on 25-02-2016 and it was made clear that the responsibility of complying with this recommendations lies with

TSTRANSCO. It was also agreed to drop this remark from the scope of NTPC-Ramagundam and include it under

TSTRANSCO scope.

NTPC - Complied;

TSTRANSCO - Pending

S.

No

Name of


The Line CVT in the Y phase of the feeder was not available in

all the feeders except SP koil 2 : To be reviewed

Communicated to TANTRANSCO.

The issue was discussed in PCSC-51 held on 25-02-2016, and it was made clear that the responsibility of complying

with this recommendations lies with MAPS (NPCIL).

Pending

S.

No

Name of


Phase-II

NTPC

PGCIL

(Phase I & II)

2 230KV MAPS

Kalapakkam

S/S (Gen)

(Phase I & II)

NPCIL

(Phase I & II)

OTHERS

Annexure- XI

Page 2 of 3

a) Distance protection, Zone- 4 timing adopted was: 1.2 sec;

Recommended 0.9 sec

GMR mail received on 09-09-2015:

As per telephonic advice by DE power system the settings retained as same because this was envisage and corrected

during commissioning by AP Transco Officials with concern of DE power System.


GMR have submitted a letter to APTRANSCO seeking the permission to issue an Approval for setiings

recommended by the protection audit team.


Settings as per CE-IPC & Power System.

The issue was discussed in PCSC-51 held on 25-02-2016 and the forum had agreed to the settings adopted by GMR

as suggested to them by APTRANSCO. And the item was dropped.

Dropped

f) Synchro check (29) Adopted: ON; Recommended: OFF








GMR informed that they would adopt the recommedned setting in presence of APTRANSCO officials.

Pending

For 220kV Line #2 Distance protection, Zone-4 timing adopted

was: 1.2 sec; Recommended : 0.9 sec











Dropped

5 220 kV GMR

Barge,

Kakinada S/S

(Gen)

In 220 kV line # 1, main # 1 & 2 protection relay following deviations observed:Annexure- XI

Page 3 of 3

Annexure-XII

Page 1 of 96

S. No Name of


Distance protection relay settings, power swing

block settings to be reviewed for 220 kV linesImplemented. Complied

Disturbance recorder, Station Event logger and

GPS to be made available

Procurement action is initiated and will be procured by 31-03-2015. Commissioning will be completed by 31-05-

2015.


Tender Process completed and Placing of Purchase Order was kept on hold for want of clearance from NLDC

regarding grant of funds.

APGENCO mail received on 29-02-2016:


regarding grant of funds. Procurement will be completed by 6 months, and Work will be completed within 6 months

thereafter. Hence total time extension required is upto Dec-2017. (Estimated that funding process will be completed

within one year.

Pending

In Tallapalli feeder-1 (P442) relay configuration

of voltage protection, CB failure are disabled. It

is also noticed that KZ RES component and

angle different from approved settings. Same to

be reviewed

Complied

In N.Sagar line (P442) relay configuration of

voltage protecgtion, CB failure and interval auto

reclose configuration disabled instead of enable

mode. KZ RES component and angle different

from approved setting. Same to be reviewed

Complied

All static relays like distance relay, differential

relay and Bus-Bar relays to be replaced with

latest version numerical relays having inbuilt

D.R

Procurement action is initiated and will be completed by 31-03-2015.Commissioning of the same will be completed

by 31-08-2015 subjected to availability of Line Clear.







thereafter. Hence total time extension required is upto Dec-2017.

Pending

STATUS OF IMPLEMENTATION OF PROTECTION AUDIT RECOMMENDATIONS

APGENCO (HYDEL)

Phase-I

1 220 kV Srisailam

Separate LBB is available and hence Breaker failure is not enabled. Over voltage protection is not required as per

APTRANSCO and hence not implemented. KZ resistive component settings are verfied with APRTANSCO and

found correct.

Annexure-XII

Page 2 of 96

Earth resistance measuring instrument to be

procured.Procured. Complied

The Generator differential protection, GT O/C+

E/F protection , GT REF Protection, Overflux

protection , UAT O/C + E/F protection settings

to be duplicated and provided in Main-2 relay

for increasing the reliability.

Procurement action is initiated and will be completed by 31-03-2015.Commissioning of the same will be completed

by 31-08-2015 subjected to availability of Line Clear.








Pending

Older version of unit 4 Main-I & II relay (REG

316*4) relay to be replaced with REG 670 or

other similar relay as provided for other units

Already replaced with new ABB make REG-670 type protection relay panel for both Main-I and Main-II in February-

2014 and is in service.Complied

GPS to be provided for time synchronization of

protection system

GPS already procured along with SCADA and will be commissioned with switchyard SCADA latest by 31-03-2015.








Pending

1 220 kV Srisailam

2 220 kV Srisailam

power station

(right bank)

Annexure-XII

Page 3 of 96

S. No Name of


Station Battery is recently commissioned. It is a

single source mDCV & charger. No stand by is

available.

Back up supply is arranged from power house by laying a cable.


Backup supply is arranged from power house battery system by laying a separate cable as a temporary

measure.However proposal is also made for procurement of new battery set with Battery charger in PSDF-DPR and

will be procured and commissioned within 12 months, after getting grants from PSDF.


Backup supply is arranged from power house battery system by laying a separate cable as a temporary measure.

However proposal is also made for procurement of new battery set with Battery charger in PSDF-DPR and the

Procurement will be completed by 6 months, and Work will be completed within 6 months thereafter. Hence total

time extension required is upto Dec-2017.

Pending

Phase-II

1 220 KV Srisailam

Project SS

Pending

All 220 KV CTs were replaced with 0.2 class CTs except for 2 two feeders. For these two feeders CTs replacement

will be taken up shortly.


1. A total of 10Nos. CBs were replaced with new ones and 4 Nos. were proposed for PSDF funding.

2. A total of 33Nos. CTs were replaced with new ones and 24 Nos. were proposed for PSDF funding.

Balance items will be completed within 12 months from obtaining clearance of grants from PSDF.


1. A total of 10Nos. CBs were replaced with new ones and 4 Nos. were proposed for PSDF funding.


Procurement of balance items will be completed by 6 months, and Work will be completed within 6 monhts


Station fault level data is not

Displayed/Available in the station. Old

equipment like CT's and CVT's to be upgraded

to new one to suite existing fault.

Annexure-XII

Page 4 of 96

Protection

PLCC: No carrier protection coupler is available

in 220 kV station feeders

Provided for Tallapally-1&2 feeders and will be procured and commissioned for remaining feeders by 31-08-2015.


Provided for Tallapally-1&2 feeders and will be procured and commissioned for remaining feeders (under

APTRANSCO scope).


with this recommendations lies with APGENCO.

Pending

CT accuracy class is 0.5. As per standards the

CT accuracy to be higher than the energy meter

accuracy class.

Will be procured and replaced by 31-08-2015.


Material already procured for all units. Replacement was completed for Unit-1. Replacement work is in progress for

other units and will be completed by March-2016.

Pending

DG SET: Earlier DG set of 800 KVA was

available. Now no DG set is available due to

submerged in heavy floods in 2009. It is

recommended for 1 MVA DG set to self start

the units during block start facility & quick

restoration.

Will be procured and replaced by 31-12-2015.



regarding grant of funds. Work will be completed within 12 months from obtaining clearance of grants.





Pending

APGENCO (THERMAL)

Phase-I

1 220 KV Srisailam

Project SS

2 220 kv Srisailam

Right Bank Power

House

(7x110MW)APG

ENCO

All Bus PTs are replaced with 0.2class accuracy CVTs. All old CTs of Units, power transformer and bus coupler are

replaced with 0.2 class SF6 CTs. Old line CVTs for two 220 KV feeders will be replaced with 0.2 class CVTs

available at site and expected to complete by 31-08-2015. For remaining CVTs procurement is in progress.


1.Complete set of 12Nos. Bus PTs were replaced with new ones of 0.2 class accuracy.


3. A total of 6 CVTs were replaced and 18Nos. were proposed for PSDF funding.

Balance items mentioned above will be completed within 12 months from obtaining clearance of grants from PSDF.


1.Complete set of 12Nos. Bus PTs were replaced with new ones of 0.2 class accuracy.


3. A total of 6 CVTs were replaced and 18Nos. were proposed for PSDF funding.

Procurement of balance items will be completed by 6 months, and Work will be completed within 6 months


Accuracy class of Bus PT's line CVT's and CT's

of units and power transformers are of 0.5 class

for metering core. As per Standards the CT-PT

should be on higher accuracy class than energy

metering accuracy class.

Pending

Annexure-XII

Page 5 of 96

S. No Name of


All static relays on feeders to be replaced with

nemerical distance relaysPending

The static Bus Bar Protection to be replaced

with numerical relaysPending

Station Event logger to be madefunctional Pending

GPS time synchronisation of relays shall be

made available.Pending

Earth fault/Strips in 220 KV Switchyard are

rusty, to be bituminous painted.Implemented Complied

DC earth leakage in station DC supply to be

rectified.Rectified Complied

Station Transformer Relays (EE Make, DTH31

Model) to be replaced with Numerical Relays

All the existing Station Transformer EE make, DTH31 model static relays of ST-1 to ST-5 were replaced with

Schneider make Numerical RealysComplied

In stage-I (Units-1&2) Back-up Impedence

Protection, Earth Fault Protection to be

reviewed

Implemented Complied

In stage-3 (Units-5&6) Non directional Earth

Fault Protection, Phase over current protection

settings in UAT to be reviewed.

Implemented Complied

1 220 kV

Rayalaseema TPS

Procurement of material is under progress. Expected time is 31-05-2015.

Latest update as on 14-09-2015:

Procurement of materials are under process. (SAPPO No.4500008292, Dt:ll.08.2015 was placed for Static Relays.

Bus Bar Protection PO will be issued before 30-09-2015) Expected time of Implementation is 31-12-2015.


Procurement of materials are under process.

1. SAP PO No.4500008292, Dt: l1.08.2015 was placed for Numerical Relays. Expected time of Implementation is

31-12-2015.

2. Bus Bar Protection PO under process. Expected time of Implementation is 31-03-2016.


Procurement of materials are under process.

1. SAP PO No.4500008292, Dt: l1.08.2015 was placed for Numerical Relays and materials recieved at site.

Expected time of Implementation is 31-03-2016.

2. SAP PO No.4500009417, Dt:10-02-2016 placed for Bus- Bar.

2 220 kV

Vijayawada TPS

Annexure-XII

Page 6 of 96

S. No Name of


1 400 KV- Dr.

NTTPS, Stage-IV,

400 KV Switch

yard. VTSStandby LT AC Supply (DG Set) is not

available for Switchyard Protection System.

Standard LT AC supply is available from EMC Board. Since Dec- 2014.

Latest Status Updated (as on 10-04-2015):

Standby LT AC supply to 400kV switchyard protection system is availed by extending supply from AC Emergency

Board at 8.5 m of main plant, duly laying cable.The work was completed during December-2014

Complied

Standby LT AC Supply (DG Set) is not

available for 220 kV Switchyard Protection

System.

Procurement of one no. DG set of capacity of 320 kVA is under Process. Expected time of completion is 31-03-2015.


Standby LT AC supply to 220 kV switchyard protection system is availed by extending supply from Emergency

Board of Stage-II, duly laying cable.The work was completed on 16-02-2015.

Complied

Only 220 V DC Source with one battery set is

available for entire 220 kV SS.It is

recommended to have redundant DC source.

Redundant 220 kV DC supply is available from station Battery Bank. Complied

Sl.

No.

Name of

SubstationObservations/Remarks Status of Implementation of Protection Audit Recommendations Remarks

The static distance protection relays available on

220KV feeders are to be replaced with latest

numerical relays with inbuild DR

Tenders are called for Procurement of Material.


4 Nos. 220KV feeder panels allotted on 27-10-2015 and 6 Nos. allotted on 21-01-2016.

4 Nos. feeders panels were replaced. Balance works for 6Nos. are under progress.

Pending

GPS to be provided for time synchronisation of

protection system.



Tenders are called for Procurement of Material. Tender analysis is in progress. Work will be completed soon after

receipt of the material.

Pending

APTRANSCO

Phase-I

1 220KV Bommur

Substation

REF is not used in APTRANSCO for 220KV

Substations

APTRANSCO requested to drop the item in view of clearance problem and constraint of place that would crop up at

Bommur SS for providing REF protection.

The issue was discussed in PCSC-48 held on 29.10.2015, when it was pointed out that REF as main protection for

clearing earth faults is required not only from system security point of view, but also mandated by CEA’s “Technical

Standards for Construction of Electrical Plants & Electric lines” under Regulation 43 (2) (c). Further, as

APTRANSCO was a party to the protection carried out, PCSC forum felt that REF protection should be provided at

Bommur SS.


At present differential protection is used as main protection and O/C and E/F protection as a back up protection for

Power Transformers which is in practices of APTRANSCO till now. Further APTRANSCO has requested to drop

this audit item vide lr. No.982r.273 dt.5-5-2015. The problem of implementation is not only with providing of REF

relay it is also needs to replace the Power Transformer.

As it is an old 220/132 KV Substation at Bommur considering the practical difficulties /aspects it is once again

requested to drop this audit item as it is not effected the protection security of the Power Transformer.

Pending

Phase-II

2 220 KV- Dr.

NTTPS, Stage-I,

220 KV Switch

yard. VTS

Annexure-XII

Page 7 of 96

Static distance relays of Main-I&Main-II on

220KV rajampeta feeder to be replaced with

numerical relays.

Tenders are called for Procurement of Material


Replaced with new GE make panel with different make Main I and Main II on 08-09-15Complied

Event logger for recording od sequence events is

not available.same shall be made available.





Pending

Time synchronisation equipment not

available.same shall be made available.





Pending

Auto reclosure to be made functional for 220 kV

feeders.

On 220KV feeders Auto recloser function not used in APTRANSCO system.


Prior to the protection audit APTRANSCO has not adopted Auto reclosure function at 220KV feeders. However the

recommendations of protection audit will be implemented by providing of the same.

Tenders are called & bid analysis is under progress. Work will be completed soon after receipt of the material.

Pending

Surge monitors to be made available for LA's on

LV side of auto Transformer-1&2.

PTR-II surge monitor replaced. PTR-I under progress.


For 100MVA PTR-II surge monitors were replaced. For 100MVA PTR-I LV side surge monitors are provided duly

replacing LAs.

Complied

Carrier aided trip to be made available for

220KV Tiruvalam & Kalikiri feeders.

Chittoor - Tiruvelam protection available, drawn for 220kV Kalikiri and working. Protection equipment diverted

towards Kalikiri direction and to be commissioned.


Commissioned on 18-11-2014

Complied

Necessary Surge moniters on LA's to be

provided where they are not availble.Provided. Complied

Insulations mats infront of the control panel to

be provided.Provided. Complied

All static distance relays of feeders shall be

replaced with numerical distance relays.



Static relays are available for main - I (ABB Make RAZFEE type) and Main - II (ABB Make RAZOA Type) for 220

KV Dhone - I feeder. 1 No. 220 KV C & R Panel is required. Static relays are available for main - I (ABB Make

REL316), numerical relay is retrofitted and for Main - II (ER make THR4PE1 type) for 220 KV Gooty RS feeder

and 220 KV Gooty RTSS feeder. 2 Nos. C & R panels required. Static relays are available for main - I (ABB Make

REL100) numerical relay and for Main - II (ABB make RAZOA type) for 220 KV Shapuram feeder. 1 No. C & R

panels required.

1 No. 220KV feeder panel already allotted & 3 Nos. 220KV feeder panels allotted on 03-02-2016.

Erection works are under progress. LC is required for completion.

Pending

2 220KV

Chinakanpalli SS

3 220KV Chittor

Substation

4 220kV Gooty

Substation

Annexure-XII

Page 8 of 96

Event logger for recording of sequence events is

not available.Same shall be made available





Pending

GPS time synchronisation equipment not

available.Same shall be made available.





Pending

Provision of additional 220kV battery charger.

Provided battery charger.


Provided battery charger on 23-07-2014

Complied

Provision of Air conditioning to the control

Room to be done.



Estimate sanctioned. Tenders to be called for.


Works under progress.Works will be completed shortly.

Pending

GPS time synchronisation of relays shall be

made availble.





Pending

The carrier aided tripping not available in

220KV Nagari feeder.

Under procurement.






Pending


feeders.





Tenders are called & bid analysis is under progress.

Work will be completed soon after receipt of the material

Pending

Surge monitors for 220KV CK Palli(R-Ph) nad

Nagari(B-ph) to be replaced.Replaced Complied

220V battery charger to be made functional. Replaced & under functional condition since Feb 2013 Complied

deffective surge moniters to be replaced. Replaced Complied

possibility of differential or distance protection

to be provided for 132KV Grindwell Norton

feeder and 132KV railway-I&II feeders.

New C&R panels erected and commissioned. Complied

5 220kV Ongole

Substation

6 220KV Renigunta

sub station

4 220kV Gooty

Substation

Annexure-XII

Page 9 of 96

Eroded flexible copper earthing provided

between CTs and structure of LV1 & LV2 of

220/132kV Transformers to be rectified.

Rectified on 26-03-2013 Complied

Surge monitor in Yph of 132kV srikalahasti

feeder to be rectified/ replaced.Replaced on 18-11-2013 Complied

Oil leak noticed in 100MVA 220/132kV BHEL

MAKE PTR to be rectified.Rectified on 02-09-2013 & arrested oil leakage Complied

PLCC equipment on 220kV Gummidipudi

feeder to be replaced/ retrofitted.

Inter State feeder (to be projected).


Procurement of PLCC equipment is under process by Telecom Wing at Head Quarters


Material will be drawn and from Gunadala stores commissioned by 30-09-2015.


New PLCC link along with Protection coupler was commissioned on 14.10.2015 at Sullurpet end.

Complied

Enabling of Auto recloser in all 220kV feeders.



On 220KV feeders Auto recloser function not used in APTRANSCO system and will be taken as per the instructions

of System Protection Wing.


Work completed on 19.12.2015 by duly commissioning GE make new panels.

Complied

8 220kV Tadikonda

Substation Dual earthing for CTs and CVTs 220kV VTS-1

feeder to be done.


Completed on 17-06-2015Complied

Carrier aided trip to be made available 220KV

palamaneru feeder.Equipment diverted and commissioned on 19-11-2014. Complied


feeders.





Tenders are called & bid analysis is under progress.

Work will be completed soon after receipt of the material.

Pending

10 400 kV Kalapaka

Distance protection relays to be replaced with

with numerical relay with inbuild DR facility.





Pending

Provision to be made for having different make

distance relays for Main I & Main II protection

for Srisailam 400kV feeders, 220kV AP

Carbides I & II ,220kV Brahmanakottur feeder,

Somayajulapalli I & II .



1 No. Main I static relay replaced with 400kV SSLM-replaced on 24-01-2015 numerical relay.

Complied

7 220kV Sullurpet

Substation

9 400KV Chittor

substation

11 400kV Kurnool

(Nannur)

Substation

Annexure-XII

Page 10 of 96

63 MVAR Bus reactor (TEED-I) Seimens make,

Model 7UT613 the actual settings in "Power

System Data 2" is different from approved

setting by APTRANSCO.

Reviewed and recommended relay settings are adopted. Complied

Pole Open Current for S1,S2 and S3 approved

setting is 0.10 and actual is 0.2. This is to be

reviewed.


All 220kV side LBB relay time setting adopted

is 100ms instead of approved setting (200 ms ).

This is to be reviewed.


400kV Kurnool (Nannur)-Gooty feeder Main-I

protection on SEL-421, the "Out-of-step

tripping/blocking" settings are different from

approved settings. This is to be reviewed.

APTRANSCO informed that this line pertains to PGCIL (SR-I), and requested for dropping it from the list.

The issue was discussed in PCSC-48 held on 29.10.2015, when PGCIL (SR-I) informed that they had already

reviewed the referred settings, and adopted the adopted settings. As such, the PCSC forum agreed to drop the

item.

Dropped

All static relays are obsolete models which are

recommended for replacement with numerical

relays.





Pending

The existing DR's and EL are obsolete models

and it is breakdown condition, which is to be

replaced immediately.





Pending

REL 100 ABB Make Distance Relay in 5

feeders (400kV and 220kV APTRANSCO

feeders) are obsolete model needs to be replaced

with new version.





Pending

Time synchronising of protection system

through GPS is to be provided unit for 400kV

and 220kV protection system.



Tenders are called for Procurement of Material. Work will be completed soon after receipt of the material.

Pending

Proper/balanced load staggering for 48 V DC

Supply to be done.Rectified Complied

11 400kV Kurnool

(Nannur)

Substation

Annexure-XII

Page 11 of 96

12 400KV Vemagiri

Substation

Provision for under frequency and df/dt

protection to be reviewed.

APTRANSCO requested that item be dropped considering that the relays are only provided on the identified feeder

and not for all substations.

The issue was discussed in the special meeting of PCSC held on 19.08.2014, and the forum agreed to drop the

Item.

Dropped

Sl.

No.

Name of

SubstationObservations/Remarks Status of Implementation of Protection Audit Recommendations Remarks

No LAs are available in 132 KV Pakala (3

No.s), 132 KV Irala (1 No.) and 132 KV

Palmner-I (1 No.)

Erection work is under progress.


Material allotted.1No. LA for 132KV Palamaneru-I feeder is provided. For 132KV Pakala and Irala will be kept

soon.Delay is due to sheet rock. Erection work will be completed shortly.

Pending

Heavy oil leak noticed in 100 MVA ASGEN

make, B-Phase, 220/132 KV Auto Transformer-

II and 50 MVA, APEX make 132/33 KV Power

Transformer.

Rectified Complied

Most of the Structures of CTs and Breakers are

single earthed only.


On 1st phase additional earthing is provided to 33kV yard equipments. Additional earthing will also be arranged for

remaining equipments shortly.


Double earthing for all CT's & breaker are completed.

Complied

It is suggested to replace the existing

STANDARD make battery with similar type of

other VRLA HBL battery with change over

switch arrangement. Also it is suggested to

provide Station battery exclusively for 33 KV

feeders

Work is under progress


Replaced with new VRLA Battery.

Complied

Possibility of introducing DC I&II source

separately to the 220KV and 132KV system to

be explored.

Under examination and indent for providing second DC source is under prepration.


1 Number of battery set is allotted. Commissioning of battery set is under progress.

Pending

Possibility of providing temparature controlled

atmosphere for control room for protecting

numerical relays.


Proposal for providing ACs in control rooms under preparation.


The following works are involved:

a) Providing of cable duct in the middle of the control room.

b) Difficulty in removal of twisted cables, which needs extra length of cables.

C) Thermal insulation wall panels are required.

Works are under progress

Pending

Phase-II

1 220 KV Chittoor

SS

Annexure-XII

Page 12 of 96

2 220 KV

Renigunta SS Possibility of introducing DC I&II source

separately to the 220KV and 132KV system to

be explored.



The Exide battery set with Amararaja Charger is meant for 132 KV system.

The Enersys battery set with Amararaja charger is meant for 220KV system which is provided on 15-10-2015.

Complied

Annexure-XII

Page 13 of 96

PROTECTION

It is noted that in Srisailam 400 kV Line (Main

CB & Tie CB), Future Bay (Tie CB), are having

PIR units removal of sameto be examined

(presence of that may lead to mal operation)

APTRANSCO informed that so far no problem faced with PIR in Tie-CB, and requested to drop the item.


Item. Dropped

Earth Resistance

Carrier aided protection for 220 KV lines to be

provided as per Grid Code.

Protection equipment diverted and to be commissioned.


Commissioned on 29-11-2014 & 18-12-2014

Complied

PLCC Battery

In ULDC equipment, 48 V DC supported

thriugh Single Battery Bank. It needs to be

examined and arrange for redundant battery

bank.


Redundant battery bank arranged and work completed.Complied

3 400 kV Kurnool

(Nannur) s/s

Annexure-XII

Page 14 of 96

220 KV feeders are not provided with Protection

Coupler. Provision of Protection Coupler for

(Carrier Inter-Tripping) 220 KV feeders to be

examined.

Procurement of the equipment is under progress.




Pending

220 KV PODILI – I & NELLORE Feeder

breakers are having provision of only one Trip

Coil (very old breaker-1980). Provision of new

breaker with 2 Trip Coil to be examined.

Replaced with new breaker. Complied

100 MVA Power Transformers OLTC Remote

operations are to be rectified. (Only local

operations available).

Rectified Complied

220 V DC source has only one battery set with

0ne chargers available. Provision of additional

one more battery set with two more battery

chargers to be examined.



Separate DC source was provided for 220 kV and 132kV newly commissioned feeders. For OLKD feeder panels and

Circuit Breakers there is no provision for 2 Nos. separate DC source connections. Hence it is provided for new

commissioned feeders only.


2nd battery set was commissioned on 14.03.2014 and 2nd battery charger of 200AH capacity was provided on

14.03.2014. 3rd charger was commissioned on 09.02.2015.

Complied

PLCC for 220 KV feeders phase to ground

coupling only available, for reliable data and

communication phase to phase coupling is to be

examined

Under execution.




1) 1 No. Wave trap commissioned on 26.11.2014 at Narasaraopet towards Podili.

2) 2 Nos. wave traps were commissioned at Podili towards Narasaraopet on 21.11.2015 and Markapur on 23.11.2015

1 No. wave trap was commissioned at Marakapur towards Podili on 02.12.2015.

Complied

220 KV feeders are not provided with Protection

Coupler. Provision of Protection Coupler for

(Carrier Inter-Tripping) 220 KV feeders to be

examined, so that auto re close scheme can be

implemented.

Under procurement




Carrier aided protection schemes were commissioned to 220KV Parchur - I & II feeders on 27.03.2015.

Procurement of the equipment for other feeders is under process.Tender analysis is under progress.

Works will be completed soon after receipt of material.

Pending

Only one source of station supply is available,

providing one more source for station supply to

be examined.



Provided on 26-04-2014. Complied

Mostly Numerical Relays are available for all

feeders. Provision of Air conditioning to the

Control Room to be examined.

Tenders called for Procurement of Material.


Work is under progress. Work will be completed shortly.

Pending

4 220 kV Ongole

Substation

5 220kV Podili

Substation

Annexure-XII

Page 15 of 96

220KV Cable duct is not available. all the

cables are seems to burried. Duct to be provided

at the earliest.

Work is under progress.


Work is under progress. Work will be completed shortly.

Pending

The dropper jumper between strung bus and the

equipments of the 132kv feeders are seem to be

long. to be provided with support wherever

necessary.


Completed. Complied

Carrier aided protection not availble in 220kv

feeders. to be provided.


Carrier aided protection providedComplied

20V DC source 2Nos. available. 1no Is

connected to 220kv and 132kv system and

1no.is connected to 33kv system. Possibility of

dc source i&ii seperately for 220kv and 132kv

system to be explored.







Separate DC source was provided for 220KV and 132KV newly commissioned feeders. For old feeder panels and

Circuit breakers there is no provision for 2 Nos. separate DC source connections, hence it is provided for new


Pending

In all the 220KV feeders, only phase to groung

coupling is used. Providing phase to phase

coupling to be examined for reliable of data

transfer and communication.

Under execution


Commissioned in Septemper 2014

Complied

All the 220KV feeeders were not provided with

carrier inter-tripping. Providing of the same to

be examined along with auto-reclosure scheme.

Under procurement




Procurement of the equipment is under process.PQB analysis is under progress. LOI will be issued by 08.03.2016.

Work will be completed soon after receipt of the material.

Pending

In the Yard, cable ducts were filled with sand.

Providing clean cable duct (without sand) and

replacement of broken slabs to be examined.

Rectified. Complied

Only one DC source (220V) available for

220KV feeders and 220/132KV Power

Transformers. Providing additional exclusive

DC source to be examined. Alternate source is

available from DC source -2 meant for 132KV

feeders and 132/33KV PTRs.

Under examination.






Separate DC source was provided for 220KV and 132KV newly commissioned feeders. For old feeder panels and

Circuit breakers there is no provision for 2 Nos. separate DC source connections, hence it is provided for new


Pending

6 220 KV Sullurpet

SS

7 220 kV

Tadikonda

Annexure-XII

Page 16 of 96

Mostly numerical relays were available for

feeders/PTRs. Hence provision of air-

conditioning to the control room to be

examined.

Tenders called for Procurement of Material.


Estimate sanctioned at zonal level. Tenders to be called for.


Works under progress. Work will be completed shortly.

Pending

S. N Name of


Configuration of SAS to be completed early for

Quick analysis of trippings.

Procurement of material is in progress and the work will be completed by the end of August 2015.


Purchase Order was placed on M/s. ABB India Ltd., Bangalore and the work will be completed by the end of August

2015.


Purchase Order was placed on M/s.ABB India Ltd., Bangalore. As per PO the Material received & erected and

waiting for licensed software from M/s.ABB.work will be completed by the end of 31.03.2016.

Pending

Possibility of separate GPS for 400 KV Switch

yard control room to be provided



Purchase Order was placed on M/s. ABB India Ltd., Bangalore and the work will be completed by the end of August

2015.


Purchase Order was placed on M/s.ABB India Ltd., Bangalore. As per PO the Material received & erected and

waiting for licensed software from M/s.ABB.work will be completed by the end of 31.03.2016.

Pending

Possibility of separate GPS for 400 KV Switch

yard control room to be provided



Requisition is under process towards Procurement of material vide Enq. No.5220282 dtd: 19-02-2015 and the work

will be completed by the end of August 2015.


The equipment offered by the vendors were not suitable for our requirement. Hence another indent raised on

propriatary basis for Intelliogent Modular System LANTIME M3000-IMS with GPS-DHQ time base. Will be

completed by 30.06.2016.

Pending

Directional Earth Fault settings of Lines may

reviewed on par with GT Back up O/C and

Earth Fault Relay.

Revision of settings under progress and the work will be completed by the end of March 2015.


Completed and Settings of lines are reviewedComplied

Station event logger to be made available

As a part of implementing the PhaseI Audit recommnendations all the existing relays are proposed to be replaced

with latest numerical relays in which the event logger facility is available.


As a part of implementing the Phase-I, Protection Audit recommnendations all the existing relays were replaced with

latest numerical relays in which the event logger facility is available.

Complied

No GPS is available. Time sync facility not

available. Same to be provided

Finalization of purchase order is under progress and will be procured by 30/04/15 and will be commissioned by

31/06/15.


GPS is already Procured and Installed. For extending GPS Time Sync to existing relys is under process. Tender

Floated and ordering will be completed by 31.03.2016, work to be completed by end of May 2016.

Pending

1 400 kV Kakatiya

TPP

2 400 kV KTPS VI

Switchyard/

Paloncha -

Kothagudem

3 220 kV N'Sagar

7 220 kV

Tadikonda

TSGENCO

Phase I

Annexure-XII

Page 17 of 96

No A/R feature and no O/V feature is available.

Same to be provided

A/R and O/V feature are available in the proposed new relays.


Existing relays were replaced with latest numerical relays and A/R and O/V feature are available in new relays

Complied

There is only 3-phase tripping. No I-phase

tripping. Same to be reviewed and provided

I-phase tripping facility is avaliable in proposed new relays.


Existing relays were replaced with latest numerical relays and I-phase tripping facility is avaliable in new relays.

Complied

Sync facility available in Main-1 relays of all

feeders except Talapalli-3. Same to be provided

Synchrozisation facility will be provided during commissioning of new relays.


Existing relays were replaced with latest numerical relay and Sync facility is available in new relay.

Complied

Mutual compensation for Talapally 1 & 2

feeders is not available. The same to be

reviewed.

Mutual compensation facility is avaliable in proposed new relays.


Existing relays were replaced with latest numerical relays and Mutual compensation facility is avaliable in new

relays

Complied

PLCC protection panels for Talapally 1, 2,3 are

to be commissioned.Completed. Complied

PLCC protection panels for Srisailam and

Chalakurthy are not available. Provision for the

same to be done

Shall be provided.


PLCC Protection panels Erection is under the Scope of TSTRANSCO.



Pending

All Electro Static Relays to be replaced with

latest version Numerical relays (This work is

covered below)

Completed. Complied

110V/220V DC source earth to be removed. Completed. Complied

Over Flux Relays to be provided for IBT and ST

Transformers.Completed. Complied

Time synchronisation equipment (GPS) to be

provided for protection system



Procurement under process. Will be completed by 31.06.2016.

Pending

The old RAZOA (Electro Static) relays to be

replaced with latest version Numerical relaysThis work is covered above. (Completed) Complied

Provision of differential protection for Jurala

line 1 & 2 (line length-1.45 KM) feeders to be

examined.

Shall be provided.


Will be Examined during the commissioning of latest numerical relays in place of existing relays. System

Protection/TSTRANSCO views will be sought and will be reviewed on this issue.

Pending

Main 1 & 2 distance relays to be of different

make and type for 220kV lines. Same to be

implemented.

It will be implemented and material procurement is under progess.


The material was procured and commisioning will be comleted by the end of February 2016.

Pending

3 220 kV N'Sagar

4 220 kV KTPS SS

A,B,C Unit (1-8) -

Kothagudem

5 220 kV Jurala

Generating

Station

Annexure-XII

Page 18 of 96

The inbuilt disturbance recorder available in

numerical relays to be activated

Existing china make relys are going to replacd with indegenius relays in which the Disturbance recorder is available.


The Material was procured and Existing relays will replace with latest numerical relays, in which the Disturbance

recorder is available. This will be completed by the end of February 2016.

Pending

In adopted distance relay setting for Main 1 &

Main 2 for Jurala Line 1 & 2 one of the settings

of piolet directional protection i.e. PIL -

Dis.resist ROZ is 0.24 ohms whereas

recommended setting is 18.05 hms which is the

major deviation.

It will be corrected.


It will be corrected. The existing relays are going to replace with latest numerical relays. Latest settings given by

System Protection/TSTRANSCO will be adopted. This will be completed by end of February 2016.

Pending

In bus bar protection settings recommended

setting for charge exit differential is on, whereas

adopted is Off. This is to be reviewed.



Charge exit Differential is OFF During BUS BAR Testing, and it is made ON.

Complied

Instrument for earth resistance measurement to

be made available

Shall be procured.


Will be procured.

Pending

DC earth leakage in DC system to be rectified Already rectified Complied

PLCC panel is erected but not commissioned



Procurement is in advance stage (Order is going to be placed by TSTRANSCO)



Pending

GPS time synchronisation for 220 kV switch

yard protective relays to be provided

Shall be provided during new relays commissiong.


GPS is already Procured and Installed. For extending GPS Time Sync to existing relys is under process. Tender


Pending

S. N Name of


One set of 48 V DC Battery set is available for

PLCC. Another set to be provided.Completed Complied

Separate DG set is not available, but same to be

provided.



Procurement under process. Will be completed by 30.06.2016.

Pending

Only one set of 48 V DC battery set is available

and another set to be provided. This work is already covered above. (Completed) Complied

2 400 KV KTPP

Switchyard

(Bhupal Pally)

Separate DG set is not available for 400 KV

Switch yard control room. Same to be provided

for reliability.



Procurement under process. Work will be completed by the end of July 2016.

Pending

5 220 kV Jurala

Generating

Station

Phase II

1 220 KV KTPS SS

A,B,C Unit (1-8) -

Kothagudem

Annexure-XII

Page 19 of 96

1 set of 48 V DC Batteries is only available.

Another set to be provided.



Battery is under commissioning. Will be completed by the end of Feb-2016.

Pending

Separate DG set is not available for 400 KV

Switch yard control room. Same to be provided

for reliability.



Procurement under process. Work will be completed by the end of June 2016.

Pending

4 Nagarjunasagar

Main Power

House (220kV)Replacement of Old CB,Las,CTs,CVTs and PTs

etc.

procurment of CTs ,CVTs, CBs and PTs and L A s are under process and shall be replaced with new ones by

29/02/16.


All old CB's were replaced with new CB's. For LA's PO was Placed. CT's and PT's were procured and available at

site.CT's & PT's will replaced during units shut down period. CVT's were replaced with new CVT's for 2 Feeders and

for remaining 3 Feeders Material were Procured.

Pending

S. N Name of


Power setting is 7.5% instead 20% Pn

(approved) for excess power condenser mode

relay in unit protection. This may be re

examined.

TSGENCO mail received on 14-09-2015:

7.5% EXCESS POWER SETTING IS STILL BEING FOLLOWED.


The recommended setting of 20% is over 3 Ph rated power, for combined 3 Phases. Where as the settings of 7.5% is

over 3 Ph power, but for single Phase. Hence Combined setting thus would come around 22.5% (7.5 X 3), which is

par with recommendation of 20%.

Pending

It is observed that the time setting knob of Dead

Machine protection Relay is indicating …..

Position instead of 0.5 position. This may be re

examined and rectify same for correction

settings.


PRESENTLY KNOB POSITION IS CHANGED TO 0.5.Complied

Setting of stub protection function in distance

relay may be re examined as setting varying

from approved and actual.


ALL APPROVED SETTINGS GIVEN BY SYSTEM PROTECTION DIVSION FOR ALL THE 400KV FEEDER

HAS BEEN ADOPTED FOR BOTH REL670 AND MICOM P442 NUMERICAL RELAYS.

Complied

Timing of Zone-2 Relay setting for Nunnar is

0.5 sec., Mamidapally is 0.6 sec. and VTP-S

earlier it was 0.6 sec. now reconfigured to 0.5

sec. as approved and actual, it may be re

examined




Complied

Setting of X IPP. XIPE values of Main-II

Distance relay in phase selection function of

VTPS-1&2 deviation in values from adopted is

observed this may be re examined.




Complied

3 400 KV KTPS VI

Switchyard/Palon

cha - Kothagudem

Phase I & Phase-II

1 400 kV Srisailam

LB S/S (Gen)

Annexure-XII

Page 20 of 96

It is observed in all feeders Main-I (REL100)

Relays are available except VTPS-II. This is the

obsolete model and support for taking prints of

settings and Disturbance records etc. It is

recommended for latest version of numerical

relays for better performance and protection

analysis.

Completed Complied

Disturbance recorders (ABB Make Indactic) are

available but not in working condition. These

Disturbance recorders are obsolete model.

Material received at site and Commissioning will be completed by 31/08/15.


DISTURBANCE RECORDER AND EVENT LOGGER CAN BE TRACED FOR BOTH REL670 (MAIN I) AND

MICOM P442(MAIN II) FOR ALL FEEDERS.

Complied

Event loggers are available but not time

synchronised due to non-availability of GPS

Material received at site and Commissioning will be completed by 31/08/15.


GPS IS AVAILABLE AND SYNCHRONISED WITH BUSBAR PROTECTION ONLY.


GPS is Installed and Synchronised with BUS BAR Protection Relays.. For Remaining Relays Tender Floated and

ordering will be completed by 31.03.2016, work to be completed by end of May 2016.

Pending

Bus bar is having static Relay. This may be

examined for numerical graphical representation

with time resolution up to milli sec. related to

the disturbances.

Completed Complied

Generator Protection id displaying only fault

data records, but no graphical representation

with time resolution upto milli sec. related to

the disturbances.


DR IS NOT AVAILABLE.


AREVA Make LGPG111 type Relay employed for which

DR IS NOT AVAILABLE. However the same will be taken care during next replacement.

Pending

No relays are synchronised due to non-

availability of GPS.

Material is already available and .Commissioning will be completed by 30/08/15.


GPS IS AVAILABLE AND SYNCHRONISED WITH BUSBAR PROTECTION ONLY.


GPS IS AVAILABLE AND SYNCHRONISED WITH BUSBAR PROTECTION. For Remaining Relays Tender


Pending

Condition monitoring of LA's through

measurement of leakage current may be carried

out.


Leakage currents are being monitored periodically and are found satisfactory.Complied

1 400 kV Srisailam

LB S/S (Gen)

Annexure-XII

Page 21 of 96

Battery:

Load sharing in DC source is 30% and 70%. At

present it is shared in such a way that DC 1 is

feed untill 1, 2 and GIS, where as DC2 is Unit

No.3,4 5 & 6 failure of DC2 may affected the

units (3,4,5&6) and failure of DC1 may affect

GIS, units (1&2). This may examined and

redumdant supply may be recommended.


When DC1 and/or DC2 failed, Battery Bank(BB-I and BB-II) will feed the respective supplies for a minimum period

of 15 hours.

Complied

110 V DC is not hot stand by, it is through

manual operation. This may be examine for

automatic changer to avoid time delay in

restoration.


Our charager is FCBC charger in which auto change over feature is not available and cannot be provided.(Already

discussed with Original Equipment Manufacturer.


Our charager is FCBC charger in which auto change over feature is not available .(Already discussed with Original

Equipment Manufacturer). However, during next replacement ,the same will be incorporated.

Pending

Plcc 48 V DC single battery set is available.

No redundant battery set with charger. Failure

may affect carrier protection and real time data

loss to the system operator due to

communication Equipment power loss


Will be reviewed at site and procurement action will be initiated accordingly. Pending

It is observed that no evidence of earth

resistance for 49 V DC is available and nopt

having practice of measuring earth resistance. It

is also noticed that no earth resistance

measuring instruments is available.


Earth resistance measurement instrument is availableComplied

1 400 kV Srisailam

LB S/S (Gen)

Annexure-XII

Page 22 of 96

S. N Name of


Replacement of existing Static Relays provided

for Distance Protection, diff protection with

numerical relays

Materials procurement is under progress. Probable date of completion is October 2015.

Latest Status update (as on 09-11-2015):

PTR C& R Panels, Feeder C&R Panels procured and allotted to the substation for commissioning.


New C&R panels are commissioned for transformers and feeders with relays having IEC 61850 protocol.

Complied

Replacement of 220 kV Dind-1 & 2

Mamidipally and Hial feeder control panels to

be reviewed

220kV Dindi-I & II and Mamidipally control panels replaced with ERL Panels with numerical Relays IEC 61850

communication Protocal. Replacement of remaining panels are under consideration and was included in the DPR.

Probable date of completion is October 2015.


220kV Dindi- I and Mamidipally control panels replaced with ERL Panels with numerical relays IEC 61850

communication Protocol. Feeder C&R Panels procured and allotment issued.


Panels replaced.

Complied

220 kV Ghanapur-2 feeder annunciation module

to be made functionalRectified Complied

The Relay panels of different bays are scattered

in different rooms and monitoring of the same is

very difficult. Hence re-arrangement of relay

panels in main control room to be examined for

proper monitoring.

The re-arrangement of relay panels in existing control room is not possible and it requires entire modification of

existing building.


Panels are placed in the best possible manner in the existing space in the control room. Re-arrangement of control

panels (relocating from the present position of being adjacent to the relay panels) is examined and observed to be not

worth the efforts as all control panels can not be brought into the control room accommadating the shift incharges.

Complied

PTR 4 (100 MVA) LV side dir E/F relay to be

made functionalMade functional. Complied

100 MVA PTR-1 LV side non directional E/F

relay provided due to non availability of

directional feature, whereas recommended relay

is directional E/F.

Directional Earth Fault Relay is Provided on 100 MVA PTR-1 and revised relay settings implemented.


Panel is replaced with new C&R panel having numerical relays with IEC 61850 communication protocol features.Complied

In PTR 1 (100 MVA) and PTR-2 (160 MVA)

LV over flux relays not provided. Also

transformer trouble trips were provided in

differential relay as inbuilt function. Providing

separate auxiliary relays for transformer troubles

to be examined.

Overflux feauters available in differential relay has been enabled.


Panel is replaced with new C&R panel having numerical relays with IEC 61850 communication protocol features.

Complied

Over flux relay is to be provided on HV side of

220/132 kV, 100MVA PTR-1.Rectified Complied

TSTRANSCO

Phase I

1 220 kV

Chandrayanaghatt

a

2 220 kV

Gachibowli

(hyderabad)

Substation

Annexure-XII

Page 23 of 96

DC earth leakage to be rectified in the 220KV

DC system-I&IIRectified Complied

Replacement of existing Static distance

protection relays for feeders, Differencial relay

of transformers with numerical relays



PTR panels are procured and allotted. Feeder panels supplies are avaited.


Panels are procured and alotted to the substation. Commissioning of panels is in progress.

Pending

Different Make and type of distance relays to be

used for Main- & Main-2 protection for Lines.

Same to be implemented

Will be exchanged with new fab city feeder at 400kV SS, Mammidipally.


Relays of different makes have been procured and retrofitting is in progress.

Pending

220 kV KAMAREDDY line distance relay

settings to be reviewed. As communicated recommended settings are adopted Complied

100MVA PTR-I, O/L Relay settings of HV and

LV side need to be reviewedAs communicated recommended settings are adopted Complied

Replacement of Static type ABB make

Differencial relays (RADSB) provided in, PTR-

1&2 with numerical relays

Materials procurement is under progress.Probable date of completion is October 2015.

Latest Status update (as on 09-11-2015) and vide mail on 25-01-2016:

PTR C & R panels are procured and allotted to the substation for commissioning.

Pending

100MVA PTR-2 OLTC tap position indicator in

RTCC panel to be made functionalRectified Complied

4 220 kV HIAL

Substation Earth leakage to be provided Rectified DC leakage problem Complied

5 220 kV

Malayalapalli S/S-

APTRANSCO Time synchronising system (GPS), Distrubance

Recorder (DR), Event Logger (ER), Synchro

check relay not available in the station.



PTR panels are procured and allotted. Feeder panels supplies are avaited.


New C&R panels are procured and allotted. Commissioning is in progress.

Pending

6 220 KV

Shahpurnagar

Substation

Over flux relay is to be provided on HV side of

220/132 kV, 100MVA PTR, 160 MVA PTR 1

& 2.

Rectified. Overflux relays are available on HV side of all 220kV PTRs Complied

2 220 kV

Gachibowli

(hyderabad)

Substation

3 220 kV side of

400/ 220kV

Gajwel Substation

Annexure-XII

Page 24 of 96

Static distance protection relays to be replaced

with numerical relaysAll 220kV feeders are having Numerical relays. Complied

100 MVA PTR-2 remote temperature indicator

to be replacedRemote temperature indicator replaced. Complied

over flux relay to be provided for 100 MVA

PTR-1Overflux relay available in differential relay has been enabled. Complied

DC earth leakage to be rectified in 220KV DC-I

systemRectified Complied

Different Make and type of distance relays to be

used for Main- & Main-2 protection for 220 KV

mamidipally & Gachibowli lines Lines. Same to

be implemented

Rectified


New panels are procured and allotted. Replacement of PTR panels completed and replacement feeder panels will be

completed as and when relay settings are communicated and shut down on the feeders is avaialble.


New panels are procured and allotted.

1) Replacement of PTR panels is completed and commissioned.

2) New Feeder C&R panels are available at the Sub-station and will be commissioned shortly.

Pending

Static differential and distance protection relays

to be replaced with numerical relays











Pending

Overflux protection to be provided for

100MVA PTR-I, LV over flux is removed.

Overflux features available in differential relay has been enabled.








Pending

100MVA PTR-III Existing LV directional earth

fault relay is to be made functional

Made functional.




Pending

100MVA PTR-III HV directional earth fault

relay is to be made functional

Made functional.



completed as and when relay settings are communicated and shut down on the feeders is available.





Pending

8 220 kV

Shivarampally

Substation

7 220 kV

Shamshabad

Substation

Annexure-XII

Page 25 of 96

LV over flux protection in 100 MVA, PTR-II to

be made available.

Overflux relay available in differential relay has been enabled.



completed as and when relay settings are communicated and shut down on the feeders is available.





Pending

DC earth fault in 220V DC system to be

rectifiedRectified Complied

220 kV Bus bar protection relay along with in-

built LBB function to be made functional220KV busbar protection scheme kept in service. Complied

Replacement of static differential protection and

distance protection relays with numerical relay





New C&R panels are procured and allotted. Commissioning is in progress.

Pending

Provision of overflux protection for

transsformersProvided. Complied

100 MVA, PTR-III Earth fault relay Time

setting for HV and LV side to be reviewedAs communicated recommended settings are adopted in the field. Complied

160MVA, PTR-II HV O/L and E/F relays to be

made functional. LV side E/F relay to be made

functional.

HV O/L, E/F relays are replaced with ER make AUGUS-II type relay. Complied

O/L & E/F setting of transformers to be

reviewedAs communicated recommended settings are adopted in the field. Complied

220 kV Gachibowli line Main-II distance relay

is be made functional(At present feeder name

changed as Shankarpally-II)

Defective Main-II relay was replaced with GE make,Type LPS-D relay. Complied

Zone-III setting in Shadnagar feeder to be

reviewedZone-III settings are changed as per the instructions of Power Systems Wing. Complied

Zone-III Timing setting in Shamshabad-II to be

reviewed.Recommended settings are adopted Complied

Replacement of PLCC panels of 400 kV

Ramagundam line to be done


Under PGCIL Scope. PGCIL authories have informed that the panels will be replaced soon as their indent for

material is under process.


with this recommendations lies with TSTRANSCO.

Pending

8 220 kV

Shivarampally

Substation

9 220 kV

Yeddumailaram

Substation

10 400kV side of

400/ 220 kV

Gajwel Substation

Annexure-XII

Page 26 of 96

315 MVA ICT-1 O/L relay setting of HV & LV

side to be reviewedRecommended settings are adopted Complied

Distance protection relay setting to be reviewed Recommended settings are adopted Complied

315 MVA ICT-2 OLTC tap position indicator in

RTCC panel is to be made functionalRectified. Tap Position indication is functioning. Complied

Procurement of testing kit for testing switchyad

equipment Tan delta and universal relay testing kit allotted Complied

Replacement of Static differencial protection

relays provided for ICT-1&2 with numerical

relays.

Materials procurement is under progress.


Materials procurement is under progress.Probable date of completion is October'2015.




Numerical differential relays procurement is in progress and static relays will be replaced as and when supplies are

received.

Pending

10 400kV side of

400/ 220 kV

Gajwel Substation

Annexure-XII

Page 27 of 96

protection settings for relays to be reviewed Protection settings are reviewed and adopted settings are as per APTRANSCO protection philosophy. Complied

Station Event logger to be made available Station E/L made available Complied

Analog meters & temperature indicators to be

replaced with Digital Meters




Pending

Review of distance protection setting of

transmission lines

Protection settings are reviewed and adopted settings are as per APTRANSCO protection philosophy.


Protection settings are reviewed and adopted settings are as per APTRANSCO protection philosophy.

Complied

Replacement of Static Relay like differential

relay (RADSB) of ICT01, Bus bar protection

relay (RADSS) with numerical relay






received.


400KV Busbar protection relay is replaced with SIEMENS make relay and commissioned.


received.

Pending

Adopted relay setting in 400 kV Line distance

relays, differential and O/C & E/F relay in ICT-3

is to be reviewed

Adopted as per approved settings. Complied

DEF function in distance protection is found not

enabled which is to be enabled/ activatedDEF functioning is activated. Complied

Dead time for Raichur Tie CB for A/R function

is set to 2 sec instead of 1 sec. same to be

rectified

Dead Time Setting Changed. Complied

11 400 kV

Mamidipally &

220 kV

Mamidipally

substation

12 400 kV

Mehboobnagar

Substation

Distance protection relays for 400 kV and 220

kV feeders to be replaced with numerical relays



New relays for replacement of old ones in 400kV feeder C & R Panels are procured for Main-I schemes and allotted

for commissioning.


Numerical distance relays have been procured and allotted for retrofitting in 400 KV system. New C&R panels

procured for 220 KV system could not be utilised in this substation as their architecture can support only double bus

system and not the double bus with transfer bus system available in this substation. New panels with revised

specification is in progress and will be commissioned as and when supplies are received.


As the allotted Panels are not as per the requirement of Mamidipally SS. New Panels with Double bus with Transfer

Bus system procurement is in progress and will be commissioned as and when supplies are received.Allottted panels

are diverted to other Substations where they are suitable.

Pending

Annexure-XII

Page 28 of 96

Event logger in Micro SCADA needs to be

properly configured. Also existing ABB make

event logger is learnt to be not communicating

with relay other than ABB make and also with

ABB make REL316 relay. Hence upgrading the

event logger to be done

New Event Logger and SIEMENS SCADA RTU Panels Commissioned Complied

ABB make distance relay of Type REL 316 to

be replaced



New relays for replacement of old ones in 400kV feeder C & R Panels are procured for Main-I schemes and allotted

for commissioning.


Numerical distance relays have been procured and allotted for retrofitting in 400 KV system

Pending

Overflux relay setting of ICT-1 on HV side to be

reviewedO/F Setting is adopted as per approved settings. Complied

Synchronising panel to be made functional Functioning. Complied

PLCC protection codes to be tested for Raichur-

Veltoor line Carrier protection equipment available and working (PGCIL scope) Complied

S. N Name of


Providing carrier aided tripping for 220 kV

feeders to be examined.Carrier aided tripping for all 220kV feeders connected to 400kV sub-stations. Complied

Providing of 2 Nos. DC sources as group-1 and

group-2 protections to be examined for reliable

protection.

2nd DC source for group 1 & 2 protection phylosophy will be adopted while commissioning new panels.New C&R

panels are under procurement. Probable date of completion is October 2015.


New C&R panels procured and allotment issued. 2nd DC source for Group-1 & 2 protection philosophy will be

adopted while commissioning new panels.


Two DC sources are avaialble. New C&R panels are commissioned with Group-1&2 DC source protection

phylosophy.

Complied

Metal spreading in switchyard was not done.

The same to be taken up.Metal spreading work completed. Complied

Carrier aided protection scheme has to be

implemented.Carrier Protection is provided for 220kV feeders Shankarpally-I&II emanating from 400kV Shankarpally. Complied

Utilising the two DC sources available for all

the control and relay panels to be examined.






Pending

2 220kV

Gachibowli S/S

12 400 kV

Mehboobnagar

Substation

Phase II

1 220 KV

Chandrayanagutta

Annexure-XII

Page 29 of 96

Metal spreading in switchyard is not available. Estimate is under preparation. Pending

Carrying out overhauling of 160 MVA PTRE-II

(Siemens) HV Breaker (BHEL) to be examined

since overhauling is not done from the date of

commissioning, i.e. on 04.02.1991.

Purchase Order placed for Breaker spares.Yet to be received from BHEL.


Purchase Order placed for Breaker spares.Yet to be received from BHEL.Breaker operations are being checked

periodically and found to be satisfactory.


Breaker operations are being checked periodically and found to be satisfactory.

Complied

Carried aided protection is not provided for 220

kV Lines. Providing the same to be examined.Implemented. Complied

Providing two DC sources for DC system to be

examined.



2 Nos. DC sources of 200 AH each are available in the substation. Group-I&2 protection phylosophy is being

adopted while commissioning new panels (work is in progress).

Complied

Bus bar protection is not available and in turn

there is no LBB protection for circuit breakers.

Bus bar panel are under procurement and probable date of completion is October 2015 as they are in DPR for R&U

of Protection in TSTRANSCO for which PSD funding is awaited.


Bus bar panel are under procurement and probable date of completion is December 2015 as they are in DPR for

R&U of Protection in TSTRANSCO for which PSD funding is awaited.


Bus bar Panal will be commissioned as and when the panels, for which orders are already placed, are recevied.

Pending

Only one set of 220 v battery bank is available.



2nd DC source will be provided as and when supplies are recevied.

Pending

5 220KV

Shahpurnagar ss -

APTRANSCOCarrier aided protection scheme has to be

implemented.

Projected in DPR, awaiting budget.


Procurement of communication equipment with PSD Funding is under progress.

Pending

Implementation of carrier aided protection

scheme to be examined.Carrier aided tripping for all 220kV feeders connected to 400kV sub-stations. Complied

Utilising the two DC sources available for all

the control and relay panels to be examined.





panels are procured and allotted for commissioning.


Group-I&2 protection phylosophy is being adopted while commissioning new panels (work is in progress).

Pending

Diesel set has to be commissioned. Commissioned. Complied

3 220 kV Ghanapur

SS

4 220 kV

Shamshabad S/S -

APTRANSCO

6 220kV

Shivarampally S/S

7 220 kV Tandur,

Rangareddy -

APTRANSCO

Annexure-XII

Page 30 of 96

APTRANSCO should have two independent

DC sources to the protection and switchgears

and one source should be for back up.




2nd DC source for group 1 & 2 protection philosophy will be adopted while commissioning new panels.New C&R

panels for PTRs allotted for commissiong and supplies for feeder C&R panels are awaited.

Latest Update vide mail on 25-01-2016 & 01-03-2016:

2nd DC source will be provided as and when supplies are recevied and Group-I&2 protection phylosophy will be

restored as all the new panels are being commissioned keeping this aspect in view.

Pending

Carrier aided protection scheme has to be

implemented.Carrier aided tripping for all 220kV feeders connected to 400kV sub-stations. Complied

7 220 kV Tandur,

Rangareddy -

APTRANSCO

Annexure-XII

Page 31 of 96

Carrier aided protection is not implemented for

some of the 220 kV feeders.

Carrier aided protection is implemented for 220kV Shamshabad, Shadnagar, Sivarampally, Chandrayangutta and

HAIL-I&II feeders.Complied

Closed circuit cameras to be arranged at

strategic points inside the switchyard as well as

along the fencing of the substation to monitor

any critical situation insie and to keep vigilance

on outside elements for taking view of changing

security threat perceptions to substation.

Providing of CCTV Cameras is under consideration.


Providing of CCTV Cameras is under consideration.

Pending

9 220 kv side of

400/ 220 kV

Gajwel SS

Carrier aided protection scheme implementation

to be examined.Carrier aided protection scheme commisioned. Complied

Implementation of carrier aided protection

scheme to be examined.Carrier protection is provided towards Shankarpally-I & II feeders Pending

providing second DC sources for all the control

and relay panels to be examined for better

reliability.






Pending

Metal sprading is not found in 220 kV S/S yard

& 132 kV yard.

Will be considered after completion of phase-I works.


Is under active consideration as many other substations have been provided with metal spreading in the recent past.

Pending

Cable Trench is not provided in 220 kV

Gachibowli, 100MVA PTR-II and B/C.

Work is under progress.


Cable trench construction will be carried out along with metal spreading work.

Pending

Providing of dedicated feeder for AC Aux.

Supply to be examined.

Work is under progress


Work is under progressPending

Carried aided protection is not provided for 220

kV Lines. Carrier aided protection scheme commisioned. Complied

Providing Reactor at 400 kV bus to be

examined.

Estimates are under preparation


125 MVAR ,400kV Reactor procurement is under progress. Probable date of completion is June,2016.

Pending

Carrier protection to be provided for 220kV

lines

Protection Couplers procurement is under progress.


Protection Couplers procurement is under progress.

Pending

10 220kV

Yeddumailaram

S/S

11 400 KV

Mahaboobnagar

12 400kV Dichipalli,

8 400 kV

Mamidipally ss &

220 kV

Mamidipally ss -

APTRANSCO

Annexure-XII

Page 32 of 96

Dedicated supply to be made available

Under examination


At present 2 Nos. 33kV feeders are available for station supply. Dedicated supply is under examination.


At present 2Nos.33KV feeders are availbale for station supply. Informed TSNPDCL (Distribution Company) to take

up the work immediately.

Pending

Sl.

No.Name of

SubstationDetails of Protection Audit observation Action taken to attend the observation Remarks

1 400kV NTPC

Ramagundam

Station (Gen)Distrubance Recorders (ABB, INDACTIC) not

having GPS time synchronisation (for 400 kV

Warangal Line, 400 kV Gajwel Line, 400 kV

Malkaram Line, 400 kV Hyderabad Line # 3,

400 kV Hyderabad Line # 4), 400 kV Dichipalli

Numerical relay (DR) not having GPS time

synchronisatiion.

Time synch is yet to be provided for 400 kV Dichipalli Numerical relay (DR) Pending

S. No Name of


Dead Earth fault in 220 V DC set 1 & 2. Completed Complied

relays not Synchronised with GPS.

The work will be completed by March 2015.


GPS received at site. The work will be completed by December 2015.


Completed.

Complied

A/R Scheme for 220 kV Lines not available for

lines.Completed Complied

2 220 kV Kadra

(Gen) Carrier protection is out of service for Karwar 1

& 2 feedersCompleted Complied

3 220 kV Kodasalli

S/S (Gen) Carrier protection is not in service for all feeders

(the real time testing is pending).Completed Complied

4

220 kV Nagjhari

Power House

The LBB relay time & current are sdet at 1.5 sec

& 0.2 A for all feeders and generating

transformers.

Completed Complied

220 V DC earth fault persisting negative dead

grounded


Negative dead ground is removed. Partial ground is present. The work will be completed by December 2015.


Completed

Complied

12 400kV Dichipalli,

5 220 kV Raichur

TPS

KPCL

Phase-I

1 220 kV BTPS

Combined (Phase-I & Phase-II)

Annexure-XII

Page 33 of 96

LBB Relay RAICA RXKL1 setting for ICT-II is

kept at 50 mA.Completed Complied

LBB relay timing is observed to be 0.7 sec

which is high, can be reduced to 250 to 300

m.sec in coordination with pole discrepancy

relay of breaker.

Completed Complied

Feeders with same Make & Type relay as Main-I

& Main-II should be changed with different

Make/Type relays for Main-I & Main-II.

LOA issued to M/s Alstom T&D India Ltd. Bengaluru. The work will be completed by December - 2015.


LOA dtd. 15.12.2014 issued to M/s Alstom T&D India Ltd. Bengaluru. Review of drawings completed. Materials

received at site. The work will be completed by December - 2015.


LOA dated: 15.12.2014 issued to M/s Alstom T&D India Ltd. Bengaluru. Erection work completed for all 8 Lines &

2 BCs except for S-2 line, which is in pregress.The erection works involve obtaining prior line clearance from the

State Load Dispatch Centre hence the erection work for remaining line is expected to complete by 31.01.2016.

Pending

Feeders having O/C and E/F relays as Main-II to

be replaced with distance relays for good

protection coordination on 220 kV Grid.

LOA issued to M/s Alstom T&D India Ltd. Bengaluru. The work will be completed by December - 2015.


LOA dtd. 15.12.2014 issued to M/s Alstom T&D India Ltd. Bengaluru. Review of drawings completed. Materials

received at site. The work will be completed by December - 2015.


LOA dated: 15.12.2014 issued to M/s Alstom T&D India Ltd. Bengaluru. Erection work completed for all 8 Lines &

2 BCs except for S-2 line, which is in pregress.The erection works involve obtaining prior line clearance from the

State Load Dispatch Centre hence the erection work for remaining line is expected to complete by 31.01.2016.

Pending

Carrier protection should be kept in service for

the feeders having no carrier protection.

The work will be completed by July - 2015.


Completed

Complied

DC earth leakage should be arrested on top

priority to avoid spurious trippings due to DC

earth leakage.

Completed Complied

Substation GPS to be connected to event logger

and protection relays for correct recording of the

sequence of events.

e-NIT floated on 15.09.2014. The work will be completed by December-2015.


NIT was issued through e-portal. LOA for Supply & Erection of Disturbance Recorder & GPS issued to M/s Alstom

T&D India Ltd., Chennai on 26.06.2015. Contract agreement executed.


Letter of Award issued to M/s Alstom T&D India Ltd., Chennai for Supply & Erection of Disturbance Recorder &

GPS on 26.06.2015. The firm has completed site visit for collection of data’s from site and is now preparing

schematic drawings.It is estimated that the work completion period may extend until 30.12.2016.

Pending

5 220 kV Raichur

TPS

6 220 kV

Sharavathi SS

(Gen)

Annexure-XII

Page 34 of 96

High setting for the bus bar differential

protection i.e. 325 V.

The work will be completed by March - 2015.


Assistance of OEM required. OEM opined that the setting is in line with latest fault levels, considering fault level as

50kA.


Assistance of OEM required. OEM opined that the setting is in line with latest fault levels, considering fault level as

50kA. This shall be reviewed as per the opinion of OEM and hence may please be removed from the list.

Complied

A/R Selection switch is kept in non auto mode

for all 400 kV lines.

A/R function for 400kV lines shall be completed by May 2015.


Timers dispatched from supplier. Software programming is completed during previous shut down availed on lines.

One more shut down is required for uploading settings and to modify wiring. A/R function for 400kV lines shall be

completed by December 2015.


Request sent to State Load Despatch Centre for availing LC for enabling A/R function for 400kV lines.The erection

works involve obtaining prior line clearance from the Sate Load Dispatch Centre hence the work completion period

may extend till 30.03.2016

Pending

Dead 220 V DC Earth fault for both sets i.e.

Positive to Earth 235 V.Completed Complied

GPS time synchronisation for all the relays &

DR not carried.

The work will be completed by May 2015.


GPS received at site. The work will be completed by December 2015.


Completed.

Complied

Pole descripency relay setting kept at 0.1 Sec for

all the lines.

The work will be completed by July - 2015.


Timers dispatched from supplier. The work will be completed by December - 2015.


Completed.

Complied

220 V DC earth fault persisting with leakage

current of 15 mACompleted Complied

PD settings for Munirabad, BTPS and

Mahboobnagar kept at 0.1 secCompleted Complied

RTPS-Munirabad line Zone-II setting (26.880

Ohm) is more than Zone-III (26.44 Ohm)Completed Complied

7 400 kV BTPS

8 400 kV Raichur

TPS SS (IS)

Annexure-XII

Page 35 of 96

No fault locator working for Munirabad and

Mehboobnagar lines

The order placed on M/s.Siemens to replace relays. The work will be completed by May - 2015.


Order placed on M/s Siemens for retrofitting of electromechanical relays with Numerical relays for both the lines.

The retrofitting of electromechanical relays with Numerical version for Munirabad line has been completed. The

fault locator is incorporated in numerical Relays. Retrofitting work for Mehaboobnagar line is pending. Awaiting for

line shutdown.


Completed.

Complied

DR communication is not working for

Munirabad and Mehboobnagar lines

The order placed on M/s.Siemens to replace relays. The work will be completed by May - 2015.


Order placed on M/s Siemens for retrofitting of electromechanical relays with Numerical relays for both the lines.

Inspection of material completed. The retrofitting of electromechanical relays with Numerical version for Munirabad

line has been completed. The fault locator is incorporated in numerical Relays. Retrofitting work for Mehaboobnagar

line is pending. Awaiting for line shutdown.


Completed.

Complied

Time Synchronisation for all relays.EL & DR

are done with GPS.The order placed on M/s.Siemens to replace relays. The work will be completed by May - 2015. Pending

Name of


Karwar 1 & 2 fereders have only R Ph CVT

available (Y and B Ph CVTs are not available).

NIT issued vide no. LOT/CEED/EE4/245kV CVT/1285 Dated: 17.07.2014. Tender finalisation will be completed by

March - 2015.The work will be completed by December - 2015.


Purchase order dtd 27.04.2015 placed on M/s Siemens ltd. Chennai. Review of technical drawings completed and

are approved. Inspection is in progress.


Purchase order dated: 27.04.2015 placed on M/s Siemens ltd. Chennai. Supply of all Materials after inspection at

firms work completed. Erection work may take 2 weeks after handing over of a line bay. However, the erection work

involves obtaining prior line clearance from the State Load Dispatch Centre and it is estimated that the work

completion period may extend until 30.12.2016.

Pending

8 400 kV Raichur

TPS SS (IS)

Phase-II

220 kV Kadra

(Gen)

1

Annexure-XII

Page 36 of 96

For Kaiga and Kodasalli feeders have only R &

B CVTs available. (Y Ph CVT not available)


March - 2015. The work will be completed by December - 2015.









Pending

Double earthing of all the supporting

structures/elements is to be ensured and neutral

of generting transformers and LAs should be

exclusively earthed.

The work will be completed by July 2015.


Work order issued. Work is under progress. The work will be completed by December 2015.


Since Kodasalli is a dam based project, double earthing of ODY structures in the existing concrete area of switchyard

could not be assessed. Work Order issued has been cancelled and NIT re-floated. The work will be completed by

30.06.2016.

Pending

2 220 kV Kodasalli

S/S (Gen)

Work order placed for Servicing of all 89T Transfer Bus isolators and Bus Coupler breaker. Wiring Work completed

partly. Letter addressed to OEM for detailed cable schedule and all the connected works.The work will be completed

by August 2015.


Servicing of all the 89T isolator & Bus coupler breaker carried out and kept ready. Also, action is being taken to

replace the faulty 220kV CT of Y-phase Bus coupler. Work order placed for procurement of CT's and auxiliaries.

The work will be completed by December 2015.


CT’s required for commission of bus coupler. Purchase order dated: 27.04.2015 placed on M/s Alstom ltd.

Bengaluru for procurement of CTs. Drawings approved and manufacturing clearance issued. Inspection call by Firm

is awaited. Erection work may take 2 weeks after handing over of Line bay. There are 13 Line bays. However, the

erection works involve obtaining prior line clearance from the State Load Dispatch Centre and Expected work

completion date: 30.12.2016.

Pending

Bus coupler and transfer bus are out of service,

bus coupler module on busbar protection panel

is kept out of service.

Work order placed for Servicing of all 89T Transfer Bus isolators and Bus Coupler breaker. Control wiring works

pending due to nonavailability of cable ICS at site. Letter addressed to OEM for detailed cable schedule and all the

connected works. BUS COUPLER module will be put into service during commissioning. The work will be

completed by August 2015.


Wiring work completed partly. Work order placed for procurement of CT's and auxiliaries. The work will be



CT’s required for commission of bus coupler. Purchase order dated: 27.04.2015 placed on M/s Alstom ltd.

Bengaluru for procurement of CTs. Drawings approved and manufacturing clearance issued. Inspection call by Firm

is awaited. Erection work may take 2 weeks after handing over of Line bay. There are 13 Line bays. However, the

erection works involve obtaining prior line clearance from the State Load Dispatch Centre and Expected work

completion date: 30.12.2016

Pending

Bus coupler and transfer bus are out of service,

bus coupler module on busbar protection panel

is kept out of service.

220 kV Kadra

(Gen)

1

Annexure-XII

Page 37 of 96

220 kV Nagjhari-Ambewadi 1 & 2 lines does

not have CVTs on the line. Carrier tripping was

not available for these lines.











Pending

Remaining six 220 kV lines have only one R-

Phase CVT and Y & B Phase CVTs are not

available.











Pending

Synchronising of 220 kV feeders is not being

done with synchroscope, only Generator

Transformer Units are being synchronised.

Synchronization of line feeders is not being done with synchronoscope. It is true that, only generator transformer

units are being synchronized at NPH. However the efforts are being made to provide synchronising facility for lines

also. The work will be completed by June 2015.


Completed

Complied

Pending

NIT issued on 17.07.2014. Tender finalisation will be completed by March - 2015. The work will be completed by

December - 2015.









i) Nagjheri Kodasalli line-1 having only R-ph

CVT (Y and B Ph CVTs are not available.

ii)Nagjheri Kodasalli line-2 CVTs are not

available. iii)Kodasalli-Kadra line having only

R and B Ph CVTs (Y Ph CVTs are not

available. iv) Kodasalli-Kaiga line having only

R and B Ph CVTs (Y Ph CVTs are not

available.

2 220 kV Kodasalli

S/S (Gen)

3 220kv Nagjhari

Power House

Separate 2 no's of raisers from earthmat have been provided for each unit & GT for connecting neutral to have

effective grounding. This is in line with the CBIP manual for earthing practices. However the efforts are being made

to provide separate earthing also. The work will be completed by June 2015.

Latest Update as on 25-08-2015 and mail on 27-01-2016:


effective grounding. This is in line with the CBIP manual for earthing practices. Hence, this item may please be

removed from list.

PendingThe Neutrals of generator transformers are not

earthed exclusively and all LAs also not found

to be earthed exclusively.

Annexure-XII

Page 38 of 96

The Emulsifier system nozzles are not directed

towards Power Transformer body in the middle.Complied. The mulsifire nozzles are already directed towards power transformer body in the middle. Complied

3 core CTs to be replaced with 5 crore CTs to

keep the Bus Bar protection in full shape with

both Main and Check Zone.

NIT issued vide no. R &M/245kV CTs/1348 Dated: 23.07.2014. Tender finalisation will be completed by March -

2015. The work will be completed by December - 2015.


Purchase order dtd 27.04.2015 placed on M/s Alstom ltd. Bengaluru for procurement of CTs. Drawings approved

and manufacturing clearance issued.


Purchase order dated: 27.04.2015 placed on M/s Alstom ltd. Bengaluru for procurement of CTs. Drawings approved

and manufacturing clearance issued. Inspection call by Firm is awaited. Erection work may take 2 weeks after

handing over of Line bay. There are 13 Line bays. However, the erection works involve obtaining prior line clearance

from the State Load Dispatch Centre and Expected work completion date: 30.12.2016.

Pending

3 CVTs to be provided on all 220 kV feeders so

as to keep the Main-II protections on Bus PT or

CVT which increases the reliability of the

protection system.








firms work completed.Erection work may take 2 weeks after handing over of a line bay. However, the erection work



Pending

Bus bar protection panels to be replaced with

new panels of numerical relay type to have the

bus bar protection in full shape with all features

(check zone, CT fail, iso fail etc. features) as the

existing scheme is not having check zone

facility. Certain CTs with 3 cores should also be

changed to have 5 cores for bus bar protection.

Complied. Commissioning of new Bus bar protection panel is completed on 16.06.2014 Complied

Feeders having same core for Main-I and Main-

II should be separated to individual cores, i.e.

Main-I and Main-II should be on different CT

cores.

NIT issued vide no. R &M/245kV CTs/1348 Dated: 23.07.2014. Tender finalisation will be completed by March -

2015. The work will be completed by December - 2015.


Purchase order dtd 27.04.2015 placed on M/s Alstom ltd. Bengaluru for procurement of CTs. Drawings approved

and manufacturing clearance issued.


Purchase order dated: 27.04.2015 placed on M/s Alstom ltd. Bengaluru for procurement of CTs. Drawings approved

and manufacturing clearance issued. Inspection call by Firm is awaited. Erection work may take 2 weeks after

handing over of Line bay. There are 13 Line bays. However, the erection works involve obtaining prior line clearance

from the State Load Dispatch Centre and Expected work completion date: 30.12.2016.

Pending

3 220kv Nagjhari

Power House

4 220 KV

Sharavathi SS

(Gen)


effective grounding. This is in line with the CBIP manual for earthing practices. However the efforts are being made

to provide separate earthing also. The work will be completed by June 2015.

Latest Update as on 25-08-2015 and mail on 27-01-2016:


effective grounding. This is in line with the CBIP manual for earthing practices. Hence, this item may please be

removed from list.

PendingThe Neutrals of generator transformers are not

earthed exclusively and all LAs also not found

to be earthed exclusively. Annexure-XII

Page 39 of 96

The battery bank-II to be replaced with VRLA

(maintenance free) type batteries to increase the

reliability of DC system, as the existing both

banks are of lead acid type are under complete

deterioration condition.

Complied. Already solved by replacing with VRLA type 1000Ah batteries on 06.01.2013 & 500Ah batteries on

24.06.2013Complied

All generator transformers OTI & WT1 shall be

brought to control room for better monitoring of

the transformer performance.

The 4-20 mA temperature signals of GT 1,3,5 & 8 have already been provided to control room recorder for

monitoring. Procurement of new guages with temperatures for GT 2, 6 & 7 is in progress. GT 9 & 10 are being

replaced & the monitoring facility will be extended after replacement.The work will be completed by June 2015.


Completed

Complied

New SF6 type circuit breakers to be replaced

without door type CTs on either side of the

breaker in place of existing old BOCBs, as the

sectionaliser breakers are very vital while

clearing the very high level bus faults.

LOA issued to M/s ABB India Ltd. The work will be completed by December - 2015.


LOA dtd. 12.12.2014 issued to M/s ABB India Ltd. Review of drawings is in progress.

The work will be completed by December - 2015.


LOA issued on 12.12.2014. Supply of all Materials after inspection at firms work completed. Erection work may

take 8 weeks after handing over of each bay. There are 2 no. of bays. However, the erection works involve obtaining

prior line clearance from the Load Dispatch Centre. Expected work completion date: 30.12.2016.

Pending

5 220 kV BTPS

220 kV Bus coupler not commissioned.

Letter addressed to EPC contractor M/s. BHEL with a request to take up the work at the earliest. The work will be



Letter addressed to EPC contractor M/s. BHEL with a request to take up the work at the earliest. The firm has

accepted to take up the work. The work will be completed by December 2015.


Letter addressed to EPC contractor M/s. BHEL with a request to take up the work at the earliest. The firm has

accepted to take up the work. The work is expected to be completed by 30.06.2016.

Pending

CVT to be provided for each Phase of the

transmission lines.








Pending

Pending

e-NIT No. LOT/CEED/EE6/R&M/ Dist.Prot/1416 dtd: 28.07.2014 was floated through e-portal for Supply, Retrofit,

Testing & Commissioning of Numerical Distance protection relays & GPS for Varahi, Gerusoppa, Kadra &

Kodasalli Power Houses of KPCL. Bid evaluation is under progress. The work will be completed by December -

2015.


NIT issued through e-portal on 05.05.2015. Price evaluation is under progress.


LOA’s issued on 08.10.2015. Inspection of relays completed. Materials received at site.The erection works involve

obtaining prior line clearance from the State Load Dispatch Centre and it is estimated that the work completion

period may extend until 30.12.2016.

Different Type of Numerical Distance protection

is to be provided as Main-II in place of Static

Over current and earth fault protection.

4 220 KV

Sharavathi SS

(Gen)

220kv Gerusoppa

Dam Power

House

6

Annexure-XII

Page 40 of 96

Main-I Distance protection (SHPM101) is not in

service due to power supply module problem for

Karwar I & II feeders.




2015.







Pending

Double earthing of all the supporting

structures/elements is to be ensured.

Earth mat purchased. The work will be completed by July 2015.




Completed

Complied

Neutrals of generating transformers and LA's are

to be exclusively earthed.

Earth mat purchased. The work will be completed by July 2015.




Completed

Complied

Pending




2015.







Different Type of Numerical Distance protection

is to be provided as Main-II in place of Static

Over current and earth fault protection.

220kv Gerusoppa

Dam Power

House

6

7 220 kV Kadra

(Gen)

Pending1. Complied for Distance Protection Scheme(Main 1) already retrofitted with Numerical relays for all lines except

Shahpur line.

2. Budget proposal is made for the year 2014-15 for replacement of old Back up protection relays with Numerical

relays for all lines and main1 & main2 for Shahpur line.

3. Budgetary offer received and under process of issuing NIT.

5. The work will be completed by December- 2015.


e- NIT floated on 03.02.2015. Job order placed on 26.06.2015 on M/s Alstom T&D India Ltd. Chennai for

retrofitting of relays for all 220kV lines at RTPS.


Work Order placed on 26.06.2015 for retrofitting of relays for all 220kV lines at RTPS. Materials received at site.

The erection works involve obtaining prior line clearance from the State Load Dispatch Centre and it is estimated

that the work completion period may extend until 30.06.2016.

Old electromagnetic relays can be replaced with

numerical relays.

220 kV Raichur

TPS

8

Annexure-XII

Page 41 of 96

DG set is not extended to 400 kV SS

The work will be completed by May 2015.


Action is being taken up


Completed

Complied

Electromechanical directional OCR & EFR

relays are existing as back up protection for

220KV line feeders. Different type of Numerical

distance relays should be replaced in place of

electromechanical relays.




2015.







Pending

There is only one CVT available on all 220KV

lines. CVTs should be provided for all the three

phases of all the 220KV lines.






Pending

Time synchronisation of the distance relays with

GPS may please be reviewed.




2015.







Pending

10 220kV Varahi

(VUGPH

Hosangadi) (gen)

1) Complied. Replacement of Old Electro-magnetic relays with Numerical has been completed for RTPS-

BTPS line & Commissioned on 17.03.2014.

2)Complied. Raichur-PG1 & Raichur-PG2 lines have already retrofitted with numerical relays.

3) NIT issued for replacement of old Electro-magnetic relays with Numerical version for 400 KV lines of Munirabad,

Mehaboobnagar, ICT-1 & ICT-2. Bid evaluation is under progress. Work will be Completed by May -2015.


Replacement of Old electromagnetic relays with Numerical relays has been completed for RTPS-BTPS line &

commissioned on 18.03.2014.

Raichur-PG1 & Raichur-PG2 lines have already retrofitted with numerical relays.

The retrofitting of electromechanical relays with Numerical version for ICT-1, ICT-2 and Munirabad line has been

completed.

Retrofitting work for Mehaboobnagar line is pending. Awaiting for line shutdown.


Completed

Complied

Old electromagnetic relays can be replaced with

numerical relays.

400 kV Raichur

TPS

9

Annexure-XII

Page 42 of 96

Sl.

No. Name of


All 220 kV line and bus coupler C&R panels

distance relays are retrofitted with ABB REL511

relays & REL670 respctively, but the existing

panels back-up electromechanical relays are

very old and sluggish, most of the TS relays are

not working properly, announciation not

working hence it is suggested to replace the

panels at the earliest.

Included under renovation and upgradation of protection system project.


The work is included under R&U project for which tender is finalised and LOI will be issued to M/s Alstom before

31.08.2015.


It is included under R&U project and the work is entrusted to M/s Alstom. LOA issued on 26.12.2015. M/s Alstom

is conducting sub stationwise survey regarding the works to finalise the purchase of materials.

Pending

For 100MVA-I No REF protection available and

over flux relay should be restored.



31.08.2015.




Pending

Main-2 protection is not available for all the 220

kV lines.

220kV control and relay panels with main-1 and main-2 distance protection are being provided under R&M works.



31.08.2015.


It is included under R&U project and the work is entrusted to M/s Alstom. LOA issued on 26.12.2015.

Pending

The Event Logger and GPS is not available.

Included in R&M works



31.08.2015.


It is included under R&U project and the work is entrusted to M/s Alstom. LOA issued on 26.12.2015.

Pending

Only one core of CTs is used for both main and

B/U relays for all feeders except Jindal 1 & 2Pending

GPS clock is not available Pending

Synchronisation relay is not working Pending

For all feeders 2 O/C and 1 E/F relay as B/U

protection can be replaced with distance scheme

mostly numerical relay is recommended.

Pending

New CTs and CVTs available at yard needs to

be commissioned at the earliest.Pending

KPTCL

Phase-I

220 kV Allipura

2 220 kV

Ambewadi RS

3 220 kV

Lingapura,

Munirabad

Attending protection audit observations at Lingapura Switching Station is being taken up under R&M works.


Complete R& M of Lingapur SS is awarded to M/s Alstom T&D India limited vide KPTCL LOI No.

CEE/T&PSEE(E)/EE-T1/T-3/9682-706; 9707-21; 9722-36 dated 4.03.2014 and the work is under execution.

Attending to the protection audit observations pertaining to Lingapura SS is taken care under R&M works.


Attending protection audit observations at Lingapura Switching Station is inculded under R&M works

1

Annexure-XII

Page 43 of 96

4 220 kV

LingasugurAll 220 kV line and bus coupler C&R panels,

distance relays are retrofitted with ABB REL511

relays & REL670 , but the existing panels back

up electromechanical relays are very old and

sluggish, most of the TS Relays are faulty,

annunciation not working, hence it is suggested

to replace the panels at the earliest.

Included under renovation and upgradation of protection system project


The work is included under R&U projectfor which tender is finalised and LOI will be issued to M/s Alstom before

31.08.2015.




Pending

Annexure-XII

Page 44 of 96

Event logger is not available. Pending

In CB two Nos. of trip coils energised from one

DC source only.Pending

For line protection, main-1, numerical distance

relay has been provided & electromechanical

relays are used as main-2 protection.

Pending

Main-II protection is not available. However,

electromechanical relay used as back up

protection.

Pending

LBB relays not available. Pending

7 220 kV A Station

Main-II protection is not available. However,

electromechanical type backup protection relays

have been provided.

Included in the renovation and upgradation of protection system works



31.08.2015.




Pending

Main-1 protection is Distance Relay and Main-2

protection is Back up relays with OCR & EFR.




31.08.2015.




Pending

Bus Bar protection relay is out of service, the

same to be put back to service for protection.




31.08.2015.




Pending

9 220 kV Kadakola

protection system to be time synchronized with

GPS

Included in the renovation and upgradation of protection system works.


The work is included under R&U project, for which tender is finalised and LOI will be issued to M/s Alstom before

31.08.2015.




Pending

Synchronisation facility not available Pending

6 220 kV HebbalIncluded in the renovation and upgradation of protection system works.



31.08.2015.




8 220 kV HSR

Layout

5 220 kV HAL




31.08.2015.




10 220 kV Kolar Latest update as on 25-08-2015:

The work is included under R&U project, for which tender is under process. LOI to be issued shortly.




Annexure-XII

Page 45 of 96

DR and EL not provided. It is suggested that

DR and EL to be provided with time

synchronisation

Pending

11 220 kV

Naganathapura

R/S

Main-1: Numerical Distance Protection and

Main-2 is Back up protection with OCR & EFR.



The work is included under R&U project,for which tender is finalised and LOI will be issued to M/s Alstom before

31.08.2015.




Pending

100MVA Transformer 1&2 220 KV LA

counters are not available.Complied

The 220 KV Belgaum lines 1 & 2, Hubli Lines 1

& 2, Ambewadi Line-1 and Haveri Line-2 LA

counters are not available.

Complied

Main 2 protection is not available for all the 220

KV lines.Pending

Separate Event Logger, Disturbance Recorder

and GPS is not available.Pending

Event logger and DRS not available for Peenya

& Vrushabavathi Lines.Pending

Main II Distance protection Relays for all 220

Kv feeders is not available & the Protection

Coupler for Peenya & Vrushabavathi Lines are

not available.

Pending

GPS, Disturbance recorder and event logger are

not available and same to be provided. Control

panel annunciation not in working condition

except transformers

Pending

Main-II Distance protections were not propvided

in all 220 kV feeders and PLCC/Protection

coupler was not provided except 220 kV Hebbal

feeder

Pending

13Included in renovation and upgradation of protection system works.






14 220 kV Peenya,

Bangalore Is being covered under R&M works under Peenya.


Complete R&M of 220kV Peenya Sub station is taken up by KPTCL.The work is awarded to M/s Micron

Electricals,Bangalore and the work is under execution. Attending protection audit observations pertaining to Peenya

SS is taken up under R&M works.


Attending protection audit observations at SRS Peenya is inculded under R&M works

10 220 kV Kolar Latest update as on 25-08-2015:





12 220 kV Narendra

SS

Latest update as on 25-08-2015 and vide mail on 03-02-2016:

LAs are provided and in working condition.







220 kV NRS

Rajajinagar

Annexure-XII

Page 46 of 96

15 220 kV Receiving

Station,

Yarandahalli,

BangaloreFor Main-II distance relays preferably numerical

relays are not available in all 220 kV feeders,

the same to be provided.

Included in renovation and upgradation of protection system works.



31.08.2015.




Pending

Protection System shall be synchronised with

GPS TimePending

Feeders having O/C and E/F relays as Main-II to

be replaced with distance relays Pending

17 220 kV Sir M.V.

(EDC) GIS

Station In CB two Nos. of trip coils energised from one

DC source only.




31.08.2015.




Pending

18 220 kV

SUBRAMANYA

PURA

protection system to be time synchronized with

GPS



31.08.2015.




Pending

19 220 kV T. K.

HALLI

To provide GPS synchronisation for 220kV

protection system.




31.08.2015.




Pending

GPS to be procured and installed for time

synchronisation of protection system.Pending

220 kV Lines provided with Main I only, Main

II protection to be provided.Pending

Event logger and Time synchronisations

facilities to be made available

Included in renovation and upgradation of protection system works



31.08.2015.




Pending

400 kV Guttur

16 220 kV ShimogaIncluded in renovation and upgradation of protection system works.



31.08.2015.




20 220 kV

Vrushabavathi

Substation







21

Annexure-XII

Page 47 of 96

ICT-1 differential, bus bar relays and some of

220 kV lines distance relays are static type

relays and are not having the disturbance

recorder facilities. Replacement of the same

with numerical type relays




31.08.2015.




Pending

400 kV Hoody

Substation

Main-II protection not provided in 220 kV

feeders instead Backup protection are provided.



The work is included under R&U projectfor which tender is finalised and LOI will be issued to M/s Alstom before

31.08.2015.




Pending

220 kV Hoody

Substation

Main-II relays not available in all 220 kV

feeders. The same to be provided.



220kV control and relay panels with main-1 and main-2 distance protection are being provided under ongoing R&M

works.



Pending

23

400 kV

Nelamangala &

220 kV

Nelamangala

Main II distance protection were not provided in

all 220 kV lines & PLCC/Protection Coupler

were not provided except Nittur & Dabuspet

lines

PLCC Protection Coupler provided for Nittur and Dabuspet lines.

The Main-II distance protection works for 220kV lines were included in Renovation and upgradation of protection

system project.



31.08.2015.




Pending

Attended Complied

Separate Event Loggers are not available, GPS

are not synchronised with SAS & Distance

Protection Relays.

Event Logger of numerical protection relays are used for analysis. SAS & distance relays are synchronized with GPS. Complied

Main II relays not in service in 400 kV Hassan

line, 400 kV Talaguppa line & 400 kV Hoody

line-1 and the same may be made available in

the above feeders.

Main-2 relays provided to 400 V Hassan, Hoody-1 and Talguppa lines. Complied

It is noticed that the LA is failed in the same

phase (Talaguppa line) for 3 times previously.

Analysis may be done and take remedial action

to avoid reoccurrence.

Failure of LAs at Nelamangala was analysed and it was observed that comparitively more failure in the particular

batch of LAs supplied. LA failure occurred in other bays such as Hassan line., ICT etc also. Hence any site specific

cause could not be arrived with respect this particular observation.

Complied

400 kV Guttur

22

Phase-II

21

Annexure-XII

Page 48 of 96

Sl.

No. Name of

SubstationDetails of Protection Audit observation Action taken for attending the observation Remarks

One DC source is being user for protection.



LOI to be issued to the successful bidder.




Pending

DG set is not available.







Pending

2 220 kV A

Station

One DC source is being user for protection.




31.08.2015.




Pending

3 220 kV HSR Lay

Out S/S

CVT not provided in all phases of all feeders in

220 kV feeders.




31.08.2015.




Pending

4 220 kV Kadakola

Recommended to put 220 kV busbar protection

system in service at the earliest possible.

Bus bar protetction scheme is being replaced by numerical bus bar protection scheme.



31.08.2015.




Pending

Numerical bus bar protection is being provided under renovation and upgradation of protection system works. Due to

space constraints for providing double bus system, providing bus sectionalizer is envisaged.

The issued was discussed in the special meeting of PCSC held on 19.08.2014, and the forum agrred to send the

modified proposal to Hon'ble CERC.



space constraints for providing double bus system, providing bus sectionalizer is envisaged.The work will be taken

up under proposed R&M works at Kolar.




Dropped220 kV Single Bus System is available and bus

bar protection not provided. It is proposed for

provision of 220 kV double bus system with bus

bar protection.

220 kV Kolar5

220 kV Hebbal1

Annexure-XII

Page 49 of 96

Bus Bar protection is not available in the station,

same is to be provided.




31.08.2015.




Pending

PLCC Batteries set to be provided.


PLCC batteries are being procured throgh tendering process.


PLCC batteries are being procured throgh tendering process.

Pending

100MVA transformer 1&2 Fire Protection

System is not available.

CTR make nitrogen fire protection system is provided to 100MVA Transformer-2. Action is being taken to procure

fire protection system to 100MVA Transformer-1 through tendering process.


CTR make nitrogen fire protection system is provided to 100MVA Transformer-2, yet to be commisioned. Providing

fire protection system to 100MVA Transformer-1 is in the tendering process,LOI will be issued shortly.


CTR make nitrogen fire protection system is provided to 100MVA Transformer-1 & 2, yet to be commisioned.

Pending

The 220 KV Belgaum lines 1 & 2, Hubli Lines 1

& 2, Ambewadi Lines-1 & 2 and Haveri Line-2

and B Phase CVTs are not available.




31.08.2015.




Pending

The 220 KV Ambewadi lines 1 & 2 and Haveri

line 2 Wave Traps are not available.




31.08.2015.




Pending

8 220 kV

SUBRAMANYA

PURATo provide Bus bar protection relays for 220kV

system.







Pending

220 kV

Lingasugur

220 KV Narendra

SS



The issued was discussed in the special meeting of PCSC held on 19.08.2014, and the forum agrred to send the

modified proposal to Hon'ble CERC.



space constraints for providing double bus system, providing bus sectionalizer is envisaged.The work will be taken

up under proposed R&M works at Kolar.




Dropped220 kV Single Bus System is available and bus

bar protection not provided. It is proposed for

provision of 220 kV double bus system with bus

bar protection.

220 kV Kolar5

6

7

Annexure-XII

Page 50 of 96

9 220 kV T. K.

HALLI - KPTCL

To provide Bus bar protection for 220kV Bus

system at the earliest.




31.08.2015.




Pending

10 220 kV

Yarandahalli,

BangaloreBusbar protection is not provided in the 220 kV

system, the same to be provided.




31.08.2015.




Pending

11 400 kV Guttur

R/S - KPTCLAtmospheric conditions as specified by the

manufaturers of relays to be maintained for

smooth operation of relays like cooling system

which is observed insufficient.

Action is being taken for resotring/enhancing the existing cooling system.


Action is being taken for resotring/enhancing the existing cooling system.Tender under process at CEE,TZ Tumkur.


Action is being taken for resotring/enhancing the existing cooling system.

Pending

Annexure-XII

Page 51 of 96

Sl.

No.Name of


Condition monitoring of switch yard equipments

need to be carried out at regular basis.Followed Complied

Synchonising is being used selectively.

Recommended for usage at all Lines.

Complete R&M of 220kV Somanahally SS is taken up by KPTCL, wherein conventional C&R panels are being

replaced by numerical relays and BCU mounted in bay kiosk .Synchroninzing facility is available in each BCU . Complied

Facility for downloading of disturbance records

is to be made available.

Set up for automatic downloading of DR &EL records is being provided under R&U project, for which tender is

finalised and the work is awarded to M/s Alstom.






Pending

Existing static type 220kV Bus Bar protection

scheme may be replaced by numerical type

scheme to have the bus bar protection in full

shape with all features.

The work is included under R&U project for which tender is finalised and the work is awarded to M/s Alstom.






Pending

Local SCADA should be kept in service on top

priority for smooth monitoring of the sub station

parameters and events.

Service support is not available for existing SCADA system of ABB. Replacement of main protection relays of lines

and ICTs by IEC 61850 protocol relays is considered under R&U project.Possibility of upgradation of the existing

SCADA by 61850 based SAS is explored by KPTCL.


Possibility of upgradation of the existing SCADA by 61850 based SAS is explored by KPTCL.


Service support is not available for existing SCADA system of ABB. Replacement of main protection relays of lines

and ICTs by IEC 61850 protocol relays is considered under R&U project.

Pending

220kV feeders having O/C and E/F relays as

Main-II, to be replaced with distance relays

The work is included under R&U project for which tender is finalised and the work is awarded to M/s Alstom.






Pending

Auto reclosure function should be kept in

service in full shapeAttended Complied

A PT/CVT selector switches may be provided to

both main-1 &2 protections and Main-1 & II

may be kept on PT and CVT respectively or

either way.

Line / Bus CVT selection is available and functional as per the scheme provided. Complied


1 220 kV

Somanahalli S/S

400 kV Talaguppa

S/S & 220 kV

Talaguppa S/S

2

Annexure-XII

Page 52 of 96

CTD trippingavailable on ICT-3. The same may

be provided on ICT-1 &2 also.Attended Complied

Earthmat resistance should be measured and

recorded periodically.Attended Complied

400 kV Talaguppa

S/S & 220 kV

Talaguppa S/S

2

Annexure-XII

Page 53 of 96

S. No. Name of


Carrier scheme to be provided for 230kV

Mylapore feeder

Fibre laying is under progress. Time extension requested upto 30.06.2016.


Fibre laying is under progress. Time extension requested upto 30.06.2016.

Pending

No protection during VT Fail condition. Same to

be reviewedComplied - Inbuilt protection is available during VT fuse fail - 11.01.2014. Complied

No Earth fault protection on HV & LV side of

transformer. Same to be provided

E/F settings for AUTOs not being adopted in TANTRANSCO.



Pending

O/L settings oauto transformers to be reviewed complied.Uniform setting procedure adopted Complied

Separate earthing for DC system (110 V DC) to

be providedProvided on 01.05.2014. Complied

Only Bus PT supply is available for Main I & II

protection, no line VT supply is available for

protection. Same needs review

PT allotted and will be completed by 31.03.2015.


PT allotted and to be erected and will be completed by 31.12.2015.


PT allotted and to be erected and will be completed by 30.06.2016.

Pending

No Capacitor Tripping Devices are kept in

service for Feeders and Transformers. Same

needs review

Capacitor trip device is not in service,since nuisance trippings were observed.


Capacitor trip device is not in service, since nuisance trippings were observed.

Pending

Relay settings for feeders and transformers need

reviewBeing reviewed whenever needed. Complied

Time synchronising with GPS to be provided

for 230kV protection system

Time sync with GPS provided and is in service.Feasibility study is under progress for GPS, DR and EL.


Procurement action initiated. Specification approval under progress. Time extension requested up to 30.06.2016.


Procurement action initiated. Time extension requested up to 30.06.2016.

Pending

Auto reclosure to be enabled for feeders. complied on 11.01.2014. Complied

Power swing block settings to be reviewed. complied.Adopted as recommended by SRPC. Complied

Earth fault relay to be provided on HV & LV

sides of Auto t/p # 1, 2 and TO # 3 t/f. Over

fluxing relayto be provided.

E/F settings for AUTOs not being adopted in Tantransco.



Pending

OT1 and WT1 indicators suspected for not

working. Same needs to be rectified. Defects rectified on 10.12.2012 and indication available at present. Complied

PRV device to be made available on Auto T/f #

1 and 2.PRV available in Auto 1. Explosion vent available in Auto 2. Complied

2 230 kV Ennore

(ETPS)

TANGEDCO

Phase-I

1 230 kV Basin

Bridge Substation

Annexure-XII

Page 54 of 96

Surge counters to be made available on

lightening arrestor.

Surge counters available in 110kV LAS.Action is taken for provision in 230kV LAS.


Surge counters available in 110kV LAS. Action is taken for provision in 230kV LAS. Time extension requested up

to 30.06.2016.


Surge counters available in 110kV LAS. Action is taken for provision in 230kV LAS. Time extension requested up

to 30.06.2016.

Pending

DC earthing in 220V DC system to be rectified Earthing checked and rectified on 08.05.2014 Complied

Zone-2 timing of distance protection relay of

23kV kines need reviewZone 2 time delay 350mSec as per SRPC recommendation. Complied

2 230 kV Ennore

(ETPS)

Annexure-XII

Page 55 of 96

Different type and Make of distance protection

relays to be provided for Main-I & Main-II

protection for 230kV feeders

Realys supplied and are to be commissioned. Time extension requested upto 31.03.2015.


Relays are being procured in phased manner. Second phase procurement under progress and will be commissioned

by 30.06.2016.



by 30.06.2016.

Pending

Remote temperature indicators to be provided

for station transformers.

Will be completed during annual shut down 2014.


Action taken for procurement. Time extension requested up to 30.06.2016.


Action taken for procurement. Time extension requested up to 30.06.2016.

Pending

4 230 kV PUSHEP

Switchyard

(Pykara Ultimate

S/S (GEN.) DC leakage in the station to be rectified complied on July 2013 Complied

Main-I and Main-II protection schemes to be fed

from separate DC source. Provision for the same

to be done.

completed during August 2014.

Complied

PLCC protection coupler to be made available

for MTPS-Stage-III and MTPH feeders.

Tender opened.Procurement action in progress. Time extension requested upto 31.03.2015.


Material supplied. Will be erected and commissioned with in two months.


PLCC protection coupler provided in MTPS Stage-III. In MTPH feeder, protection coupler will be provided.

Pending

Synchronisation cores of Line VT and Bus VT

are of different voltage ratios and same needs

review

Reviewed. No practical difficulties experienced. Complied

3 230 kV North

Chennai TPS

5 230kV Mettur

Thermal Power

Station

CTD protection to be provided in all 230KV

feeders and Transformers.

It is noted that in case of DC supply failure, the capacitor trip device would trip the circuit breaker. TANTRANSCO

requested the item be dropped as the reliability of DC supply is ensured by two DC sources for the trip coils. The

issue was discussed and the PCSC forum concluded that if provision for two DC sources were there for trip coils in

the Substation, then capacitor trip device could be dispensed with.


Item.

Dropped

Annexure-XII

Page 56 of 96


for protection relays.

Feasibility study is under progress for GPS, DR and EL.





Pending

Both Main-1& Main-2 distance protection relays

of 230 kV feeders to are be of numerical type.

Static distance relays to be replaced with

numerical relays.

Relays supplied and are to be commissioned. Time extension requested upto 31.03.2015.



by 30.06.2016.



by 30.06.2016.

Pending

5 230kV Mettur

Thermal Power

Station

Annexure-XII

Page 57 of 96

S. No. Name of


For 230 kV Mylapore Feeder Protection

DC System

For 48V (PLCC) only 1 set of Battery, No back

up is available.

PO placed. Will be commissioned by 31.3.15.


Procurement action under progress. Time extension requested up to 30.06.2016.



Pending

General

DG set is required for alternate source.

Procurement to be made. Will be provided by 30.06.2015.


Administrative approval obtained. Procurement action under progress. Time extension requested up to 30.06.2016.



Pending

Synchronisation relay not available for feeders.

Being done manually by watching indicating

meters

Procurement to be made.Will be completed by 30.09.2015.


The issue was discussed in the special meeting of PCSC held on 19.08.2014, and the forum agreed to drop the Item.

Pending

Since switchyard is very old, it is advisable to

physically see the rusting status of earth mat.

Switchyard equipment earthing needs to be

improved.

Earth mat is being watched and improved regularly Complied

No LA is available on R-phase LV side of Auto

# 2LAS provided on 05.12.2012 Complied

Dedicated feeder PT/CVT not available for

feeders protection. However, single phase CVT

available for measurement and synchronisation

purpose.

Procurement to be made. Will be completed by 30.06.2016 .





Pending

3 230 kV Kundah

PH - II S/S

230 kV GC Breaker to be erected and

commissioned urgently to avoid tripping of tie

feeders in the event of tripping of auto

transformers

CT to be allotted .Work will be taken up on availing LC.Time extension requested upto 30.06.2015.


Breaker & CT erected. Control cables to be layed. Defective isolator to be replaced. Time extension requested up to

30.06.2016.


Breaker & CT erected. Control cables to be layed. Defective isolator to be replaced. Time extension requested up to

30.06.2016.

Pending

4 230 kV Kundah

PH - III S/S -

TANTRANSCO2 sets of LA's have been provided at bus only.

Second core of Bus VT has been used for line

protection. Line CVTs are only for

synchronising purpose.

Procurement to be made. Will be completed by 30.06.2016





Pending

TANGEDCO

Phase-II

1 230 kV Basin

Bridge SS

2 230 kV Ennore,

Chennai (ETPS) -

TANTRANSCO

Annexure-XII

Page 58 of 96

5 230 kV NCTPS

S/SAs per the data available regarding 2

nd source of

D.C supply it is not reliable to depend on this

supply. It was also discussed with Generation

wing and found that the 2nd

source of supply

cannot be relied on Gen station battery. Hence it

is suggested for a new battery system as 2nd

source of supply for the switch yard.

Procurement action initialized. Time extension requested upto 30.06.2016.


Procurement action initialized. Tendering in progress. Time extension requested up to 30.06.2016.


Procurement action initialized. Tendering in progress. Time extension requested up to 30.06.2016.

Pending

6 230 kV Valuthur

SS

LA is not available for 230 kV & below

Procurement to be made. Will be completed by 30.06.2016.





Pending

Annexure-XII

Page 59 of 96

S. No. Name of


Static relays are to be replaced with numerical

relays



230kV feeder 5 numbers replaced, 110 kV feeder 10 numbers replaced.

Complied

V/F protection for transformers to be made

availableEnabled. Complied

REF protection to be implemented for

Transformers (Capacity below 100 MVA)

Neutral CT is to be provided. Procurement to be done.Time extension requested upto 30.06.2016.


Neutral CT is to be provided. Procurement to be done.Time extension requested upto 30.06.2016.

Pending

DC leakages are to be complied for DC source I. complied on 16.03.2013 Complied

synchronizing facility to be made available.

TANTRASNCO informed that since synchronizing trolley is available for synchronizing purpose. The

synchronizing facility by synchronizing panel need not to be insisted . TANTRANSCO requested to drop the audit

point.


Item.

Dropped

REF protection to be made available. REF protection enabled on 25.11.2013 Complied








Pending

Static distance relay to be replaced with

numerical relays. Pending

Diiferent type and Make of distance protection


protection for 230kV Arasur feeder.

Pending

TANTRANSCO

Phase-I

1 230 kV Arni

Substation

3 230 kV Gobi

Substation



Phase-I Relay procurement completed & commissioned. Second phase procurement under progress. Time extension

requested up to 30.06.2016.


1. 7 nos. Static Relays replaced with Numerical Relays and 3 more Static Relays are to be replaced.

2. Phase-I Relay procurement completed & commissioned. Second phase procurement under progress. Time

extension requested up to 30.06.2016.

Annexure-XII

Page 60 of 96








Pending

Static distance relay to be replaced with

numerical relays. Complied on 08.02.2013. Complied



protection for 230kV Arasur and K.R.Thoppur

feeders.



Main-II relay MICOM.P.442 replaced by CG make ZLV relay on 11.6.2015 for 230 kv KR'Thoppur feeder

1.No Relay for Arasur Feeder to be replaced. This will be replaced before 31.10.2015.


Main-II relay MICOM.P.442 replaced by CG make ZLV relay on 11.6.2015 for 230 kv KR'Thoppur feeder.

1.No Relay for Arasur Feeder to be replaced. This will be replaced before 30.06.2016.

Pending

In Busbar Protection same CT is used for Main

& Check zone relay. Same needs review

UE make Bus bar protection scheme available. The current circuits of Main and Check are in series and hence taken

from same core.CT circuit supervision and metrosil are common for main and check and hence separate CT cores

cannot be used. If BBP panel is replaced with numerical relay also, the low impedance scheme has built in check

zone . However the stability in operation of BBP is ensured in the scheme and hence replacing the existing 4 core CT

with 5 core CT is felt not necessary.

Complied

5 230 kV Kayathar

Substation Earth resistance to be measured and recorded. Earth resistance is measured and recorded on 21.3.14 (0.6Ω). Complied

During VT fail condition no protection is

available (Backup 1> disabled). Same needs

review

complied on 07.08.2014. Complied

No E/L relay protection on ATR 1, 2 & 3 HVs.

Same to be provided




Pending

V/F protection is not available on ATR-1, 2 & 3.

Same to be provided.Enabled on 03.07.2014. Complied






Relays are being procured in phased manner. Second phase procurement under progress and will be completed by

30.06.2016.


Different type relays available for Main I and Main II.

Complied


protection. There is no line VT supply available

for protection. Same to be reviewed and

rectified.

PT to be procured and will be completed by 30.06.2016.


Administrative approval obtained.Procurement action under progress. Time extension requested up to 30.06.2016.



Pending

4 230 kV Ingur

Substation

6 230 kV Korattur

Substation

Annexure-XII

Page 61 of 96

No capacitor tripping devices are provided on

230 kV feeders & ATRs. Provision for the same

to be done






Item.

Dropped

Relay settings for feeders and transformers need

reviewReviewed whenever needed Complied


for 230kV protection system






Pending





Procurement action initiated. Specification approval under progress. Differential & Busbar Relays will be replaced

before 30.06.2016.



Pending

Static distance protection relays to be replaced

with numerical relays.




before 30.06.2016.


In ALUNDUR 230kv ss all the 230kv feeder relays are replaced with numerical relays (Main I MICOM P442, Main

II CG ZIV)

Complied

Station Event loggerto be provided



Procurement action initiated. Specification approval under progress. Differential & Busbar Relays will be replaced

before 30.06.2016.



Pending

O/C and E/f relay setting on HV & LV sides of

both auto transformers need review.

Uniform setting adopted for O/C. E/F setting not adopted in TANTRANSCO.


Uniform setting adopted for O/C. E/F setting not adopted in TANTRANSCO.

Pending


relays for Main-I & Main-II protection to be

provided for 230kV feeders




by 30.06.2016.



by 30.06.2016.

Pending

DC earthing in 220V DC system to be rectified DC earthing rectified on 08.11.2012. Complied

8 230 kV Manali

Substation

6 230 kV Korattur

Substation

7 230 kV Alundur

Substation

Annexure-XII

Page 62 of 96

Earth resistance meaured on 07.02.2009. It is

observed to be violating in more number of

earth pits. The same to be rectified

Combined earth resistance measured.Individual earth resistance will be measured on availing LC by

30.09.14..

Latest Update as on 27-08-2015 and vide mail on 03-02-2016:

Upgradation to 400/230kV GIS SS work has been taken up.

Pending

Carrier scheme to be provided for 230kV Basi

bridge feeder

Fibre laying is under progress.Time extension requested upto 30.06.2016.


Fibre laying is under progress.Time extension requested upto 30.06.2016.

Pending

No protection during VT Fail condition. Same to

be reviewedComplied Complied

Static Main-2 relay of 230kV Basin bridge

feeder to be replaced with Numerical relaycomplied on 14.4.2013. Complied

No Earth fault protection on HV & LV side.

Same to be reviewed and provided




Pending

Earth leakage monitoring system to be provided complied Complied

Separate earthing for 220 V & 48V DC system

to be providedProvided on 30.07.14 Complied


protection, no line VT supply is available for

protection. Same needs review

Procurement action in progress. Time extension requested upto 30.06.2016.





Pending


for 230kV protection systemPending

Provision for station event logger to be done Pending

8 230 kV Manali

Substation

9 230 kV Mylapore

Substation











Item.

No Capacitor Tripping Devices are kept in

service for Feeders and Transformers. Same

needs review

Dropped

Annexure-XII

Page 63 of 96


for protection relays.Pending

Station Event Logger, Disturbance Recorder

with dedicated computer systems, printers to be

provided.

Pending

Trip circuit supervision relay to be provided for

both trip coils for 230 kV Veerapuram, 230 kV

Kalpakkam, 230 kV Kalivanthapattu, 230 kV

Oragadam, 230/110 kV Auto 1 HV side

Time extension reuested upto 30.06.2017 since approval being sought for R&M.


R&M work for the substation is approved. Total renovation and comply with recommendation will be done. Time





Pending

Provision for supervision of all the trip coils

through the TSR relay to be examined.








Pending

High water content in auto transformer oil test

report needs review and suitable actionsOil circulation completed 24.03.2014. Complied

It is found that relays of the same C&R panels

are placed in different locations of other C&R

panels in many bays. It is very difficult for the

SS operator to identify the relays during

emergency condition. Hence relays shall be

placed on the respective feeder panel to be

examined.








Pending

TMS of auto transformers for over currrent

relays (HV/LV) to be reviewed and correctedUniform setting adopted Complied

Replacement of all static relays (Differential,

Busbar, Distance etc) to be done with numerical

type relay



4 Nos. Numerical distance protection relays replaced in 230 kV feeders. Complied

Since the length of 230 kV Veerapuram line is

around 650 mts, sensitivity of performance of

distance protection for that shortest line needs to

be examined.

Numerical relay available and performance satisfactory Complied

10 230 kV Pugalur

SubstationFeasibility study is under progress for GPS, DR and EL.





11 230 kV

Singaperumal

Koil Substation

Annexure-XII

Page 64 of 96

Carrier aided protection scheme to be provided

for 230 kV Oragadam feeder

PO issued for end equipments. Will be completed by 31.03.2015.


Equipment erection work under progress. Will be commissioned within two months.


Equipment erection work under progress. Will be commissioned by 30.06.2016.

Pending

Provsion for Direct trip transmission signal on

operation of Bus bar/LBB relay for all the lines

to remote end to be provided.

Already adopted Complied

DC earthing in DC system to be rectified

leakage Pending

Labelling to be done for all the relays in panels

to be provided Pending

Cable Duct near Auto transformer 3 needs to br

repairedPending

Over flux protection to be provided for Auto

transformers .



Over flux protection enabled for Auto 4. Relays allotted for other 3 Auto transformers . Will be commissioned

within a month.


Over flux protection enabled for Auto 4. Relays allotted for other 3 Auto transformers . Will be commissioned by

30.06.2016.

Pending

Battery earth leakage meters provided for DC

source I & II are not in working condition. Same

needs to be rectified.

Earth leakage meters rectified and in service. Complied

Non Directional Over Current relay with 150%

on both sides of all Auto Transformers are

provided. Earth fault relay on both side are not

adopted. Same needs review.

Uniform setting adopted for O/C. E/F settings for AUTOs not being adopted in Tantransco.



Pending

Transmission line earth wire not connected to

SS earth mat at Tondiarpet. Same needs review

and rectification

Work will be takenup. Time extension requested upto 31.03.2015.


Work to be takenup. Time extension requested up to 30.11.2016.Pending

100 MVA, 230/110 kV transformer # 1 &2,

back up O/C relays setting need review. Earth

fault relays to be provided on both HV & LV

side of ICT's

Uniform setting adopted for O/C. E/F settings for AUTOs not being adopted in Tantransco



Pending

11 230 kV

Singaperumal

Koil Substation

Time extension reqested upto 30.06.2017 since approval being sought for R&M.







12 230 kV

Thiruvalam

Substation

13 230 kV

Tondiarpet

Substation

Annexure-XII

Page 65 of 96

REF for transformer # 1, overfluxing relays for

both t/f # 1, 2 to be provided

Neutral CT to be provided for REF protection. Tender opened for procurement of relay. Time extension requested

upto 30.06.2016.


Neutral CT is to be provided. Administrative approval obtained. Procurement action under progress. Time extension

requested up to 30.06.2016.

Pending

DC earthing in 220V DC system to be rectified complied on 3.8.2012. Complied

Separate treated earthpit for DG set to be

provided. Body of DG Set to be earthed with

suitable flat or conductor.

Separate earth pit provided on 21.05.2014. Complied

Zone separation for Bus Bar Protection needs to

be done. .








Pending

Staticrelays to be replaced with Numerical

Relays.Pending

V/F Protection to be enabled in autotransformers

upto the level of 230 kVPending


for 400 & 230kV protection system






Pending







by 30.06.2016.



by 30.06.2016.

Pending

Earth leakage Relays to be made functional Complied on 17.05.2014. Complied

Possibility of providing time synchronising

system (GPS Unit) for protection relays.




Complied

14 230kV

Singarapettai

Substation








15 400 kV Alamathy

Substation &

230kV Alamathy

Substation

16 400 kV

K.R.Thoppur

Substation

(Salem)

13 230 kV

Tondiarpet

Substation

Annexure-XII

Page 66 of 96

The existing Static Distance Protection Relays

to be replaced with Numerical Relays.



5 nos static Distance relays were (Main I) replaced by numerical relays on April 2015. 9 Nos relays in Main

II yet to be replaced. Time extension requested up to 30.06.2016.


Out of 12 Static relays, 5 nos. Static relay replacement completed. The balance 7 nos. Static relays have to be

replaced. Time extension requested up to 30.06.2016.

Pending

Dedicated event Logger to be provided for post

tripping analysis.






Pending

Separate auxiliary relays for transformer

mounted protection.

Provided for ICT 1,3&4. Action taken for provision in ICT 2.Time extension requested upto 31.03.2015.


Provided for ICT 1,3&4. Action taken for provision in ICT 2Pending

Control cable duct to be properly sealed to

avoid entry of rain water.complied on 19.05.2014. Complied







by 30.06.2016.

Pending

Tap position indication of some of the 1 phase

ICTs are not showing properly, which is to be

rectified

Refered to OEM. Time extension requested upto 31.03.2015.


Available for ICT 4 . For other ICTs, refered to OEM.

Pending

Enabling of "directional earth fault protection in

main-1 and main-2 distance relayscomplied on 28.12.2013. Complied

The differential protection relay in ICTs has

inbuilt function of differential protection, ref

protection, overflux protection, aux. protection

for transformer mounted relays, breaker failure

protection. So provision for additional

differential protection relay with all the above in

built function as a main-II to be reviewd for

improving reliability

Two relays are available. Required Transformer protections are segregated in two groups and each relay is used for

one group of protection as recommended in CBIP publication 274. Complied

Providing of Trip-Neutral-Close (TNC) switch

for all the bays in C&R panel for emergency

operation

Will be provided. Time extension requested upto 31.03.2015.


TNC switches to be procured. Time extension requested up to 30.06.2016.

Pending

Providing of "Stub protection" for 400 kV lines

Provided for NCTPS #1&2. For SPDR and Pondy feeder STUB protection will be enabled during Annual relay test

before 31.12.2014.


Stub protection enabled for all feeders.

Complied

16 400 kV

K.R.Thoppur

Substation

(Salem)

17 400 kV

Sunguvarchathira

m & 230 kV

Sunguvarchathira

m Substation

Annexure-XII

Page 67 of 96

Provision to be made for continuous monitoring

of dc earth leakage measurementsEarth leakage being monitored Complied

Enabling "Direction Earth Fault" function in

numerical type main-1 and main-2 distance

relays

Adopted as recommended by SRPC on 02.12.2013. Complied

Replacement of static distance, differential &

busbar protection relays with numerical relays



Out of 11 relays which needs replacement 7 relays commissioned. Others will be commissioned on availing LC.

Differential & Busbar Relays will be replaced before 30.06.2016.


All Static Distance Relays replaced with Numerical Relays. Differential & Busbar Relays will be replaced before

30.06.2016.

Pending

Different make & type of distance relays to be

used for Main-1 and Main-2 protection


Time extension requested up to 30.06.2016.Pending

Time synchronising of protection system with

GPS to be provided




Pending

Carrier aided protection to be provided for

230kV Sriperumbudur-Nokia, 230kV

Sriperumbudur-Mambakkam (sipcot), 230kV

Sriperumbudur-Oragadam

Battery and charger are to be commissioned at other end substations. Will be completed by 31.03.2015.


OPGW laid for Nokia,Oragadam and Mambakkam. End equipments erected and are to be commissioned. Time


Pending

S. No Name of


Lightning Arrestors are not provided for 230 kV

feededrs.






Pending

Second source of DC to be reviewed for

connectivity.

Dual DC source is available in the station. Scheme to be modified for two sources. Time extension requested upto

30.06.2016.


Dual DC source is available in the station. Scheme to be modified for two sources. Time extension requested upto

30.06.2016.

Pending

DG set is under faulty and enhancement

proposed.

Additional capacity to be procured. Will be provided by 30.06.2015.





Pending

2 230 KV Gobi SS As neutral bushing CT is not available for Auto

transformer2. Neutral CT provided and REF in service 25.11.2013. Complied

18 400 kV

Sriperumbudur

Phase-II

1 230 kV Arni SS

Annexure-XII

Page 68 of 96

Renovation of control room to be done.

Estimate sent for approval. Time extension requested upto 30.06.2017.



Pending

Proper fire fighting and oil drain pit to be

provided for transformers.


Time extension requested up to 30.11.2016.



Pending

Providing LAs at entry and connecting TL

earthwire to SS mat to be looked into.Pending

The existing 25 KVA DG set to be enhanced to

50 KVA.

Procurement to be made. Will be provided by 30.06.2015 .



Pending

An additional 48 V battery set to be provided for

reliable PLCC operation.




Pending

For 230 kV Basin Bridge Feeder Protection

Auto Transformers I & II

LAs to be provided for desired protection of

Auto Transformers



Procurement to be made. Will be completed by 30.06.2016. Pending

DC System

For 48V (SCADA/PLCC) only 1 set of Battery

and Charger, No back up is available.




Pending

General

To maintain the adequate temperature for GIS

equipments air conditioned to be required.

High ceiling and hence A/C cannot be provided.


High ceiling and hence A/C cannot be provided.

Pending

3 230 kV Kayathar

SS

4 230 kV Manali,

Chennai

Upgradation of 230kV SS into 400kV GIS SS has been sanctioned. Work to be takenup. Time extension requested

upto 30.06.2017.


Upgradation of 230kV SS into 400kV GIS SS has been sanctioned. Work to be taken up.


Upgradation of 230kV SS into 400kV GIS SS has been sanctioned. Work to be taken up.

5 230 kV Alundur

Substation

6 230 kV Mylapore

The condition of 230 kV & 110 kV switchyard

is observed to be execessively deteriorating.

May faults were attributable to conductor

leads/jumpers cut or damage and non operation

of circuit breakers. Heavy rusting on equipment

and its earth flats is observed. It is felt that this

fast deterioration to be due to prevailing

environment conditions. To maintain the

reliability of this substation, suitable alternatives

to be explored to obviate the fast deterioration in

future.

Pending

Annexure-XII

Page 69 of 96

Possibility of providing CB for sectionalised bus

to be explored.

Space is not available for providing breaker. Time extension requested upto 30.06.2017 since feasibility to be

explored.


Space is not available for providing breaker. Time extension requested upto 30.06.2017 since feasibility to be

explored.

Pending

DG set capacity to be enhanced to 50 KVA from

25 KVA by providing additional 25 KVA DG

set.

Pending

Fire extinguisher system of the power

transformer to be enhanced.Pending

All Telk and Rade Koncar make 230/110 kV

CTs has the short term current rating 19.7 KA,

which is as per station fault MVA (7325 MVA)

is under rated and replacement of CTs suitable

to bus fault level to be examined.

Pending

Strengthening of 230/110 kV bus to be

examined (presently two conductors as 230 kV

Bus and 1 conductor as 110 kV bus).

Pending

Providing LAs on 230 kV line side to be

examined.Pending

Providing fire protection system for auto

transformer to be examined.Pending

It is found that the Tan Delta measurement of

CTs of Auto Transformer 1 & 3 are in higher

side, replacement of CTs to be examined.

Pending

Providing dual channel for carrier protection for

230 kV feeders duly integrated with main-1 and

main-2 distance relays to be examined.

Pending

Accuracy class of 230 KV Bus PT's to be

verified and replacement of the same by 0.2

class accuracy and other protection core to be

examined since the existing PTs are very old

commissioned during 1979.

Pending

There is one group control breaker for all the

three 50 MVA transformers - to be replaced by

individual control.

Pending

LA is not provided for 230 kV feeders Pending

7 230 kV Pugalur

Procurement to be made. Will be provided by 30.06.2015.





8 230 kV

Singaperumal

Koil SS

R&M Work to be taken up. Time extension requested upto 30.06.2017.







9 230 kV

Singarapettai SS R&M Work to be taken up. Time extension requested upto 30.06.2017.







Annexure-XII

Page 70 of 96

Single DC source is provided for breaker

operation. Additional source to be provided.Pending

10 230 kV Madurai

SS

LA is not available for the lines (230 kV &

below), Earth Resistance value not available.

Procurement to be made. Will be completed by 30.06.2016 .





Pending

11 230 kV

Thiruvalam SS

Lightning Arresters are not provided on all 230

and 110KV feeders.






Pending

Provision of LAs at line entry for 230 kV

feeders to be considered.






Pending

Synchronous relay not available. Being done

manually.

Procurement to be made.Will be completed by 30.09.2015


The issue was discussed in the special meeting of PCSC held on 19.08.2014, and the forum agreed to drop the Item. Pending

Availing tertiary connection to be explored for

auxiliary supply of station.

Already two sources available for station supply. Tertiary connection for auxiliary supply is not used in TN.


Loading of tertiary not in practice in TANTRANSCO. However Station supply from two sources are available.

Pending

In the 400 kV & 230 kV yard the following

observations were made. i) Earth mat was

designed and installed at the time of

commissioning only. There is no provision to

measure earth resistances. The Neutral of each

ICT have individual earth pit but there is no

provision to measure earth resistance and the

earth pits are not maintained at regular periods.

ii) The Mulsifire Systems are found to be not

installed properly. Also since installation, no

maintenance has been carried out.

Mulsifier system restoration will be taken up shortly. Estimate sanctioned for provision of 60 No earth pits

measurement of earth resistance. And work to be taken up. Time extension requested upto 31.03.2015.


Mulsifier system restoration will be taken up shortly. Estimate sanctioned for provision of 60 No earth pits

measurement of earth resistance and work to be taken up. Time extension requested up to 30.06.2016.

Pending

400 kV Alamathy

SS (IS) & 230 kV

Almatty SS

13

9 230 kV

Singarapettai SS R&M Work to be taken up. Time extension requested upto 30.06.2017.







12 230 kV

Tondiarpet,

Chennai

Annexure-XII

Page 71 of 96

The existing 50 KVA DG set to be enhanced to

250 KVA.

Additional capacity to be procured. Will be provided by 31.03.2015.



Pending

Possibility of providing the Fire Protection wall

to 400/230 KV AUTO Transformer 2 to be

explored and AUTO Transformer 3 & 4 to be

heightened.

Fire protection wall will be hightened by 31.03.2015 for Auto 3&4. For Auto 2 space is not available .


New Fire protection wall constructed for 400/230 KV Auto Transformer – II and heightening of existing Fire

protection wall work for 400/110 KV Auto Transformer – III & Auto Transformer – IV has been completed on

21.01.2016.

Complied

The tie CB of ICT 1 & 2 is kept in open

condition due to isolator mechanical problem

from last 6 months. Early action to be taken to

keep DIA in closed condition.

complied on 28.01.2013. Complied

Incorporating the status of station aux. system

like battery charger, dg set, IT a.c. etc in the

HMI shall be examined.

Feasibility discussed with SAS supplier. Estimate to be prepared for provision. Time extension requested upto

30.06.2016


Feasibility discussed with SAS supplier. Estimate to be prepared for provision. Time extension requested upto

30.06.2016

Pending

Jelly spreading in the switchyard is insufficient. complied on 21.07.2014. Complied

It is suggested that providing separate dual DC

source to be examined. One set of dual DC

source for 400 kV side and second set of dual

DC source 230 kV and 110 kV side so that fault

in the dc system can be identified from where it

develops.

Dual DC source is available in the station. Separate DC panel available for each souece with MCBs for each circuit.

Hence identification of fault is possible with present arrangement.Complied

Fire protection system is not provided for ICTs.




Pending

LAs on 230 kV line side is not provided.

Provision of LAs on 230 kV side to be

examined.




Pending

In carrier aided protection, one channel is used.

Provision of dual channels integrated to main-1

& main-2 distance protection relay to be

examined.

Procurement to be made. Time extension requested upto 30.06.2016.





Pending

The existing emulsifier system (for ICTs) meant

for fire extinction is not in service.

The existing emulsifier system (for ICTs) meant for fire extinction is to be reconditioned.Action being taken. Time

extension requested upto 30.06.2016.


New system with nitrogen extingusing system proposed and sent for approval. Time extension requested up to

30.06.2016.


New system with nitrogen extingusing system proposed. Time extension requested up to 30.06.2016.

Pending

15 400 kV

Sunguvarchathira

m SS & 230 kV

Sunguvarachathir

am SS

16 400 kV

Sriperumbudur

14 400 KV K R

Thoppur SS -

Salem (230 KV

SS)

Annexure-XII

Page 72 of 96

It is suggested that providing separate dual DC

source to be examined. One set of dual DC

source for 400 kV side and second set of dual

DC source 230 kV and 110 kV side so that fault

in the dc system can be identified from where it

develops.

Dual DC source is available in the station. Separate DC panel available for each souece with MCBs for each circuit.

Hence identification of fault is possible with present arrangement.Complied

Centralised AC to be expedited for proper

functioning of protection system panels and to

prevent failure of numerical protection system.

Centralised AC made fully functional on 05.03.2014. Complied

LAs on 230 kV line side is not provided.

Provision of LAs on 230 kV side to be

examined.

Pending

Replacement of 25 years old gaped surge

surrestors with new gapless type for auto

transformers to be examined.

Pending

The three phase but fault level on 400 kV side is

21901 MVA and on 230 kV side is 15239

MVA. The fault current based on the above

fault level is 31.6 KA on 400 kV side and 38

KA on 230 KV side. The CTs and CBs which

are in service are having the rated SC capacity

of 40 KA which is almost on the verge.

Exploring the possibility of upgrading the

ratings of CBs and CTs are reducing the fault

level to be reviewed.

18300 MVA on 400kV side and 13398 MVA on 230kV side as on 31.3.2014. Hence upgradation of CBs and CTs

not required.Complied

S. No Name of


S. No Name of


The existing Main-1 (Electrostatic Quadramho)

Distance Relays should retrofitted with latest

version Numerical Relays for easy and quick

analysis of the faults.


Complied by December 2014Complied

Static THR relay - Main-II Vallur - I & II feeder

has been replaced - retrofitted with REL 670 N

relay. Because of i) Ma-operation of Zone-2 and

Faulty. Ii) Mal-operation of Zone-3 and Zone-2

and Zone-3, tripping time delay might be kept

uniform throughout all feeders at Sriperubudur.

(Other Main Zone-1 other Zone tripping

including the reverse sign is not uniformly

adjusted and to be reviewed.)

Complied Complied230 kV

Sriperumbudur

S/S

1

16 400 kV

Sriperumbudur



Administrative approval obtained. Procurement action under progress.Time extension requested up to 30.06.2016.



Combined (Phase-I & Phase II)

KSEB

Phase-I

1 220 kV Areacode

S/S

Annexure-XII

Page 73 of 96

Over flux protection is not available 220/110

kV, 160 MVA Transformer.


Complied by December 2014Complied

Main-2 relay is not available inall 220 kV

feeders. Only backup protection relays are

provided.


Complied by December 2014.Complied

Protection couplers are not provided in 220 kV

AMBR 1 & 2 and 220 kV BRKL - 1 &2 feeders

AMBR feeders- complied. BRKL (renamed as COBR)- OPGW link to be established by PGCIL.


Protection couplers are provided in BR KL renamed as COBR 1 & 2 feeders . Relay interfacing for COBR 1& 2

will be completed in 1 month.


Complied by 10.2015

Complied

Ratio test on CTs are done at lower currents

only. Higher capacity not done due to non

availability of kits with sufficient capacity.

Under final stage of Procurement(Will be installed in Jan 2015)


PO placed for new current injection kit of 200A.


Injection Kit received

Complied

Separate DC ground fault annunciation (+ve to

GND & -ve to GND) to be provided.


Complied by August 2014Complied

GPS & Event logger is not available.

PO issued.Will be issued by Jan 2015


Completed by July 2015.

Complied

Zone 3 setting not common for all feeders.Latest update as on 24-08-2015:

Completed by Dec 2014Complied

Carrier inter tripping not available for SBEM 1,

2 & 3 feeders.



Main 2 distance protection for EMPC 1 feeder

not available.



LBB not in service for SBEM 2, 3 and EMPC 1Latest update as on 24-08-2015:


3 220 kV Edamon

SS

1 220 kV Areacode

S/S

2 220 kV

Brahmapuram

Substation

Annexure-XII

Page 74 of 96

LBB protection for all Circuit Breakers shall be

included.



Automatic change over facildity shall be made

available for 110 V Switch Yard Battery system.


Completed by March 2015Complied

Main-II Distance protection shall be propvided

for feeders



Distance Relay with Quadrilateral

characteristics shall be provided for high

resistance faults



All Electro Mechanical Relays to be replaced

with modern numerical relays.



Main-2 relay is not provided on 220 kV BRKL-

1 feeder. Backup relays are provided in all

feeders



Protection couplers are not provided in 220 kV

BRKL-1 & 2 feeders


Protection couplers are provided in 220 kV COBR 1 & 2 feeders . Relay interfacing for COBR 1& 2 will be

completed in 1 month.


Complied by 10.2015

Complied

CT ratio tests are done at lower currents only.

Higher capacity not done due to non-availability

of kits with sufficient capacity.

Under final stage of Procurement(Will be installed in Jan 2015)


New current injection kit PO placed. Will get within 1 month.


Injection Kit received

Complied

GPS & Event logger is not available.



Completed by Dec 2014

Complied

4 220 kV Idukki

HEP

5 220 kV

Kalamassery

Substation

Remarks: Earth mat of 220 kV, 66kV switchyardsand the power house are interconnected and the total resistance

value is within safe limits.Due to difficult terrain of switchyard independent measurement of earth resistance is not

possible at present. The earth mat is already interconnected with tail race earthing system.The requirement of the

protection audit committee will be considered during renovation period. Would be considered during renovation

period (Recommended by PCSC forum)


Earth mat of 220kV ,66kV switchyards and the power House are interconnected and the total resistance value is

within safe limits.Due to the difficult terrain of switchyard independent measurement of earth resistance is not

possible at present. The earth mat of Idukki HEP is made with Copper conductor and the earth mat is already

interconnected with tail race earthing system.


The earth mat is already interconnected with tail race earthing system.

Provision for measuring earth resistance to be

explored.

Complied

Annexure-XII

Page 75 of 96

Bus-bar protection is not available. The same to

be provided.

Time extension requested.


PO placed for bus bar protection panel and work scheduled to be completed befored 31.12.2015


To be completed before 31.12.2016


Purchase order placed.PO-22/15-16 dt.17.2.16 of Chief Engineer Transmission South to M/s.Danish. Material will

be received in April.So the work may be completed by 31.12.2016. While carrying out work, there are many critical

220kV feeders including interstate and feeders from GSs will have to switched off for long periods. The delay in

obtaining shutdown of these feeders may delays the work. So the time extension required up to 31.12.2016.

Pending

6 220 kV

Kaniyambetta S/SThe 220 kV line's Main I (Electrostatic

QUADRAMHO) Distance Relays should

retrofitted with latest version Numerical Relays

for easy and quick analysis of faults.



7 220 kV

Madakkathara1 phase auto reclosing to be provided for 220

kV feeders.Complied Complied

Resistance reaches to be examined for each zone

of protection instead of setting it as a commoin

parameter as in the 220 kV New Pallom-

Kayamkulam 1 & 2.


Completed by Nov 2014Complied

Load encroachment impedance and the

loadability of the relay to be examined

depending upon the line length and loading nof

the feeder.



Providing of stub/EFP protection to be

examined for 220 kV lines.

It is informed that at 220 KV level stub protection is not provided. Bus PT is used for distance protection. KSEB

requested the item be dropped. The issue was discussed and the forum accepted the proposal.


Item.


When line is switched off, line CB and bus isolator are kept open.Hence stub/EFP protection not required

Dropped

For 220 kV Busbar protection check zone to be

reviewed to take it from a separate PS class

core to have additional security to prevent

inadvertent tripping of bus zone protection due

to main core saturation.


Numerical bus bar protection panel PO placed and scheduled to be completed before 31.12. 2015.


Will be completed before 31.12.2016


Purchase order placed.PO-21/15-16 dt.31.12.15 of Chief Engineer Transmission North, Kozhikode to M/s. G E

India Industrial Pvt. Limited Material will be received in April. So the work may be completed by

31.12.2016.While carrying out work, there are many critical 220kV feeders including interstate and feeders from GSs

will have to switched off for long periods. The delay in obtaining shutdown of these feeders may delays the work. So

the time extension required for this work is up to 31.12.2016

Pending

The carrier aided trip to be examined to have

different channel for main-1 and main-2

protection as twin channel is available in

protection coupler at different frequencies.



8 220 kV New

Pallom Switching

Station

5 220 kV

Kalamassery

Substation

Annexure-XII

Page 76 of 96

Delay in operating time for zone-2 and zone-3 to

be reviewed to be set at 350ms and 800ms

respectivedly as per SRPC & PGCIL direction,

otherwise ensure setting to be identical for both

local and remote end.



Enabling functionality for both main-1 and main-

2 relay to be reviewed.



220 kV Idukki-New Pallom feeder has main-1

static version relay and main-2 has overcurrent

relay which to be considered to be replaced with

numerical distance protection relay.



Relay settings of LBB to be checked and

corrected as per norms.Complied Complied

Back-up relay in service in all 220 kV feeders Complied Complied

Main-2 relay and PLCC are not available in all

220 kV ELPK-1 and ELPK-2 feeders. Complied Complied

CVT ratio is beyond permissible limit in R and

Y phases of ELPK-2 and Bus-1 CVTComplied Complied

Load encroachment impedance and the

loadability of the relay to be examined

depending upon the line length and loading nof

the feeder.



Providing of stub/EFP protection to be

examined for 220 kV lines.

It is informed that at 220 KV level stub protection is not provided. Bus PT is used for distance protection. KSEB

requested the item be dropped. The issue was discussed and the forum accepted the proposal.


Item.


When line is switched off, line CB and bus isolator are kept open.Hence stub/EFP protection not required

Dropped

Possibility of providing different make

distancve protection relay for main-1 and main-2

protection to be explored.



The carrier aided trip to be examined to have

different channel for main-1 and main-2

protection as twin channel is available in

protection coupler at different frequencies.



Enabling functionality for both main-1 and main-

2 relay to be reviewed.



220 kV Sabarigiri-Pallom feeder protection is

proposed to be replaced with numerical relay

protection system may6 be expedited.



8 220 kV New

Pallom Switching

Station

9 220 kV Palakkad

S/S

10 220 kV Pallom

Annexure-XII

Page 77 of 96

Constructing of oil sump adjacent to the

transformer at suitable location to be explored

for collecting of oil in the case fire brokes out in

the case of emergencies.

WO issued. Will be done by Jan 2015.


Work in progress and scheduled to be completed before 30.09. 2015.


Completed by 10-2015

Complied

10 220 kV Pallom

Annexure-XII

Page 78 of 96

UFR setting needs to be changed as per

recommended setting.



Galvanizing to be done for the supporting

structures in the 220 kV switchyard.


Completed by April 2014Complied

Some of the CTs error is found above he

recommende value. Retesting is required.



Control Panel for transformer 1 & 2 numerical

relay to be provided.


Completed by Feb 2015.Complied

Earth resistance value is found to be on higher

side. Remedial measures shall be taken.

Exploring proper measurement provision.(Time extension recommended by PCSC forum)


Done- Found 0.42ohms

Complied

Even though two 110 V DC sources available,

redundancy for protection system not ensured.


Cable laying & terminal connections pending and scheduled to be completed before 30.09.2015.



Complied

48V DC positive earthing not proper in the

carrier communication panel and also

redundancy not ensured.



Main-II independent distance relay not available

for all the lines.


Completed by Mar 2015Complied

Line distance relays zone-3 and zone-4 settings

are found to be same but timings are different.



Some of the isolators not able to be operated

from SCADA PC.



66/11 kV, 4MVA Transformer CB closing voil

taking 50A approximately for operation, hence it

shall be replaced.

New CB to be installed taking care of space constraints. (Time extension recommended by PCSC forum)


Breaker received. Erection will be completed before 31.05.2016.



Complied

High resistance fault are frequent in these lines,

so lines tripping on back up E/F protection for

the in zone line fault. It shall be avoided by

providing carrier aided earth fault protection.


Resistance coverage of distance relays have been revised. Presently high resistance faults are detected by distance

relays. So immediate implementation of carrier aided earth fault protection for DEF is not required.

Pending

LBB protection pickup current is less so it is to

be compared with line charging current and set

above it and LBB time delay to be reduced.



S. No Name of


1 220 kV Areacode

S/SPossibility of using separate DC Sources for

Main-1 & Main-2 to be explored for reiability of

DC supply.


Complied by June 2015Complied

11 220 kV

Pothencode

12 220 kV Sabarigiri

Moozhiyar HEP

Phase-II

Annexure-XII

Page 79 of 96

DG set is not available in the station.



Completed by July 2015.

Complied

The % error in some of the CVTs found to be

high and there is proposal for replacing them.Complied Complied

Substation is under renovation hence earth pits

shall be incorporated.


New earthmat provided in the 220kV yard. Complied

DG set not available.

PO issued.Will be issued by Jan 2015.


DG set erection completed Commissioning will be done before 31-08-15.


Completed by 12.2015

Complied

48 V dc supply redundancy not available.Latest update as on 24-08-2015:

Complied by Dec 2014.Complied

Only one bus available, transfer bus shall be

provided.

Design and tendering in progress.


Administrative Sanction accorded for 25 crores . Tender procedures started and the work scheduled to be

completed before 31.12.2016.


1.Tender process in progress (Price bid opened awaiting Board sanction for proceeding further) and the completion

date may extent up to 31.12.2016. While carrying out work, the inter state feeders namely Thirunelveli No I & II

feeders will have to switched off for long periods. The delay in obtaining shutdown of these feeders may delays the

work. The time of completion may be extended up to 31.12.2016

Pending

Fire protection operation with electrical sensor

shall be provided for generator transformers.

To be carried out during renovation.(Recommended by PCSC forum)


PO placed for new current injection kit of 200A.


Included in R&M work


This work has been scheduled for execution along with the proposed R&M of first stage units of Idukki HEP. The

tender invited for the R&M work has been cancelled and is being retendered. The time of completion may be

extended to 31.3.2017.

Pending

In some of the CTs, the ratio errors are found to

be in higher side. It shall be checked and

corrective measures to be taken.


The CTs were tested with meters and test kit of high accuracy and error found within limits. December 2014Complied

Bus bar protection is not available.



Tender invited for bus bar protection panel and scheduled to be completed before 31.05.2016.


PO placed for new bus bar protection Panel.Will be completed by 30.6.2016.


PO issued for Busbar protection Panel & 220KV CTs . .PO-13/15-16 dt.16.11.15 of Chief Engineer

Transmission North, Kozhikode to M/s. DANISH Pvt. Limited .Material will be received in March. Work can be

completed wihin one month from the date of receipt of balance materials.

Pending

DG Set is not available.Latest update as on 24-08-2015:

Complied by Nov 2014.Complied

3 220 kV Edamon

SS

4 220 KV Idukki

HEP

5 220 kV

Kaniyambetta S/S

2 220 kV

Brahmapuram

Substation

Annexure-XII

Page 80 of 96

Only one set of Battery charger and battery set is

available.


Complied by Nov 2014.Complied

Transfer breaker scheme to be examined for

substitution of main breaker.

Due to space constraints KSEB requested to drop the item. The PCSC forum discussed the issue and suggested to

have a bus Sectionaliser scheme instead of transfer bus scheme. KSEB agreed for the suggestion.

The PCSC forum (Special Meeting

of Protection Co-Ordination Sub-Committee (PCSC)

held at SRPC, Bangalore on 19.08.2014) agreed to send the proposal to Hon’ble CERC for consideration and

allowing KSEB to implement the bus Sectionaliser scheme.


Not possible due to space constraints

Dropped

DG set is not available for emergency purpose

for LT source and a 250 kVA DG set is

suggested to be installed as a commom external

electrical power source for both New Pallom

and Pallom sub-stations.

Under Progress


Common DG set for Pallom and New Pallom Substations and erection scheduled to be completed before

30.9.2015.


Complied by 9/2015

Complied

Earth mat to be provided for Pallom 220 kV sub-

station to have effective earthing.



Work in progress and scheduled to be completed before 31.12. 2015.


Will be completed by 5/2016

Pending

220 kV Busbar protection & LBB protection are

not there at Pallom 220 kV sub-station and it is

suggtested to add up 220 kV numerical busbar

protection & LBB protection to prevent severe

damage to equipments and ultimate financial

loss.



Numerical bus bar protection panel PO placed and scheduled to be completed before 31.12. 2015.


Will be completed by 31.12.20016


PO placed. PO-21/15-16 dt.31.12.15 of Chief Engineer Transmission North, Kozhikode to M/s. G E India

Industrial Pvt. Limited Material will be received in April and scheduled to be completed before 31.12. 2016.

Pending

DG set is not available for emergency purpose

for LT source and a 250 kVA DG set is

suggested to be installed as a commom external

electrical power source for both New Pallom

and Pallom sub-stations.

PO issued.Will be installed in Jan 2015.


Common DG set for Pallom and New Pallom Substations and erection scheduled to be completed before

30.9.2015.


Complied by 9/2015

Complied

Compact size bus coupler [PASS (PLUG AND

SWITCHED SYUSTEM) - HYBRID

SWITCHGEAR] proposal to be considered for

flexibility of operation and reliability to the 220

kV source for the station.



Tendering in progress. Work scheduled to be completed before 31.03 2016.


Will be completed by 31.12.20016


PO will be issued soon after getting approval of purchase committee. Work scheduled to be completed before 31.12

2016.

Pending

5 220 kV

Kaniyambetta S/S

6 220 kV New

PallomSwitching

Station

7 220 kV Pallom

S/S

Annexure-XII

Page 81 of 96

8 220 kV

Pothencode

Double Bus arrangement is required for 110 kV

switchyard



Lay out finalised.Work to be tendered and scheduled to be completed before 31.07.2017.


Will be completed by 31.12.2017.


Due to space constraints in yard , 110 kV CT-CB hybrid unit is being explored for 200 MVA, Transformer bays.

Administrative sanction awaited from Board. The process time of material purchase of the above work will also take

one year. So the over all time to complete the above work may extended up to 31.12.2017.

Pending

9 220 KV Sabarigiri

Moozhiyar HEP

Bus-I & II current carrying capacity is around

1600A, which is not sufficient hence Bus MVA

capacity shall be reviewed by considering the

bus fault level.

Weak portions of the bus conductors replaced during total shutdown of the station during May-June 2014.Extensive

S/D is required for total replacement of conductor.Will be carried out as early as possible.


DPR prepared and scheduled to be completed before 31.5.2016.


DPR prepared will be submitted to NLDC for availing PSDF sanction and scheduled to be completed before

31.12.2017.

Pending

10 400 kV

Madakkathara

substation Fire hydrant system to be provided. Complied Complied

S. No Name of

SubstationDetails of work Status of Implementation of Protection Audit Recommendations Remarks POWERGRI

D SR I / II1 400 KV Arasur

SubstationDistance protection Zone-2 & Zone-3 timing of

230 KV feeders need review complied Complied

POWERGRI

D SR II

2 400 kV Bidadi

Substation Synchronisation check relay setting is to be

reviewed.


Settings reviewed and implemented.Complied

POWERGRI

D SR II

Enabling of stub protection in Ramagundam-3

& 4, Kurnool feeders Scheme implemented in the new numerical realys during retrofitting. Complied

Replacement of static relays by Numerical Relay

provided for Distance, Differential Bus Bar and

Reactor Protection

All distance relays are retrofitted with Numerical protection relays. Complied

Static differential relays to be replaced with

numerical relays on reactors and ICTsAll distance relays are retrofitted with Numerical protection relays. Complied

Electromagnetic back up directional O/C and

E/F relays to be replaced with numerical relays

on ICT-1.

PGCIL informed that the relay is healthy and not mal operated. PGCIL also informed the existing static relays are

meeting all protection requirements of the bus bar relay as per CBIP guidelines. PGCIL requested that the item be

dropped.


Item.


All Differential relays are retrofitted with Numerical protection relays.

Dropped

3 400 kV Ghanapur

(Hyderabad)

SubstationPOWERGRI

D SR I

4 400 kV Gooty

Substation

POWERGRI

D SR I

PGCIL

Phase-I

Annexure-XII

Page 82 of 96

Old PLCC protection couplers to be replaced

with new protection couplers

Action for replacement of Protection coupler initiated and is in process. Schdld by end of Jan'15.


The PLCC of Nsagar feeder has been replaced with ETL41. For Bangalore feeder the NSD 60 of Channel-I is

replaced with NSD50.

Complied

5 400 kV HassanBased on Setting of distance protection relays to

be reviewed as per the revised line parameters

received from KPTCL.


Settings based on revised line parameters adopted in both relays.Complied

POWERGRI

D SR II

Static distance relays of 400 kV feeders to be

replaced with numerical relays All the (03 nos.) LZ 96 relays in 400kV lines replaced in Dec-12. Complied

Static bus bar protection relay to be replaced

with numerical relays

Existing busbar protection relay complies to all CBIP guidelines. This matter was discussed in previous PCC

meetings and this point was removed. The Bus Bar protection is healthy and in line with CBIP guidelines/gazette

standards. Hence the same was not replaced.

Dropped

8 400 kV

Kalivanthapattu

S/S

230 kV feeder distance protection Zone-2 and

Zone-3 timings need review


Changed to 350ms/800ms.Complied

POWERGRI

D SR II

9

230 kV

Kalivanthapattu

S/S

230 kV feeder Zone-2 and Zone-3 trip timings

are 250 m sec and 500 m sec. where as in TNEB

it is 350 m sec and 800 m sec. This may be

looked into.

Complied CompliedPOWERGRI

D SR II

10 400 KV

Khammam

Substation

Old Static line protection (Distance) relays to be

replaced with numerical relays


All distance relays are retrofitted with Numerical protection relays.Complied

POWERGRI

D SR I

11 400 kV

MadakkatharaTime synchronising of protection system with

GPS to be providedcomplied Complied

POWERGRI

D SR II

Replacement of static relays (THR, CAG,

RADHA etc.) with numerical relays to be

looked into.


Replacement completed in 400kV lines. 220kV lines are carried out by May 13.Complied

4 400 kV Gooty

Substation

POWERGRI

D SR I

6 400 kV Hiriyur

Substation

POWERGRI

D SR II

12 400 kV Mysore

Substation

POWERGRI

D SR II

PGCIL informed that the relay is healthy and not mal operated. PGCIL also informed the existing static relays are

meeting all protection requirements of the bus bar relay as per CBIP guidelines. PGCIL requested that the item be

dropped.


Item.


1. All Differential relays are retrofitted with Numerical protection relays.

2. Numerical Busbar protection is not envisaged as per Gazzett notifications.

3. O/V feature is implemented in Ditance protection relays during the retrofitting of the relays.

Electromagnetic and static relays for ICTs,

Reactor, Bus bar,over voltage, distance

protection to be replaced with numerical relays.

400 kV Kadapa

Substation

7

Dropped POWERGRI

D SR I

Annexure-XII

Page 83 of 96

Co-ordination of protection settings for 220 kV

Downstream lines to be done to avoid un

wanted trippings at Mysore SS.


Reviewed and Revised.Complied

Plug setting multiplier setting of back up over

current relays of CTs to be reviewed.


Reviewed and found ok.Complied

Distance protection Zone-2 and Zone-3 timings

of 220 KV lines need review


Reviewed and revised.Complied

Bus sectionaliser direction to be reviewed (both

sides operation).


The direction was kept based on the faulty history and discussed in 18PCSC meeting.Complied

Zone-2 & Zone-3 time settings of distance

protection relays of 230kV feeders need review.


The revised time settings as per approved settings implemented.Complied

LBB & Bus Bar protection are in-built in the

same Siemens SIPROTEC 75552 Relay for both

Main 1 & 2. Same needs review

PGCIL informed that separate LBB and Bus Bar protection schemes are not specified in the CBIP guidelines. Hence

PGCIL requested for dropping the item. The PSCS forum discussed the issue and accepted the request.


Item.

Dropped

15 400 kV PugalurDistance protection zone-2 and zone-3 time

settings for 230 kV Lines needs review.complied Complied

POWERGRI

D SR II

16 400 kV Salem

Substation Static distance protection relays of 400 kV

feeders to be replaced with numerical relays


All static distance protection relays has been replaced with numerical relays.Complied

POWERGRI

D SR II

Nomenclature of Binary Inputs/Binary Outputs

& function to be done in DR.


In feeder,already ensured. In transformers, will be done during next ICTs S/D.

The issue was discussed in PCSC-51 held on 25-02-2016 held on 25-02-2016, when PGCIL (SR-II) informed that

the Nomenclature of Binary Inputs/Binary Outputs & function had been completed for transformers also.

Complied

The high set setting of HV side DOCR & DEFR

of each 500 MVA Transformer needs review.


All T/F settings have been reviewed and found OK.Complied

18 400 kV Trichy

Substation Old electromagnetic/static relays to be replaced

with numerical relays.


All four (04) distance relays have been replaced with numerical relays in Jan 13.Complied

POWERGRI

D SR II

Old Static line protection (Distance) relays to be

replaced with numerical relays.All distance relays are retrofitted with Numerical protection relays. Complied

Evaluation unit is to be made available for

Disturbance recorder of 400 KV Vemagiri-I & II

feeders.

DR PC installed and configured for collecting data from DR. Complied

13 400 KV Narendra

Substation

POWERGRI

D SR II

14 400 kV

Puducherry

Substation & 230

kV Puducherry

Substation

POWERGRI

D SR II

12 400 kV Mysore

Substation

POWERGRI

D SR II

17 400 kV

Somanahalli

Substation

POWERGRI

D SR II

19 400 KV

Vijayawada

(NUNNA)

Substation

POWERGRI

D SR I

Annexure-XII

Page 84 of 96

The DRs (Indactic65C) and Event Logger

(SER7000) of 400KV VTPS-I & II Feeders are

not healthy and need to rectified.

The DRs ( Indactic65C) and Event Logger ( SER7000) of 400KV VTPS-I&II feeders are not working (Belongs to

APTRANSO & being persued with APTRANSCO).


DR & EL PCs installed and configured for collecting data.

Complied

Monitoring source to be provided for DC earth

leakage to be provided


The faulty cables have been addressed and presently DC Earth fault is not present in the system.Complied

Over voltage protection time setting to be

reviewed complied Complied

Review of zone-3 setting for 220kV Kochi-

Brahmapura and 220kV Kochi-Kalamashery complied Complied

21 400kV Munirabad

Substation Numerical relay to be provided for differential

protection of ICT-1&2complied Complied

POWERGRI

D SR I

Old relays to be replaced with numerical relays

for feeders, ICTs and Reactors.


All Differential relays are retrofitted with Numerical protection relays.Complied

Mutual compensation to be incorporated in

distance protection settings of 400kV N'Sagar-

Ramagundam ckt-1&2.


During retorifitting of relays the Mutual compensation is carried out.Complied

S. No Name of


POWERGRI

D SR I / II

1 400 kV Kochi SS

220V Battery bank-1&2 for protection system to

be replaced with lead acid batteries

VRLA batteries are inline with the standard guidelines.

The issue was discussed in PCSC-47 held on 15.09.2015, and the forum agreed to drop the Item.

DroppedPOWERGRI

D SR II

2 400 kV Palakkad

SS Outsource supply supplied from 11 kV Para

feeder is having low reliability and hence

alternate arrangements to be made for reliable

supply.


The tertiary supply from ICT#2 erection completed. Request for availing aux supply is being processed by KSEB.

The issue was discussed in PCSC-51 held on 25-02-2016 when PGCIL (SR-II) informed that they have started

availing supply from the tertiary of ICT # 2 from 3rd week of Jan, 2016.

CompliedPOWERGRI

D SR II

3 400 kV Trichy SS

Existing 50 V set-1 Batteries to be enhanced to

adequate capacity. Same to be replaced


The 50 V set 1 commissioning has been completed on 15-01-13.Complied

POWERGRI

D SR II

4 400 KV

Vijayawada

(Nunna) SS

Fire fighting system is out of service for

replacement of old damaged pipe line.

All the works on Fire fighting system at Vijayawada are completed. Presently the Fire Fighting system is functional

and put into service and the same is in Auto mode since 01/03/2014. Communication sent vide letter dtd 28/04/14Complied

POWERGRI

D SR I

S. No Name of


1400 kV Gajuwaka

S/S (IS)

LZ96 and RAZFE relays are being replaced with

numerical relays having DR facility.Complied Complied

20 400kV Kochi

SubstationPOWERGRI

D SR II

22 400kV N'Sagar

(Tallapalli)

SubstationPOWERGRI

D SR I

19 400 KV

Vijayawada

(NUNNA)

Substation

POWERGRI

D SR I


Phase-II

Annexure-XII

Page 85 of 96

2

HVDC Kolar S/SArrangements may be made to replace the

battery

electrolyte level indicators wherever not proper

Complied Complied

S. No Name of


Distrubance Recorders (ABB, INDACTIC) not

having GPS time synchronisation (for 400 kV

Warangal Line, 400 kV Gajwel Line, 400 kV

Malkaram Line, 400 kV Hyderabad Line # 3,

400 kV Hyderabad Line # 4), 400 kV Dichipalli

Numerical relay (DR) not having GPS time

synchronisatiion.

a) These disturbance recorders are connected to a PC. The PC has now been time synchronized through GPS. The

PC synchronizes the DRs with the batch process (WINCOM) on regular basis. - Complied

b) 400 kV Dichipalli Numerical relay (DR): Time synch problem has been taken up with TSTRANSCO, the owner

of the equipment.

The issue with regard to time synchronisation of Dichipally feeders numerical relay was discussed in PCSC-51 held

on 25-02-2016 and it was made clear that the responsibility of complying with this recommendations lies with

TSTRANSCO.

Complied

Distrubance recorder of 400 kV Nagarjunasagar-

2 sent for repair. However, built-in DR

available with the relay MICOM442.

The disturbance recorder installed. Complied

DC supply-II: +ve to Earth voltage measured is

158 V, -ve to Earth voltage measured is -80 V.Ongoing routine activity Complied

Over current & earth fault protection enabled in

Chandrapur - 1 & 2 and N'Sagar 1 & 2 as per

instructions of NTPC CC (Mail copy verified)

The Overcurrent protection is active only in case of VT fuse fail condition. This is in line with present protection

philosophy.Complied

CT ratio test results for Dichipalli (Tie & Main),

Auto-5 (Main & Tie), Auto-4 (Main & Tie),

Hyderabad-2 (Main & Tie), Hyderabad-1 (Main

& Tie), Warangal (Main & Tie), Main & Tie Cts

of Gen-1, Gen-3, Tie-1, Tie-2 will be submitted

to SRPC, Bangalore by NTPC Ramagundam

subsequently.

All the data has been sent to SRLDC in the first week of Dec, 2012. Complied

CVT test results for Warangal, Auto-1, 2, 3 & 4

and Hyderabad 3 & 4 will be submitted to

SRPC, Bangalore by NTPC Ramagundam

subsequently.

Submitted to SRLDC in the first week of Dec, 2012 Complied

NTPC Ramagundam has confirmed that copy of

recommended/adopted relay settings for all the

feeders will be submitted to SRPC, Bangalore

subsequently.

Submitted to SRLDC in the first week of Dec, 2012 Complied

2400 kV NTPC

Simhadri S/S

(Gen)

NTPC informed that the existing MICROMHO

relays of Stage-I lines are being replaced with

REL 670 relay of ABB make which will be

integrated to ABB Micro SCADA of Stage-2.

Complied Complied

NTPC

(Phase I & II)

400 kV NTPC

Ramagundam S/S

(Gen)

1

Annexure-XII

Page 86 of 96

3

220 kV NTPC

Kayamkulam S/S

(Gen)

Zone-2 and Zone-3 relays may be considered to

be adopted as 350 ms and 800 ms as per the

SRPC directions, otherwise zone-2 & zone-3

timing may be adopted uniformly at both ends -

local end & remote end.

Complied Complied

PLCC facility for protection is not available for

220 kV lines

OPTCL is the owner of the associated PLCC system of the 220 kV Lines. The scheme for PLCC aided tripping for

220 Kv Lines is in place at Kaniha but non functional due to absence of protection coupler in associated PLCC

system.

OPTCL may be pursued to provide protection coupler in the associated PLCC system.

Pending

Auto reclosing feature is not available in all 220

kV lines

The scheme of Auto reclosing function for 220 Kv lines is in place at Kaniha end. This feature is non-functional due

to absence of protection coupler in the assoclated PLCC system.OPTCL may be pursued to provide protection

coupler in the associated PLCC system.

Pending

Static relays may be replaced with numerical

relaysThe Main- II distance protection Relays of 400 Kv Rourkela D/C have been replaced with numerical relays. Complied

Earth switches are not provided for Talcher-

Rourkela 400 kV line I & II and Talcher-Rengali

400 kV line I & II to facilitate earthling during

maintenance.

The line earthing is achieved through the corresponding Tie bay isolators. Complied

S. No Name of


The line relays 220 KV side are provided with

01 primary protection ie. Static Relay, and a

back up relay is to electro mechanical relay with

high set. Blocking of High set protection in the

back up relay needs to be reviewed. NPCIL-

Kaiga to review the same

Completed during May 2014 Complied

Instead of Static Relays, Numerical Relays to be

provided with different make for all lines as

Main-I and Main-II. NPCIL-Kaiga to review the

same

Completed Complied

The test reports of CT, CVT & CB are to be

furnished.Complied Complied

The stability test conducted was confirmed

orally however no records could be verifiedComplied Complied

Synchronizing relay details to be furnished. Complied Complied

Latest Tested dates of Line protection Relays

MI, MII, LBB & PLCC are to be furnishedComplied Complied

220 KV Kaiga-

Generating

Station-1&2

NPCIL

(Phase I & II)

230KV MAPS

Kalapakkam S/S

(Gen)

2

400kV Talcher

STPS, NTPC

4

1

Annexure-XII

Page 87 of 96

Line Parameters for Acharpakkam & Bhavini

are yet to be furnished.Yet to be furnished. Pending

Recommended line protection relay settings

with the latest fault levels and the adapted

settings could not be verified. The revised

recommendations & copy of adapted relay

settings to be submitted by MAPS, NPCIL

Complied Complied

The Line CVT in the Y phase of the feeder was

not available in all the feeders except SP koil 2 :

To be reviewed

Communicated to TANTRANSCO.

The issue was discussed in PCSC-51 held on 25-02-2016, and it was made clear that the responsibility of complying

with this recommendations lies with MAPS (NPCIL).

Pending

S. No Name of

SubstationDetails of work Status of Implementation of Phase I Recommndations Remarks

Protection system to be synchronized with

available GPS Complied Completed

Event logger to be rectified and made functional Complied Completed

Disturbance Recorder to be rectified and made

functionalComplied Completed

Existing micro mho distant protection (Main I)

relays to be retrofitted with numerical relay.Complied Completed

2 400 kV NLC TPS-

II Expn.O/V protection for stage-II time setting to be

revised for instantaneous tripComplied Completed

S. No Name of


NLC

Phase-I

1 400 kV NLC TPS-

I Expn.

230KV MAPS

Kalapakkam S/S

(Gen)

2

Phase-II

Battery bank to be provided for OPGW will fulfil the 2nd source requirement.Completed by 31.04.2015


Expected date of completion is 31-12-2015.


Order has been placed for second 48V DC source in OPGW package being implemented by PGCIL, which is

expected to complete by 31-Dec-2015.


Battery bank to be provided for OPGW will fulfil the 2nd source requirement. Supply of battery bank in PGCIL's

scope. PGCIL has informed NLC that the work would be

completed before 31.12.2015. It was informed that the two pending phase-II activities will be completed before

31.12.2015 as prayed in NLC's affidavit dt. 05.09.2015.


Battery bank to be provided for OPGW by PGCIL will fulfil the 2nd source requirement. Materials are received at

site. Erection works will be taken up shortly. Expected date of completion is Before 30.06.2016.

The issue was discussed in PCSC-51 held on 25-02-2016, when NLC informed that the second source for 48 V

PLCC battery system was commissioned in the 3rd week of February, 2016. It was also informed through an email

dated 26-02-2016.

2nd source for 48 V PLCC battery system to be

considered.

400 kV

Switchyard - NLC

TPS-II Expn.

1

Complied

Annexure-XII

Page 88 of 96

Battery bank to be provided for OPGW will fulfil the 2nd source requirement.Completed by 31.04.2015




Order has been placed for second 48V DC source in OPGW package being implemented by PGCIL, which is

expected to complete by 31-Dec-2015.


Battery bank to be provided for OPGW will fulfil the 2nd source requirement. Supply of battery bank in PGCIL's

scope. PGCIL has informed NLC that the work would be

completed before 31.12.2015. It was informed that the two pending phase-II activities will be completed before

31.12.2015 as prayed in NLC's affidavit dt. 05.09.2015.


Battery bank to be provided for OPGW by PGCIL will fulfil the 2nd source requirement. Materials are received at

site. Erection works will be taken up shortly. Expected date of completion is Before 30.06.2016.



dated 26-02-2016.

2nd source for 48 V PLCC battery system to be

considered.

400 kV

Switchyard - NLC

TPS-II Expn.

1

Complied

Purchase action in progress. Work will be completed by 31.03.2015.Latest Status is by 30.09.2015.




Purchase action initiated and expected to be completed before 31.12.2015.


Purchase action in advanced stage of completion. P.O. likely to be issued in October-2015 and erection and

commissioning will be taken up in Nov-Dec 2015. Work will be completed by 31.12.2015.

It was informed that the two pending phase-II activities will be completed before 31.12.2015 as prayed in NLC's

affidavit dt. 05.09.2015.


Purchase Order issued to vendor. Expected date of completion is before 30.06.2016.



dated 26-02-2016.

Only one bank of 48V battery for PLCC is

available. 2nd bank to be provided

400 kV

Switchyard - NLC

TPS-I Expn.

2

Complied

Annexure-XII

Page 89 of 96

S. No Name of


1

400 kV JSWEL

S/S (Gen) The over voltage stage - 2 and stub protection

functions for 400 kV lines may please be

enabled for better protection schemes.

Complied Complied

It is observed that 400 kV BuS voltage is on the

higher side since from the commissioning of

400 kV Hassan-Udipi line 1,2. Action needs to

be taken to reduce the stress on the equipment.

VAR compensation is suproted by the Generator. Complied

The extension of permissive trip to Hassa SS in

the event of O/V trip also at Udipi end needs to

be verified & rectified at Udipi end.

Complied Complied

Based on the revised line parameters received

from KPTCL, new settings adopted in Main-

1&2 relays during October 2012.

Complied Complied

DC Main battery, +ve ground is observed & the

same may be rectified.Attended Complied

The distance protectio-Main-I and Main-II and

busbar protection - periodic testing not

conducted so far from commissioning. The same

may be tested immediately for the healthyness of

the above system.

Attended Complied

PLCC / Protection Coupler not in service. The

same may be put into service.Attended Complied

OTHERS

(Phase I & II)

2

400 kV UPCL S/S

(Gen)

3

220 kV ITPL S/S

220 kV Spectrum

PGL S/S (Gen)

4

Dropped

APTRANSCO requested that item be dropped considering that the relays are only provided on the identified feeder,

and not for all substations. The issue was discussed in the special meeting of PCSC held on 19.08.2014, and the

forum accepted the proposal.


Item.

Spectrum mail recieved on 15-09-2015:

We plan to replace 220 KV Spectrum-Kakinada line distance

Protection relays with two different make numerical protection relays with lEC 61850 compatibility during our

Renovation &Modemization activity in December 2015. We have received quotes for the said relays of make

Alstom, ABB and siemens. Siemens offered model nos-SIPROTEC 47SA6 and 47SA522. The Technical

specifications of Alston and ABB relays are enclosed here with . Basing on your recommendations and

approvals, we shall proceed further to procure the relays.




Renovation &Modemization activity in December 2015. We have received quotes for the said relays of make Alstom

and ABB and we are in the process of procurement of the relays.

It is observed that there is no O/V protection,

df/dt & UFR protection for both the 220 kV

feeders.

Annexure-XII

Page 90 of 96

PLCC inter trip protection is not in service for

both feeders.

Spectrum mail received on 15-09-2015 and 19-10-2015:

Carrier inter tripping scheme of SPGL-Kakinada lines 1 &2 has been tested in co-o rdina tlon with MRT team,

Rajahmundry and kept in service.Complied

GPS is not available.

Spectrum mail received on 15-09-2015 and 19-10-2015:

Disturbance recorder and Event logger are available presently. But the Time Synchronization facility for global

common time reference will be studied and implemented in December 2015 during R&M of our plant.

Spectrum Mail received on 27-01-2016 and 23-02-2016:

We have been evaluating technical specifications of two different make numerical distance relays with IEC 61850

compatibility. We will install these numerical distance relays positively, during our Plant Renovation &

Modernisation in APRIL-2016. These two relays will provide the GPS facility.

Pending

220 kV Spectrum

PGL S/S (Gen)

4

Dropped





Item.




Renovation &Modemization activity in December 2015. We have received quotes for the said relays of make

Alstom, ABB and siemens. Siemens offered model nos-SIPROTEC 47SA6 and 47SA522. The Technical

specifications of Alston and ABB relays are enclosed here with . Basing on your recommendations and

approvals, we shall proceed further to procure the relays.




Renovation &Modemization activity in December 2015. We have received quotes for the said relays of make Alstom

and ABB and we are in the process of procurement of the relays.

It is observed that there is no O/V protection,

df/dt & UFR protection for both the 220 kV

feeders. Annexure-XII

Page 91 of 96

For 220 kV line # 2 protection relay

recommended settings to be adopted.


Settings are adopted as per recommendations and relay calibrated. Complied

a) Distance protection Zone: 4 time of operating

t 1 pp adopted: 1.2 sec; Recommended 0.9 sec











Dropped

b) Power swing detection I base current

adopted: 3000 A; Recommended: 800 A


Base current changed to 800 A.Complied

c) Time delayed phase overcurrent protection

(18) Adopted: ON; Recommended: OFF


Kept in OFF.Complied

d) Time delayed phase overcurrent protection

(18) Adopted: ON; Recommended: OFF



e) Time delayed over voltage protection (24)

Adopted: ON; Recommended: OFF



f) Synchro check (29) Adopted: ON;

Recommended: OFF








GMR informed that they would adopt the recommended setting in presence of APTRANSCO officials.

Pending

For 220kV Line #2 Distance protection Zone: 4

time of operating t1 pp Adopted: 1.2 sec;

Recommended : 0.9 sec











Dropped

Auto reclose scheme is kept in OFF position for

both 400 kV feeders.

GVK mail received on 16-09-2015:

Auto re-closure scheme was enabled and kept in service at 400KV Gautami SS end as per approved settings of

APTRANSCO, confirmation of the same was communicated to APTRANSCO CE (Power Systems) in Jan 2013.

Complied

In 220 kV line # 1, main # 1 & 2 protection relay following deviations observed:

220 kV GMR

Barge, Kakinada

S/S (Gen)

400 kV GVK

Gautami S/S

(Gen)

6

5

Annexure-XII

Page 92 of 96

Over voltage stage-1 time setting of line-2 is

deviating from recommended setting i.e.

recommended setting is 5 sec & adopted setting

is 4 sec.


Relay settings for over voltage protection were revised as per the ref. letter #4.Complied

It is observed that there is no under frequency

and df/dt protections for both 400 kV feeders.





Item.

Dropped

Recommended relay settings are not available

with the utility

Reliance mail received on 18-09-2015:

Recommended relay settings were implemented on 02/05/2015, in the presence of MRT Wing, APTRANSCO,

Bommur

Complied

Main-I protection zone settings are deviating

with recommended settings as per record of M/s.

Reliance.


Recommended relay settings were implemented on 02/05/2015, in the presence of MRT Wing, APTRANSCO,

Bommur

Complied

PLCC Inter Tripping Scheme was not in service.


PLCC Inter tripping was taken into service, on 02/05/2015, in the presence of MRT Wing & Telecom Wing,

APTRANSCO.

Complied

O/V, U/F & df/dt protections are not available

for both the feeders.





Item.

Dropped

Over current relay High. Set value of STGT is

9.5 instead of 7.5

KGPL mail received on 19-09-2015:

The Over current relay High-Set value of STGT has been changed from 9.5 to 7.5.Complied

Over voltage stage-1 time delay setting is 4 sec

instead of 5 sec in 400 kV Line #2.


Over voltage stage-1 time delay setting of 400kV line-2 has been changed from 4sec to 5 sec.Complied

Observed Auto reclose selection is in non auto

mode for both the 400 kV feeders


To implement Auto-reclosure scheme for 400kV Line 1 and 2 Breakers technical support is required from OEM who

have supplied the line protection relays and communication is in progress with them. After getting support from

OEM, Auto-reclosure scheme implementation period will be informed.

Pending

Observed there is no U/F & df/dt functions for

both the 400 kV feeders




The PCSC forum agreed to drop the item.

Dropped

Auto reclosing scheme is in off condition for

both Line-1 and Line-2.


AttendedComplied

400 kV GVK

Gautami S/S

(Gen)

6

220 kV Reliance,

Samalkot S/S

(Gen)

7

400 kV

Konaseema S/S

(Gen)

8

400 kV GVK

Jegurupadu Extn.

S/S &

220 kV

Jegurupadu Extn.

S/S (Gen)

9

Annexure-XII

Page 93 of 96

O/V Stage-1 protection setting is observed at

115% (73V) instead of recommended 110%

(70V)


AttendedComplied

Overvoltage stage-1 protection was disabled in

Main-1 protection relays of both the 400 kV

feeders.


Enabled in Main-I protection relay for both 400kV feeders and complaince was submitted to CE/ Power System vide

letter dated 30th Sept, 2013.

Complied

Over voltage stage-2 was deviating from

recommended setting. (settings: Adopted Valve:

133V, 50 Milli seconds, recommended valve: 77

V, 0 sec.


Over voltage Stage-2 setting was revised as per CE/Power Systems and same was tested with the help of external

agency for correct operation and complaince submitted vide letter dated 30th Sep,2013.

Complied

Over voltage protection configuration Main 1

protections of both the feeders were deviating

from recommended configuration, i.e.

recommened is phase to neutral, adopted is

phase to phase.


Over voltage protection configuration Main-1 protections of both feeders were corrected as per initial approved

settings (i.e, Phase to Neutral)

Complied

Auto reclosure scheme was kept in non Auto

mode for both the 400 kV feeders.


Auto Scheme for both 400kV feeders was kept in Auto mode.Complied

All the Numerical Protection relays are not time

synch as the GPS is not available.Complied

All the Main-1 & Main-2 relays are showing

different timings.Complied

It was observed that over voltage stage 1 in

Main-1 relays of both the feeders are tested at

120.89V, but as per the relay setting it is in

disable condition.


Over voltage stage-1 in Main-1 relay settings was enabled for both feeders and same was tested as per setting with

the help of external agency for correct operations.

Complied

Power swing detection settings are deviating

from recommended settings (recommended is

1.0 OHM adopted is 0.5 OHM)


Power swing detection settings were corrected as per approved settings.Complied

GT Generator Transformer over current & high

set values are deviating from recommended

values (over current Recom. Set: 0.6, adopted

set point: 1 and high set recom. Set is 4.5,

adopted set 4)


GT Gernerator Transformer over current and high set values was corrected as per approved settings.Complied

As the recommended settings for Main 2

Protection relays are not available for both the

400 kV feeder relays, those were not verified.


Recommended settings for Main-2 Protection relays were available and same checked for correctness, it as per

approved settings.

Complied

All distance static relays should be retrofitted

with latest version Distance Relays for quick

and accurate analysis for the tripping.

APGPCL mail receieved on 14-09-2015:

Procurement is under progress.

APGPCL mail received on 29-01-2016:

Procurement action for numerical distance protection relays(Siemens make Siprotech relays, Type: 7SA522-5CB92-

5HR5/LOR and ABB make REL 670 model relays) with time sync is intiated and got delayed due to chennai fluds.

The same are expected to received & Commissioned by end of May 2016 and complience will be sent.

Pending

11

400 kV GMR

Vemagiri S/S

(Gen)

220 kV

Vijjeswaram

Stage-I S/S (Gen)


All the numerical relays time was corrected and GPS installation feasebility checks are under progress. The expected

date of installation and commisiioing of the GPS system for protection relays is 31 Oct, 2015.


Complied by 21st December, 2015

400 kV GVK

Jegurupadu Extn.

S/S &

220 kV

Jegurupadu Extn.

S/S (Gen)

9

10

Annexure-XII

Page 94 of 96

GPS may be provided considering the criticality

of the station for accurate analysis of tripping.







Pending

Distance relay should be tested periodically as

per schedule (last test carried out - 1997).

APGPCL mail receieved on 14-09-2015 and 29-01-2016:

Since we are procuring new relays it is not applicable and new relay will be tested before commissioning.Complied

Numerical relays SIEMENS & ABB clock

timing to be corrected.


CompletedComplied

All distance static relays should be retrofitted

with latest version Distance Relays for quick

and accurate analysis for the tripping.







Pending

GPS may be provided considering the criticality

of the station for accurate analysis of tripping.







Pending

Only one set of Battery charger is available.

Another set of charger may be provided.


Interconnection cable laid between battery chargers at Stage-I & II for better redundancy. Hence necessity of

additional battery charger is eliminated.


Complied

Complied

11

220 kV

Vijjeswaram

Stage-II S/S (Gen)

12

220 kV

Vijjeswaram

Stage-I S/S (Gen)

Annexure-XII

Page 95 of 96

DEFR relay may be provided in any of the

distance protection relay to clear the high

resistance fault.







Pending

Distance relay should be tested periodically as

per schedule (last test carried out - 1997).

APGPCL mail receieved on 14-09-2015 and 29-01-2016:

Since we are procuring new relays it is not applicable and new relay will be tested before commissioning. Complied

There are no recommended settings. The

settings given by the vendor (AREVA) are being

adopted. These settings shall be got

reviewed/Approved.

LANCO mail received on 16-09-2015:

Generators, Generator Transformers, 400 KV Lines relay testings, Protection Schemes and SLD of 400 KV

Switchyard submitted to PGCIL prior to commissioning of Transmission lines. Further, these settings were submitted

to Audit team on Kondapalli SIS 17 December 2012 during their visit to Site.

Pending

It is observed that there are no line tripping till

date.


Lines were mostly kept under idle charge from Mar'13 to Jun'15 as Generators were not in service. PGCIL is carrying

out regular Patrolling and carrying out lines inspection. Complied

GPS is not available.LANCO mail received on 16-09-2015:

The relays installed in 220 KV substation are of static relays. Hence GPS cannot be connected to these relays.Pending

All trip reports are reviewed. Maloperation of

busbar protection at Lanco end for CT blast at

VTPS end. It is requested to review and rectify

the same.


Stability test of the 220 KV busbar protection relays tested during the scheduled Plant Outage in 2013-14 and found

to be working normal.

Complied

Earthing system to be improved. Additional earth pits provided during April 2014 Complied

Dedicated hot line speech facility to SLDC to be

established.

TANTRANSCO requested the item be dropped.


Item.

Dropped

Real time data transfer facility to SLDC shall be

established.Established on 14.3.14. Complied

There is no standby battery bank and charger. Standby battery bank and charger commissioned on 02.12.2014 Complied

220 kV

Vijjeswaram

Stage-II S/S (Gen)

12

400 kV Lanco

Kondapalli S/S

13

15 230 kV Hi-Tech

Carbon Co-Gen.

14 220 kV Lanco

Kondapalli S/S

(Gen)

Annexure-XII

Page 96 of 96

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