th protection committee meeting - wrpcwrpc.gov.in/pcm/94pcm_minute.pdf · 2006-10-18 · welcomed...

Minutes of 94th PCM

No:PROT./94PCM/2006-07/WRPC-7421 dated 17th OCT 2006

MINUTES OF THE 94th PROTECTION COMMITTEE MEETING

The 94th Protection Committee Meeting was held on 21st & 22nd September 2006 at Auramgabad. The list of participants is placed at Annex -I.

At the outset, Shri Chandrashekhar Modi, Chief Engineer, MSETCL, Aurangabad welcomed the members and participants to 94th Protection Committee Meeting. He said that it was a great pleasure for MSETCL in holding this 94th WRPC PCM in the historic city Aurangabad and thanked WRPC for giving an opportunity to host the Protection Committee Meeting by MahaTransco at Aurangabad. Welcoming Shri Patel, Member Secretary WRPC and members & participants to 94th Protection Committee Meeting, Shri Shishir Tamotia, Director (Operation), MSETCL expressed that the discussions during the 94th Protection Committee Meeting would give fruitful results and the Protection Engineers of the constituents of WRPC would share their experiences and implement the decisions/recommendations of the Protection Committee to improve the overall performance of the Western Grid. A brief presentation on MSETCL’s programmed development of Maharashtra Grid was given by MSETCL representative. Shri P. Patel, Member Secretary, WRPC welcomed all the participants to the 94th Protection Committee Meeting. He thanked MSETCL for having consented to host the meeting at Aurangabad and for the excellent arrangements made for the meeting and comfortable stay of participants. He expressed special thanks to Shri Tamotia, Director (Operation), MSETCL for attending the meeting in spite of his busy schedule and stated that not only during the last quarter but in the last three years, no major grid disturbance had occurred in Western Regional grid, which is the largest power grid combined with Eastern & North Eastern regional grids in the country. In the region, though demand is increasing, the matching generation capacity is not being added. As a result, gap between demand and availability is widening over a time and efforts are made to import maximum available power from neighboring regions thereby loading the transmission network to its limit. As such, the system is forced to operate in critical operating conditions.

He indicated that Protection Committee Meeting is a gathered team of experts from various utilities in the field to evolve solutions to problems in the area of protection and provides platform for exchange of technical information for safe and secure operation of the regional grid. He informed that Northern Regional grid has now been synchronized successfully with the Central Grid comprising WR-ER-NER at 12:22Hrs on 26.08.2006 and thus only SR grid remains to be integrated with this enlarged grid to form the National Grid. He requested protection engineers to keep operational all protection schemes including Under Frequency Relays. He emphasized on monitoring of operation of these relays, load relief obtained and expected for safe & secured operation of the enlarged grid.

He informed the participants that a presentation by Shri Shrikant B. Potnis, GM, Crompton

Greaves Ltd, Nashik on Online Condition Monitoring of Extra High Voltage Circuit

Minutes of 94th PCM

Breakers is arranged on 22nd September 2006. He then requested Shri S. D.Taksande,

Superintending Engineer (Protection), WRPC, to take up Agenda items for discussion.

Shri S. D.Taksande, Superintending Engineer (Protection), WRPC, welcomed all the members and invitees to the 94th Protection Committee Meeting. He informed the participants that WRPC PCM Agenda & Minutes are made available on WRPC website (www.wrpc.nic.in). The agenda items were taken up for discussion in seriatim.

Item No.1: Confirmation of Minutes of 93rd Protection Committee Meeting. Minutes of 93rd Protection Committee Meeting of WREB held on 23rd & 24th May 2006

at Kakrapar Atomic Power Station, NPCIL, Kakrapar were circulated vide WRPC letter

no. Prot./93-PCM/2006-07/WRPC/ 4342 dated 15th June 2006. WRTS, PGCIL vide their

letter No. WRTS/O&M/R/141/3659 dated 27.06.2006 have proposed following

amendments in the minutes of 93rd PCM:

Sr. No. 2.06:

As reflected in Minutes: “POWERGRID informed that daylight UV camera for

observing existence of corona on insulator string even during day time are also

available in the market.”

To be amended as: “No such instrument is available in the market which can detect

pollution related problem of insulator through corona. In fact, POWERGRID had

carried out many experiments in this respect but no camera found of this

capability.”

Committee suggested to delete the sentence recorded in Minutes.

Sr No. 9.04:

AS reflected in Minutes: “POWERGRID agreed to provide DRs on Chandrapur –

Bhadravati ckt 1 & 2 at Chandrapur end.”

To be amended as: “POWERGRID has not agreed to provide DRs at Chandrapur MSEB end. What they have agreed for replacement of one of main protection with DR facility as per their R & M plan.”

Committee opined that it was correctly recorded in the minutes. However, POWERGRID representative insisted that POWERGRID has agreed to replace one of the Main Protections with DR feature in both 400 KV Bhadrawati – Chandrapur Ckt 1 & 2 at Chandrapur, MSTCL end before 31st March 2007.After further discussions, it was decided that the minutes were recorded correctly and there was no need to amend the same.

Minutes of 94th PCM

The minutes for 93rd Protection Committee Meeting were confirmed with above

modifications.

Item No.2: System disturbances

2.01: System disturbance at 220 kV Ukai TPS S/S in GSECL system on 11-04-2006

The representative of GSECL explained that on 11.04.2006 at 04:20Hrs, R- ph CT (BHEL make in service from 1975) of 220kV Bus Coupler bay at 220kV Ukai TPS Switchyard failed due to bursting and caught fire. This resulted in operation of Bus Bar differential protection of both buses and tripping of all generating units, feeders & transformers connected to these buses. Restoration started by availing power from Ukai (Hydro) through 220kV Ukai (Th) – Ukai (Hydro) Tie line # 2 and thereby charging 220kV Bus – I at 05:00Hrs. Subsequently other feeders, transformers and generating units were charged. GSECL representative informed that 3 CTs were replaced. Committee suggested for providing two CTs i.e. one each on both sides of Bus Coupler in order to avoid tripping of both the buses in case of failure of one CT as happened in this occurrence. Committee observed that IR value alone is not enough to ensure healthiness of CTs and therefore recommended for measuring capacitance & tan delta every six months particularly in case of old CTs and if there is an increasing trend or tan delta value is more than 0.7 then CT may be overhauled at manufacturer’s works for improvement of tan delta and removal of moisture etc.

2.02: System disturbance at 400 kV Lonikhand S/S in MSETCL system on 12-04-2006

The representative of MSETCL explained that on 12.04.2006 at 00:40Hrs, 220kV B

phase jumper of ICT-II at 400kV Lonikhand S/S failed with flashover on string insulator

connected to gantry. 220kV Bus bar protection scheme (RADSS) failed to operate

resulting into tripping of all lines / equipments at remote ends.

The non-operation of 220kV Bus bar protection scheme (RADSS) was tested and it was

found that Rd11 resistor in TMD unit of B phase got opened. The matter was taken up

with M/s ABB for the failure of components in the scheme and the faulty Rd11 resistor

was replaced.

Normalcy of supply restored at 04:05Hrs on 12.04.2006. Committee observed that all lines / equipments correctly tripped at remote ends in absence of Bus bar protection scheme (RADSS).

2.03: System disturbance at 400 kV Chandrapur S/S in MSETCL system on 29-04-2006

Minutes of 94th PCM

The representative of MSETCL explained that on 29.04.2006 at 11:01Hrs, 400kV

Chandrapur – Parli ckts II & III (carrying 1000MW) tripped at both ends on transient line

fault. The disturbance data retrieved from the numerical relay at Chandrapur and Parli

indicated the transient A-N fault on ckt III and C-N fault on ckt II, affecting ckt III earlier

and thereafter ckt II. 400kV Chandrapur–Parli ckt. III auto-reclosed at Parli end but at

Chandrapur it went into lockout. 400kV Chandrapur–Parli ckt. II went into lockout at

both ends due to persistent faults. 400kV Chandrapur–Parli ckt II & III is a double ckt

line. The transient fault probably was on common tower location around 37.5 kM from

Chandrapur end. The line was later patrolled near the suspected location but nothing

reportedly found cognizable. However, one large bird (Gidhad) was found dead near the

probable location. The tripping of both the circuits on transient fault is in order.

400kV HVDC pole I & II (carrying 1400MW) tripped at GCR Chandrapur end and also

at HVDC receiving station Chandrapur end. Thus transmission capacity for evacuation of

power from East to West was drastically reduced resulting in over loading of 400kV

Chandrapur –Koradi, 400kV Chandrapur –Parli ckt I and 400kV Koradi – Bhusawal D/C.

Consequently low voltages were observed almost at all 400kV S/stns in MSETCL

network. The tripping of HVDC ckt I & II at Chandrapur GCR end is suspected spurious

on following grounds:

• The HVDC I & II Control & Relay panels are located in the control room of

400kV GCR Chandrapur.

• The primary protective relays for these two ckts are located at HVDC

receiving station end and the initial tripping command is extended from

RXMS 1 relay at HVDC end to a combination of ABB make RXMVB4 &

RXMS 1 tripping relays at GCR end.

• For extending the initial tripping command from HVDC to Tripping Relays

at GCR end, a control cable is laid between these two stations, the route

length of which is over 1 kM.

• It is felt that the longer length of control cable between HVDC station and

GCR (> 1kM) might have caused spurious operation of RXMS 1 tripping

relays at GCR due to capacitive discharge of the cable, as the RXMS 1 relay

is low burden fast acting tripping relay. The matter was discussed with M/s

Minutes of 94th PCM

ABB and they also have affirmed the possibility.

DC leakage of source –I had appeared at 2200Hrs on 28.04.2006 and the work of DC

leakage detection was taken up immediately. The DC leakage however disappeared at

0900Hrs on next day i.e. 29.04.2006 but reappeared again 20 minutes later and was

persisting during and after occurrence. The DC leakage was later detected in auxiliary

contact of Y pole of breaker of newly commissioned 400kV POWERGRID ckt IV at

Chandrapur GCR, which was attended by POWERGRID on 30.04.06.

Emergency load shedding of about 300MW was carried out at Lonikhand, Bhusawal and

Bableshwar S/Ss and Koyna generation was picked up by 500MW.

Restoration started by taking 400kV Chandrapur – Parli ckt III into service at 11:12Hrs

and then other 400kV Chandrapur – Parli ckt II at 11:18Hrs. HVDC pole I & II were

restored at 11:39Hrs and 12:53Hrs respectively.

Committee felt that capacitance of 1 kM long cable between HVDC station and 400kV GCRcoupled with d.c. leakage could be the reason for the spurious operation of RXMS 1 relay as this relay is low burden, fast acting relay. Committee recommended for checking of grounding of both GCR and HVDC switchyards. MSETCL confirmed that ABB had replaced RSXM 1 relay with RSXF relay, which is more stable under similar situation. Committee observed that tripping of both 400kV Chandrapur – Parli ckts II & III simultaneously on transient fault was in order as these are on same tower.

2.04: System disturbance at 400 kV Solapur S/S in MSETCL system on 01-05-2006

The representative of MSETCL explained that on 01.05.2006 at 18:15Hrs, “D” clamp of

the jumper of “B” phase of 220kV side of 400/220kV, 500MVA ICT between CT and

“D” isolator broke and resulted in operation of bus bar protection in Bus –I. 220kV

Solapur lines connected to 220kV Bus-I at Solapur and 400/220kV, 500MVA ICT along

with Bus Coupler tripped. The ‘D’ clamp connected by nut bolts was cracked/broken and

resulted into operation of Bus Bar protection.

Normalcy of supply restored at 00:42Hrs on 02.05.2006.

Committee observed that it was a correct operation of Bus Bar Protection Scheme.

2.05: System disturbance at 220 kV Satpura TPS Switchyard in MPPGCL on 01.05-2006

Minutes of 94th PCM

The representative of MPPTCL explained that on 01.05.2006, 220kV Y-ph CT connected to Generator Unit # 7 of Satpura TPS got burst and caught fire. As a result R & B phases CTs were also damaged. This resulted in operation of Bus bar protection zone-I. Generator Units #1, #3, #5 & #7; 220kV Satpura – Itarsi ckts 1 & 2; 220kV Satpura – Kalmeshwar; 30MVA, 200kV/6.6kV Station Transformers 1 & 3 tripped on Bus Bar Zone-I operation. 30MVA, 200kV/6.6kV Station Transformer No. 4 connected to Bus –II, tripped on operation of Y-ph differential protection and 220/400kV ICT also connected with Bus – II tripped on inst. over current protection Y-ph relay.

All tripped elements were restored on the same day between 21:45Hrs and 23:45Hrs

except Generating Units #3 & #7 which were synchronized at 05:22 hrs on 02.05.2006

and 17:15Hrs on 03.05.2006 respectively.

Committee observed that tripping of elements connected to Bus –I was in order but tripping of Transformer No. 4 (on Y-ph differential protection) and 220/400kV ICT (on over current protection), both connected to Bus - II were unwarranted. As regards to tripping of Station Transformer No. 4 on Y-ph differential protection, Committee felt that it might be due to ionization / arcing fault, as it was the nearest bay to the Generator # 7. As regards to tripping of 220/400kV ICT on over current protection, Committee observed that high setting was instantaneous, therefore time setting should be co-ordinated with Bus Coupler trip. High side settings could be revised after fault level findings.

2.06: System disturbance at 400 kV Koradi S/S in MSETCL system on 08-05-2006

The representative of MSETCL explained that on 08.05.2006 at 23:05Hrs, 400kV Koradi

– Bhusawal ckt –I tripped on Y-N fault at Koradi end on Main 1 & Main 2 (REL 521).

Simultaneously, 400kV Koradi – Chandrapur line also tripped at Koradi end on Main-I

(7SA513) protection. On yard inspection, Y ph CT (BHEL make, 25yrs old) of 400kV

Koradi – Bhusawal ckt –I was found burst. 400kV Koradi – Bhusawal ckt –I tripped at

Bhusawal end on Y-N fault with aided trip. 400kV Koradi – Chandrapur line did not trip

at Chandrapur end. The line was later hand tripped. For this CT failure, Bus Bar

protection check zone relay operated but main Bus Bar Protection Relay (ABB RADSS)

did not operate.

Minutes of 94th PCM

The tripping of 400kV Koradi - Chandrapur line at Koradi end in forward Y-N, Zone-I

fault for Y-phase CT failure of 400kV Koradi – Bhusawal ckt –I was undesired. The

disturbance data retrieved from Siemens numerical distance relay 7SA513 also indicated

a forward Zone I fault. It is suspected that the behaviour of Y phase line CVT of this ckt

is consistent for close up faults (forward or reverse). The non-operation of Bus Bar

protection (ABB RADSS) in this case was due to module faulty. The check zone relay

has operated correctly in this case.

400kV Koradi – Chandrapur line was restored at 00:05Hrs on 09.05.2006. Also, 400kV

Koradi – Bhusawal ckt –I was restored at 18:25Hrs on 11.05.2006 after replacement of

all the R, Y & B phases CTs of the line at Koradi end.

Committee observed that tripping of 400kV Koradi – Bhusawal ckt I at both ends for Y ph CT fault at Koradi end was in order whereas 400kV Koradi - Chandrapur line tripped at Koradi end due to CVT input problem, as there is a tendency of CVT giving wrong signals for close up fault. This has to be looked into and the CVT may be replaced if required 2.07: System disturbance at 220 kV Dahej S/S in GETCO system on 11-05-2006

The representative of GETCO explained that on 11.05.2006 at 15:25Hrs, 220kV Dahej –

LNG line no.1 was under planned shut down and while charging this line, bus fault

occurred and all feeders connected to 220kV Dahej bus tripped from remote end only. It

has been reported that d.c. fuses of Bus Bar protection panels were kept out due to earth

leakage as such the bus bar protection did not operate.

It was reported that the lineman tried to fix the isolator with the help of the earthing rod

(with earth wire attached) during recharging of 220kV Dahej – LNG line no.1 resulting

into bus fault and a non-fatal accident to personnel.

All tripped feeders were charged between 16:10hrs and 16:35Hrs except 220kV Dahej –

LNG line no.2 which was charged at 18:00Hrs on the same day. 220kV Dahej – LNG

line no.1 was again placed under planned shut down.

Minutes of 94th PCM

Committee observed that there was no need to remove d.c. fuses as in centrally grounded, no d.c. leakage will take place. Also it was suggested that d.c. leakages can be located on line with Geo Scope which works on the principle of low frequency current injection. MPPTCL representative stated that they are inserting ammeters in +ve and –ve of ground circuit. The scheme being used by MPPTCL is enclosed at Annexure – 2.07. Committee felt that standard practice was not followed at 220 kV Dahej S/S and Sub-Stations staff should be suitably instructed to be vigilant and careful so that similar mistakes are avoided in future.

2.08: System disturbance at 400 kV Nagda S/S in MPPTCL system on 27-05-2006

The representative of MPPTCL explained that on 27.05.2006 at 17:30Hrs, total supply

interruption took place at 400kV Nagda S/S due to disablement of 400kV Bimco,

Hyderabad make, Pentagraph on Bus-II for 400kV Nagda -Sardar Sarovar ckt-I.

All the 400kV and 220kV lines from Nagda S/S tripped at remote ends resulting in total

supply interruption for 10 to 52 minutes at many EHV Sub–stations, viz. 400kV Nagda,

220kV Nagda (including Rly. Traction Nagda), 220kV Ujjain, 220kV Neemuch and other

132kV S/Ss fed from 400kV Nagda S/S.

On checking, it was observed that 2 nos. Pentagraph arms got detached from the

clamping mechanism, housing base over the support insulator of Pentagraph. The

detached arms got stuck to operating rod insulator of R phase and sheared the insulator

from top flange. Bus Bar protection provided at 400kV Nagda S/S was not in service.

After doing necessary rectification work needed, Pentagraph was taken into service on

31.05.2006 at 17:15Hrs.

Committee observed that the Bus Bar Protection was not in service at the time of fault. Committee recommended for early rectification of Bus Bar Protection scheme and also suggested for up-gradation of the scheme suitably so as to accommodate four more bays, which are likely to be commissioned with the completion of 400kV Bina – Nagda – Dehgam lines.

2.09: System disturbance at 220kV GTPS Uran S/S in MSETCL system on 31.05.2006

Minutes of 94th PCM

The representative of MSETCL explained that on 31.05.2006 at 13:37Hrs, Y-ph isolator

arm base of Bus coupler connected to Bus I got burnt and flashover occurred on Bus I.

Also, Y & B phase isolator arm bases of Bus coupler connected to Bus II got burnt and

flashover occurred on Bus II as well. Thus, all the breakers connected to 220kV Bus I &

Bus II including Bus Coupler at 220kV Uran S/S tripped on bus bar protection and the

220kV Uran bus became dead. The Bus Coupler isolators are in service since 1982 and

because of ageing and continuous heating, the flexible copper bands connected to isolator

got burnt resulting in flashover and in Bus fault on sections I & II of the bus.

220kV Main Bus I was charged through 220kV Kharghar # II line at 14:28Hrs on 31.5.06

and all tripped generators & feeders connected to bus I were taken in service between

14:30 Hrs & 16:37Hrs of 31.05.06. 220kV Main Bus II was charged through 220kV Apta

# IV line at 20:00Hrs on 31.05.06 and all tripped generators & feeders connected to bus II

were taken in service between 20:00 Hrs of 31.05.06 and 09:20Hrs of 02.05.06. The load

at the S/S was catered through Main Bus I & II functioning independently in absence of

Bus Coupler which was restored on 13.06.06 at 18:05Hrs after replacing the defective

arms of Main Bus I and Main Bus II isolators.

Committee observed that the load flow through Bus Coupler connecting Bus I & II was

428 Amps (163MW), though undesirable, was not higher than the isolator rated value of

1250Amps.

Committee observed that this occurrence could have been avoided if loads on two buses were properly distributed by keeping minimum load flow on Bus Coupler. Committee also suggested for frequent hot spot identification through Thermovision Camera so as to avoid such isolator arms burnt out.

2.10: System disturbance at 220 kV Dahej S/S in GETCO system on 31-05-2006

The representative of GETCO explained that on 31.05.2006 at 22:30Hrs, all feeders

connected to 220kV Dahej bus – II tripped due to operation of Bus Bar protection zone-

B. None of the breakers connected to bus – I tripped. There was thunderstorm and heavy

rains with lightning, which might have caused bus fault on Bus-II.

Minutes of 94th PCM

All tripped feeders were charged between 10:15hrs and 01:45Hrs of 01.06.2006.

Committee observed that as the earth wire was provided, lightning should not have caused bus bar protection to operate but felt that it could be due to ionization effect of lightning in near vicinity of equipments. 2.11: System disturbance at 220 kV Bhilad S/S in GETCO system on 31-05-2006

The representative of GETCO explained that on 31.05.2006, 220kV Bhilad – Tarapur

line connected to Bus A was tripped at 03:16Hrs and while charging the same line at

07:00Hrs, it tripped on SOTF, with a trip time of 280.4 ms and fault was measured in

Zone-2 on Areva make Micom P 442 DPR. On tripping, R – pole of circuit breaker stuck

resulting in LBB operation and in turn Bus fault. All feeders connected to Bus A tripped.

220kV Bhilad – Tarapur line, while charging, tripped on SOTF due to persisting fault on

line because of insulator failure. R phase insulator flashover at location 1009 was found

and on tripping, the ‘R’ phase pole of BHEL make Hydraulic AV3 breaker was stuck up.

All tripped feeders except 220kV Bhilad – Tarapur line were charged between 07:35hrs and 09:15Hrs of 31.05.2006. 220kV Bhilad – Tarapur line was taken into service at 21:57Hrs on 01.06.2006. Committee observed operation of SOTF on 220kV Bhilad – Tarapur was correct as fault was of permanent nature. As the fault was not cleared in less than 200 ms due to breaker getting stuck, operation of LBB is also correct. 2.12: System disturbance at 400 kV Soja S/S in GETCO system on 01.06-2006

The representative of GETCO explained that on 01.06.2006 at 13:20 Hrs, bus fault for

Bus-I took place at 400kV Dehgam (PGCIL) S/S and.400kV Dehgam (PGCIL) - Soja

line tripped at both ends. It tripped at Soja end on receipt of D/T command from remote

end Dehgam. As the scheme being one and half breaker at PGCIL S/S Dehgam, the D/T

command to trip the remote end breaker at Soja was not necessary, hence the direct trip

command from 96 relay was removed. As the fault feeding continued, the LBB relay of

the other breaker connected to Bus –I operated and it tripped the breaker connected to

Bus-II of the 400kV Dahegam –Wanakbori line and sent D/T command to Wanakbori

S/S so as to trip remote end breaker. The tripped feeders were taken into service at

Minutes of 94th PCM

14:40Hrs.

Committee observed that the DT command sent to Soja for 400kV Soja – Dehgam line without taking tie breaker in series is not correct and hence instead of blocking DT, it should be clubbed with opening of tie breaker between 400kV Soja – Dehgam and 400kV Ranchhodpura II - Dehgam. GETCO agreed to carry out changes in association with POWERGRID. 2.13: System disturbance at 220 kV Ranasan S/S in GETCO system on 20.06-2006

The representative of GETCO explained that on 20.06.2006 at 21:35 Hrs, fault occurred

on 220kV Ranasan – Karamsad line no.1 connected to Bus – A, due to its B-ph jumper of

palm connector rod of isolator assembly falling on ground. This resulted in operation of

Bus bar protection of ‘Zone-A’ and all feeders and transformers including bus coupler

tripped.

All tripped feeders and transformers except 220kV Ranasan – Karamsad line no.1 and

Bus Coupler were taken into service on the same day between 22:25Hrs & 23:25Hrs.

220kV Ranasan – Karamsad line no.1 and Bus Coupler were taken into service on

21.06.2006 at 00:25Hrs and 11:30Hrs respectively.

Committee observed that it was a correct operation of Bus Bar protection.

2.14: System disturbance at 220kV GTPS Uran S/S in MSETCL system on 22.06.2006

The representative of MSETCL explained that on 22.06.2006 at 11:12Hrs, all the

breakers connected to 220kV Bus –I including Bus Coupler at 220kV GTPS Uran S/S

tripped on operation of Local Breaker Back-up (LBB) protection, making the 220kV

Main Bus I dead. During tree cutting in switchyard at Uran, B phase LA of 220kV Apta-I

feeder catering load of 95MW through TBC instead of own breaker failed. The TBC was

connected to Main-I bus. At Uran S/S, the 220kV Apta-I C.B. cleared the fault in Zone-II

time whereas at Apta S/S, 220kV Uran-I C.B. tripped on distance protection B phase. The

TBC breaker (BHEL make MOCB) at Uran S/S cleared the fault with delay resulting in

operation of LBB protection and tripping of all feeders, transformers and Generators

connected to Bus –I catering load of 295MW.

Minutes of 94th PCM

All tripped generators & feeders connected to bus-I were taken into service between

11:29 Hrs & 13:50Hrs on the same day by recharging 220kV Bus Coupler at 11:20Hrs,

thereby charging Bus-I.

Committee observed that delayed opening of MOCB might be due to Mechanical Jamming. Committee also suggested for low voltage d.c. test to check healthiness of MOCB. ITEM NO. 3: Tripping of lines / ICTs:

The incidences of tripping of lines and ICTs during the period 01-04-2006 to30-06-2006

were discussed during the meeting.

Observations of the committee are enclosed at Annex –3.

ITEM NO. 4: Information on A/R, DR and SER in Western Region:

Constituents were requested to furnish the details and program for installation of

A/R, DR & SER at all 400kV locations and important 220kV generating &

interstate locations where the same are yet to be provided. Also, constituents were

requested to furnish any change in status already furnished by constituents for reviewing

by the committee.

MPPTCL informed that single phase auto re-close mode is in service for 400kV feeders

namely Sarni-ISP, Sarni-Bhilai, Sarni-Koradi and Sarni-Itarsi. D/R is also available on

these feeders except for 400kV Sarni-Bhilai where RALDA relay is being changed by

REL-521 providing inbuilt D/R.

Constituents are requested to furnish these details to WRPC for proper monitoring the progress and working conditions of A/R, DR and SER in Western Region. Committee once again emphasised that SERs and DRs along-with GPS time synchronisation are essentially to be provided on priority at all 400kV S/Ss first and then at all important 220kV S/Ss for proper analysis of the events during disturbance and for taking required preventive measures. ITEM NO.5: Under Frequency Relay (UFR) Settings of NR, ER & WR

Member Secretary, WRPC stated that Central Grid comprising of WR-ER-NER power

grids synchronized successfully with NR power grid at 12:22 hrs on 26.08.2006. Thus the

Minutes of 94th PCM

combined grid is of 80000MW having around 1800MW as power number.

In the meeting taken by Member (GO&D), Central Electricity Authority on 5.7.2006 to

review preparedness of interconnection between WR-ER-NER power grid with NR

power grid after commissioning of Tala Units with ER grid, UFR settings in the different

grids were discussed and it was felt that in view of the increased power number of the

combined grid, initially the settings of the under frequency relays in the NR & WR

should be raised from the present level of 48.5Hz to 48.8Hz which could be reviewed

after about a month, based on actual experience of operating the combined NR-WR-ER-

NER grid. It was decided that the settings of UFRs would be modified as under:-

Sl. No. Present quantum of UFR

Load Shedding

Proposed quantum of UFR

Load Shedding (All instantaneous)

1. Northern Region

800MW at 48.5Hz

1000MW at 48.4Hz

1250MW at 48.0Hz

1000MW at 47.9Hz

800MW at 48.8Hz

1000MW at 48.6Hz

2250MW at 48.2Hz

2. Western Region

960MW at 48.5Hz

960MW at 48.2Hz

1280MW at 48.0Hz

960MW at 48.8Hz

960MW at 48.6Hz

1280MW at 48.2Hz

3. Eastern Region

300MW at 48.5Hz with 0.3sec delay

300MW at 48.2Hz Instantaneous

410MW at 48.0Hz

300MW at 48.5Hz

710MW at 48.2Hz

As desired, the settings of UFRs were revised by all the constituents of Western Region in line with the above before actual synchronization of the NR grid with WR – ER – NER system. Member Secretary, WRPC requested all the constituent representatives to once again check up and confirm that the required loads are connected at revised frequency settings. He stated that WRLDC had suggested revised df/dt relays i.e. at 48.8Hz / 0.1Hz /sec in the regional grid and were expected to explain their observations during this

Minutes of 94th PCM

meeting but may be due to pre-occupation they could not attend the meeting. However, he requested WR constituents to arrange to provide Frequency Trend relay at 48.8Hz / 0.1Hz / sec as an additional stage without connecting any load so as to know the number of instances for operation at this setting in the changed grid scenario of combined operation of Central Grid with Northern Grid. Constituents agreed to put this stage in alarm mode alone and observe the performance.

ITEM NO.6: Follow up points:

6.1: A/R scheme of 400kV Tarapur – Boisar ckt. 1 & 2 and 400kV Tarapur –

Padghe ckt 1 & 2 at Tarapur NPCIL end

Presently the A/R selector switch of all the 400kV lines emanating from

TAPP 3 & 4 is kept in non-auto mode at TAPP end. NPCIL fully subscribes

to the view that single phase auto re-closure on all 400kV lines should be

commissioned to improve the transient stability of the regional power

system. NPCIL is of the view that the prime mover of the nuclear units vary

in design from their counterparts of thermal stations and the suitability of

the prime mover at the generating station needs to be ascertained before

provision of auto re-closure feature on the lines emanating from Nuclear

Power Station. Accordingly, NPCIL have referred to manufacture BHEL

for indicating the suitability of the prime mover for the auto re-closure duty.

NPCIL informed that reply from manufacturer is awaited and action based on the recommendation of the manufacturer would be taken in the matter. Member Secretary, WRPC advised NPCIL to expedite the feedback from the manufacture, so that A/R scheme shall be put into service at both ends for stability of system 6.2: Commissioning of PLCC system in 220kV lines of other utilities

emanating from POWERGRID sub – stations

A: Raipur Sub-station:

Four nos. 220kV lines of CSEB are connected to Raipur S/S of Powergrid.

These lines were commissioned in the year 1999-2000. The PLCC panels

were supplied and commissioned in stand alone mode since commissioning

of lines at Raipur S/S. CSEB was requested to expedite for early

Minutes of 94th PCM

commissioning of PLCC protection couplers at their end so that for all these

lines protection coupler can be used for inter tripping. CSEB representative

had during 93rd PCM informed that Protection Couplers would be

commissioned within two months.

CSEB representative informed that they are waiting for shut downs and the work would be completed by the end of October, 2006.

B: Satna Sub-station:

Two nos. 220kV lines of MPPTCL are connected to Satna S/S of Powergrid.

These lines were commissioned in the year 1999-2000. The PLCC panels

were supplied and commissioned in stand alone mode since commissioning

of lines at Satna S/S. MPPTCL was requested to expedite for early

commissioning of PLCC protection couplers at their end so that for all these

lines protection coupler can be used for inter tripping.

MPPTCL representative informed that they are already in the process. He stated that some of the Protection Coupler cards in both Satna & Katni ckts are not working and the same would be replaced and commissioned by the end of October,2006.

C: Khandwa Sub-station:

Four nos. 220kV lines of MPPTCL are connected to Khandwa S/S of

Powergrid. These lines were commissioned in the year 2005. The protection

coupler had not been procured at both ends, the same needs to be procured

and commissioned by MPPTCL at the earliest.

MPPTCL representative informed that Protection Couplers are installed and testing is to be done. They are already taking PGCIL related works on priority. Commissioning of Protection Couplers of 220kV Nepa Ckts. 1 & 2 would be completed by October,2006 and that of 220 KV Julwania & Barwaha lines by the end of November,2006.

D. Boisar Sub-station:

Three nos. 220 KV lines of MSETCL are connected to Boisar S/S.

MSETCL has installed & commissioned only SPEECH panel on these

Minutes of 94th PCM

lines for communication purpose. MSETCL may expedite for procurement

and early commissioning of PLCC protection couplers at both ends so that

for all these lines protection coupler can be used for inter tripping mode.

MSETCL representative informed that four protection couplers are required for the work and they have taken up the matter with their Head Office. Work will be completed at the earliest within two months.

Committee agreed to follow CBI & P guidelines in the matter. As per the CBI&P manual, there should be at-least one carrier aided non-switched three zone distance protection scheme to protect 220 kV lines. As such, Committee recommended for early commissioning of PLCC panels and protection couplers.

6.3: Problem of PLCC in 400kV Korba-Raipur Ckt.# 2

NTPC representative informed that the problem in one PLCC channel 200 Rx /

252 Tx KHz is still persisting even after removing jumper at one location. The

signal levels in other PLCC channel 136/140 KHz has been found normal in ideal

condition and this signal levels getting disturbed during fault condition.

Committee felt that one of the additional jumpring was still existing which might be removed to improve the performance. Alternatively, other possibilities for improving PLCC signal levels on priority may be explored.

ITEM NO. 7: Other items:

7.1 Problems in newly commissioned GETCO bays at Dehgam SS:

POWERGRID representative informed that 400 KV Wanakbori – Soja line of GETCO was made LILO at POWERGRID Dehgam SS in the month of March 2005. Since commissioning, following C&R problems are being encountered in Soja & Wanakbori bays at Dehgam SS:

a. At Dehgam, LBB protection of Wanakbori tie CB has operated due to spark in CT terminal, which resulted in tripping of Busbar-I on 01.06.06.

b. Disturbance Recorder and Event logger are not working for both lines.

c. For Soja line, during hand tripping of only main CB, direct trip signal

extended to remote end i.e. without tripping tie CB at Dehgam end For Wanakbori line, during hand tripping of CB, direct trip signal not extended to remote end i.e. PLCC inter trip command not connected in case of hand tripping.

Minutes of 94th PCM

GETCO representative informed the present status in the matter as below:

a. Already discussed in occurrence 2.12. b. Commissioning of Disturbance Recorder and Event logger is pending.

Matter taken up with M/s ABB and would be completed by Nov’2006. c. Standard practice would be followed and GETCO would carry out

the necessary changes in association with POWERGRID Dehgam to resolve the problem.

7.2. Problem in Bhopal # 2 Main CB At ItarsI S/S:

POWERGRID representative informed that at Itarsi S/S, main CB of 400 KV

Itarsi – Bhopal # 2 is not in service due to leakage of air from magnetic ventile

from 16.06.06. Matter was taken up by POWERGRID with MPPTCL to expedite

the rectification of the faulty CB.

MPPTCL representative informed that spare parts ordered to M/s ABB are awaited from them and rectification/restoration of above CB would be completed as early as possible i.e. within a month.

7.3. Simultaneous tripping of 220 kV Kakrapar – Vav I & II on 14.07.06

POWERGRID representative informed that both 220 KV Kakrapar – VAV Ckt. 1

& 2 tripped simultaneously at KAPP end only at 05:41 HRS on 14.07.06 for the

fault in 220 KV Kakrapar – Ukai line.

As no representative from KAPS NPCIL attended the meeting, the reasons for undesirable tripping of KAPP-VAV lines for the fault in other line and the remedial measures to be taken could not be discussed. Matter will be taken up with KAPP to ascertain the reason etc.

7.4. Tripping of 400kV Raipur – Sipat line.

POWERGRID representative informed that 400 KV Raipur – Sipat line had

tripped on 03.07.06 & 05.07.06 at Sipat NTPC end only. Line remained charged

from Raipur end on both occasions. Matter was taken up by POWERGRID with

Sipat, NTPC to investigate and rectify the problem to avoid unwanted tripping of

healthy line.

Minutes of 94th PCM

NTPC representative informed that in the first instance it was by mistake and this was then demonstrated in second instance of tripping. NTPC have replaced the relay and problem has been solved.

7.5. Non – Auto Reclose of 400kV Indore – Asoj Ckt # 2 at Indore end

POWERGRID representative informed that 400kV Indore – Asoj Ckt # 2 tripped

on transient B-ph to E/F at 16:05Hrs on 25.01.2006 and also at 06:14Hrs on

17.07.2006 on transient R-ph to E/F. During both the instances, line A/R at Asoj

end only whereas it could not A/R at Indore end due to low air pressure. Frequent

failure of A/R for the line at Indore end require thorough examination by

MPPTCL so as to eliminate pressure system problem in order to achieve

successful A/R for faults of transient nature in the trunk line transmitting power to

Gujarat state.

MPPTCL representative informed that the CB A/R air pressure switch settings were checked and found frequent drifting. The defective pressure switch was to be arranged by PGCIL and the same would be replaced on priority for successful A/R operation. Committee requested MPPTCL and POWERGRID to examine jointly for taking required action in the matter as 400kV Indore – Asoj ckt II is a vital link.

7.6. Rectification of Bus Bar Protection Scheme at 400kV Nagda MPPTCL S/S

POWERGRID representative intimated that Bus Bar protection scheme, type

SBNH 163 of EE make, at 400kV Nagda S/S of MPPTCL is presently not in

service. Four numbers new 400kV PGCIL bays (Bina – Nagda – Dehgam) are

likely to be commissioned in the month of March 2007 at 400kV Nagda S/S. For

connecting these new bays, POWERGRID has already taken up the matter with

MPPTCL, Nagda for expediting the up-gradation of existing Bus bar protection

scheme at 400kV Nagda S/S.

MPPTCL representative informed that matter is under process. Committee requested Member Secretary, WRPC to take up the matter with Managing Director, MPPTCL for early provision / up gradation of Bus Bar protection scheme at 400kVNagda S/S of MPPTCL.

ITEM NO. 8: Any other issues:

Minutes of 94th PCM

Other issues were circulated as Supplementary Agenda for 94th Protection Committee

Meeting for discussion.

8.1: Interruption of bipole transmission on Chandrapur – Padghe HVDC bipole

link due to tripping of HVDC Pole II on DC differential protection at Padghe

on 2.6.06 at 11:09Hrs

Superintending Engineer, Testing & Communication Circle, MSETCL, Vashi vide

their letter No. SE/TCC/Vashi/366 dated 20.6.06 have intimated that the Pole II of

Chandrapur – Padghe HVDC bipole had tripped on DC differential protection on 2.6.06

at 11:09Hrs with following alarms on SCADA system interrupting bipole transmission.

1) Commutation failure

2) DC Differential trip

3) Smoothing reactor oil pressure trip

4) Smoothing reactor buchholz alarm

The gas was observed in the Buchholz relay of Smoothing reactor of Pole II. M/s BHEL

advised to replace the Smoothing reactor of Pole II with spare reactor.

After filtration and necessary tests, the HVDC Pole II was re-commissioned on 14.6.06 at

12:29 Hrs and bipole operation was restored.

During the period from 11:09Hrs on 2.6.06 to 12:29Hrs on 14.6.06, the Pole I in earth

return mode was available. The representative of MSETCL informed that total

transmitting capacity of HVDC link for both the poles is 1500MW and each pole is

capable of transmitting 750MW in both modes i.e. metallic return mode and earth return

mode with 5% & 3% transmission loss respectively. A restriction of 30 days per year is

applicable to Earth return mode transmission.

The failed Smoothing reactor Sr. No. 6005554 was inspected. Flashed over marks were

observed between X2 line lead to bottom flux plate shield. Carbon deposition was

observed on tank walls and in the vicinity of base of the tank. The matter of failure of

Smoothing reactor is under study by M/s BHEL.

MSETCL representative informed that the failed Smoothing reactor would be shifted to M/s BHEL within a month. Committee noted. 8.2: Frequent tripping of 400kV SSP – Dhule lines at 400kV Dhule S/S

Minutes of 94th PCM

MSETCL representative explained that 400kV SSP – Dhule ckt # 1 tripped at 400kV

Dhule S/S on 07.04.06 at 07:01Hrs on operation of Over Voltage Stage-I Relay of R &

Y phases and the line was restored on 18.04.06 at 11:15Hrs. Similar Over Voltage relay

operations resulted in tripping of 400kV lines emanating from 400kV Dhule S/S. In

order to avoid such Over Voltage tripping of 400kV SSNL ckt # 1 & 2 at 400kV Dhule

S/S, MSETCL is procuring 50MVAR line reactor for these ckts and proposing

procurement of 50MVAR CSR for 400kV Dhule ckt # 1 & 2 at 400kV SSNL S/S.

Also, MSETCL have requested for restoration of 2x80MVAR Line Reactors for 400kV

Khandwa ckts # 1 & 2 at 400kV Itarsi S/S in order to minimize O/V problem at 400kV

Itarsi S/S, which is feeding S/S for Dhule. Frequent tripping of 400kV SSP – Dhule

lines on over-voltage is affecting other 400kV lines at 400kV Dhule S/S and Western

Grid as well.

Member Secretary, WRPC informed that the issue of high voltage during monsoon

period in Western Maharashtra system was discussed in the 1st WRPC meeting held at

Pune on 31st May 2006 wherein WRLDC had suggested that the reactor at Itarsi, which

is proposed to be removed by POWERGRID for shifting it to the other location for

Sipat transmission project, should not be removed till reactors are provided at Khandwa

and Dhule. In the meeting Chairman, WRPC / CMD, MPPTCL observed that the

existing one reactor at Itarsi should not be removed. Member Secretary suggested that

MSETCL should take up this issue of providing reactors at different locations with the

Standing Committee, meeting of which is scheduled on 30th September,2006, wherein

MSETCL may propose for a bus reactor at Itarsi. He suggested MSETCL to take up the

matter for SSP lines with GETCO through NCA. GETCO representative informed that

SSP sub station is a GIS S/S and there is no space for reactor.

Member Secretary opined that the need of providing additional reactors in the system should be decided only after studying the voltage profile of entire WR EHV grid network, which is presently in the process of strengthening,

8.3: Rotor Earth Fault Protection For Main Generators Of TAPS-3&4

The problems in rotor earth fault scheme for TAPP-3&4 main generators were

Minutes of 94th PCM

discussed in the meeting. TAPS-3&4 representative informed that TAPS-3&4

generators are 659 MVA sets (BHEL make) with brushless excitation system and with

rotor earth fault detection brushes on main excitor neutral and shaft as shown in the

figure 8.3(1) using IWX + YWX relay (ABB make).

The problems included:

(a) TAPS-3&4 had apprehension regarding effect of a postulated earth fault on the

main excitor phase side, wherein it was felt that a.c. back voltage might appear

into the relay [refer fig 8.3(2)] terminals, which may discharge through the

relaying circuit and may damage it.

(b) TAPS-3&4 was facing problems related to instability of the relay in case of brush

wear out and informed that the scheme had mal operated twice at TAPS-3&4 due

to brush wear out leading to unit outage.

With the above referred problems the committee noted that none of the constituents

having brushless excitation systems for main generators were using this type of

scheme / relay for rotor earth fault protection. The committee was of the view that the

protection should give a measurement fault instead of operation in case the

measurement circuit goes faulty i.e. in case of a brush wear out condition.

Most of the constituent representatives viz. 1) NTPC 2) TATA Power Co., Trombay

3) Dahanu Power Station, Reliance Energy Ltd. confirmed that Siemens make relay

based on injection principle was being used by them and that they have not faced any

major problem up till now in this type of scheme.

NTPC representative stated that the relay presently used, i.e. IWX + YWX of M/S

ABB is not suitable for machines having brushless excitation. This relay has been

used for rotor earth fault protection of 200 / 210 MW BHEL Units employing Static

Excitation. For all 500 MW machines of NTPC employing brushless excitation the

relay used is 7UR 22 of M/S Siemens which employs low frequency pulse injection

principle. This relay has feature of blocking incase of interruption of measurement

Minutes of 94th PCM

circuit. The performance of this relay is excellent and no mal-operation has been

reported. However presently this model is obsolete and instead M/S Siemens is

offering 7UM 62 Relay which is a numerical relay having combined stator earth fault

and rotor earth fault protection. This numerical relay has been used in recently

commissioned 500 MW machines of NTPC. Alternately following other model relays

are also available which employ low frequency pulse injection principle for detection

of rotor earth fault.

MRR-1 of Control & Switchgear

XRR-1 of SEG Controls

Committee was of the view that TAPS-3&4 may opt for replacement of the relay with other make to resolve the issue. As Siemens make relays are already in use by most of the constituents for their brushless excitors, the same may be given active consideration.

Rotor earth fault scheme for main generator of TAPS3&4

Fig 8.3(1)

Minutes of 94th PCM

Effect of earth fault on Main exciter phase side

Fig 8.3(2)

8.4: Presentation on Online Condition Monitoring of Exta High Voltage Circuit Breakers

A presentation by Shri S.B. Potnis, General Manager, Crompton Greaves Limited,

Nashik, Maharashtra was arranged on 22nd instant on Online Condition Monitoring of

EHV Circuit Breakers. The presentation was well received and appreciated by

participants. A copy of presentation by Shri Potnis is enclosed at Annexure – 8.4.

Minutes of 94th PCM

ITEM NO. 9: Date and Venue of the next meeting.

The next meeting is proposed during November/December 2006 wherein system

disturbances during the period 01-07-2006 to 30-09-2006 will be discussed. Exact date

and venue will be communicated separately.

Minutes of 94th PCM

ANNEX-I

LIST OF PARTICIPANTS

94th Protection Committee Meeting held on 21st & 22nd September, 2006 at Aurangabad (Maharashtra)

CSEB ( Chhatisgarh State Electricity Board )

Shri A. K. Saxena Superintending Engineer (T&C), Korba (East) Shri M.Z. Rahman Addl. Superintending Engineer (MRT), Bhilai Shri M.K. Sharma Executive Engineer (Testing), Korba (East) GETCO (Gujarat Energy Transmission Corporation Limited) Shri M.K. Mehta Superintending Engineer (Testing), Baroda GSECL (Gujarat State Electricity Corporation Limited)

Shri U.D. Adhvaryu Executive Engineer (Testing), Baroda MPPTCL (Madhya Pradesh Power Transmission Corporation Limited)

Shri V. K. Job Addl. Superintending Engineer (T&C), Bhopal Shri R.A. Sharma Executive Engineer (LD), SLDC, Jabalpur MSETCL (Maharashtra State Electricity Transmission Company Limited)

Smt. R.R. Bhide Superintending Engineer (TCC), Pune Shri P. D. Deshpande Superintending Engineer (TCC), Nagpur Shri R.N. Tonge Superintending Engineer (TCC), Vashi Shri B.T. Mahale Superintending Engineer (TCC), Nashik Shri N.D. Kudlikar Superintending Engineer (TCC), Aurangabad Shri R.L. Lahare Superintending Engineer (Trans. O&M),Parli(V) Shri B.H. Gujarathi Executive Engineer (LD), SLDC, Kalwa ShriV. B. Khanale Executive Engineer(Telecom &Testg), Aurangabad Shri S.P. Vasekar Executive Engineer, MSETCL, Aurangabad Shri P.S. Ingle Dy. Executive Engineer (TCC), Pune Shri J.G. Nandapurkar Dy. Executive Engineer (TCC), Nagpur Shri D.Y. Chavan Dy. Executive Engineer (TCC), Nashik Shri R.D. Pedgaonkar Dy. Executive Engineer (TCC), Aurangabad Shri S.M. Kulkarni Dy. Executive Engineer (Tele. Dn.), Aurangabad Shri D.P. Nath Dy. Executive Engineer (T), Aurangabad Shri B.D. Choudhary Dy. Executive Engineer (Testg Dn), Nanded Shri S.S. Kulkarni Asstt. Engineer, 400kV R.S. Waluj, Aurangabad

Minutes of 94th PCM

Shri A.P. Joshi Jr. Engineer, 400kV R.S. Waluj, Aurangabad Miss V.B. Sawant Jr. Engineer, (TCC), Vashi NTPC (National Thermal Power Corporation)

Shri B.P. Nanda Dy. General Manager (EM), KSTPS, Korba NPCIL (Nuclear Power Corporation of India Limited) Shri S.V. Shivalkar S.M.E.(E), TAPS 1 & 2, Tarapur Shri Mahesh P. Karia SO/C (EMU) TAPS 3 & 4, Tarapur PGCIL (Power Grid Corporation of India Limited)

Shri D. Bruhananda Senior Engineer (O&M), WRTS, Nagpur TPC (Tata Power Company)

Shri Pravin Jain Assistant Manager (EQAG), Trombay, Mumbai TP AECo (Torrent Power Ahmedabad Electric Company)

Shri A.A. Shaikh Manager (Elect.), Ahmedabad REL (Reliance Energy Limited)

Shri A.M. Waknis Addl. Manager (Trans.), R/S Goregaon, Mumbai Shri S.S. Chaudhary Manager (Elect.), DTPS, Dahanu WRPC (Western Regional Power Committee) Shri P. Patel Member Secretary Shri S. D. Taksande Superintending Engineer (P) Shri B. R. Joshi Executive Engineer (P)

Minutes of 94th PCM

ANNEXURE-3

TRIPPINGS OF LINES / ICTS

Sl. No.

NAME OF S/S

DATE OUT AT

NAME OF THE LINE/ICT

SYSTEM DATE/ CHARGED AT

REASON

3.01

220kV KAPS

01.04.06 14:10

220kV KAPP- Vav # 2

POWERGRID 14:43 A/T on C-ph to E/F.

3.02

220kV KAPS

01.04.06 14:14

220kV KAPP- Vav # 1


3.03

400kV Itarsi

03.04.06 00:39

400kV Itarsi- Indore # 1

POWERGRID 01:21 A/T due to operation of O/V stage-I protection at Indore S/S.

3.04

220kV Haldarwa

03.04.06 15:05

220kV H’wa – Jhanor # 1

POWERGRID 15:17 A/T on transient 2ph (B&C) fault.

3.05

220kV Haldarwa

03.04.06 15:05

220kV H’wa – Jhanor # 2

POWERGRID 17:05 A/T on transient 2ph (B&C) fault.

3.06

400kV Koradi

04.04.06 18:03

400kV Koradi- Chandrapur

MSETCL 05.04.06 08:50

A/T on B-ph to E/F. Suspension string found broken at loc. No. 114.

3.07

400kV Satpura

06.04.06 05:26

400kV Bhilai- Satpura

MPPTCL 06:10 A/T at Satpura end on through fault by RALDA relay and due to line remaining in charged condition from Bhilai end, O/V stage-I relay operated at Satpura end and resulted in tripping at Bhilai end on D/T received.

3.08

400kV Bhilai

06.04.06 05:24

400kV Korba- Bhilai # 2

POWERGRID 06:05 A/T on B-ph to E/F. A/R was unsuccessful at Bhilai due to mal -operation of Main-II (MM3T) protection. At Korba end, A/R did not occur & line tripped on CB Pole discrepancy. At the same time 400kV Bhilai-Sarni also tripped.

3.0 deleted

Minutes of 94th PCM

9 3.10

400kV Itarsi

07.04.06 07:01



3.11

400kV Kasor

07.04.06 07:01

400kV Kasor- SSP

GETCO 09:21 A/T on R ph O/V stage-I at SSP and D/T received at Kasor.

3.12

400kV Vindhyachal

07.04.06 09:52

400kV V’chal- Jabalpur # 4

POWERGRID 22:08 A/T on O/V stage-II. R-phase CVT failed & resulted in O/V.

3.13

400kV Waluj

08.04.06 15:08

400kV Waluj- Bhusawal

MSETCL 15:08 A/T on transient R-ph to E/F. A/R successful at both ends.

3.14

400kV Chandrapur

08.04.06 17:24

400kV C’pur- Parli # 1

MSETCL 09.04.06 13:42

B-phase conductor de-capped at loc. No. 189.

3.15

400kV Satna

10.04.06 03:55

400kV Satna- Bina # 1

POWERGRID 17:40 A/T due to failure of Y-phase insulator string at Loc. No. 689.

3.16

deleted

3.17

220kV Vapi

10.04.06 13:05

220kV KAPP- Vapi # 2


3.18

400kV Koradi

13.04.06 13:50

400kV Koradi- Bhusawal # 1

MSETCL 14:20 A/T on transient Y-ph to E/F.

3.19

400kV Raipur

14.04.06 19:53

400kV Korba- Raipur # 2

POWERGRID 20:37 A/T on transient R-ph to E/F. Line A/R successfully at Raipur end only. At Korba end, Main-2 relay has processed three phase tripping and caused auto reclose lock out.

3.20

400kV Koradi

15.04.06 19:28

400kV Bhilai- Koradi

POWERGRID 19:28 A/T on transient R-ph to E/F. A/R successful at both ends.

3.21

400kV Bhadra-vati

16.04.06 06:11

400kV Raipur- Bhadravati # 2

POWERGRID 06:40 A/T on transient R-ph to E/F. Line A/R successfully at at Raipur end only. At B’vati end A/R was unsuccessful due to wrong

Minutes of 94th PCM

configuration of A/R auxiliary blocking relay.

3.22

400kV Chandrapur

17.04.06 18:32


MSETCL 18:48 A/T on transient R-ph to E/F.

3.23

400kV Jabalpur

17.04.06 21:22

400kV J’pur- Itarsi # 2

POWERGRID 21:43 A/T due to R & B phase fault. A/R got lockout due to multiphase fault.

3.24

400kV Dehgam

20.04.0611:02

400kV Jhanor- Dehgam # 2

POWERGRID 11:46 A/T at Dehgam end due to receipt of Direct Trip Signal from Jhanor end.

3.25

400kV Koradi

21.04.06 11:31


MSETCL 12:25 Reactor protection operated for R-ph at Bhusawal end and line A/T on L/O trip for remote end fault at Koradi end on receiving D/T signal.

3.26

400kV Itarsi

21.04.06 17:24



3.27

220kV Haldarwa

22.04.06 13:00

220kV H’wa – Kawas # 1

POWERGRID 13:40 A/T due to transient B & C phase fault.

3.28

400kV Itarsi

23.04.06 17:34



3.29

400kV Satpura

28.04.06 03:00

400/220kV ICT At Satpura

MPPTCL 03:54 ICT A/T from both sides due to operation of Over Fluxing protection at 400kV side.

3.30

400kV Kasor

01.05.06 07:02

400kV Kasor- SSP

GETCO 08:10 A/T on Y & B ph O/V stage-I at SSP and D/T received at Kasor.

3.31

400kV Satpura

01.05.06 21:20

400/220kV ICT At Satpura

MPPTCL 22:35 ICT A/T from both sides. On 220kV side, Y-ph O/C protection operated due to 220kV Sw. Yd. Gen.-7; Y-ph CT burst.

3.32

400kV Koradi

03.05.06 12:05


MSETCL 12:05 A/T on transient B-ph to E/F. A/R successful at both ends.

3.3 400kV 03.05.0 400kV MSETCL 21:25 A/T on transient B-ph to

Minutes of 94th PCM

3 Koradi 6 13:00

Koradi- Bhusawal # 2

E/F. Line A/R but went into L/O due to persisting of fault. Line patrolled from Bhusawal end but nothing found abnormal. Hence line recharged and stood OK.

3.34

400kV Waluj

05.05.06 14:14

400kV Waluj- Bhusawal

MSETCL 14:14 A/T on transient B-ph to E/F. A/R successful at both ends.

3.35

220kV Haldarwa

10.05.06 06:00

220kV H’wa – Kawas # 2

POWERGRID 19:24 A/T due to R-ph insulator flashed over at Loc. No. 207.

3.36

400kV Raipur

13.05.06 18:59

400kV Rourkela - Raipur # 2

POWERGRID 19:07 A/T on transient B-ph to E/F. Line A/R successfully at Raipur end only.

3.37

400kV Koradi

14.05.06 13:03


MSETCL 15:10 A/T on transient R-ph to E/F. Delay in line charging due to broken spring charging interlock of breaker at Koradi end.

3.38

400kV Satpura

17.05.06 17:17


MPPTCL 02.06.06 03:57

A/T at both ends as some towers at 80% distance from Sarni fell down due to storm.

3.39

400kV Satpura

17.05.06 17:30

400kV Satpura -Indira Sagar

MPPTCL 18:22 A/T due to operation of O/V stage-I protection at Indira Sagar and D/T signal received.

3.40

400kV Nagda

17.05.06 17:30

400kV Nagda -Indira Sagar

MPPTCL 18:10 A/T due to operation of carrier L/O relay and A/R lock out.

3.41

220kV Vav

18.05.06 00:20

220kV Vav- KAAP-1

POWERGRID 11:00 A/T at Vav end only due to defects developed in DPS.

3.42

400kV Satpura

18.05.06 17:50

400kV Satpura -Indira Sagar

MPPTCL 18:15 A/T due to operation of O/V stage-I protection at Indira Sagar and D/T signal received.

3.43

400kV Nagda

18.05.06 17:50


MPPTCL 18:30 A/T due to operation of carrier L/O relay and A/R lock out.

3.44

400kV Dehgam

19.05.0602:54


POWERGRID 03:43 A/T due to operation of O/V protection at Jhanor end and D/T Signal

Minutes of 94th PCM

received at Dehgam end. 3.45

400kV Itarsi

23.05.06 12:07


POWERGRID 20:52 A/T on Y-ph to E/F due to snapping of earth wire between location nos. 173-175..

3.46

400kV Raipur

23.05.06 15:32


POWERGRID 16:16 A/T on transient B-ph to E/F. Line A/R at Raipur end only.

3.47

400kV Chandrapur

23.05.06 15:46



3.48

400kV Chandrapur

23.05.06 15:46


MSETCL 16:29 A/T on transient Y-ph to E/F.

3.49

400kV Chandrapur

23.05.06 16:27

400kV C’pur- Bhadravati # 4

POWERGRID 16:27 A/T on transient B-ph to E/F. A/R successful at both ends.

3.50

400kV Khandwa

24.05.06 14:55

400kV K’dwa – Dhule # 2

POWERGRID 25.05.06 15:28

A/T on Y-ph to E/F. Line A/R at Khandwa end only.

3.51

400kV Itarsi

24.05.06 17:06

400kV Jabalpur- Itarsi # 1

POWERGRID 17:41 A/T on Y-ph to E/F. A/R un-successful due to persisting nature of fault.

3.52

400kV Koradi

26.05.06 13:00


MSTCL 23:57 A/T on B-ph to E/F. CVT jumper reportedly disconnected at Bhusawal end.

3.53

400kV Chandrapur

26.05.06 16:15

400kV C’pur- Koradi

MSETCL 16:28 A/T on transient B-ph to E/F.

3.54

400kV Chandrapur

26.05.06 19:07



3.55

220kV Navsari

30.05.06 05:10

220kV Navsari – Nashik #1

GETCO/ MSETCL

23:25 A/T due to R-ph insulator flashed over at Loc. No. 178.

3.56

220kV Navsari

30.05.06 23:28

220kV Navsari – Nashik # 2

GETCO/ MSETCL

31.05.06 22:30

A/T due to L.A. flashed over at Nashik end.

3.57

220kV TAPS

31.05.06 00:34

220kV TAPS- Borivali

MSETCL 01.06.06 00:00

A/T on transient Y-ph to E/F.

3.58

220kV Haldarwa

31.05.06 21:06

220kV H’wa- Kawas # 1

POWERGRID 01.06.06 20:45

A/T due to B-ph insulator flashed over at Loc. No. 152.

Minutes of 94th PCM

3.59

220kV Haldarwa

31.05.06 21:08

220kV H’wa- Kawas # 2

POWERGRID 01.06.06 21:07

A/T due to B-ph insulator flashed over at Loc. No. 152.

3.60

220kV Navsari

31.05.06 21:11

220kV Navsari – Kawas # 2

GETCO/ MSETCL

01.06.06 13:35

A/T due to R-ph insulator flashed over at Loc. No. 178.

3.61

400kV Vapi

31.05.06 05:04

400kV Vapi – Boiser

POWERGRID 05:37 A/T on B-ph to E/F. A/R succe-ssful from both ends but tripped due to persisting nature of fault. Special patrolling carried out but no abnormality observed.

3.62

220kV Vav

31.05.06 21:25

220kV Vav- Kawas

POWERGRID 01.06.06 20:27


3.63

220kV Bhilad

31.05.06 03:16

220kV Bhilad- Tarapur

POWERGRID 01.06.06 21:57


3.64

220kV Vapi

31.05.06 06:35

220kV Vapi- Tarapur

POWERGRID 17:55 A/T due to B-ph insulator flashed over at Loc. No. 1008 & earth wire broken at 1010,1011,1012.

3.65

400kV Jabalpur

01.06.06 21:18

400kV V’chal- Jabalpur

POWERGRID 22:48 A/T on Y-ph to E/F & simultan-eously operation of line reactor differential, REF protection at Jabalpur end. Line charged without reactor. No abnormality found during internal inspection of the reactor by M/s BHEL rep-resentative. Reactor taken in to service after oil filtration on 28.06.06.

3.66

400kV Indore

02.06.06 04:38

400kV Indore- Asoj # 2

POWERGRID 05:45 A/T due to operation of O/V stage-I protection at Asoj end.

3.67

400kV Dehgam

02.06.0600:35


POWERGRID 02:16 A/T on B-ph to E/F. A/R was unsuccessful due to persisting nature of fault. Charging of line delayed due to persisting of system over voltage.

3.68

400kV Dehgam

02.06.0606:18


POWERGRID 06:58 A/T on B-ph to E/F. Line A/R successfully from Dehgam end only.

Minutes of 94th PCM

3.69

400kV Bhilai

02.06.06 10:51


MPPTCL /CSEB

06.06.06 19:44

Main I protection operated at Bhilai. A/R Lock Out, Carrier L/O, Code I received.

3.70

400kV Koradi

06.06.06 07:37


MSTCL 07:40 L/O tripping at Bhusawal end due to receipt of spurious DT signal from Koradi end while shifting of line to TBC due to dc leakage and earthing of TBC dc bus in DT ckt.

3.71

400kV Koradi

06.06.06 08:45


MSTCL 09:07 Line was on TBC. While opening of line isolator under process, TBC side isolator (29C) also opened partially as opening command was extended to TBC isolator due to dc leakage. Line tripped at both ends due to sparking at TBC isolator jaws.

3.72

400kV Korba (NTPC)

07.06.06 01:55

400kV Korba- Korba(West)

CSEB 02:20 A/T at Korba(W) end only. D/T received at K(W) due to PLCC problem in channel –2.

3.73

400kV Asoj

11.06.06 17:05

400kV Asoj – SSP

GETCO 12.06.06 10:43

A/T on O/V stage-I.

3.74

400kV Kasor

12.06.06 07:00

400kV Kasor – SSP

GETCO 08:10 A/T on O/V stage-I.

3.75

400kV Nagda

12.06.06 07:04

400kV Nagda -SSP 1

MPPTCL 07:40 A/T due to operation of carrier L/O relay and A/R lock out. O/V stage –I at remote end

3.76

400kV Asoj

12.06.06 12:32

400kV Asoj – SSP


3.77

400kV Kasor

12.06.06 12:35

400kV Kasor – SSP


3.78

400kV Kasor

12.06.06 17:37

400kV Kasor – SSP


Minutes of 94th PCM

3.79

400kV Asoj

12.06.06 17:37

400kV Asoj – SSP


3.80

400kV Nagda

12.06.06 17:38


MPPTCL 18:25 A/T due to operation of carrier L/O relay and A/R lock out. O/V stage –I at remote end

3.81

400kV Asoj

16.06.06 07:00

400kV Asoj – SSP

GETCO 14:10 A/T on O/V stage-I & II.

3.82

400kV Kasor

16.06.06 07:00

400kV Kasor – SSP


3.83

deleted

3.84

220kV KAPS

16.06.06 10:30

220kV H’wa- KAPP # 2

POWERGRID 10:38 A/T on transient C-ph to E/F in Zone-I.

3.85

220kV Haldarwa

16.06.06 10:35

220kV H’wa- KAPP # 1

POWERGRID 10:38 A/T on transient B-ph to E/F.

3.86

220kV Navasari

17.06.06 11:40

220kV Navasari- Nashik # 2

GETCO / MSTCL

12:47 Transient tripping.

3.87

220kV Navasari

17.06.06 13:05

220kV Navasari- Nashik # 2

GETCO / MSTCL

19:34 Transient tripping. Patrolling carried out due to repeated tripping.

3.88

400kV Koradi

20.06.06 14:10


MSTCL 14:35 A/T on transient B-ph to E/F.

3.89

400kV Bhilai

21.06.06 18:42

400kV Bhilai- Chandrapur

POWERGRID 18:42 A/T on transient A-ph to E/F. A/R successful at both ends.

3.90

400kV Jetpur

22.06.06 15:17

400kV Jetpur- Amreli

GETCO 23.06.06 11:25

Earth wire broken between Location No. 788-789.

3.91

400kV Asoj

22.06.06 18:23

400kV Asoj – Ukai

GETCO 23.06.06 17:53

Earth wire snapped between Location 3 to 9.

3.92

400kV Koradi

23.06.06 07:02


MSTCL 25.06.06 20:05

L/O tripping for remote end fault at Koradi end due to operation of O/V stage-I protection at Bhusawal end. B & Y phase line CVTs

Minutes of 94th PCM

were reportedly giving higher voltage output & replaced.

3.93

400kV Itarsi

23.06.06 16:35


POWERGRID 16:59 A/T on B-ph to E/F. A/R was unsuccessful due to selector switch kept in Non Auto Mode at both ends as Ckt-1 of Double ckt tower was under maintenance works.

3.94

400kV Bhilai

23.06.06 21:05

400kV Koradi- Bhilai

POWERGRID 21:53 A/T on transient R-ph to E/F. Line A/R at Bhilai end but tripped on PDR at Koradi end due to non-operation of A/R scheme, reason was investigated & problem rectified during line outage on 06.07.06.

3.95

220kV Vav

25.06.06 01:55

220kV Vav- KAPP # 2

POWERGRID 06:45 A/T on transient R-ph to E/F.

3.96

220kV Vav

25.06.06 03:30

220kV Vav- Kawas

POWERGRID 06:50 A/T on transient.

3.97

400kV Raipur

28.06.06 05:31


POWERGRID 05:46 A/T on transient B-ph to E/F. Line A/R at Raipur end only.

3.98

400kV Itarsi

28.06.06 18:56

400kV Satpura - Itarsi

POWERGRID 20:04 A/T at Satpura end only due to suspected DC earth leakage at Satpura end.

3.99


POWERGRID 11:39 A/T on transient Y-ph to E/F. Line A/R at V’chal NTPC end only. Non-attempt of A/R at Jabalpur checked and found drift in the A/R pressure settings. The same corrected and A/R operation checked for O.K.

3.100

400kV Jabalpur

29.06.06 11:32


POWERGRID 11:32 A/T on transient Y-ph to E/F. A/R successful at both ends.

th protection committee meeting - wrpcwrpc.gov.in/pcm/94pcm_minute.pdf · 2006-10-18 · welcomed...

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