typical limiting values of substation equipments

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TypicalLimitingValuesofSubStationEquipments.

MARCH31,2011 12COMMENTS(HTTPS://ELECTRICALNOTES.WORDPRESS.COM/2011/03/31/TYPICALLIMITINGVALUESOFSUBSTATIONEQUIPMENTS/#COMMENTS)

TypicalLimitingValuesofSubStationElectricalEquipments.

1.Transformer/Reactor:

Sr.No. Equipment/testdata Permissiblelimits Reference

A)

Transformeroil

a)BDV

Atthetimeoffirstcharging 600kV(Gap2.5mm)Minimum IS1866

DuringO&M 50kV(Gap2.5mm)Minimum IS1867

b)Moisturecontent IS1868

Atthetimeoffirstcharging 15PPM(Max.) IS1869

DuringO&M 25PPM(Max.) IS1870

c)Resistivityat90degreeC 0.11012OhmCM(Min.) IS1871

d)Acidity 0.2mgKOH/gm(Max.) IS1872

e)IFTat27degreeC 0.018N/M(Min.) IS1873

f)Tandeltaat90degreeC 0.20(Max.) IS1874

g)Flashpoint 126Deg.C(Min.) IS1875

B)Vibrationlevelforreactors 200Microns(PeaktoPeak) IS1876

60Microns(Average) IS1877

C) Tandeltaforbushingat20Deg.C0.007* IEC137

D) Capacitanceforbushing +5%variation IEC138

E) IRvalueforwinding 1000MOhmBy5.0/10.0kVMeggerIEC139

F) Tandeltaforwindingsat20Deg.C0.007* IEEE/C57.12.90.1980

G) Contactresistanceofbushingterminalconnectors10M.Ohm/Connector NGC.UK

Recommendations

H) TurretNeutralCTratioerrors 39 IS2705

2.CircuitBreakers




A) DewpointofSF6gas DewpointvaluesasperAnnexureII

B) Dewpointofoperatingair 45Deg.CatATM.Pressure

C)

CBOperatingtimings 400kV220KV

a)Closingtime(Max.) 150MS200MS

b)Triptime(Max.) 25MS35MS

c)Close/triptime,Polediscrepancy

PhasetoPhase(Max.) 3.33MS3.33MS

Breaktobreak(Max.)ofsamephase 2.5MS2.5MS

D)

PIRtime

BHELmake 1216MSManufacturersRecommendations

ABBmake 812MSManufacturersRecommendations

NGEFmake 812MSManufacturersRecommendations

M&Gmake 812MSManufacturersRecommendations

TELKmake 812MSManufacturersRecommendations

ABBmake(HVDC) 812MSManufacturersRecommendations

E)PIRopeningtimepriortoopeningofmaincontacts(ABB,CGL,NGEFmakeCBs) 5MS(Min.)atratedpressure

ManufacturersRecommendations

F)Pirandmaincontactsoverlaptime[BHEL,M&G,ABB(imported)makeCBs] 6MS(Min.)atratedpressure

ManufacturersRecommendations

G) Tandeltaofgradingcapacitors 0.007at20Deg.C

H) CapacitanceofgradingcapacitorsWithin+10%/5%oftheratedvalue IEC359

I) ContactresistanceofCB 150M.Ohm

J) ContactresistanceofCBterminalconnector 10M.OhmperconnectorNGC,UKrecommendations

K)

IRvalue:

1.Phaseearth 1000MOhm(Min.)by5.0/10.0kVMegger

2.Acrossopencontacts 1000MOhm(Min.)by5.0/10.0kVMegger

3.Controlcables 50MOhm(Min.)by0.5kVMegger

L)

Pressureswitchsettings

SF6gaspressureswitches Within+0.1Barofsetvalue

Operatingairpr.Switches Within+0.1Barofsetvalue

Operatingoilpr.Switches Within+0.1Barofsetvalue

M)

BDVofoilusedforMOCB

Atthetimeoffilling 40kVat2.5mmGap(Min.) Mfgs.Recommendation

DuringO&M 20kVat2.5mmGap.(Min.) Mfgs.Recommendation



3.CurrentTransformer


A)

IRvalue

1.Primaryearth 1000MOhm(Min.)by5.0/10.0kVMegger

2.Secondaryearth 50MOhm(Min.)by0.5kVMegger


B) Tandeltavalue 0.007*at20Deg.C

C) TerminalConnector 10MOhmperconnectorNGC,UKRecommendations

D) CTratioerrors +3%Protectioncores IS2705

D) CTratioerrors +1%Meteringcores IS2706

4.CapacitiveVoltage


A) TanDelta 0.007*at20Deg.C

B) Capacitance Within+10%/5%oftheratedvalue IEC358

C Contactresistanceofterminalconnector 10MOhmperconnectorNGC,UKRecommendations

D)

IRValue IRValue

1.Primaryearth 1000MOhm(Min.)by5.0/10.0kVMegger

2.Secondaryearth 50MOhm(Min.)by0.5kVMegger


E)

EMUtankoilparameters EMUtankoilparameters

a)BDV(Min.) 30kV(Gap.2.5mm) IS1866

b)Moisturecontent(Max.) 35ppm do

c)Resistivityat90Deg.C 0.11012Ohm.CM do

d)Acidity 0.5mgkOH/gm(Max.) do

e)IFTat27Deg.C 0.018N/M(Min.) do

f)Tandeltaat90Deg.C 1.0Max. do

g)Flashpoint 125Deg.C(Min.) do

F) CVTvoltageratioerrors +5%protectioncores IEEE/C93.1.1990

F) CVTvoltageratioerrors +0.5%meteringcores IEC186

5.Isolators


A) Contactresistance 300MOhm.(Max.)



B) Contactresistanceofterminalconnector 10MOhmperconnector

NGC,UKRecommendations

C)

IRvalue

1.Phaseearth 1000MOhm(Min.)by5.0/10.0kVMeggerNGC,UKRecommendations

2.Acrossopencontacts 1000MOhm(Min.)by5.0/10.0kVMeggerNGC,UKRecommendations


6.SurgeArrester


A) Leakagecurrent 500MAmp.(Resistive) Hitachi,JapanRecom.

B) IRvalue 1000MOhm.(Min.) Hitachi,JapanRecom.

7.Miscellaneous


A) Stationearthresistance 1.0Ohm(Max.)

B)

Thermovisionscanning

Temp.upto15Deg.C(aboveambient) Normal

Temp.above1550Deg.C(aboveambient) Alert

Temp.above50Deg.C(aboveambient) Tobeimmediatelyattended

C) TerminalconnectorsContactresistance 10MOhmperconnectorHGC,UKRecommendations

D)

IRvalues

1.Allelectricalmotors 50MOhm(Min.)by0.5kVMegger

2.Controlcables 50MOhm(Min)by0.5kVMegger

3.Lt.Transformers 100M.Ohm(Min.)byMegger

4.Lt.Switchgears 100MOhm(Min.)by0.5kVMegger

8.Batteries


A) Terminalconnectorresistance 10MOhm+20% ANSI/IEEE4501989

B) Specificgravity 1200+5GM/Lat27Deg.C

TemperatureCorrectionFactorforTanDeltaMeasurement

Sr.No. OiltemperatureDeg.C Correctionfactor(K)



1 10 0.8

2 15 0.9

3 20 1.0

4 25 1.12

5 30 1.25

6 35 1.40

7 40 1.55

8 45 1.75

9 50 1.95

10 55 2.18

11 60 2.42

12 65 2.70

13 70 3.00IfTanDeltaofbushing/winding/CVT/CTismeasuredatoiltemperatureTDeg.C.ThenTanDeltaat20Deg.Cshallbeasgivenbelow:

TanDeltaat20Deg.C=TanDeltaatTempTDeg.C/FactorK.

DewPointLimitsforSF6GasinEHVCircuitBreakers

Sr.No MakeofC.B DewpointatratedPr.Deg.C

CorrespondingdewpointatAtmospheric.Pr. Remarks

1 BHEL15 36

Atthetimeofcommissioning

7 29 DuringO&M

5 27 Critical

2 M&G 39


32 DuringO&M

3 CGL15 35


10 31 DuringO&M

4 ABB15 35


5 26 DuringO&M

5 NGEF15 36


7 29 DuringO&MNote:DewpointofSF6gasvarieswithpressureatwhichmeasurementiscarriedout.Soitistobeensuredthatifmeasurementisdoneatpressureotherthanatmosphericpressure,itneedstobeconvertedtotheatmosphericpressure.



FILEDUNDERUNCATEGORIZED

AboutJignesh.ParmarJigneshParmarhascompletedM.Tech(PowerSystemControl),B.E(Electrical)fromGujaratUniversity.Hehasmorethan13yearsexperienceinPowerTransmissionPowerDistributionElectricalenergytheftdetectionElectricalMaintenanceElectricalProjects(PlanningDesigningcoordinationExecution).HeisPresentlyassociatewithoneoftheleadingbusinessgroupasaDeputyManageratAhmedabad,India.HeisFreelancerProgrammerofAdvanceExcelanddesignusefulExcelSheetsofElectricalEngineeringasperIS,NEC,IEC,IEEEcodes.HeistechnicalAuthorforElectricalMirrorandElectricalIndiaMagazines.HeisTechnicalBloggerandFamiliarwithEnglish,Hindi,Gujarati,Frenchlanguages.HewantstoSharehisexperience&knowledgeandhelptechnicalenthusiaststofindsuitablesolutionsandupdatingthemselvesonvariousEngineeringTopics.

12ResponsestoTypicalLimitingValuesofSubStationEquipments.

S.Krishnamurthysays:July25,2011at6:44amVeryusefulinformationforallsubstationoperating&maintenancepersonnel.Allequipmentsdataisindicatedinoneplace.Bestwishes.

S.K.MURTHY

ReplyVVNRaosays:December17,2011at5:13amHappytoseetheusefulinformation.Ifpossiblepleaseaddrangeandcriticalityoftandeltavaluesandalsotheinternationalstandaredsofclearancesinasubstationaswellasinlines.

Replyvighneshsays:January3,2012at11:20amiamunabletolocateIEC139pertainingtoIRvaluesofwindings.WhatshallbercommendedvaluesofIR?

ReplySsatishShindesays:May25,2012at5:50amThanxforprovidinginstantimportantinformation.

Replymasoomkhansays:July4,2012at10:09amcananyoneprovide380EHVSurgearresterpowerfactor10KVTESTpermissibilelimits

ReplyTikaramwaghadesays:July19,2012at1:04pmThisparametersisexcellencetoimpruvecomfidenceinequptesting

ReplyDineshSinghsays:July31,2012at11:04amThanksforprovidingimportantlimitinginformation.

Replyvinodrathodsays:June10,2013at2:42pmthanksbosscontinuewithstudy

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ReplykirankumarGudlasays:July17,2013at7:25amAtthetimeoffirstcharging

600kV(Gap2.5mm)Minimum

Correctedis

60kV(Gap2.5mm)Minimum

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ReplyAnilPrajapatisays:October8,2013at4:49pmItswonderfulandyouhaveexplainedeverythinginverysimplebutinpowerfulandeffectivewayEr.AnilPrajapati,Jodhpur

ReplyAAAXXXsays:February4,2015at1:50amWhenIwillgofortestingof100MVAtransformerturretcttesting,whattestsIhavetotake?andminimumandmaximumvaluesofthetestswithunit.

Reply

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typical limiting values of substation equipments

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