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MinimumAcceptableSpecificationofC.T&P.TforMetering

APRIL1,2011 4COMMENTS(HTTPS://ELECTRICALNOTES.WORDPRESS.COM/2011/04/01/MINIMUMACCEPTABLESPECIFICATIONOFCTFORMETERING/#COMMENTS)

Min.AcceptableSpecificationofCurrentTransformerforMetering:

Sr.No

Particulars 11kV 33kV 132kV 220kV

1 HighestSystemVoltage(kVrms)

12 36 145 245

2 CTratio. 20001000/11 800400/11 400/11 800/11

1600800/11 600300/11

1200600/11 400200/11

800400/11 300150/11

600300/11 10050/11

400200/11

300150/11

15075/11

3 Numberofmeteringcores

TwoNos TwoNos TwoNos TwoNos

4 Ratedcontinuousthermalcurrent.

120%ofratedprimarycurrent

120%ofratedprimarycurrent

120%ofratedprimarycurrent

120%ofratedprimarycurrent

5 Ratedshorttimethermalcurrentofprimaryfor1sec.(kA)

25 25 31.5 40

6 CTcharacteristics:a)Ratedprimarycurrent(Amps.)

20001000 800400 400 800

1600800 600300

1200600 400200

800400 300150

600300 10050

400200

300150

15075

(b)RatedSecondarycurrent(Amps.)

1 1 1 1

(c)Classofaccuracy. 0.2 0.2 0.2 0.2

(d)Max.instrumentsecurityfactor

5 5 5 5

(e)Ratedburden(VA). 30 30 30 40

7 IStowhichCTconforms.

8 IStowhichinsulatingoilconforms.

Min.AcceptableSpecificationofVoltageTransformerforMetering:

Sr.No

Particulars 245kVCVTs

145kVCVTs

1 HighestSystemVoltage(kV)

245kV 145kV

2 RatedCapacitance(pF) 4400pfwithtolerance+10%and5%

3 Forlowvoltageterminaloverentirecarrierfrequencyrange.

(a)Straycapacitance Shallnotexceed200pf

(b)Strayconductance Shallnotexceed20us

4 (a)Highfrequencycapacitanceforentirecarrierfrequencyrange

within80%to150%ofratedcapacitance

(b)Equivalentseriesresistanceovertheentirefrequencyrange.

lessthan40Ohms

5 No.ofsecondarywindingsforpotentialdevice.

Two Two

6 Transformationratio:

(i)WindingI 20kV\/3/110\/3V

(ii)WindingII 20kV\/3/110\/3V

7 Ratedsecondaryburden

(i)WindingI(VA) 50VA 50VA

(ii)WindingII(VA) 50VA 50VA

8 AccuracyClass:

(i)WindingI(VA) 0.2formetering

(ii)WindingII(VA) 0.2formetering

9 VoltagefactorforwindingIVoltagefactorforwindingII

1.2Cont.&1.5for30secs.1.2Cont.&1.5for30secs.

10 IStowhichCVTsconform.

IS3156withlatestamendment

11 IStowhichInsulatingOilconform.

IS335withlatestamendment

MinimumAcceptableSpecificationofSinglePhasePTforMetering:

Sr.No Particulars 33kV 11kV

1 HighestSystemVoltage(kVrms) 36 12

2 Transformationratio. 33kV/V3/110/V3

11kV/110V

3 Numberofwindings. Two Two

4 Ratedoutput/burden(VA)perwinding/phase.

50 50

5 Accuracyclass.(At10to100%ofVAburden)

0.2 0.2

6 Ratedvoltagefactorandduration.

1.2continuous&1.5for30secs.

7 IStowhichPTconforms. 3156withlatestamendment

FILEDUNDERUNCATEGORIZED

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

4ResponsestoMinimumAcceptableSpecificationofC.T&P.TforMetering

waqasahmedsays:April2,2011at5:18amdearsir!!

yourpostareveryinformative..irequestyoutopleaseguideusonrealytestingfordifferentschemesofcableandOHTLprotection..pleaseshareusyourpracticalknowledge..Regards

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WaqasAhmed

Replyrajivpandeysays:May10,2011at4:26amItisreallyinformative.Pleaseguidemeaboutthefollowing:Wehaveanewsteelplantcomingupinthestateofwestbengal.Theplantisstillininstallation&commissioningstage.Wehaveerectedone220KVlinefromsupplyingutilitytothe220/33KVMainreceivingstationoftheplant.theCTratiointhelineis400/1,0.2Class.Weneedabout1.5MVAatpresenttokeeptheMRSchargedandforcommissioningoffewoftheequipment.However,supplyingutilityhastoldusthattheywillnotbeabletosupplylessthan5MVAinthe220KVline,assupplyoflessthan5MVAmaycauseerrorinmetering.Kindlyguideuswhetherthestandofsupplyingutilityiscorrectornotwithreasoning.

Regards,

Rajiv

Replyrcsays:July30,2011at12:05pmVerygood.keepitup

Replyparijatsays:December16,2014at5:46pminmaharastraitisrequiredtoputcheckmeterontheconsumersideforhighMDcosumer.pleasecouldutellmeitspossibletoconnectwithsamecoreofctorPTorwehavetoinsatallseparatemeteringtemple

Reply

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