Circuit Breakers
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Sr. No. Equipment / test data Permissible limits Reference A) Dew point of SF6 gas Dew point values as per Annx – II B) Dew point of operating air -45 Deg. C at ATM. Pressure C) CB Operating timings 400 kV 220KV a) Closing time (Max.) 150 MS 200MS b) Trip time (Max.) 25 MS 35MS c) Close/trip time, Pole discrepancy – Phase to Phase (Max.) 3.33 MS 3.33MS -Break to break (Max.) of same phase 2.5 MS 2.5MS D) PIR time BHEL make 12-16 MS Manufacturers Recommendations ABB make 8-12 MS Manufacturers Recommendations NGEF make 8-12 MS Manufacturers Recommendations M&G make 8-12 MS Manufacturers Recommendations TELK make 8-12 MS Manufacturers Recommendations ABB make (HVDC) 8-12 MS Manufacturers Recommendations E) PIR opening time prior to opening of main contacts (ABB, CGL, NGEF make CBs) 5 MS (Min.) at rated pressure Manufacturers Recommendations F) Pir and main contacts overlap time [BHEL, M&G, ABB (imported) make CBs] 6 MS (Min.) at rated pressure Manufacturers Recommendations G) Tan delta of grading capacitors 0.007 at 20 Deg. C H) Capacitance of grading capacitors Within + 10% / -5% of the rated value IEC 359 I) Contact resistance of CB 150 M. Ohm J) Contact resistance of CB terminal connector 10 M. Ohm per connector NGC, UK recommendations K) IR value: 1. Phase – earth 1000 M Ohm (Min.) by 5.0 / 10.0 kV Megger 2. Across open contacts 1000 M Ohm (Min.) by 5.0/10.0 kV Megger 3. Control cables 50 M Ohm (Min.) by 0.5 kV Megger L) Pressure switch settings -SF6 gas pressure switches Within + 0.1 Bar of set value -Operating air pr. Switches Within + 0.1 Bar of set value -Operating oil pr. Switches Within + 0.1 Bar of set value M) BDV of oil used for MOCB -At the time of filling 40 kV at 2.5 mm Gap (Min.) Mfgs. Recommendation -During O&M 20 kV at 2.5 mm Gap. (Min.) Mfgs. Recommendation Circuit Breakers
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Circuit Breakers
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Sr.
No.Equipment/testdata Permissiblelimits Reference
A) DewpointofSF6gas DewpointvaluesasperAnnxII
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 12-16MS ManufacturersRecommendations
ABBmake 8-12MS ManufacturersRecommendations
NGEFmake 8-12MS ManufacturersRecommendations
M&Gmake 8-12MS ManufacturersRecommendations
TELKmake 8-12MS ManufacturersRecommendations
ABBmake(HVDC) 8-12MS ManufacturersRecommendations
E)
PIRopeningtimepriortoopeningof
maincontacts(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) Capacitanceofgradingcapacitors Within+10%/-5%oftheratedvalue IEC359
I) ContactresistanceofCB 150M.Ohm
J) ContactresistanceofCBterminalconnector 10M.Ohmperconnector NGC,UKrecommendations
K) IRvalue:
1.Phaseearth
1000MOhm(Min.)by
5.0/10.0kVMegger
2.Acrossopencontacts
1000MOhm(Min.)by
5.0/10.0kVMegger
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
CircuitBreakers
