MOCBs Pre commissioning ChecksOil sampling , testing for BDV and replacing ,if needed.Nitrogen gas pressure checking and topping up. PRV checkingTerminal clamp tightness checkingPhase to phase and phase to earth clearances are to be checkedTermination of power and control supplies Slow operations of CB

Checking sinking gap of main contacts symmetrical movement of operating insulatorsMechanical interlock for spring charging Mechanical interlock to avoid second closingCheck for all split pins,dowels pins, circlips, check nuts etc.Lubrication of all moving partsChecking operations of CB (local & remote)Checking pole discrepancy relay and anti pumping featuresCheck all possible trippingsInterlocks between CB ,isolators,earth switches etc.

245 kV and 400kV SF6 Breakers Preparation of hydraulic oil systemsOpen all the air venting screws,PRVFill aero shell fluid-4 through 60 micron filterStart the oil pump and priming of the pumpClose venting screws and PRVCheck priming pressure of Nitrogen in accumulatorVenting of oil at accumulator inlet and at drive assemblies of all 3 poles

Connect standard pressure gaugeCheck for a. General Lock out b. Closing Lock put c. Auto reclosure lock out d. Pump on and off pressuresCheck for any oil leaks in pipe lines,in pilot valve/ main valveTopping up of oil

Preparation of Pneumatic Pressure SystemStart the motor and check for direction of rotationDuring building up pressure,check for leaks by listening / soapy waterVenting and drainingCheck for all pressure settings as aboveLeak Test: Note P0 at T0.After 24 hrs note Pe at Te.Then P = Pe X (273+T0/273+Te centigrade Peff = Po-P < 2.0 bar

Air consumption measurement for c-o-co-oco operations

Preparation of SF6 gas systemCharging of filtersMaking density monitor operationalEvacuation of the CB up to 20mbarFilling of SF6 gas up to 1barConnect the standard pressure gaugeFilling SF6 gas up to lock out pressureCheck for vanishing/appearance of lock out signalContinue filling SF6 gas till loss of gas pressure

Check for vanishing / appearance of loss of gas signalCheck for SF6 gas leak test with detector Dew point measurement

EHV SF6 Breaker operating values400kV SF6 CIRCUIT BREAKERS:Oil: Pump Start : 313 +/-3 bar Stop : 325 +/-3 bar Pressure Low : 303 +/- 3 bar

Closing Lock Out Oil pressure Less than 273 +/- 3 bar Loss of SF6 :Less than 6.7 bar

General Lock outOil Pressure : Less than 253 barSF6 gas pressure : Less than 6.5 bar

230kV SF6 CIRCUIT BREAKERS:

AIR: Compressor Start : 19.5 bar Stop : 20.5 bar Low air pressure : Less than 19 bar

Auto Reclosure Lock Out: Air : Less than 18 bar Closing Lock Out: Air Pressure : Less than 17.5 bar Loss of SF6 : Less than 6.2 bar General Lock out: Air Pressure : Less than 16.7 bar SF6 gas pressure : Less than 6.0 bar