Station Blackout

IDENTIFICATION OF TOTAL AC FAILURE
Simultaneous happening of the following:

• Unit tripping.

• All HT, LT drives tripping.

• 400KV, 11KV, 3.3 KV Bus dead.

• DC lights getting on.

• DG set starting in auto.

1. Ensure starting of following equipments on auto otherwise start manually/from Local starting panels :

Main TG DC EOP.

DC Seal oil pump.

DC EOP of TDBFP – A & B.

DC Scanner fan.

DC JOP at TG speed of 510RPM

All Air heaters air motor.

Switch on DC lighting if does not come on auto. 2. Charge Cooling water of CC pumps from Emergency overhead tank. (Open vent Valve in the cooling water return line to establish flow. Keep close watch on cavity temp of all CC pumps.)  3. Emergency bus charging Emergency bus charging through DG incomer & BC closing on auto otherwise do it manually /from Local after ensuring tripping of both normal incoming breaker.(ensure no fault in relay) If both DG sets does not come on auto, start it manually & charge emergency bus. 4. To avoid rupturing of LPT and TDBFPT diaphragms :- Ensure opening of vacuum breaker. Give manual open command also. Close Turbine & TDBFP A&B seal steam supply valves from UCB. Close manual isolating valves from Local. Close all Mall drains. Close all drain valves to SDFT & HP/LP Flash Tank. Close MS – 1 & 2 valves. Open MS strainer drains to UFT and CRH Pot drain to atmosphere. Isolate CRH/Aux steam to Deareator 5. Ensure the following equipments running once Emergency bus gets charged through DG: Main TG : AOP 2, AC seal oil pump 2,H2 side seal oil pump,AC JOP , Vapour extraction fan 2 of MOT and Gen. Brg.chamber fan 2 TDBFP A&B: AOP 2, JOP, Vapour extraction fan 2. Boiler : AC Scanner air fan, AC lighting.(ELP) Electric motors of all APHs. Air motors stops. Stop DC equipments whose corresponding AC is started 6. Stop stand by DG set & monitor DG set diesel level, Winding, engine temperature 7. Ensure opening of barring gear valve at 210 RPM. Do hand barring if does not come on barring. Maintain Following parameter to avoid stalling of barring:- Maintain TG lub oil temperature 55-60 degree Maintain TG JOP pressure > 150 ksc & run both TG AOP Maintain hotwell level -150 mm 8. Put TDBFP-A & B on barring 9. Run DG fire pump.(Monitor FW tank level) 10. Note down relay flags on :- 11KV / 3.3KV buses. Generator protection panel. Boiler/Turbine first up cause of tripping 11. Observe the following parameters closely :- Hydrogen pr. from local gauge & UCB. Purge Hydrogen by CO2 in case of problem in maintaining Seal oil DP. 12. Check 220 Volt, 24V and UPS charger came on load & monitor voltage. 13. Ensure following isolations after unit tripping:- Ensure closing of HOTV / LOTV Isolate SH / RH / HP bypass spray isolating valves Isolate all oil guns Isolate soot blowing steam line if charged Switch off all ESP fields Ensure closing of HP/IP stop & control valves Ensure closing of all turbine extraction valves Restoration of supply and normalization Charging of 400kv buses and ST#3 Normalize 11KV station bus 3SA, Normalize Unit buses through UT/Station Bus. Normalize 3.3 KV switch gear UAA both sections. Normalize Switchgears :USS,SSS,TMCC,BMCC,Service Building MCC,ESP MCC,Offsite Switch Gears (Charge all 3.3 KV / 415 V Switch gear independently) Normalize Emergency Bus from USS:- Synchronize UES with USS and close I/C from USS. OR Charge dead bus by putting DG on manual and closing I/C from USS. Trip the DG breaker and stop DG Set.(While dead bus charging, first of all changeover all the running drives in EMCC) Normalize supply of PT plant, DM Plant Fire pump house, CW MCC, SACW, ASH HANDLING MCCs, AC MCC,FOPH MCC etc. Start DM make up pumps Start electric fire water pump & stop DG fire pump Start Raw water pump & start CLW pump for Forebay/OAC makeup. Start SACW and service water pumps. Run Main Plant A/C System. Prior to start 11KV equipments, take permission from Switchyard Control Room.This is to avoid overloading of station Transformer. Start CW pumps (Before starting ensure discharge valves are closed and vent valves in condenser inlet / outlet ducts are open). Charge both passes of condenser. Start ACW and ECW pumps. Start Instrument and plant air compressor and maintain header pr 6 ksc Start CEP Start oil pump (LDO/HFO) & charge oil lines on the short recirculation. Start MDBFP and fill the Boiler drum up to normal level. Charge aux. PRDS (MSPRDS may also be opened slightly to maintain adequate seal steam temp otherwise open PRDS drains and seal steam drains Normalize the system further for unit synchronization: Start stator water pump Start CF pumps & its vapour fan. Put recirculation pumps in service Start LOPs of ID/FD/PA/MILLS/APH Maintain hotwell, deareator & drum level Maintain HFO pressure 16 ksc & temperature 120 degree Take round of Boiler and TG area for any abnormal sound/ water /steam /oil leakages/any hammering Start ID/FD fan & start purging Put HFO in long recirculation and maintain HFO temperature >115 degree Light up boiler with 04 LDO oil guns Charge APH soot blowing from PRDS Open CBD & Eco recirculation valve Start vacuum pump & observe condenser vacuum Charge TG & TDBFP gland sealing system at -0.2ksc Open drains of MS/CRH/HRH/ Mall drains Open drains before boiler stop valve Charge MS lines Charge HP/LP bypass valves Raise boiler & turbine rolling parameters as per starting procedure

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