Does anyone know the recommended run hours necessary to maintain the DC emergency pumps after a loss of AC power for a 7FA unit?

since you have a hydrogen cooled generator, you need to keep your seal oil pump running continuosly until you get power from other standby diesel generators, if not you will lose filled hydrogen. lift oil prussure is required until you bring your turbine to zero speed, may be after enough cooling either on natural on turning gear or by force cooling finally, so things are depend on your requirements and operation limitations.

Dose anyone have a loss of DC Power / Safe Shutdown plan for a 7FA - Mark V control system?
Dose anyone know of an event were DC Power was lost while online / off-line / or on Crank?

Thanks
Jon Mansell

Thanks for the feed back. We do weekly, monthly and quarterly inspections.

Our Company requires a procedure to be developed for a loss of DC control power contingence. I have analyzed each CKT as listed below, CKT 6 and 7 I have as causing a Unit Trip, my analysis is only an educated guess, I was curious to find a plant that had actually lot DC control power to see what happen to them as a bench mark.

If you have any additional info, i.e. if the CKTs below are similar I would appreciate your feed back.

Jon

CKT 1FN = E - Lube Oil Pump 88QE-1 - Pump will not Run
CKT 2FN = E - Seal Oil Pump 88ES-1 - Pump will not Run
CKT 1 = Fire Protection Relay - CO2 Fire protection would not activate i.e. DC is required to cause CO2 Discharge ?? This relay is tied into each blower motor to shut down if Co2 is discharged. Also provides DC power for relay feedback to MKV when fire protection is triggered from the ANSUL system.
CKT 2 = Standby Lights - will have No DC lights but AC will be on.
CKT 3 = Isolation Control Power - This is for DC power for the LCI static start interlock relay protection. When it is turned on, it powers the relay associated with preventing the static start switches from both closing (S1SG, S2SG)
CKT 4 = EX2000 - Exciter can operate using AC or DC power. So with a loss of DC only, the exciter will still remain on.
CKT 5 = Generator Control Power 86RE, 50RE - will loose supervisory signals to 74/86RE and 50RE will not operate due to loss of power. DC power is required to pick up trip coil on LORs.
CKT 6 = Generator Control Panel Control Power @ PEECC - Will trip the unit due to loss of generator protection via the lockouts if it is configured as a "b" contact on the DGP/LPSO.
CKT 7 = Turbine Control Panel Control Power @ PEECC - Loss of DC power will trip the unit..no DC power permissive
CKT 8 = LCI / EX2000 compartment control power will Loose of DC to motors that drive Switches S1SG and S2SG