Hello smart guys,

Frame 7EA, MarkVIe control. When does emergency Seal oil pump come in? If I drain seal oil differential switches and keep Aux Seal oil Pump breaker open, will it start ESOP?

Thanks in advance

 

Sardar99,

To be absolutely certain, one would need to look at the application code running in the Mark VIe.

In general, the ESOP only runs if there's no AC power to the MCC section housing the Aux. SOP motor starter, and there's a hydrogen purge in progress.

If there is hydrogen in the generator and you're going to "drain" the seal oil differential pressure switches then it's likely you're going to initiate a hydrogen purge sequence. You'll want to make sure the hydrogen control panel/system is in MANUAL, and the Aux. L.O. Pump is in HAND, and you may even want to block the CO2 and ensure the vent is manually closed, also (either upstream of the purge solenoid, or downstream of the purge solenoid, as found on your system).

It's really risky if you're trying to do this with hydrogen in the generator. What you don't want to do is introduce CO2 into the generator, because if that happens you'll need to go through a complete purge and charge. Even if you lose some hydrogen through the vent if a purge is unintentionally initiated you can always manually introduce hydrogen to bring the pressure back up, but if CO2 gets into the generator then a complete purge and charge will be necessary. Especially if the unit is on slowroll (cooldown) as there WILL be mixing of CO2 and hydrogen.

Usually, CO2 is admitted at a pressure slightly higher than generator casing pressure (30 psig) to help push the hydrogen out. So, any CO2 which gets into the generator will cause some mixing even if the unit is at zero speed.

Another thing you could also do if this is for pressure switch operation verification (commonly (incorrectly) referred to as "device calibration" during maintenance outages) is to just force the logic in the Mark VIe to make it believe the pressure switches are in their normal state, and just monitor contact closure/openings at the JB nearest the pressure switch while applying/removing pressure during verification; just don't forget to remove the forces when finished.

Hope this helps!