The 86G Reset knob on GCPP won't reset even when there is no standing alarm indicator. But there is a P28 VDC TTPW Bus ground alarm on our frame 5 model MS5001PA GT with GE mark 6 control system HMI.

I need some help in how to rectify the alarm and also resolve the 86G reset relay.

Thank you.

 

Fourtotwentyma,

Here is a recent thread which describes how to find all the devices which actuate the 86G lock-out relay:

http://control.com/thread/1471414361

Unfortunately, the original poster did not write back to let us know what was preventing the lock-out from being reset.

Really the only way to know what actuates the 86G lock-out relay is to use the electrical schematic drawings for the GCPP. There have been cases where the electro-mechanical protective relay contacts welded shut because people had been holding the lock-out relay in the reset position for 10-30 seconds in the mistaken hope that it would latch--but the current flowing through the closed contacts of the relay that was trying to actuate the lock-out resulted in permanently closing the contacts. When that happens, it's necessary to use the electrical schematics to check each pair if contacts in the series-parallel strings to find the one or ones that are closed.

Failed contacts have also been found in digital generator protection relays, most likely caused by the same mistaken hopes and actions.

Holding the lock-out relay in the reset position for 10-30 seconds can also permanently damage the coil of the lock-out relay, so that when it needs to actuate it won't. And that can be catastrophic to the generator and turbine.

I don't have access to Mark VI manuals at this writing to help with suggestions for the TTPW issue; sorry.

Please write back to let us know what you find!

 

Give me an email address and I can send you a document on TTPW.