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GE MKV Generator RTDs Alarm Trip
GE PG6581B MKV Generator RTDs alarm trip Alarm Drop 0283, 0284,0285, 0271, 0274, 0275 & 0278

Dear Sir,

I am C&I in power plant, I had a problem of GE MKV Generator RTDs alarm trip of Gas turbine Unit 1A & Unit 1B about 3 - 4 times/year, alarm transient (657 ms every time) same time of
- Drop 0283, GEN HOT AIR RTD FAULT
- Drop 0284, BEARING METAL TEMPERATURE HIGH
- Drop 0285, BEARING METAL TEMPERATURE SHUTDOWN
- Drop 0271, BEARING DRAIN TEMPERATURE HIGH
- Drop 0274, GENERATOR HOT GAS TEMERATURE HIGH
- Drop 0275, GEN STATOR RTD FAULT
- Drop 0278, GEN HOT AIR TEMP HIGH HIGH
now bypass signal by logic forced.

Best regards,
CMan

CMan,

What Diagnostic Alarms accompany these events?

It's not typical for GE-provided turbine control systems to trip (emergency shutdown) the turbine and generator on high generator RTD temperatures, but some purchasers (owners) do request the unit be tripped on high-high generator RTD temps (but, again, it's not all that common).

In the Mark V the RTDs are connected to the <C> processor, and it's possible there is a wiring problem with the circuits or with the <C> processor card (TCCA, I believe) that receives and scales the RTD inputs. It could even be a problem with the I/O terminal board on <C> the RTDs are ultimately connected to.

Wiring problems are usually the most common cause of RTD issues. And, if the unit was actually packaged by GE (not one of its licensees) it's VERY common for an unusual--but adequate--wiring scheme using only two-conductor, twisted, shielded pairs to connect the three- or four-wire RTDs to the Mark*. This confuses a LOT of people, but it has worked fine for decades (literally).

So, provide us the list of Diagnostic Alarms which occurred at the same time as the RTD problems and we might be able to be of more help. If you want to save time, just try replacing the I/O card which scales the RTD signals, and/or the I/O terminal board which the RTDs are terminated on. BUT, do yourself a favor--and check the wiring to the junction box where the RTDs are connected on the generator (between the generator JB and the Mark V). You may save yourself a lot of time and expense (Mark V printed circuit cards are expensive!).

Please write back to let us know what you find.

Dear CSA,

Thank you for your advice and information.
For Diagnostic Alarms not issue that time, I tried to fix by:

1. Replace new the <C> TCCA, TBCA & TBCB
2. Tighten the terminal on JB

Now the event had occurred the same before.

I would like your advice to find the root cause and fix it.

Best regard,
CMan