Hi..

Dear Mark V Experts..
I have a question?
I work in CCPP which have two GT (F9E and MS9001E)

There is alarm L63ET1H Exhaust Pressure Switch Trouble one of the GTs. Before alarm occurred, We saw diagnostic alarms from R processor and then from other processors. However, the alarm is true and false. I assume cable is broken or short circuit. I want to learn, This signal we can force? How is troubleshoot this problem while operation?

Thank you..

 

Dear Mark V,

typically there are two exhaust pressure switches and possibly a transmitter to measure pressure in the exhaust collector. Usually the signals from the switches are inverted so that when exhaust pressure is normal the contact input is true, but the logic signal to trip is false. So it is possible that a broken wire would indicate to logic that the exhaust pressure is high enough to trip.
Sometimes there is an alarm, L63ETF_SENSR that will be true if both of the exhaust pressure switches, and the exhaust pressure transmitter don't agree.

You definitely should be investigating this situation as it can lead to a unit trip. I can't suggest which exact signal you should be forcing as I do not understand the intent of your force, and I do not have a copy of your logic to view. Typically to disable the trip you would need to force the signal that leads to the trip block, if you understand the flow of logic you should have no problem identifying this signal. I assume you understand the issues involved with forcing any signal, and the situations that can result from forcing the wrong signal, and lastly the loss of machine protection that results when any signal is forced. The safest diagnosis of any problem is done with the machine offline.

Please write back and let us know how you progress in your diagnosis.

 

Hi..

Thank you for your reply

I want to force L63ET1H because It is faulty (I think Switch or cable are faulty). If one of L63ET2H or L63EAH is true GT will trip. In fact, one alarm and one trip switch must be true or two trip switch must be true for trip. We know that exhaust pressure is normal and We think that it is enough for trip L63EAH and L63ET2H signals until off-line.

 

Dear Mark V,

that sounds like the most logical way to handle the situation, minimizing the risk, until you are able to take the unit offline. Your unit does sound like the typical configuration using two redundant switches and a single pressure transmitter. Logic is built that requires both switches to indicate a trip, or one switch and the pressure transmitter indicating high pressure to trip. Good luck with your diagnosis.