Pls I need help with troubleshooting an issue on GE MK VI. There are certain alarms that are active and holding the unit from getting to Ready to Start. These alarms are:....

Checks show that those alarms are from instruments and signals connected to TBCI 1E1 & 2E1 terminal cards. These terminal card J cables J44 and J33 are now connected to VCRC slot 8 TMR.

Checking the diagnostics alarms on the VCRC shows the following alarm: "Excitation voltage not valid, Contact inputs not valid"
We changed the terminal cards from another unit dat has been out of service but the situation hasn't changed.

Pls what do you think is the cause of that Diagnostic alarm on the VCRC and the many annunciated alarms coming from the 1E1 & 2E1 terminated signals? Can someone pls advise on the solution that can be used in this situation.

Thank you in anticipation.

 

Alarms that are active and holding the unit from getting to Ready to Start. These alarms are:

-TURBOGENERATOR LOCKOUT
-GENERATOR TRIP
-MCC UNDERVOLTAGE
-LUBE TANK PRESSURE HIGH
-HYDRAULIC RATCHET PUMP UNDERVOLTAGE
-GENERATOR COMMON ALARM
-LUBE OIL COOLER FAN VIBR. ALARM

Amongst others.

 

obiliko4,

Always refer to the Mark VI System Guide, GEH-6421, for details of how circuit boards work. In this case, you want to be referring the section for the VCRC card, specifically the TBCI card details, and the PDM Power Distribution Module.

Discrete (Contact) inputs require a voltage source to work properly; that is called "excitation voltage," and is also sometimes called "wetting voltage." For the majority of GE-design heavy duty gas turbines that voltage source is 125 VDC which is applied to the TBCI terminal board using plug connections JE1 and JE2. USUALLY the incoming power comes in at JE1, and JE2 can be used to "jumper" the 125 VDC over to another TBCI.

So, it would appear the VCRC is telling you that there is something wrong with the power (the excitation voltage) coming into the TBCI at JE1. That may be coming from a nearby TBCI's JE2, or it may be coming from a switched/fused output of the PDM.

Hope this helps!

Please write back to let us know how you fare!