Hi all
My name is Tim vo
We have a GE mark V steam turbine system that control the hydraulic of ETD1 and ETD 2 is trip due to the header pressure from the pressure switch ps282 is zero psi. This is the HPM-15 module for the lube oil skid. Testing the solenoid from external power is working fine. But when running is not. We troubleshoot the GE MARK V and found out that the PTBA CARD pin 59 and pin 60 for etd 1 and pin 63 and pin 64 for edt 2 had low voltage on the positive side instead od 65 vdc but it only read 14 vdc. The negative side is good -67 volts. When we disconnected the load it is back to 65 volts on both positive and negative. Something is pulled down the positive side
Repacing the TCTS CARD and also the PTBA CARD is still the same.
Any suggestions please help
Thanks very much
Tim

 

You need to trace down the circuit on the positive side of the trip circuit. There is something in the circuit that is not CLOSED or MADE all the way. The low voltage on the positive side tells you it is on that side of the trip circuit.
check for 65vdc at each interlock upstream of the PTBA connection.

 

You need to trace down the circuit on the positive side of the trip circuit. There is something in the circuit that is not CLOSED or MADE all the way. The low voltage on the positive side tells you it is on that side of the trip circuit.
check for 65vdc at each interlock upstream of the PTBA connection.

Thanks for your fast response.
According to the ge steam turbine diagram and I am not 100% sure that on the positive side is power by the etd1 and etd2 that controlled by the tcea cards and ptr1 and ptr2 negative signal is on tcts card.
the only upstream is power by the two cards and sent the signal through the JM and JN CABLE to PTBA TERMINAL Do you know which pin I should look into from either the tcea relay (which I don’t see any relay on the tcea card) or the Tcts card relay. I know it is from the relay may be weak but I am clueless right now and hope you can give me some guidance. Thanks

 

Your best bet is to find the drawings that show the circuits for the ETDs and PTRs. They will include all the terminals and devices in the circuit on both positive and negative sides. I don’t have steam turbine drawings in front of me, sorry.

 

Inspect the solenoid wiring harness, connectors, and terminals for any signs of damaged insulation, moisture ingress, corrosion, or loose/weak connections.

 

Hi all
My name is Tim vo
We have a GE mark V steam turbine system that control the hydraulic of ETD1 and ETD 2 is trip due to the header pressure from the pressure switch ps282 is zero psi. This is the HPM-15 module for the lube oil skid. Testing the solenoid from external power is working fine. But when running is not. We troubleshoot the GE MARK V and found out that the PTBA CARD pin 59 and pin 60 for etd 1 and pin 63 and pin 64 for edt 2 had low voltage on the positive side instead od 65 vdc but it only read 14 vdc. The negative side is good -67 volts. When we disconnected the load it is back to 65 volts on both positive and negative. Something is pulled down the positive side
Repacing the TCTS CARD and also the PTBA CARD is still the same.
Any suggestions please help
Thanks very much
Tim

sorry for a long delay about this issued.
here is what I found the problem.
the TCEA card has a short circuit causing the 5 volts fuse keep popping and its 4 Omron 24v relay doesn't switch. so one side has -67 volts and the other plus voltage is not. Hope is help some others out there. thanks