My client is using an EX2000 panel. They are continuously facing an issue where the DS200LDCCH1A and DS200DCFBG1B are failing.
On inspecting we found that the capacitor C52 In the LDCC card had burnt.
What would be the reason for this?
Hmmm.... I doubt if your Customer could persuade GE to do a RCA (Root Cause Analysis) on EX2000 cards since they no longer support that technology.
However, one of the advertisers here on control.com, Gas Turbine Controls (GTC) does do card repairs and they MIGHT be able to tell you what is causing the capacitor failures.
Having said that, capacitors do fail over time. We don't know how old the cards are or how long they've been in service, nor what Diagnostic Alarms are being annunciated by the EX2000. And, to my knowledge, GE never released the "back sheets" for the TC2000 series of cards (Mark V; EX2000), and back sheets would be the schematic diagrams for the printed circuit cards that would be pretty crucial to understanding what voltages/currents/signals pass through what components.
I have been hearing more and more about TC2000 cards experiencing capacitor failures, and I believe there was even a TIL issued by GE about it some years back (though that might have been about the Mark VI, or maybe even both--I don't have an archive of TILs to refer to; your Customer should have TILs, though). Age is a factor with some kinds of capacitors and we don't know what kind of capacitor has failed or is failing.
My experience is that if one keeps failing the same card in the same location multiple times, and in a short period of time--it's not a card issue, it's a field device/wiring/voltage/current issue. Something connected to the control system which is going through the card(s) which keeps failing is the problem. And, if there are Diagnostic Alarms then that could help pinpoint the circuit/input/output.
Hope this helps--it's not exactly what you were looking for, but without back sheets it's very difficult to say what might be happening. Unless you get extremely lucky and someone else reading this post has had exactly the same issues with the same cards. Again, you might ask some of the parts sellers which are offering card repairs if they would try to evaluate the failures, but that's probably about the best course of action--unless someone reading this post has a similar experience and can offer some information.
We suspect a problem with the LDCC or the DCFB cards on our exciter. We are getting fault code 22 on our backup control core.
What were the alarms or faults that you experienced?
What troubleshooting steps did you take to find the problem?