I faced a new problem this week. This time with my STG exciter. My excitation system is of GE EX2000 digital exciter with hot back up configuration and connected to my Mk V control system. My EX2000 exciter tripped out of sudden with the alarm V/Hz active. However I believe that the alarm is a false alarm as it was not detected by my digital generator protection (DGP). Moreover the alarm stayed even after reseting when the unit on turning gear.

After a hard reset on both Master 1 and Master 2, I changed the Active Master from Master 1 to Master 2, the alarm was gone but when I transfer back to Master 1, the alarm was there again.

I did try to sync the unit with Master 1 (alarm present) but unsuccessful. Then I transfered to Master 2 and successfully sync the unit.

Everything went well until yesterday when the FVR changed from ac regulator to DC regulator due to a PT failure alarm. The transfer voltage at terminal and field went up to -18.71kVac and -244Vdc. After some time the transfer voltages came down to 0 and I managed to reset the alarm and transfer it back to ac regulator. The sad thing is that after some time in ac regulator mode, it changes back to dc regulator due to the same reason and condition.

I repeated several times but the results are still the same. Any idea on what to be looked into to resolve the problems? I have an outage in early May which I hope I can do something to resolve the V/hz active on my Master 1 and the ac-dc regulator change in my Master 2? (fuhh.. so many things to resolve next month..)

 

i have have experience this type of problem in other system. perhaps you'll take a look at the output card on master 1. this i think based on your statements, it looks like your card is having a problem.

 

Does changing the cards except the SDCC need any kind of downloading of control constants? i was thinking of replacing the protection card for my Master 1 and PTCT card for my Master 2.