Transformer Ground Over Current
Transformer Ground Over Current
(OP)
I have a new transformer, 3 phase 3 winding. 115KV/13.8kv/13.8kv, high side wye, low side delta. It recently tripped on high side winding ground time over current. The system operators claim there was a spike on the system around the time the transformer tripped. I also have another identical transformer connected to the same line that showed no faults. What causes high transformer ground current? Did this trip most likely come from the system, the transformer, or my plant?






RE: Transformer Ground Over Current
And since you are still operating it, I doubt if it came from the transformer winding.
As a best guess, I'd say there was a 115 kV ground fault somewhere on the utility system. The fact that it tripped on time overcurrent, not instantaneous would make me believe it was a real ground fault. Your transformer will act as a ground source for any 115 kV faults.
This leaves unexplained the lack of fault operation for the identical transformer. I don't have an explanation other than the possibility that your relays are not set the same.
RE: Transformer Ground Over Current
RE: Transformer Ground Over Current
RE: Transformer Ground Over Current
Wouldn't a CT wiring problem cause problems during high loads and not low loads?
yes, I have fault records generated from the multilyn 745. This didn't happen during an outage. The transformer has been energized for 9 months with no problems and we start and stop on a daily basis.
RE: Transformer Ground Over Current