thomasmwilson89
Member
- Location
- California
- Occupation
- Industrial Electrician
Catchy title huh? Lol
A few days ago we lost power at our plant, and after some digging and talking to our utility, I ended up finding out that our substation was showing 6 amps on b phase and ground, thus, shutting the substation down.
I'll spare you all of the troubleshooting steps, but here are the "end" facts.
At times, A Phase, B phase and ground are showing 6 amps to ground at 21kv. I say "at times", because during initial troubleshooting, we did not see the ground fault initially. This ground fault can be sustained for a period of time (let's call it 1 minute).
We have isolated this issue to a 21kv to 480v delta wye transformer. This transformer also has a breaker on the 21kv side, that when opened, the ground fault disappears. So initially, one would think that something on the secondary side is causing the issue. But after thinking a little deeper about this, I'm of the mindset that I don't believe our utility would be seeing a ground fault on the secondary side of this transformer. I believe the issue is much more likely between the bottom of the transformer breaker and the 480 side coils, i.e, the buss bars or the 21kv coils. A quick background on this particular transformer... it blew up a year ago... enough said.
So the reason I came here is to hopefully ask a simple question, and hopefully get a simple answer (although I know this never happens lol).
If the secondary side of a delta wye transformer has a ground fault, will this be detectable on the primary side?
A few days ago we lost power at our plant, and after some digging and talking to our utility, I ended up finding out that our substation was showing 6 amps on b phase and ground, thus, shutting the substation down.
I'll spare you all of the troubleshooting steps, but here are the "end" facts.
At times, A Phase, B phase and ground are showing 6 amps to ground at 21kv. I say "at times", because during initial troubleshooting, we did not see the ground fault initially. This ground fault can be sustained for a period of time (let's call it 1 minute).
We have isolated this issue to a 21kv to 480v delta wye transformer. This transformer also has a breaker on the 21kv side, that when opened, the ground fault disappears. So initially, one would think that something on the secondary side is causing the issue. But after thinking a little deeper about this, I'm of the mindset that I don't believe our utility would be seeing a ground fault on the secondary side of this transformer. I believe the issue is much more likely between the bottom of the transformer breaker and the 480 side coils, i.e, the buss bars or the 21kv coils. A quick background on this particular transformer... it blew up a year ago... enough said.
So the reason I came here is to hopefully ask a simple question, and hopefully get a simple answer (although I know this never happens lol).
If the secondary side of a delta wye transformer has a ground fault, will this be detectable on the primary side?
