jhochb
Active Member
Good morning all
I’m doing a festival at a Miami sound stage and I have an issue with one of the three disconnects. Please read the post before responding.
The room
There is a 1200A, 480V serves feeding 3-250A, 480V Breakers.
The 250A breakers go to disconnects in the room.
I am told this is a WYE setup without the neutral.
Out of these cans I’m feeding 480V to the Delta input of the 480/ 208V transformers, WYE output.
The issue
One of the 3, 250A breakers trip when it has a transformer connected.
This is the second gig in this room and the house electrician told me they replaced the breaker. The issue persists.
What I’ve done
On the first gig I tied in my tails and checked power at all 3 cans.
All good
All connections are done cold, no power.
I had a 112KVA & 2 - 75KVA transformers. We later swapped the 112KVA for a 150KVA.
I powered down and connected the transformers, powered up with no load.
Cans , A & C were fine. Can B tripped the 250A, 480V breaker.
All 4 transformers worked fine on cans A & C but tripped can B
Cans A & C ran the week just fine, we didn’t use can B
This gig
It happened again. This time the transformers are not on wheels. so it's harder to swap them.
This time the house provided the tails. I metered power and connected my 3 150KVA transformers.
B tripped.
The house called in an electrician, the can metered OK. The electrician suggested the phasing was off. ???????
Any real thoughts?
I don’t have a MEGA or. a HIPOT meter but I would like to check the lines back to the breaker. I used my Fluke 179, no help there. With what I have here I can’t go further.
*
Help me Obi Wan.
I’m doing a festival at a Miami sound stage and I have an issue with one of the three disconnects. Please read the post before responding.
The room
There is a 1200A, 480V serves feeding 3-250A, 480V Breakers.
The 250A breakers go to disconnects in the room.
I am told this is a WYE setup without the neutral.
Out of these cans I’m feeding 480V to the Delta input of the 480/ 208V transformers, WYE output.
The issue
One of the 3, 250A breakers trip when it has a transformer connected.
This is the second gig in this room and the house electrician told me they replaced the breaker. The issue persists.
What I’ve done
On the first gig I tied in my tails and checked power at all 3 cans.
All good
All connections are done cold, no power.
I had a 112KVA & 2 - 75KVA transformers. We later swapped the 112KVA for a 150KVA.
I powered down and connected the transformers, powered up with no load.
Cans , A & C were fine. Can B tripped the 250A, 480V breaker.
All 4 transformers worked fine on cans A & C but tripped can B
Cans A & C ran the week just fine, we didn’t use can B
This gig
It happened again. This time the transformers are not on wheels. so it's harder to swap them.
This time the house provided the tails. I metered power and connected my 3 150KVA transformers.
B tripped.
The house called in an electrician, the can metered OK. The electrician suggested the phasing was off. ???????
Any real thoughts?
I don’t have a MEGA or. a HIPOT meter but I would like to check the lines back to the breaker. I used my Fluke 179, no help there. With what I have here I can’t go further.
*
Help me Obi Wan.