unbalanced primary voltage
unbalanced primary voltage
(OP)
I have encountered a problem with equipment burning up for no appearent reason.
This is a large site and the problem that I have is with temperary power. There are several pad mount tranformers 4160/600v as you can tell I'm in canada and generally use delta wye.
Earler this week we had a disconnect blow up. There was no load on this disconnect and the cable on the load side megered good and the welding machine bank was off.
When it blew it did not take all of the fuses but it did melt two of the line side lugs completly off and burnt the third off in the splitter trough. This causing the disconnect to be blown off the skid hanging with the door open.
The secondary voltage has two lines at 600v and the third 630v.
Could this type of imbalance cause a surge?
This is a large site and the problem that I have is with temperary power. There are several pad mount tranformers 4160/600v as you can tell I'm in canada and generally use delta wye.
Earler this week we had a disconnect blow up. There was no load on this disconnect and the cable on the load side megered good and the welding machine bank was off.
When it blew it did not take all of the fuses but it did melt two of the line side lugs completly off and burnt the third off in the splitter trough. This causing the disconnect to be blown off the skid hanging with the door open.
The secondary voltage has two lines at 600v and the third 630v.
Could this type of imbalance cause a surge?





RE: unbalanced primary voltage
Keith Cress
kcress - http://www.flaminsystems.com
RE: unbalanced primary voltage
RE: unbalanced primary voltage
Voltage imbalance would not cause this. A remote ground fault on the 4160V system could cause 4160 V to appear phase-to-ground and this can sometimes cause insulation failures if it persists.
RE: unbalanced primary voltage
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: unbalanced primary voltage
Are you sure of your facts?
It's sort of like. "This body has a bullet hole in it but they say he wasn't shot..."
Keith Cress
kcress - http://www.flaminsystems.com
RE: unbalanced primary voltage
Can you tell me more about this "A remote ground fault on the 4160V system could cause 4160 V to appear phase-to-ground and this can sometimes cause insulation failures if it persists" This sounds more like what happened.
RE: unbalanced primary voltage
Also, if the 4160 V system is solidly grounded, the ground fault shouldn't persist long enough to cause problems.
RE: unbalanced primary voltage
I considered rodents as a first response but if rodents were the cause I would expect the damage to be concentrated in one area. One connection damaged in the splitter trough and two connections damaged on the feed lugs of the switch seems more like a surge. Another possibility may be a three phase short downstream and some less than perfect connections let go under fault current. I favor a voltage surge as the most probable but not the only possibility.
Bill
--------------------
"Why not the best?"
Jimmy Carter