Welder Causing PQ Problems

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HotConductor

HotConductor

Senior Member
Location
Philadelphia
I have a customer who is having power quality problems when they weld. The welder makes the lights in the office dim and the UPS's go off.

The building is supplied with a 3 ph. grd. delta service. There is a wye transformer that feeds the shop where the welder is as well as the panel for the office. The transformer is properly sized for the loads. Could this be a grounding issue? If the system is bonded in the xfrmr and the panels could this cause this type of problem?
 
What size of welder?
How big are the SE conductors?
Is this a POCO transformer or customer owned?
If customer's what is the voltage on the line & load side of xfmr with no load, and full load?

I do not believe the double bonding of the neutral will cause this problem. More likely there is a poor connection or undersized service to the building. Has it always been a problem or just since the welder installation?
 
why pvc conduit for industrial welder feeders?

why pvc conduit for industrial welder feeders?

The factory I'm working in has a 400 amp industrial welder and we were told by an engineer that the welder will require parallel runs in pvc pipe, not emt. I beleive the manufactorer may have required this....not sure. Any guesses as to why this would be required?
 
I disconnected the bonding jumpers in the two discos because there was already bonding in the xfrmr- no change.

One phase was dropping 10v at rec. and 3v at panel. Ran new dedicated 10/2 mc to computer rec. Only about a 50' run- no change.

So I just moved all the computers and lights off "b" phase- problem solved but still would like to know why???
 
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