60V Single Phase

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mattmulka

Member
Re: 60V Single Phase

What is your guess as to what happened Loren?

Yes, it is possible it was being backfed by a generator, but the fact that it was 60V for a long time would make me guess it was a combination of an open phase a transformer with a delta primary. Besides, wouldn't the generator overload if it tried to pick up too much load?

The pole fire could have been caused by lightning. The point is you phase was open and being backfed. I don't see how radial transformers losing the neutral would give 60 volts, especially a consistent 60 volts. When the utility makes the repair, a lot times they only isolate the bad phase and leave the other 2 energized.

[ July 01, 2004, 09:01 PM: Message edited by: mattmulka ]
 

sdbob

Senior Member
Re: 60V Single Phase

I had the same thing happen at my house a few months ago. It turns out a wet palm frawn had fallen across a couple of primarys coming up the street and popped a primary fuse at the bottom of my hill. I never did figure out where that 60 volts came from. :D
 

highkvoltage

Senior Member
Re: 60V Single Phase

Question. If the primary was a delta system and you lost one of the primary phases wouldn't also measure half the voltage one the secondary? Some areas around here still use delta system for the primary.
 

kschirra

Member
Re: 60V Single Phase

This scenario would explain many unexplained AFCIs that cannot be reset. If you lose the neutral and have 60V on one phase, you'd see 180V on the other phase. Any AFCIs on the circuits that see the 180V could burn up the MOVs that are protecting the circuit board. Typically the MOVs in AFCIs are 150V MOVs but some manufacturers use larger MOVs. When the MOVs get fried, the breaker should trip for safety but it depends on the specific manufacturer.
 
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