I installed a mag starter the other day for a customer. He called me today and said the mon press or won't start. When i get there and check the voltage at the kill switch box, (it's a 240 single phase) L1 to L2 reads 322v. N to L1 was 140 same with n to L2. And so on and so on. Until now I have 370v. What the hell is going on? Please help!
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voltage keeps going higher!
- Thread starter jinxjinx
- Start date
toplessHO
Well-known member
where is that power derived from? If its a transformer it could be going bad.
justsam
Well-known member
Agree with *******, important to know how this 240 single phase is derived.
Is there three phase in the shop as well?
Is this a replacement job? What was there before?
What is the voltage on other 240, single phase equipment?
Something is very odd if line to neutral sums do not equal line to line, so confirm there is not an issue with the neutral, inside the building or from PoCo.
Is there three phase in the shop as well?
Is this a replacement job? What was there before?
What is the voltage on other 240, single phase equipment?
Something is very odd if line to neutral sums do not equal line to line, so confirm there is not an issue with the neutral, inside the building or from PoCo.
alfredeneuman
Well-known member
Check at the the incoming service.
If you get the same readings there, call the Power Company.
If you get the same readings there, call the Power Company.
wyliesdiesels
Well-known member
Ive seen this once before. It was in oakland in the cliff bar HQ. Their UPSs were going crazy. The incoming service was going haywire with the neutral voltage floating and unstable. Called the PoCo turned out that the old transformers feeding the building(old manu plant) were going bad.
I would check the main service! Sounds like the insulation in the transformers are breaking down...
I assume these are L-N readings?
What do u get L-L? (All 3 legs) What about L-G at equipment- the same as above?
I would check the main service! Sounds like the insulation in the transformers are breaking down...
Just checked again 172,172,344v.
I assume these are L-N readings?
What do u get L-L? (All 3 legs) What about L-G at equipment- the same as above?
Last edited:
vhol5
Well-known member
Coming in as 3 phase delta high leg on right. Old system. I've used 3 meters all the same reading.
Check the batteries in your meter. Strange things can happen with dead / dying batteries.
Guess you missed that part...
FullRaceMerc
Well-known member
We had a power company transformer that fed our shop burn thru. We didn't have any warning, but had enough voltage to arc & burn thru conduit in places. I was closing up & in the head. I heard humming that I thought was the bath fan at first, since the pole was outside that wall. When I ran towards the box I could hear the hum was bigger than the bath fan, so I (Stupidly, I realized later) pulled the disconnect. The hum continued & I got out of the building to see smoke coming out of the weatherhead. I called the FD & pulled our trucks & forklifts out of the other side of the building, figuring gas & propane would make whatever was coming next worse. Eventually a fuse burned thru & the t-former quit. They showed us the fuse remains, & it looked like a 1" diameter bolt that was gone in the center.
The power company guys said as the t-former burned thru, we got fed some portion of the 17,000 volts that it normally reduced to 440 volts. And I was lucky to not have been fried grabbing that switch. We found the burned thru conduit later.
Bottom line is that I don't know what your problem is. But if there are windings that are burning thru in a t-former you can get an increase in voltage. And if that is the case it can get much higher in a hurry. I wouldn't hesitate to call the power company if the lines coming in read wrong.
The power company guys said as the t-former burned thru, we got fed some portion of the 17,000 volts that it normally reduced to 440 volts. And I was lucky to not have been fried grabbing that switch. We found the burned thru conduit later.
Bottom line is that I don't know what your problem is. But if there are windings that are burning thru in a t-former you can get an increase in voltage. And if that is the case it can get much higher in a hurry. I wouldn't hesitate to call the power company if the lines coming in read wrong.