Voltage issues

N

nickelec

Senior Member
Location
US
Just looked at something today. Very preliminary so far

Inside this pump house they have three pumps being fed from DB panel 277/480.

Every time more then one pump kicks on the voltage drops down to about 300. On one phase.

Going to send some guys to trouble shoot. But what are the possibilities of an under ground 4.1kv feeder being compromised?

Any other ideas in where to look.. will look at all connections in pump house.

I've attached a one line for reference.
b3d49e2b79e23d32faa62a47b836218c.jpg


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Something is SERIOSULY wrong with that one-line...
According to that, you have a 4160 feed to the utility transformer at the top, then no mention of the secondary of that xfmr, but it feeds a 4160-208V 225kVA xfmr?? Then that 208V feeds another 4160 to 480V XFMR???? Either that or someone doesn't know how to draw a one-line diagram.

Oh wait, is it possibly that the first transformer is stepping down to 208V, then the second one is stepping back UP to 4160V, then back DOWN to 480V again at the pump house? That's a lot of transformers and impedance going on there and lots of places for there to be a bad connection. How big are the pumps? I would be checking every connection before I would jump to any conclusions about the failed 4160V line...
 
Jraef said:
Something is SERIOSULY wrong with that one-line...
According to that, you have a 4160 feed to the utility transformer at the top, then no mention of the secondary of that xfmr, but it feeds a 4160-208V 225kVA xfmr?? Then that 208V feeds another 4160 to 480V XFMR???? Either that or someone doesn't know how to draw a one-line diagram.

Oh wait, is it possibly that the first transformer is stepping down to 208V, then the second one is stepping back UP to 4160V, then back DOWN to 480V again at the pump house? That's a lot of transformers and impedance going on there and lots of places for there to be a bad connection. How big are the pumps? I would be checking every connection before I would jump to any conclusions about the failed 4160V line...
Click to expand...
The 600 a switch feeds a step up transformer and sends 4160 to the pump house I'm guessing because of the distance.

Once it gets to the pump house it steps back down to 277/480

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Agreed who ever did that messed up. But I was there today that's actually what's going on . It goes out to the. Pump station,4160 . I agree will check everything before I trouble shoot the high voltage side

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nickelec said:
Agreed who ever did that messed up. But I was there today that's actually what's going on . It goes out to the. Pump station,4160 . I agree will check everything before I trouble shoot the high voltage side

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Click to expand...
So how big are the pumps?
Might be irrelevant actually, given that the severe VD is only on the one phase. That really points to a bad connection somewhere in that chain, maybe a bad winding in one of those transformers. A faulted cable would be bad all the time, not just under load.
 
I didn't get a chance to get a size of the pumps I had another appointment

I'm going to be sending guys there this week but I agree the first step is to verify everything is good on the secondary side of the transformer before we dig into the high voltage

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It looks like they pulled a neutral to the low voltage side of the 208Y-4160V step up transformer. This is not usually done on non-utility installations as it can cause overheating and voltage regulation issues when there are imbalances on the delta side.

Is this a new installation? Your picture looks like it is old equipment.
 
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