Voltage fluctuations
Voltage fluctuations
(OP)
I was called out to the plant today for a Phase Loss trip on one of the MV synchronous mill motors. Upon arriving I checked the event recorders in the MVC soft start and the 469 hooked up to this motor and found that the voltage at the time of the trip was 3950, 3962, 3700. I pulled a trend from our ECS and noticed that the voltage had dipped on that incoming line also. I checked the incoming line voltage on the power monitor and it read 4255, 4251, 4217.
I pulled a trend for the three phases, and noticed for about the last three months the third phase has been a little lower than the other two, and the also the graph was a little choppy compared to the other two, wich remain smooth and stable. It seems like this problem is originating from the utilities. We were experiencing a snowstorm at the time this motor tripped.
I decided to reset and try again. Everything started up and ran just fine, but we still have this unbalance. Where should I start my investigation on Monday?
I pulled a trend for the three phases, and noticed for about the last three months the third phase has been a little lower than the other two, and the also the graph was a little choppy compared to the other two, wich remain smooth and stable. It seems like this problem is originating from the utilities. We were experiencing a snowstorm at the time this motor tripped.
I decided to reset and try again. Everything started up and ran just fine, but we still have this unbalance. Where should I start my investigation on Monday?






RE: Voltage fluctuations
RE: Voltage fluctuations
Keith Cress
kcress - http://www.flaminsystems.com
RE: Voltage fluctuations
It might be worth your time to drive the line the serves your facility all the way back to the substation and see if there any pole-mounted regulators, switched capacitors or other little surprise packages on your feeder. It's always good to know what's between you and the substation transformer.
RE: Voltage fluctuations
RE: Voltage fluctuations
RE: Voltage fluctuations
RE: Voltage fluctuations
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If we learn from our mistakes I'm getting a great education!
RE: Voltage fluctuations
Possible not good contact too.
Regards.
Slava
RE: Voltage fluctuations
I don't think that we have any voltage drop issues in the plant. I think that it originates from the incoming lines or the 46/4.16kV transformer. We own the transformers, but they are serviced by the utility.
RE: Voltage fluctuations
Mills been running fine since yesterday, no other issues so far.
RE: Voltage fluctuations
RE: Voltage fluctuations
I agree that the incoming voltages only appear to show about a 0.5% unbalance which is not all that bad.
RE: Voltage fluctuations