AC to DC power converting generator failure

[noel0589]

Hi all,

We had a failure of an AC to DC converting generator on the AC side. The failure coincided with a power outage. Would someone help give reasons as to how a power surge could have caused failure of the generator?
Thank you in advance for any response!

 

[noel0589]

Actually, the motor shop says it was due to a power surge, but a consultant is saying that it wasn't likely. So I was hoping someone might be able to shed some light. Thanks!

 

[itsmoked]

First if you would give even some vague definitions as to why you are calling it a "failure" it would help us in giving you answers that are even close...

"This guy died... can you give me reasons why he died?"

Is akin to what you have asked us.

 

[noel0589]

from pictures all I can see is that there was a turn to turn short in at least one coil

 

[itsmoked]

Others will no doubt have lots of suggestions.

I would posit that if the power blinked then the motor could have been subjected to a large current surge because it essentially started generating and then had power reapplied while it was way out of sync with the incoming power.

 

[noel0589]

yeah... that sounds like a reason. I don't really know why they are using power surge and outage together. When power is reapplied after an outage, is there usually an above normal surge of voltage/current? Is that a misconception?..or are surge protectors at home made to protect against lightning. etc.?

 

[HCBFlash]

Kinda tells you that something wasn't really very well engineered!

A load of this sort shouldn't be wired as an on/off device. You should be sure that only qualified people install and maintain electrical equipment. Wire the unit with a motor FVNR starter with LVP, and start/stop control. Proper fusing is also very important, and was apparently missing also.

Power surges and voltage spikes are 2 different things. As far as your motor goes I'd be very very surprised if either caused your equipment failure directly.
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Please let us all know how this works out for you!

 

[Skogsgurra]

"the motor shop says it was due to a power surge"

That's what you hear most of the time. Especially if it was the same shop that delivered or repaired the motor. Motors are built to survive surges, brown-outs and transients. If the deviations are very large, yes, the motor may be damaged. But then, other equipment on the same grid often go with it. Any such reports?

What about motor cooling? A motor covered with dust or whatever will not get the right cooling and more often than not fries its windings, which causes shorts as the insulation and laquer get soft.

It could also be plain old failure from age and use - such things also happen. Motors have a limited life and the statistical distribution varies a lot.

Gunnar Englund

http://www.gke.org

 

[noel0589]

But since the ac/dc motor generator failure coincided with the power outage, its hard not to draw any conclusion that doesn't include the fact that power integrity was not optimal. Maybe it was already in bad shape and maybe power did blink during the power outage causing an out of sync reconnection.

 

[Marke]

What was the cause of the power outage?? How about an insulation breakdown in the motor caused a major current surge which caused the outage??

Seriously, this is a little bit like how long is a piece of string.
All winding wire has pinholes in the insulation. If there is a transient that occurs between two turns and is high enough to breakdown the insulation between the pinholes, you will get a breakdown. Note, the insulation can be compromised by contaminants in the windings due to the environment age etc.
The transient voltage can be due to a transient on the supply, or may be a local transient resulting from some other stimulae, possibly on the supply.

If you could possibly show pictures of the failure, I am sure that some of the experts on line could offer an educated opinion ans to a possible cause.

Best regards,

Mark Empson

http://www.lmphotonics.com