Help with Burned up Leroy-Somer Alternator

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wolfman56

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A brand new one just burned up. The question is why?

The unit arrived set up for 480 volts three phase. The application required 220 three phase.
I correctly set up the windings taps for 220 volts. (Verified by the tech that came out to see the burned out unit.)
The problem is that upon setting this up for a different voltage I overlooked a setting on the AVR.

It is the Leroy Somer, A.V. R. R438 the setup instructions for this thing are at this link;

http://www.leroy-somer.com/documentation_pdf/alternateurs_pdw/notices_pdf/3971e_en.pdf

The system is AREP.

On page 4 you will see terminals 220, and 380 (marked for voltage) This appears to be the voltage sensing circuit. I failed to change the connection from 380 to 220. that was all anyone could find wrong with setup.

I'm being told that the windings were "set up" for 220, but the AVR thought it was supposed to be 380+. Therefore it overexcited the unit to death trying to bring the voltage up to the expected 380+.

Is it possible that this incorrect setting could cause the unit to self destruct?
This thing burned up so bad it is not repairable!

I would of thought that the worst case would be blowing the AVR.

Thanks
Rick
 
wolfman56 said:
A Is it possible that this incorrect setting could cause the unit to self destruct?
This thing burned up so bad it is not repairable!

I would of thought that the worst case would be blowing the AVR.

Thanks
Rick
Click to expand...
Yes, if the AVR is trying to get 380V out of 220V windings it could cause the unit to self destruct.
An alternator is not a lot different to a synchronous motor and you wouldn't expect a sync motor to survive long if you put nearly double the rated voltage on its windings.

Sorry if it's not the answer you wanted to hear.
 
(Think Urkel from Family Matters) "Did I do that?"

Sadly, yes it look like a boo-boo was made by not resetting that jumper on the AVR module.

I have made a similar mistake with an old style xenon power supply, completely fried the main transformer in it and exploded the filter caps. It was a $2,500 mistake.

I now double and triple check all tap settings before throwing the switch.
 
Leroy Somer AREP

Leroy Somer AREP

IMHO you make a mistake when changing the arrangement 480 to 220 volts.
Instead of paralleling the windings stator you certainly short-circuit them.
You will see in the attachment the connection diagram for this 12 wires - 7 terminals alternator.
The change is from D(480 volts) to A(220 volts).
 
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