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Alterantor rotor heating using DC current

Alterantor rotor heating using DC current

Alterantor rotor heating using DC current

(OP)
Dear All

We have chemical washed an alternator on major overhaul.

Now its rotor is showing very low megger value.

We have tried other heating methods.

Now i want to heat the rotor using DC source.

Can somebody tell me the procedure. We can not run the generator.

Thanks

RE: Alterantor rotor heating using DC current

Hello Aneeliftikhar,

Yes you could heat the windings with a DC Source like an STATIC WELDING MACHINE(Transformer Type).For Procedure provide more information:  What Other Heatings Methods did you try? Slip Ring Type? Brush Less? KVA? Volts? it is dissambled??.Megger Readings??

Regards

Petronila

RE: Alterantor rotor heating using DC current

(OP)
Thanks for your reply

We have tried Infra red  bulbs. Also heaters with blowers.

Its a 18MVA , 11kV alternator. Right now rotor is pulled out of the stator. Megger value is zero.

It is brushless.

Your early reply will be apprecieted.

Aneel

RE: Alterantor rotor heating using DC current

That reference rates a pls, edison123.
respectfully

RE: Alterantor rotor heating using DC current

The above  thread is excellent for assambled generators and is a good  practice and is very well supported by Edison 123.

Taking account the rotor is pulled out of the stator I will look more than the heating and will check inside of the wires,windings and all rotorĀ“s insulation material   in order to find the root cause of this EARTHING .May be the Zero could come like an insulation failure due to winding explosion. You could perform an static test with MCEMAX instrument manufactured by PDMA in order to find short circuits or other failures.  I am totally agree with the posted by Skogs in the Same   thread No. 237-165089, recommended by EDISON 123:  "Conclusion: Not all bad insulation levels can be cured by heating"

Regards,

Petronila


RE: Alterantor rotor heating using DC current

As petronila says, you should rotor earth fault before attempting any dry-out.

I wouldn't advise DC energising the rotor outside the stator since it is a very powerful magnet and all iron items (screw drivers, spanners, watches etc.) nearby will fly toward to the rotor. Have the rotor inside the stator before you apply DC.

RE: Alterantor rotor heating using DC current

correction

you should "rule out" rotor earth fault.

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