Space-heater and impregnation

[elinBG]

Hello,

We are going to put a space-heater in the winding, but we are arguing about when it should be placed on the motor winding.

I think it should be placed over the winding after the impregnation of the repaired motor. Because if it is impregnated together with the winding it will heat the winding but will not heat the "space" which should be heated against condensation.

My colleague thinks the oposite, that it should be impregnated together with the winding.

Thank you for your replys!

 

[electricpete]

I assume this would be random wound low voltage motors?
I'd be more comforable with tieing space heaters on endwinding after impregnation. For one thing it removes any concern that the space heater might vibrate against the leads and short them. For another thing, it would be easier to replace or reposition if for some reason you need to do that.


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(2B)+(2B)' ?

 

[waross]

The heaters that I have serviced were placed low in the end bells or, for flexible the sheet type, laid on the case below the stator. The purpose is to heat the windings and the iron a few degrees above the ambient temperature so that in the event of a simultaneous rising temperature and rising dew point, the windings and iron are always above the dew point. The heaters are typically energized at 50% of rated voltage and energized 24/7 when the motor is not running. I have never seen them baked with the windings. The failure mode is more often corroded connecting leads than burn-out.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[electricpete]

Yes, it would have to be the strip type to use on the end windings. As Bill says, these do go open circuited occasionally which is one reason not to vpi it. ...we replaced one on site recently in a 100HP 2 pole ODP motor. Electricians decided to use glyptol as glue . We got some smoke when we started the motor from that glyptol baking so Operations called fire and tripped the motor...whoops. Decided to megger and retry and had not much more smoke. String would have been better attachment method.

http://ramindustrialservices.com/space-heaters/

.


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(2B)+(2B)' ?

 

[electricpete]

Our motor shop suggested the string afterward...not just any strung...the type they use in windings

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(2B)+(2B)' ?