Motor Space Heater

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FaradayFF

Senior Member
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California
Hi Gents,

For a small outdoor motor installed in a damp environment, do you typically spec out a space heater enclosed in motor housing supplied by a separate 120 V circuit? I'm not sure if motor vendors put a heater wrapped around the winding for such a small motor say 2-4 HP. If this is feasible, then I could run 120 ckt to it and have the heater controlled by a thermostat or a combination of thermostat& contactor NC contact.

Any wisdom from experience is appreciated.
Thank you,
EE
 
FaradayFF said:
For a small outdoor motor installed in a damp environment, do you typically spec out a space heater enclosed in motor housing supplied by a separate 120 V circuit? ...
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Yes
However, I do work in extreme environments. It's amazing how much water a Pulp Mill operator can get inside of a TEFC while cleaning up with a fire hose.

And then there are the motors that sit outside at -40 (C or F - you pick :) and only run a few minutes a year.

So, the application matters - Is the motor running once a week or once a year"
And the definition of "damp" matters - It this rainforest damp or Middle America damp?
And, of course, criticality - Is this motor keeping the thermo-baric field containing the aliens at area 51, or is the owner upset if the spa motor only lasted 10 years?

If the additional 120V circuit is an issue, one can get motor winding heaters that put chopped AC across two windings (three phase motors) when the motor is off. These are usually set for 1 to 3 Watt/hp. AB quit making their MWH1410 a year or so ago. However, the Milltronics looks good. I'll likely try one of those next time a client needs one.

So, the worm says, pts is right - highly likely no.
Still, check the specific application.

Damn - still need a one-armed engineer.

ice
 
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