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Running electric motors in high ambient temps

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Hippo41

Mechanical
Joined
May 18, 2003
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98
Location
GB
I have a situation in which I am required to run small 3-phase motors (0.18KW; 0.37KW and 0.09KW) in an enclosed space at 90 celsius ambient temp.

I understand that the motor efficiency will decrease drastically. We have used Class F insulation motors in the past. The loads are light, and there are very infrequent starts/stops.

Can anyone offer comment on the expected reliability of motors in this environment?

Should we used forced cooling fans to get some airflow over the windings?
Should we specify Class H insulation?

Any advise welcome. Thanks!

Lester Milton
Telford, Shropshire, UK
 
Suggestion: The H insulation will increase the life expectancy of motors. In some applications, it is possible to develop an external water-cooling system, essentially a water spray, if the motor housing permits is.
 
Motors used to drive fans of horizontally mounted fin-fan process heat exchangers, if mounted in the discharge air stream above the fin-fan coils, are in ambients that easily exceed 90 deg ambients.

Class H insulation is the choice all the time!
 

Also, lubricants may need review for the applicaton.
 
You are probably already aware that a standard motor will have to be severely derated for operation at this ambient. So you will need to oversize the motors or purchase motors nameplated for this ambient.
 
Thanks for the advice.

Lester Milton
Telford, Shropshire, UK
 
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