What are the temperature ratings of Empire Magnetics’ extended temperature HT series motors?

Has Empire Magnetics provided motors for greater operating temperatures than 120° C?

Why is -40° C the lower temperature limit?

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How much heat can a motor stand?

The answer to this question depends on the materials selected in the motor construction and the cooling capacity of the environment where the motor is used. Generally speaking, the insulation system in the motor is the limiting factor. When the temperature rating of the insulation is exceeded, the insulation melts and the wires in the winding short to undesirable locations. Typical industrial motors have class B insulations which melt at 130° C. Upgraded motors include class F (155° C), Class H (180° C) and Class 220 (220° C).

What are the temperature ratings of Empire Magnetics’ extended temperature HT series motors?

Empire Magnetics’ extended temperature HT series motors have a case temperature rating of -40° C to +155° C (this does not include ice problems). Since motors generate their own heat (and since that heat must be dissipated) the maximum recommended operating ambient temperature is 120° C.

Has Empire Magnetics provided motors for greater operating temperatures than 120° C?

Empire Magnetics provided a motor for a Japanese nuclear reactor where the operating temperature was 220° C. As the temperature requirement increases, however, the required materials become more exotic and the cost grows exponentially.

Why is -40° C the lower temperature limit?

The basic problems with lower temperatures have to do with the following:

1) Different rates of expansion and contraction for the different materials in the motor

2) Residual stresses and weakened bonding from thermal cycling

3) Stiff lubrication

These problems can be solved. We have done so in our cryogenic motors.