Question

My TEFC (totally enclosed fan cooled) motor had an insulation failure? I changed direction and ran it at lower speeds on some occasions.

Answer

The two basic concerns are direction and speed.

There are 3 main types of cooling fans used with TEFC motors.

• Radial type (some two and four pole motors; most six pole and larger motors)
  
• Sirocco type (most four pole motors)
  
• Propeller type (most two pole and some smaller motors)

Radial type fans are bi-directional and do not have a problem changing speeds. The sirocco and propeller types are uni-directional which means one direction only.
The general rule of thumb is half the rated rpm or 30Hz on a 60Hz drive. The best bet is to speak to the motor manufacturer.

If a motor cannot get adequate cooling, it will fail.

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FAQ Subcategory: None

This item was last updated on 2021-02-17
Document ID: 855

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