Electric Motor Failure

Most motor failures stem from damaged bearings or stator windings.

The most common failures are:

  1. bearing failure
  2. stator winding failure
  3. overheating
  4. power supply anomaly
  5. humidity
  6. contamination
  7. unusual mechanical loads

Bearing Failure

The main reasons for bearing failure are:

Stator Winding Failure

Electrical insulation deteriorates at a rate that doubles for every 10°C increase in temperature.


The reasons for overheating are numerous and include:

Power Supply Anomaly


If the motor is stopped and cools down it may drop below the dew point. Moisture weakens the insulation and contributes to bearing corrosion.


This results in: abrasion, corrosion and overheating. Small particles in the windings can gradually wear the insulation away as the wires flex during operation.

See also: Electric Motor Bearings, Electric Motor Windings, Electric Motors.

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Subjects: Electrical Engineering