Diagnosing electric motor faults by examining copper windings

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Diagnosing electric motor faults by examining copper windings

Electric motor abnormalities caused by copper windings in the rotor or stator can be clearly apparent. Examples include greatly reduced torque, abnormal overheating and complete failure to operate. When the motor has been disassembled for maintenance, the copper winding components can be checked as follows:

1. Dirt
Check whether dirt has accumulated in the copper windings, as this impairs cooling. Dust on conductors also attracts moisture, degrading the insulation coating on the copper wire. Windings can be cleaned by blowing air or vacuuming, using air pressure that is not excessive.

2. Dust  
Dust and abrasive particles can damage the winding insulation. If the insulation is worn or corroded, the winding may need fresh varnish or replacement.

3. Humidity  
reduces the properties Dielectric Strength of the insulation. It is therefore important to understand how to clean and dry motor windings.

4. Oil deposits
Remove oil or grease from the windings, taking care with cleaning chemicals that could damage the copper winding insulation.

5. Cracks
If winding insulation is brittle, cracked or darkened as if burned, it must be recoated with insulation.

6. Loose terminals
If copper windings or connection terminals are loose and move easily, motor rotation and vibration can damage the winding insulation, abrade it or cause connections to come apart.

7. Stator windings
Check that the rotor windings are secure, because they must withstand centrifugal force during rotation. Loose windings can cause further damage.