What are the reasons for harmonics in the motor?

What are the reasons for harmonics in the motor?
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1 Answer

Answer :

Generally even harmonics are not expected to be present in three phase motors.

Triple-n harmonics like 3rd, 9th, 15th etc. are also not expected. The dominant odd harmonics expected are 5th, 7th, 11th and 13th etc.

 Presence of strong 2nd harmonics indicates unbalance voltage, unbalance winding impedance, rotor defects, magnetic imbalance, faulty rotor skewing etc.

 Very strong 3rd harmonics indicates magnetic saturation, ground leak currents, overloads etc. Overloading causes overheating, resulting in non-linear magnetization which gives high 3rd harmonic winding faults, short circuits. Hot spots in rotor or stator also may indicate higher harmonics.
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