a) Frame : • Vibration • Circulating currents • Earth faults • Loss of coolants b) Lamination: • Core slackening • Core hot spot c) Stator windings faults: • End winding portion (turn-to-turn faults, fretting of insulation, local damage to insulation, damage to connectors, discharge erosion of insulation, displacement of conductors, contamination of insulation by moisture, oil or dirt, cracking of insulation and so forth).

Faults in Three Phase Induction Motor : Motor Fails to Start : Motor Giving Noise : Motor is Overheated : Bearings Overheated : Motor Starts and Stops : Motor Works With Reduced Speed : Motor Works With High Speed :

3-Phase Induction Motor Problems – Possible Faults and Remedies Motor fails to start Motor Noisy operation after start Bearing overheated 3-phase Induction Motor Problem – Motor overheated Motor Starts and Stops Motor runs below its rated speed Motor Runs at a Slow Speed when External Resistance is cut in the case of a Slip-Ring Induction Motor.

These faults include phase to phase faults, earth faults, and inter turn faults. Faults in motor windings are generally occur due to failure of insulation which causes due to the excess heating in the windings of the machine. Phase to phase faults are rare because enough insulation is provided between the phases.