Abnormal Operating Condition and Causes of Induction Motors

 

Mechanical Overload

• Block the pump or gear system connected with motors
• Damaged bearings or No Lubrication
• Lock rotor or more time to starting the motor
• Stalling the motor (When motor does not start due to heavy load)
• In this case, motor is disconnected from supply as well as from mechanical load. After that, motor is started to satisfy the mechanical overlord condition.

Abnormal Supply Conditions

• Low Supply Voltage
• Unbalance supply voltage
• Increase in Supply Voltage
• Low Frequency (than normal frequency)

Faults in Supply Circuit

• Not availability of three phases
• Short circuit in supply cable
• Damaged links of the contactor
• Melted Fuse

Internal Faults in Motor

• Phase to Phase faults
• Phase to Earth faults
• Open Circuit
• Bad Insulation of The motor windings (in this case, motor is checked with megger)