Voltage Imbalance (Electric Motor)

A condition of unequal voltages at the motor stator terminals that degrades the performance and shortens the life of a three-phase motor. Voltage imbalance is defined by the National Electrical Manufacturers Association as 100 times the absolute value of the maximum deviation of the line voltage from the average voltage on a three-phase system, divided by the average voltage. It is recommended that the voltage imbalances at the motor terminals not exceed 1%.