Experimental Study of Induction Motor Performance with Unbalanced Supply.

A summary of the literature about the effect of unbalanced supply voltage on induction motors is presented. An experimental study was carried out, where rotor currents of a wound-rotor induction motor were measured under different unbalance conditions with respect to positive and negative sequence voltage magnitudes and phase angles. Rotor overcurrent is not a function of the angle between positive and negative voltage components. Effect of rotor overcurrent is under-estimated by the measured stator overcurrent, and rotor currents are closely similar. The currently used unbalanced-voltage derating factors do not seem to consider rotor winding heating, which is only applicable to squirrel-cage rotors. [ABSTRACT FROM AUTHOR]