JALILIAN - Dept of Electrical Engineering Iran University of Science and Technology Narmak, Tehran, ۱۶۸۴۴, Iran
PERERA - Integral Energy Power Quality Center School of Elec., Comp. & Tele. Eng. University of Wollongong Wollongong, NSW, Australia
GOSBELL - Integral Energy Power Quality Center School of Elec., Comp. & Tele. Eng. University of Wollongong Wollongong, NSW, Australia

Voltage unbalance affects the performance of power system loads and equipment. This paper deals with the performance of three-phase induction motors under unbalanced voltage conditions. Two common definitions of the voltage unbalance are given and their methods of calculation are presented. Experimental tests are conducted on a 7.5 kW high efficiency induction motor supplied by nominal balanced and unbalanced supply voltages wider different loading conditions. Experimental results are utilised to investigate the effects of unbalanced supply voltage on motor losses as well as on motor output power. Also a derating factor has been introduced to specify the motor loading level under unbalanced supply voltage conditions. The effect of unbalanced voltage on hot spot temperature has not been studied in this paper.

Polyphase induction motors, unbalanced supply voltage, voltage unbalance factor, derating factor