Impact of Unbalanced Voltage on Induction Motor

This work investigated the impact of rated voltage, under voltage and over voltage unbalance on induction motor operational performance using the International Electrotechnical Commission's (IEC) definition of voltage unbalance to investigate the level of difference in the operating performance of induction motors working under balanced and unbalanced voltage and determined the percentage of unbalance voltage that is tolerable for effective operational performance of an induction motor. MATLAB®Simulink was used to build a model for the performance analysis of a 2h.p induction motor and operated under balance and unbalance voltages at no load and loaded condition using IEC's definition of voltage unbalance. The results obtained indicated gross inefficiency when the motor is operated under various unbalanced conditions of rated voltage, under voltage and over voltage. The worst adverse effect of unbalance was most severe at under voltage conditions; drastic load reductiondid not produce good motor performance even with a low Voltage Unbalance Factor (VUF). At over voltage unbalance however, motor indicated fair performance at VUF of 2-4% with a load reduction of 50%.