Abstract: - Three phase supply system is found to be quite balanced in both magnitude and displacement at the generation levels but it is not so at distribution end. Voltage unbalance which is a common and global phenomenon is found to be very effective in deteriorating the performance of electrical apparatus at user end. Such environment badly affects the performance of induction motors, an important class of electric machines which is widely used in industrial. Present paper is an attempt to tackle such operations with specific recommendations & proposals. Symmetrical component approach is adopted to estimate the performance of a three-phase induction motor operating with unbalanced supply system. Further MATLAB/SIMULINK & PSIM environments have been used simultaneously for simulation purpose. A new approach is proposed to rerate the motor operating with voltage unbalance.