Induction motors are widely used in industries due to various techno-economic advantages .Voltage unbalance causes a lot of ill effects on induction motors. The problem of voltage unbalanced has attracted special attention amongst electrical engineers dealing with power quality issues in recent past. The adverse effects of voltage unbalance in Induction motors are Over heating, line-current unbalance, derating, torque pulsation, and inefficiency. The overheating leads to winding insulation degradation. This paper examines the proper application of the three phase induction motors when supplied by unbalance Voltage. The proposed work show that poor power quality voltages have bad effects over the motor performance: loss temperature rise, rated hp, efficiency, reliability. Finally this paper presents some recommendations to improve the performance.