Analysis of the performance of three phase induction motor under supply source unbalance

Abstract

Presence of voltage unbalance adversely affects the operation of three phase induction motors. Influence of unbalanced supply voltages on the adverse performance of the motor is intensified by the fact that a small unbalance in phase voltages can cause a disproportionately larger unbalanced phase currents. Thus, the additional heat produced in both the stator and the rotor windings lead to a reduction in the motor efficiency, demanding motor de-rating which was established to depend on the voltage unbalance factor. This study investigates the effects of varying unbalanced voltages which lead to the same voltage unbalance factor, on the operation performance of an induction motor and the effect of positive sequence voltage on it. Statistical analysis is carried out to identify the possible variation range for the performance parameters of induction motors of different scales for different unbalance voltage conditions.