Effect of voltage supply unbalance on temperature distribution of three-phase induction motor

Abstract

Three-phase induction motor is the most popular kind of electric motor used in industrial applications. To operate in ideal condition, a three-phase induction motor should work on balance three-phase voltage supply. Unfortunately, it is often found that a three-phase induction motor operates under unbalance three-phase voltage supply. A three-phase induction motor operate under unbalance three-phase voltage supply shows different performances to that operate under balance three-phase voltage supply. In this paper, effect of three-phase voltage supply unbalance on temperature distribution of a three-phase induction motor is analysed. Three different laboratory experiment have been set-up. The first one is a three-phase induction motor connected to balance three-phase voltage supply. The second one is a three-phase induction motor connected to magnitude unbalance of three-phase voltage supply. The magnitude unbalance is set at 3%, 4% and 5%. The last one is a three-phase induction motor connected to magnitude and phase unbalances of three-phase voltage supply. Considering high temperature that may occurs, experiment under magnitude and phase unbalances is run only for 3% and 2° of magnitude and phase unbalances respectively. For each experiment set-up, the motor load is varied at 0%, 50% and 70% of its nominal load. Experiment data show that the higher the unbalance level, the higher temperature of three-phase induction motor. The temperature at motor bearing is higher than temperature at motor body. Most non-ideal condition is when the motor supplied by three-phase voltage source with magnitude and phase unbalances.