Loss of Life in Induction Machines Operating With Unbalanced Supplies

Abstract—This paper estimates motor life when a motor is sup-plied with a combination of over- or undervoltages with unbalanced voltages. The motor life is predicted by estimating the stator wind-ing insulation life of squirrel cage motors using Arrhenius ’ equa-tions. Electrical and thermal models are used to calculate motor losses and temperatures, respectively. The thermal model parame-ters are obtained from simple motor testing techniques rather than from complex methods requiring motor design data. Index Terms—Motor life and temperature rise, voltage unbal-ance. I