Assessment of Stresses on Induction Motors Due to Momentary Service Interruptions

Abstract

This dissertation presents an assessment of the worst case stresses produced in an induction motor when the motor is allowed to ride through a power supply voltage disturbance. Results from laboratory experiments and computer simulations are shown. The experimental results are obtained from tests conducted on three squirrel cage induction motors, sized 10 hp, 50 hp, and 75 hp. Each motor is tested with three different load inertias, various motor loadings, and numerous interruption durations. The computer simulation results are obtained using a non-linear motor-load model, whose parameters are derived from a non-linear least squares parameter estimation technique. Experimental data acquired in the lab is used for the parameter estimation data and for the validation data. Deficiencies in the standard motor-load model are presented and addressed. Good agreement between the experimental data and the non-linear motor-load model data is achieved. Results show significant current and torque transients, but caused no significant damage to the motors or loads used for testing.