Abstract: Induction motors have a long life and a high reliability in service at normal working conditions. To predict the life of motors in a short period of time, one simple and available accelerated degradation testing method is presented. To simulate the unbalanced load stressing on the motors, the lamina with some circular holes is easily mounted on the shaft of the motor eccentrically, and simulate different unbalanced load by changing the mounted places of the lamina. A motor accelerated test with 3 kinds of stresses is applied, and the Orbit Areas of the shafts to reveal the performance degradation index of the motors are obtained. Linear drift Brownian motion and Power Law model are used to analyze the relative ratios of the Orbit Areas, and the estimates of the model parameters are solved by the unbiased estimates methods and the least squares methods. With a balanced lamina mounted on the shaft as normal working condition of the motors, the life and reliability are predicted and evaluated by using the extrapolated unbalanced gravity moment and the estimates of the model parameters, and the accelerated degradation testing method has been proven to be practical and efficient to predict the life of the motors.

Key words: Induction motor, Life prediction, Accelerated deGradation testing, Holes lamina, Brownian motion, Parameter estimate