Aging investigation of motor winding insulation subjected to PWM-supply through PD measurements

This paper deals with an investigation of the relationship between partial discharge (PD) activity and aging of PWM-controlled motors. Online and offline PD measurements were carried out with the purpose of evaluating PD inception voltage, amplitude and repetition rate on motors aged by different electrical stresses. As insulation degradation progresses, PD inception voltage decreases, while PD amplitude and repetition rate raises. It is shown that these procedures can constitute an effective tool for quality control on manufactured motors, as well as for aging diagnosis on motor windings during operation.