On-line motor winding early diagnostic based on dynamic leakage current monitoring

This paper presents a new on-line method for motor winding deterioration diagnostic based on the increase in the high frequency leakage current. A differential current sensor is used for the measurement of the leakage current. Traditionally, differential current sensors are used as a protection device, however, in this work their use is extended for health monitoring. In order to validate the proposed approach, motor windings are aged using the accelerated thermal method. The reduction of the leakage impedance in the aged winding is compared with online measurements for verification purposes.