High Frequency Signal Injection Method for Online Condition Monitoring of Electric Machines

In this study, a new high frequency current injection method to assess the health condition of induction machines is proposed. The deterioration in the isolation material of an induction motor is determined by analyzing the high frequency response of the machine while considering the rotor-to-stator, rotor-to-frame, stator-to-frame, and bearings-to-frame structural capacitances. A machine model is built to simulate the effect of aging in the structural materials of the motor. The response of the motor is analyzed by simulating the effect of aging/deterioration as changes in the structural capacitances. Induction machines are used in the laboratory experiments. The experiments presented in this paper validate the proposed method and its feasibility.