LAUSR

Summary The coil is used to detect partial discharge (PD) in the 3.3-kV motor. Because of the noise issue, most studies detect PD of the motor at the power bus or at neutral. However, we use three coils inserted in the slot of three motor frames to detect PD. This conflicts with conventional thought. For safety, the motor frame is always grounded to the earth. In addition, most people think it is impossible to detect PD on the grounded motor frame. Most researchers say we measure noise or high-frequency current on the motor frame. In this paper, we design an experiment to prove that what we measure is the induction magnetic field of PD. From the amplitude variation of the PD signal, the imperfect motor can be identified. Moreover, by measuring the PD signal and the three-phase 60-Hz waveform, we can determine the phase at which PD occurs. Copyright © 2016 John Wiley & Sons, Ltd.