Early detection of induction motor's defects using an inductively coupled impedance extraction method

Based on inductive coupling approach, an on-line impedance frequency response method is proposed for early detection of defects in induction motors. Using a 4-pole induction motor as a system-under-test, the proposed method is validated experimentally through emulated inter-turn and shorted coil. Statistical indicators are also introduced for better detection of faults in the motor. As the setup has no direct electrical contact to the high voltage power supply, it can be easily installed on site without modification of existing motor wiring, and hence no interruption to the operational motor.