Oscillating circuit design for inter-turn fault diagnostic in low-voltage induction motor

Turn fault caused by winding insulation deterioration is the most frequently fault occurring in induction motor. In several cases, induction motor that gets inter-turn fault with a small value has same current waveform as a nomal condition. Therefore, the inter-turn fault in induction motor can´t be only identified by monitoring the motor current. In this paper, a new method to overcome that issue is proposed. The idea utilizes an oscillating wave to detect small number of inter-turn fault. The oscillating wave is produced using the Cockcroft-Walton Multiplier circuit and some additonal circuits that is more economical. This paper presents experimental test on several inter-turn fault conditions to confirm the effectiveness of this method. Moreover, Error Area Ratio (EAR) is also used to further emphasize the advantage of the method. The results show that the proposed method is more sensitive and has better precision to identify small number of inter-turn fault.