Reliable stator fault detection based on the induction motor negative sequence current compensation

- The NSC generated in a faulty IM is caused by the superposition of several unbalances.
- To achieve precise incipient stator fault detection, an experimental method is proposed to extract the NSC representing only the stator fault.
- As a result, a good improvement of the value of the NSC is obtained using the proposed method.

The objective of this work is the compensation of the negative sequence current of the faulty induction motor in the aim to increase the accuracy and the sensitivity of the incipient stator fault detection under different disturbances. This is because, the negative sequence current generated in a faulty machine is the superposition of the different negative sequences current generated by the fault and others disturbances, which are the inherent asymmetry in the machine, the unbalanced supply voltage and the sensor inaccuracy. Thus, this paper proposes an efficient experimental method that allows the compensation of the negative sequence current of the faulty machine, by subtracting the negative sequence current of the different disturbances from the total negative sequence current of the faulty machine to isolate the negative sequence current due to the fault. Thus, the negative sequence currents of the different disturbances are isolated using an original experimental technique. The efficiency of the proposed method is validated experimentally on a 1.1 kW motor under inter-turns short circuit faults and phase to phase faults.