Experimental compensation of the negative sequence current for accurate stator fault detection in induction motors

The negative sequence current can offer an efficient and fast monitoring technique to detect incipient stator fault in induction machines. However, unbalanced supply voltage, inherent machine asymmetry and non ideal sensors can also contribute to the generation of this negative sequence current. Thus, it is rather difficult to extract the negative sequence current caused only by the fault. To improve the accuracy of fault detection, this paper proposes an efficient method based on the use of experimental techniques to identify and separate the negative sequence current due to the inherent asymmetry in the machine and the non-calibration of the sensors in order to extract the negative sequence current caused only by the fault. The efficiency of the proposed method is demonstrated by the use of experimental data´s coming from 1.1 kW motor supplied by a balanced voltage.