Diagnosis of broken rotor bar fault in open- and closed-loop controlled wye-connected induction motors using zero-sequence voltage

This study proposes a method to detect and quantify broken rotor bar fault using zero-sequence voltage in a wye-connected squirrel-cage induction motor. The zero-sequence voltage is analysed and two fault severity factors are defined. The factors are almost independent of motor speed and load torque. Furthermore, it is proved that closed-loop control has little influence on the diagnosis results. Consequently, the method can detect broken rotor bar fault for induction motors in both open- and closed-loop drives. Moreover, the method can discriminate the broken bar fault from a low-frequency load oscillation, even when these two phenomena occur simultaneously. In addition, the influence of unbalanced voltage supply on the diagnosis results is negligible. The effectiveness and robustness of the proposed method have been validated by experimental results.