Influence of Single or Multiple Faults Short-circuit, Broken Rotor Bar and Eccentricity on the Torque and Rotor Force in Induction Motors

Based on finite element analysis in time domain of a squirrel cage induction motor, this paper studies the influence of the three faults - stator short-circuit, broken rotor bar and static eccentricity, on the mean values and on the harmonics of motor torque and unbalanced rotor force. Results for healthy motor operation and for seven faulty cases, with single, double and triple faults, are evaluated and compared. The influence of the broken bar fault on the motor torque, single or in combination with the short-circuit fault or/and with the eccentricity, is much more important than the influence of the other two faults. Related to the rotor unbalanced force, all faulty cases are characterized by important or very important increase of this force compared with the healthy case.