Steady state analysis of induction motor with broken rotor bars

The paper presents a mathematical model of a squirrel cage induction motor, taking account of higher space harmonics, and a computer simulation of induction motor fault states. The authors have studied the case of broken rotor bars as the source of rotor electrical asymmetry. Based on the mathematical model, the computer simulation of the influence of rotor cage defects on torque and current characteristics of induction machines at different slip values is presented. The practical monitoring of cage asymmetry is discussed by using spectral analysis of the line current of an induction machine. The laboratory tests of both healthy motors and motors with broken rotor bars show good agreement with these simulation results.