Models for Bearing Damage Detection in Induction Motors Using Stator Current Monitoring

Abstract—This paper describes new models for the influence of rolling-element bearing faults on induction motor stator cur-rent. Bearing problems are one major cause for drive failures. Their detection is possible by vibration monitoring of charac-teristic bearing frequencies. As it is possible to detect other ma-chine faults by monitoring the stator current, a great interest exists in applying the same method for bearing fault detection. After a presentation of the existing fault model, a new detailed approach is proposed. It is based on two effects of a bearing fault: the introduction of a particular radial rotor movement and load torque variations caused by the bearing fault. The theoretical study results in new expressions for the stator cur-rent frequency content. Experimental tests with artificial and realistic bearing damage were conducted by measuring vibra-tion, torque and stator current. The obtained results by spec-tral analysis of the measured quantities validate the proposed theoretical approach. Index Terms—Induction motor fault diagnosis, bearing dam-age, motor current signature analysis, airgap eccentricity, torque variations. I