ABSTRACT
This chapter summarizes motor fault conditions and their cause, especially for the induction motor. It considers eccentricity related faults, broken rotor bar faults, bearing faults, and stator faults, which account for more than 90% of overall induction motor failures. Bearing faults account for more than 40% of all electric motor failures. Bearing faults can be classified as outer raceway, inner raceway, ball defect, and cage defect. The chapter discusses the important electrical and mechanical failures in the synchronous machines and corresponding diagnosis techniques proposed in the literature. Some faults like rotor winding faults, broken damper bars, or end-rings, are specific to wound rotor synchronous machines, and demagnetization faults are limited to permanent magnet synchronous machines. In comparison to other types of alternating current motors, permanent magnet synchronous Machines are becoming more popular in applications with high-speed operation and precise torque control. The fundamentals of the eccentricity fault in a synchronous motor are the same as that of the induction motor.
