A Review of the Monitoring and Damping Unbalanced Magnetic Pull in Induction Machines Due to Rotor Eccentricity

Condition monitoring can diagnose the inception of fault mechanisms in induction motors, thus avoiding failure and expensive repairs. Therefore, there is a strong need to develop an efficient condition monitoring approach. The main aim is to achieve a relatively low cost and non-invasive system which is still powerful in terms of monitoring for online detection of developing faults. The paper addresses rotor eccentricity faults and studies conventional monitoring techniques for induction motors. The eccentricity-generated additional air-gap flux waves should be reduced in order to reduce the unbalanced magnetic pull (UMP) when there is an eccentric rotor. The radial forces in an induction motor are calculated, and the characteristics of UMP are described.