Detection of rotor fault in an induction motor under standstill condition

The purpose of this paper is to present a study on the power quality issue based on the harmonics present in the slots of induction motor due to broken bar fault in induction motors. This paper presents numerical magnetic field analysis of squirrel cage induction motor based on finite element method. Finite element analysis can be used for predicting the performance of an induction motor having different faults implemented in their structure. Magnetic field is calculated for the case of symmetrical rotor cage and for several cases of rotor electrical asymmetry due to broken rotor bars. It shows the relation between the increasing number of broken bars and unproportional distribution of induced rotor currents, which results as a degradation of steady-state and dynamic performance of induction motor. For this study, a squirrel cage induction machine with thirty six stator slots and twenty eight rotor bars has been investigated. It provides rotor quality assessment independent of load operating conditions.