Detection of Stator and Rotor Winding Faults by Monitoring Air-Gap Flux Spectrum of Slip-Ring Induction Motor

In the literature, the detection of winding faults using flux analysis is found more suitable as compared to classical techniques, like current signature analysis. The detection of inter-turn winding faults, by using external stray flux sensor is reported by most of the researchers. The induced emf in the external stray flux sensor is the function of the position of the sensor. Also, the amount of induced emf in millivolts. To overcome these problems, the air-gap flux sensor (AGFS) based technique is recommended. In this technique, the AGFSs are made up of copper coils of few turns. In the stator core, the AGFSs are placed in addition to stator winding (coils). This paper deals with, the detection of inter-turn faults in stator and rotor windings. It also, detect the unbalanced supply voltage in the three phase wound rotor induction motor (WRIM). The asymmetry in the supply voltage and inter-turn faults in stator and rotor windings lead to the variation in the air-gap flux thereby, induced emf in AGFS. By analyzing flux spectrum of induced emf in all AGFSs, the type of abnormality is identified. Also, in case of stator winding fault the exact fault location is identified. The proposed technique is a new technique as, AGFSs are placed internally for the detection of proposed abnormalities in the wound rotor induction motor.