Stator fault detection in induction motor under unbalanced supply voltage

Abstract

Induction motors are the most commonly used machine in industry because of their robust nature. As any other machine, due to the mechanical and electrical stresses, induction motor is also subjected to various types of failures. Among these, after bearing faults, stator faults are found to be the most frequent faults in induction motor. Interturn short circuit(ITSC) faults constitute a large percent of all electrical faults and it is the root cause of all other stator faults. So continuous monitoring of ITSC fault is necessary as rewinding the motor is usually preferred than replacing it. Several techniques have been developed for the detection of stator short circuit faults. But they have limitations due to the dependence onload variation, machine inherent asymmetry and unbalanced supply voltage. Among these a more reliable and simple method for practical implementation is found to be the symmetrical component method. Negative sequence current method insensitive to supply voltage unbalance is discussed here. Simulation study is carried out for different voltage unbalance. An experimental setup to model stator fault is developed. Also, a hardware setup is developed for on-line fault detection of induction motor.