Broken Rotor Bar Fault Diagnosis in VFD Driven Induction Motors by an Improved Vibration Monitoring Technique

Motor current signature analysis (MCSA) is widely used condition monitoring technique for fault diagnosis of induction motor drives. Application of variable frequency drive (VFD) to operate induction motors is increasing day by day due to their high energy savings compared to conventional speed varying devices like belt drives, gear-boxes etc. One of the limitations of MCSA technique is its inability to detect the presence of incipient level of single BRB fault in VFD driven induction motors at light load conditions up to 15%. Detection of this type of fault using current signatures requires expertise in signal processing techniques. Early detection of BRB fault can avoid the risk of consequent failures in induction motor. In this paper, additional fault frequency features have been proposed to detect the presence of single BRB fault using vibration analysis. The results have been validated at various light load conditions by comparing the vibration signatures of healthy and single BRB state of the motor.