Monitoring and diagnoses by a vibration analysis procedure of incipient failures in squirrel cage induction motors due to cracker or broken bars

In this paper a vibration analysis based diagnostic procedure for the detection and monitoring of incipient faults as cracks or bar breaks on squirrel cage motors is presented. A mathematical model from the Authors set up for the determination of axial vibrations due to these faults is utilized as reference incipient fault model in order to determine prefault indexes for the above mentioned procedure. The experimental investigations, performed on a test bench set up for this purpose, confirmed the effectiveness both of the mathematical model and of the diagnostic procedure. Finally, the architecture of the diagnostic system that implements the proposed diagnostic procedure and its functioning mode are described.