Mechanical failures detection by means of induction machine current analysis: a case history

This paper addresses the problem of the detection of the mechanical disturbances and failures in a mechanical system driven by asynchronous machines through motor´s current signal. Since the load behavior modifies the motor´s supply current, it is possible to use the machine itself through motor current signal analysis (MCSA), as a torque sensor to defect mechanical condition. In this paper low frequency torque disturbances, that cause a quasi-stationary machine-load behaviour are used to diagnose the different mechanical anomalies, exploiting the relationship between current and torque. Specifically a mechanical system constituted by a high-ratio gear and a grinding table with rolling wheels for raw coal was analyzed through MCSA.