A Novel Investigation on Multi-Sensor Signal Signatures for Induction Motors Diagnostics

Multi-sensor diagnostics for induction motors can provide numerous signal signatures. In this work, novel diagnostic signatures in the time and frequency domain are shown, for the first time, in stray flux, stator current and vibration. The time domain envelope of the stray flux can give information on the slip of the machine. Moreover, new observations on the waveform are highlighted to describe peculiar features of the stray flux. A study on the phase shift of the electromagnetic signals in different load conditions is presented for both healthy and faulty machine with localized bearing defect. The phase-shift between the current and the radial and axial stray flux changes, demonstrating that the radial flux contains information more similar to the current. Vibration harmonics at frequencies below the rotational one are observed with faulty bearing and new signatures are proposed.