Bearing diagnosis methodologies by means of Common Mode Current

The most bearings diagnosis methodologies has been designed typically by means of vibration analysis, but a numerous studies in the last years are focused in non-invasive techniques Motor Current Signature Analysis (MCSA) based. This paper shows two different methodologies for bearings diagnosis over induction motors by means of the stator Common Mode Current (CMC). It is acquired directly the CMC from the source that inverter provide to the motor. The first analysis is performed directly over a temporal acquisition of stator CMC. The second analysis is based in the spectral analysis of a single CMC discharge. It is shown also the development of a CMC probe, which corresponds to the tool used to check the first methodology. Finally, it is presented a vibration analysis over the same induction motors in order to confirm the bearings diagnosis extracted from the previous methodologies CMC based.