Taking advantage of the induction motor inherent eccentricity aiming to discriminate the broken bar fault from load oscillations

It has been noted that, in the induction motor the mechanical load oscillations can produce stator current spectrum harmonics, similar to the ones of the broken bar fault. As a consequence, these two different conditions have to be reliably distinguished. This paper proposes a new method aiming to this direction. More specifically, it is proposed to monitor the inherent eccentricity harmonics and their sidebands in order to reliably distinguish whether there is a broken bar fault or not, in the presence of mechanical load oscillations. The proposed method has been tested experimentally for different load and saturation levels of a cage induction motor and the results prove to be satisfying for all studied conditions.