Gearbox-Induction Machine Bearing Fault Diagnosis Using Spectral Analysis

Induction motor-gearbox group vibrations, caused by bearing defects, result in the modulation of the stator current. In this research, bearing defect is detected using the stator current analysis and mechanical vibration. The advantage of this method is in the detection of incipient faults. Faulty balls in bearing suspension and eccentricity are the relatively common faults in induction motors coupled with a mechanical speed reducer, which are responsible for a significant number of induction system failures. These effects have been extensively investigated during the 80psilas and the 90psilas. Several methods have been developed for the identification of this kind of faults, originally based on thermal vibration monitoring and current monitoring. Motor current signature analysis (MCSA) is nowadays a widely used method for the detection of mechanical fault. In previous works numerous MCSA methods have been proposed. The purpose of this paper is the evaluation of asynchronous motor current signature analysis and vibration spectra approaches, in order to determine the faulty origin. This paper discusses the potentials of current spectral analysis combined with vibratory analysis. Although the discussion is focused on these electromechanical devices, most of the content can be applied to the mechanical diagnosis of a large variety of other systems.