New Vision about the Mixed Eccentricity Fault Causes in Induction Motors and its relationship with the Rolling Element Bearing Faults : Analytical model dedicated to the REB faults

This paper presents the mechanical fault detection in squirrel cage induction motors (SCIMs). Rotor eccentricity is a common fault in SCIMs. In addition, rolling element bearing (REB) faults is a major problem among different faults, which cause catastrophic damage to rotating electrical machines. This fault is systematically, resulting in undesirable vibrations in several machines. Generally, the REB faults create a static, dynamic and mixed eccentricity type. The questions that arise are:- What are the logical reasons that verify the existence of mixed eccentricity, even in the new rotating electrical machines?- What is the relationship between rolling element bearing faults and the eccentricity faults?Physically, the additional harmonics due to static eccentricity and dynamic eccentricity in stator current spectra are firstly derived with the rotational direction of electromagnetic force (EMF) harmonics into consideration. Motor current signature analysis (MCSA) has become one of the most important techniques in the fault diagnosis field. MCSA has become popular for detection and Iocalization of many faults. It is generally based on fast Fourier transform FFT of the stator current in healthy and faulty state of the induction motors (IMs). This study tried to answer the questions previously asked. On the other hand, this paper has made the analysis of the bearing fault carefully. A new analytical model dedicated to bearing failure has been proposed. The conclusions drawn from the analytical and simulation results are validated experimentally. Finally, the experimental results demonstrated the high sensitivity and clarity of this technique.