On-Line Fault Diagnostics Of Three Phase Squirrel Cage Induction Motor Based On Motor Current Signature Analysis Method
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Date
2012-01
Authors
J. Hammadi, Khaleel
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Studies of rotor asymmetries in three-phase squirrel cage induction motors have traditionally focused on analyses of the effects of the broken rotor bars on the magnetic field and current spectrum. Major motor manufactures have reported cases where damage bars are randomly distributed around the rotor perimeter of large motors. The motors were being monitored under maintenance programs based on motor current signature analysis (MCSA) in some of these cases, and the degree of degradation found in the rotor was much greater than that predicted by analysis of their current spectra. A complete study was carried out for this reason, comprising a theoretical analysis, as well as simulation and test, to investigate the influence that the number and location of broken bars has on the traditional MCSA diagnosis procedure. The proposed methodology is generalized for the estimation of the sideband amplitude in the case of multiple bars broken and validated by simulation using a finite-element based model as well as by laboratory test.
In this research, LabView2010 technique is used to diagnose the broken rotor bars faults in induction motor with direct online monitoring. Two algorithms are proposed to track and detect the broken rotor bars faults in induction motors under full load and light load conditions, namely Fast Fourier Transform (FFT) algorithm and Wavelet Transform (WT) based multi resolution analysis algorithm. The results obtained from the experiments show that FFT is significantly dependent on the loading condition of induction motor. From the experiments result, Wavelet Transform technique (WT) by LabView data acquisition system shows a capability of
detecting the number and location of broken rotor bars under light load condition. The results show that the magnitude of the sideband frequency component increases when the number of broken bars is increased and concentrated over one pole. Therefore, the MCSA method which employs both the FFT technique and Wavelet Transform can be satisfactorily and successfully applied to detect broken rotor bars fault in a three-phase squirrel-cage induction motor.
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Keywords
Rotor asymmetries in three-phase squirrel cage induction motors , the effects of the broken rotor bars on the magnetic field and current spectrum