Novel approach for diagnosis and detection of broken bar in induction motor at low slip using fuzzy logic

This paper presents a new automated practical implementation for noncontiguous broken bars diagnosis and detection in electrical induction machine. In this work, a method for detection and diagnosis based on spectral analysis via fast Fourier transform (FFT) of the stator current envelope (SCE) is used. According to the fault diagnosis objective, two features are selected from the (SCE) spectrum: the amplitude of the harmonic representing the broken bars defect 2sf (s is the slip and f the fundamental harmonic) and the dc value. These features will be used as inputs for fuzzy logic bloc, where the decision about the state of rotor is made. The results obtained are astonishing and its is capable to detect the correct number of broken bars.