Improvement of Frequency Resolution for Three-phase Induction Machine Fault Diagnosis

This paper deals with the use of the zoom FFT algorithm (ZFFTA) for the electrical fault diag-nosis of squirrel-cage three-phase induction machines with a special interest in broken rotor bar situation. The motor current can be analysed to observe the side bands harmonics around the fundamental frequency. In this case, it is necessary to take a very long data sequence to get high frequency resolution. This is not always possible due to the hardware and software limitations. The proposed algorithm can be considered for solving high frequency resolution problem with-out increasing the initial data acquisition size. The ZFFTA is applied to detect incipient rotor fault in a three-phase squirrel-cage induction machine operating at two speeds with pole number change by using both stator current and stray flux sensors