Application of extended DFT for fault detection of electric motors

Abstract

This paper proposes a method of fault detection and quantification for induction motors. The method is based on Extended Discrete-Furrier Transform or EDFT. The principle is that any fault either in the stator or the rotor may distort the sinusoidal response of the motor RPM and the main frequency. Because the EDFT relates to both amplitude and frequency of number of harmonics in a signal, hence it is expected to show some harmonics around the mains frequency and some frequencies which have ability to differentiate the faults. The method is tested on 3 different motor conditions: healthy, stator fault, and rotor fault motor at full load condition. The experiments show that it can differentiate conditions clearly by observing the change in specific harmonic amplitudes. The method can also indicate the level of the fault severity by observing the percent change in the harmonic amplitudes. © 2010 Springer-Verlag.