Online Unbalanced Rotor Fault Detection of an IM Drive Based on Both Time and Frequency Domain Analyses

An effective maintenance program provides incipient fault detection of rotating machines which reduces interim, unscheduled, and excessive maintenance actions. By applying suitable online condition monitoring accompanied with signal processing techniques, machines' irregularity can be detected at an early stage. Therefore, this paper presents an online condition monitoring based fault detection of an unbalanced rotor induction motor (IM). Characteristic features of motor current and vibration signals are analyzed in time domain as a fault diagnosis technique, which is a key parameter to the fault threshold. Motor current and vibration signals are analyzed based on fast Fourier transform (FFT), Hilbert transform, envelope detection, and discrete wavelet transform (DWT) to detect the severity of the fault and its possible location under different load conditions. The DWT is used to extract the information from a signal over a wide range of frequencies. The Daubechies wavelet is selected for the healthy and faulty condition analysis of IM. It is found that the DWT can more precisely identify the fault as compared to the conventional FFT for a three-phase, two-pole, 0.246 kW, 60 Hz, 2950 r/min IM drive.