Investigation of motor faults in NPP using in service motor monitoring system

Induction motor is mostly used in Nuclear Power Plant due to ruggedness and durability. Due to stringent safety requirements for continuous operation in Nuclear Power Plants. In-service motor monitoring systems are employed to detect the incipient fault at early stage that results in reduced down time of motors. Motor current analyzing methods are generally used to detect the various types of induction motor faults such as rotor fault, air gap eccentricity fault, short winding fault, bearing fault etc. This work mainly focused on rotor fault and bearing fault. For detection of characteristic fault frequencies current spectrum is being used. In the presence of any fault, the frequency spectrum of the motor current changed from healthy motor. In this work the various algorithms like Fast Fourier Transform-algorithm, Wavelet Transform based multi resolution analysis algorithm are used to detect the rotor and bearing faults in induction motors under different load conditions. To perform the analysis on induction motors, an experimental set up is designed that can precisely measure current signals. Detail analysis of both faults is presented separately along with the comparison of experimental and theoretical results. Experimental facility established at nuclear plant workshop described at component level at the end.