CONDITION MONITORING ALGORITHM FOR INDUCTION MOTOR USING WAVELET TRANSFORM

Abstract

Squirrel Cage Induction Motors (SCIM) are largely prevailing machines which areused to convert electrical energy into mechanical energy in a wide number of applications in rolling mills, petrochemical industries, power plants etc. In the thesis work, I have discussed about the major Induction motor faults like rotor faults, bearing faults, stator winding faults, air-gap eccentricity, unbalance supply fault and load faults etc. The possible causes or stresses for the occurrence of these faults are also been listed in the thesis. Wide discussion on different types of harmonics, related to these faults, is also provided in this literature. Thesis also gives a detailed literature survey in the field of data dimension (Current signals) reduction using Park’s Vector approach. Fast Fourier Transform (FFT) is a spectrum estimation technique, comprehensively used with Motor Current Signature Analysis (MCSA). However FFT does not bestow us with substantial outcome when frequency resolution is taken into account. Multi Resolution Analysis (MRA) is used to analyse any signal in order to obtain better resolution. Discrete Wavelet Transform (DWT) gives a superior idea about the variation in specific frequency band all through the bearing fault(s). In this thesis, for fast analysis and minimalism, Current Signal Energy calculation is described. The different fault cases have been created using artificial signals for validation. The variation in the energy of healthy and faulty conditions gives us a fair idea relating to fault detection. Actual data analysis reveals that FFT is not suitable for practical situations. Comparative study of DWT and WPT has been done to provide a deep insight into early detection of rotor fault and bearing fault. MATLAB based analysis has developed a “Base-Algorithm” so that it can be processed on by any non-programming personal too for further implementations in the fields like condition monitoring of SCIM in case of severefaults, provided the studies are being held on Steady State Currents.