METHODS OF CONDITION MONITORING AND FAULT-DIAGNOSIS FOR INDUCTION-MOTORS

The study gives a synopsis over condition monitoring methods both as a diagnostic tool and as a technique for failure identification in high -voltage induction motors. Methods of fault detection are reviewed and analyzed: mechanical (vibrations, shock pulses, acoustic, speed fluct uations), electro-mechanical (currents, surges, partial discharges, le akage fluxes) and temperature-, oil particle-, gas analysis, and perfo rmance- and visual methods. The study indicates how different types of faults generate different frequency components in vibration spectra, in motor supply current, in torque and in magnetic field, and relation ships between fault types and spectra have been developed. Supply curr ent waveform analysis has been applied to demonstrate the detection of broken rotor bars and bearing faults.