Comparative Study of Induction Motor De-Rating Factors

Induction motors are the commonly used motors in power industries, due to its lowprice, maintenance and easy to control, it consumes about 40% of the electricalenergy all over the world. It is very common to find problems of power quality inelectric supply systems, among of these problems unbalanced phase voltage andunder / over voltage deviation. The developments in the power electronics fieldhave led to an ever-increasing use of static switching devices to control the torqueand speed of ac motors. Invariably, the output voltage and current waveforms ofthese devices are harmonically distorted in shape due to the existence of numerousharmonic orders; they primarily affect the performance operation of inductionmotors. Symmetrical component approach is adopted to estimate the performanceof a three phase induction motor operating with unbalanced supply system or otherfactors. Further MATLAB/SIMULINK has been used simultaneously forsimulation purpose. A new approach is proposed to de-rate the motor operatingwith these external factors in order to safe induction motors and increase its lifetime. This paper, therefore, presents a comprehensive study the influence of theseexternal factors on induction motors behavior. A comparative study of inductionmotor de-rating factors is presented