Induction motors are the commonly used motors in power industries, due to its low
price, maintenance and easy to control, it consumes about 40% of the electrical
energy all over the world. It is very common to find problems of power quality in
electric supply systems, among of these problems unbalanced phase voltage and
under / over voltage deviation. The developments in the power electronics field
have led to an ever-increasing use of static switching devices to control the torque
and speed of ac motors. Invariably, the output voltage and current waveforms of
these devices are harmonically distorted in shape due to the existence of numerous
harmonic orders; they primarily affect the performance operation of induction
motors. Symmetrical component approach is adopted to estimate the performance
of a three phase induction motor operating with unbalanced supply system or other
factors. Further MATLAB/SIMULINK has been used simultaneously for
simulation purpose. A new approach is proposed to de-rate the motor operating
with these external factors in order to safe induction motors and increase its life
time. This paper, therefore, presents a comprehensive study the influence of these
external factors on induction motors behavior. A comparative study of induction
motor de-rating factors is presented