EQUIVALENT CIRCUIT OF INDUCTION MOTOR WITH UNSYMMETRICAL UNBALANCE ON THE SECONDARY SIDE

Abstract

In the present work, a steady-state equivalent circuit has been developed for the general case of rotor unbalance in an induction motor ug ng three different methods based on symmetrical components concept, Generalised Jbtating-Field Theory and Generalised Electrical Machines Theory. The equivalent circuits so derived: have been found compatible and represent the same circuit. It has been showi that the equivalent circuit developed in the present study is of general nature and covers all special cases studied by earlier authors. It is found valid in all cases of symmetrical or unsymmetrical rotor unbalance. The effect of variation of resistance or reactance or both in the rotor circuit over the torque/ship characteristic can be conveniently studied. Using the circuit, fast and economical computerised calculations can be carried out for a large number of asymmetri cal. cases for computing the performance characte ri-sties of the machine. The equivalent circuit can also be used for predicting the transient behaviour of the machine.