UNBALANCED OPERATION OF POLYPHASE SOLID ROTOR INDUCTION MOTOR

Abstract

In the present dissertation work, the unbalanced operation of Polyphase Solid rotor Induction Motor has been studied utilizing electromagnetic theory and Symme-trical Component approach. As a preliminary step„ starting from Maxwell's equations, the impedance of the solid rotor at various slips for both positive sequence equivalent circuit as well as negative sequence equivalent circuit are found out. A critical review, on unbalanced operation of induction Motors, in general, has been presented. Later, using the derived rotor parameters of the equivalent circuits, the operation of a particular Solid rotor induction Motor is studied especially with reference to the additional losses incurred due, to the negative sequence currents. It has also been shown how the different phases are loaded when various percentages of negative sequence voltages are present. The operation of the motor while one of stator phases is open, is also investigated. In the end, heating effects are studied and an attempt is made to determine approximately the variation of derating factor of Solid rotor induction Motor