ELECTROMECHANICAL TRANSIENTS IN A 3-PHASE INDUCTION-MOTOR DURING PHASE FAILURE AND PLUGGING

A transient, two dimensional finite element study of a 3-phase, delta connected squirrel cage induction motor is presented. The cases consid ered are sudden loss of all three supply lines, loss of a single line, loss of a phase minding on a balanced supply and braking by plugging. The ensuing behaviour of the motor is predicted by the step by step s olutions of the electromagnetic field and mechanical equations of moti on. In all cases the transients in speed, torque and currents are pres ented and discussed. The finite element analysis models only a quarter of the 4-pole induction motor and includes rotor mesh movement in dis crete steps.