Electromechanical transients in a three-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 considered are sudden loss of all three supply lines, loss of a single line, loss of a phase winding on a balanced supply and braking by plugging. The ensuing behaviour of the motor is predicted by the step by step solutions of the electromagnetic field and mechanical equations of motion. In all cases the transients in speed, torque and currents are presented and discussed. The finite element analysis models only a quarter of the 4-pole induction motor and includes rotor mesh movement in discrete steps