Transient performance of induction motors under plugging operation

Induction motor transients under `plugging´ is investigated. A realistic plugging contractor is considered, which includes disconnecting the supply, `coasting´-a period when no voltage is applied, and applying a negative sequence voltage to cause braking. A mathematical model to simulate the plugging process is presented and used to predict the transient behaviour of an industrial induction motor under plugging operation, Corresponding results obtained experimentally are also presented and discussed. The effect of the timing of contractor operation on the braking performance is studied. Simulated results indicate that the braking time and peak braking torque are affected considerably by the instant when negative sequence voltage is applied.