Induction-motor reswitching transients

The transient behaviour of an induction motor when disconnected from the supply and reswitched to the same or to a different supply before the complete decay of rotor currents is investigated. A digital-computer program is described for calculating the internal voltage generated by the decaying rotor currents and the transient torques and currents produced on reswitching. Experimental measurements of the transients experienced by a 7 5hp motor following reconnection to the same supply, plugging and dynamic braking are compared with computed results. Tests were made both at rated and at reduced supply voltage, and better agreement between theory and measurement is obtained at the lower voltage.