Motor reacceleration

[jasl]

I would like to know the effect of re-acceleration of motors on transient stability. What would be the effect of load transfer (induction motor loads) from one bus to another in the event of failure of supply if my motors do not have any reacceleration feature? Will natural reacceleration come into picture within the set time?

 

[aolalde]

When re-closing is faster than 10 cycles (170milliSec. for 60 Hz) you will have an out of step condition due to the remaining magnetism in the motor. The currents became as large as for a short circuit.
When re-closing is done after several seconds, depending on total system load, inertia and friction, the speed will drop and the starting current will be around six times the full load current until the cusp of the speed torque curve is reached again.
Sub-transient performance has been discussed before in this forum.