Motor Protection under System Fault Conditions

[microaid]

Hi,
For a large motor (5MW) supplied from an 11kV bus connected to a 36MVA generator is it advantageous to also disconnect the motor should the generator CB fail to trip for a fault on the 11kV bus and is this common practice?

If the motor remains connected to the fault will its contribution to the fault decay at a faster rate than if it were open circuited as a result of the current from the system flowing into the fault acting against the effects of armature reactance in the motor or are there other factors to be considered?
Thanks for your assistance.

 

[RRaghunath]

Motor (Squirrel cage induction variety) need not be disconnected for a bus fault as

The squirrel cage induction motor terminal voltage dies rapidly once it is disconneceted from power supply and cannot contribute to the fault for more than, say, 5cycles.

2) Moreover HT motors are normally provided with undervoltage protection which disconnects them on undervoltage (once the generator is tripped).