A three phase 20 pole induction motor is connected to a 600

A three phase, 20 pole induction motor is connected to a 600 V, 60 Hz source. The synchronous speeds, when the voltage is 600 V and when it is reduced to 300 V are given respectively by

Solution

Synchronous speed is dependent on frequency and poles.

Ns=120f/p=360rpm

Therefore synchronous speed is 360rpm for both 600v and 300v supply.