Answer / vinothkumar.m

the average torque exerted on the rotor is zero. And hence the synchronous motor is not self starting.

Answer / khalidulislam7@gmail.com

As per the operating principle of the Synchronous motor, due to continuous & rapid rotation of stator poles,the rotor is subjected to a torque which is rapidly reversing i.e. in quick succession,the rotor is subjected to torque which tends to move it first in one direction & then in the opposite direction.Owing to its large inertia,the rotor cannot instataneously respond to such quickly-reversing torque,with the result that it remains stationary or in other words it is not self starting......by
khalidulislam7@gmail.com

Answer / gokulnath

Synchronous motor cannot exert high starting torque at a time of starting because of its construction. so it needs starters.

Answer / rupesh

The rotar is acted by two forces in opposite direction ,it does not rotate so thats why syncronous motor is not self started.

Answer / tapiwanashe

because the torque is only developed when the synchronous motor is running at the speed of magnetic flux , therefore, the motor needs some type of device such as damper winding to bring the rotor to synchronous speed

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