Synchrous Motor

Question 1

How is a synchronous motor started

Answer 1

A 3 phase supply is connected to the stator windings produces a magnetic field

A pony motor is used to run the rotor up close to synchronous speed

A DC supply is then placed on the rotor windings to make an electromagnet.

That locks onto the rotating magnetic field and rotates at synchronous speed

Question 2

What is damping windings starting

Answer 2

Motor starts like a induction motor

A DC supply is switched onto the rotor
And locks onto the rotating magnetic field

Question 3

What is wound rotor starting

Answer 3

Uses resistors to start the Motor
Max speed when XL=R

Question 4

What is the pony motor

Answer 4

During start up all mechanical load I’d uncoupled from the motor shaft

The pony motor is only suitable for turning the rotor

Once the rotor is a sync speed the supply to the pony motor is disconnected

Question 5

Name an advantage of sync motors

Answer 5

Provide power factor correction

Question 6

Disadvantage of a sync motor

Answer 6

Two supply’s are needed a ac for stator and a DC. For the rotor