What are the methods of starting the 3-phase synchronous motor?

There are a number of ways of starting a synchronous motor.
1.
Use a pony motor to get it up to speed first.
(This assumes the load can be removed for start) 2.
The rotor has amortisesur windings on it.
These act as a fairly crude squirrel cage just for starting.
(Start currents tend to be high but motor can be rated to start "on load") 3.
The rotor can have extra windings that act like a "wound rotor" motor for start.
These can use start resistors to limit starting currents and will start "on load".
One type of these is an "auto synchronous" that doesn't require the starting method mentioned later as it will "synchronize itself (the dc must still be applied after near synchronous speed is met).
The dc winding and one of the start windings can be the same in wound rotor (synchronous induction) For options 2 and 3, some form of control is needed.
During start, the dc is not applied.
When the motor reaches "near synchronous" speed, the dc needs to be applied.
This has to be done at the correct time when the synchronous field is aligned with the rotor.
This can be done manually by watching an analogue voltmeter connected to the rotor and applying the dc as the voltmeter reaches its maximum swing.
There are relays that sense this and apply the dc automatically.
http://www.geindustrial.com/publibrary/checkout/38652.30055.22278.50388/PDF/spm-a7_3.pdf

       As seen earlier, synchronous motor is not self starting.
It is necessary to rotate the rotor at a speed very near to synchronous speed.
This is possible by various method in practice.
The various methods to start the synchronous motor are, 1.
Using pony motors 2.
Using damper winding 3.
As a slip ring induction motor 4.
Using small d.c.
machine coupled to it.

Start as a3 phase(DOL Starter ) Induction motor ie wound rotor silipring,3 terminals to be shorted by means of links with change over switch, note down the current speed ,power factor<0.8 (lagging) .
keep ready DC excitation supply with rehostatic controller maximum position , with this condition release the change over switch to apply dc excitation slowly increase to rehostat to increase the d.c current up to the(near to over excitation) Motor attain synchronous speed ,P.F meter shows unity.Note down all the reading.