Instead, when the rotor’s speed is close to synchronous, the regular field current
can be turned on and the motor will operate normally. In real machines, field circuit
are shorted during starting. Therefore, if a machine has damper winding:
1.Disconnect the field windings from their DC power source and short them out;
2.Apply a 3-phase voltage to the stator and let the rotor to accelerate up to nearsynchronous
speed. The motor should have no load on its shaft to enable motor
speed to approach the synchronous speed as closely as possible;
3.Connect the DC field circuit to its power source: the motor will lock at
synchronous speed and loads may be added to the shaft.