What precautions should be taken during the startup period o

What precautions should be taken during the start-up period of a synchronous motor? 2. If the squirrel-cage winding were removed from a synchronous motor, could it start by itself? What function does the damper winding serve? (4)

Solution

1.)

The following are the precautions should be taken during the start-up period of a synchronous motor,

1.First reduce the speed of the stator magnetic field.

2.An external prime mover should be used to accelarte the synchronous motor upto synchronos speed.

3.Damper winding must be used.

2.)

If the squirrel cage winding was removed from a synchronous motor, then the synchronous motor could not start by iteself because generally a synchronous motor has a wound rotor with an external resistance that is reduced to increase the rotor current to bring the motor up to slip (asynchronous) speed, then DC is applied to the rotor windings to \'Lock\' onto the rotating filed to bring it up to synchronous speed. If the squirrel cage winding was removed from a synchronous motor then it is difficult  to bring the motor up to slip speed. If DC is applied then the DC, the motor would stall but it will not rotate.

3.)

Damper windings serve very important function in synchronous machines and generators normally damper windings are auxiliary windings.These damper windings are connected in series with the field windings.The purpose of this damper winding is to help the main windings to set up the complete and sufficient field for the satisfacory working without any discontinuity. In case of synchronous machines ,both the fields(field and armature) should be in synchronism. So therefore Damper windings are very important.