SOLUTION

Synchronous Motor Construction

• The basic construction of a synchronous motor is identical to that of a synchronous generator or Alternator.
• In small sizes, the rotor carries the three-phase windings, and in large sizes, they are provided in the stator and the rotor carries the field winding.
• The stator is made up of laminations with suitable slots to accommodate the winding. The stator winding is also of the same type as in the alternator.
• The rotor is usually of salient pole type except in cases of special application like the synchronous capacitor which is run at high speeds which requires round rotor construction.
• The synchronous motor is likely to hunt and so, damper winding is necessary on the rotor poles.
• Sometimes the damper windings are designed not only for damping out the oscillations in their speed but also for starting.
• When there is an active power reversal at terminals, then the same machine uses it to generate mechanical torque, as now field MMF falls behind armature MMF and in trying to align itself along resultant MMF axis, it generates electromagnetic torque to drive the mechanical load
• Therefore a given synchronous machine can be used as an alternator when driven mechanically.