Generally All motor like water Pumping Motors, fans are having different speeds at different loads.The only motors which having constant speed at any load is called as Synchronous motor.The speed of the rotor is equal to the speed of rotating magnetic field of the stator at constant frequency so it named as "Synchronous" Motor.
A Synchronous motor has the following two parts:
A stator which is having 3-phase armature winding in the slots of the stator core and receives power from 3- phase supply, A rotor that as a set of salient poles excited by direct current from alternate N and S poles. the exciting coils are connected in series to two slip ring and current id fed into the winding from external excited mounted on the rotor shaft.
A Synchronous motor has the following two parts:
A stator which is having 3-phase armature winding in the slots of the stator core and receives power from 3- phase supply, A rotor that as a set of salient poles excited by direct current from alternate N and S poles. the exciting coils are connected in series to two slip ring and current id fed into the winding from external excited mounted on the rotor shaft.
A synchronous motor run at synchronous speed is constant (Synchronous speed) at all loads. The only to change its speed is to alter the supply frequency (Ns=120f/p). The outstanding characteristic of a synchronous motor is that it can be made to operate over a wide rang of power factors (lagging, unity or leading) by adjustment of its field excitation. Therefore, a synchronous motor can be made to carry the mechanical load at constant speed and at the same time improve the power factor of the system. Synchronous motors generally of the salient pole type.When the three phase uniformly distributed winding wound on the sator & is supplied with 3-phase a.c supply, a rotating magnetic field of constant magnitude rotating at synchronous speed is produced.
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