Three Phase Synchronous Motor

Notes

Operating Principle and Starting Methods of Three Phase Synchronous Motor

The 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 a various method in practice.

No load and load Operation, Effect of Excitation, V and Inverted V curves,Hunting

When the load on the synchronous motor increases, rotor poles lags the stator poles by larger angle and the phase angle between V and Eb will increases.V curve is the graph of rotor current versus stator current & inverted v curve is graph of power factor versus rotor current.

Power Angle Characteristics of Cylindrical Rotor Synchronous Machine and Two Reaction Model of Salient Pole Machine.

In case of cylindrical rotor machine,the reluctance to air gap flux is uniform at any position of rotor and therefore effect of armature reaction fluxes and voltage induced can be treated in a simple way.But in case of salient pole machine the reluctance to air gap flux is not uniform at any position of rotor due to the asymmetrical construction of rotor.So, inductance and hence reactance of armature coil is not constant unlike in a cylindrical rotor.