Salient pole rotor
2
Relative velocity between the stator and the rotor mmfs is zero
The rotor mmf and stator mmf are stationary with respect to each other
Remains stationary with respect to stator
Synchronous motor
Remains constant at all loads
The armature mmf leads the air gpap flux and air gap flux leads the field mmf
All the above machine
No starting torque
24
Continuously
Leads the applied voltage by 900
Remains constant and additional load is supplied by shift in relative position no of the rotor with respect to stator rotating magnetic field
The rotor pole falls back relative to the stator pole causing an increase in motor current
Increase in resultant voltage across the armature
Phasor difference
Load
Rotor speed either exceeds or falls below the synchronous speed
Rotor and stator poles of opposite polarity