In a 3-phase, 4-pole, 50 Hz synchronous motor, the frequency, pole number and load torque all are halved. The motor speed will be____________?
A. 3000 r.p.m.
B. 1500 r.p.m.
C. 750 r.p.m.
D. none of the above
A. 3000 r.p.m.
B. 1500 r.p.m.
C. 750 r.p.m.
D. none of the above
A. armature current and field current
B. power factor and speed
C. field current and speed
D. field current and power factor
In a synchronous motor, V-curves represent relation between____________? Read More »
Synchronous Motors A. By changing the supply frequency
B. By interchanging any two phases
C. By changing the applied voltage
D. By changing the load
A. the supply voltage and the back e.m.f.
B. magnetising current and back e.m.f.
C. the rotating stator flux and rotor poles
D. none of the above
The torque angle, in a synchronous motor, is the angle between_______________? Read More »
Synchronous Motors A. the motor will stop
B. the motor continue to run in the same direction
C. the winding of the motor will burn
D. the motor will run in the reverse direction
E. none of the above
A. vector sum of Eb and V
B. arithmetic sum of Eb and V
C. arithmetic difference of Eb and V
D. vector difference of Eh and V
The net armature voltage of a synchronous motor is equal to the_______________? Read More »
Synchronous Motors A. stator frame
B. rotor shaft
C. pole faces
D. none of the above
In a synchronous motor, damper windings are provided on____________? Read More »
Synchronous Motors A. supplied with unbalanced voltage
B. under-loaded
C. over-loaded
D. none of the above
A. High field current
B. Low short circuit ratio
C. High core losses
D. Low field current
A. d.c. shunt motor
B. d.c. series motor
C. d.c. compound motor
D. induction motor
E. synchronous motor
A rotory converter can also be run as a___________? Read More »
Synchronous Motors