A. zero or 0.8 leading
B. unity or 0.8 lagging
C. unity or 0.8 leading
D. unity or zero
The standard full-load power factor ratings for synchronous motors are___________? Read More »
Synchronous Motors A. d.c. source
B. armature input
C. motor input
D. supply lines
The rotor copper losses, in a synchronous motor, are met by____________? Read More »
Synchronous Motors A. supply voltage fluctuates
B. load in motor varies
C. excitation winding gets disconnected
D. supply voltage frequency changes
A synchronous motor will always stop when:______________? Read More »
Synchronous Motors A. 1%
B. 0.5%
C. positive
D. zero
The speed regulation of a synchronous motor is always___________? Read More »
Synchronous Motors A. Windage loss
B. Bearing friction loss
C. Copper loss
D. Core loss
. In a synchronous motor which loss varies with load ? Read More »
Synchronous Motors A. armature current and power factor
B. terminal voltage and load factor
C. power factor and field current
D. field current and armature current
For V-curves for a synchronous motor the graph is drawn between:_______________? Read More »
Synchronous Motors A. leading current
B. lagging current
C. both A. and (b)
D. none of the above
An over-excited synchronous motor takes__________? Read More »
Synchronous Motors A. the force required to accelerate the rotor to the synchronous speed in an instant is absent
B. the starting device to accelerate the rotor to near synchronous speed is absent
C. a rotating magnetic field does not have enough poles
D. the rotating magnetic field is produced by only 50 Hz frequency currents
The synchronous motor is not inherently self-starting because_______________? Read More »
Synchronous Motors A. V
B. V312
C. V2
D. 1/V
A. no slip-rings
B. one slip-ring
C. two slip-rings
D. three slip-rings
A three-phase synchronous motor will have_____________? Read More »
Synchronous Motors