The construction of a synchronous motor resembles____________?
A. a series motor
B. an induction motor
C. an alternator
D. a rotary converter
Synchronous Motors
For power factor correction, synchronous motors operate at____________?
For power factor correction, synchronous motors operate at____________?
A. no-load and greatly over-excited fields
B. no-load and under-excited fields
C. normal load with minimum excitation
D. normal load with zero excitation
Which of the following losses is not dissipated by the stator core surface in a synchronous motor?
Which of the following losses is not dissipated by the stator core surface in a synchronous motor?
A. Eddy current losses in the conductors
B. Iron losses in the stator
C. Copper losses in the slot portion of the conductors
D. Windage losses
E. None of the above
The size of a synchronous motor decreases with the increase in___________?
The size of a synchronous motor decreases with the increase in___________?
A. flux density
B. horse power rating
C. speed
D. all of the above
Which of the following losses, in a synchronous motor, does not vary with load?
Which of the following losses, in a synchronous motor, does not vary with load?
A. Windage loss
B. Copper losses
C. Any of the above
D. None of the above
In a synchronous motor, the armature current has large values for____________?
In a synchronous motor, the armature current has large values for____________?
A. high excitation only
B. low excitation only
C. both high and low excitation
D. none of the above
The back e.m.f. in the stator of a synchronous motor depends on____________?
The back e.m.f. in the stator of a synchronous motor depends on____________?
A. number of poles
B. flux density
C. rotor speed
D. rotor excitation
E. none of the above
If the field of a synchronous motor is underexcited, the power factor will be_____________?
If the field of a synchronous motor is underexcited, the power factor will be_____________?
A. zero
B. unity
C. lagging
D. leading
In a synchronous motor, the damping winding is generally used to______________?
In a synchronous motor, the damg winding is generally used to______________?
A. reduce noise level
B. reduce the eddy currents
C. provide starting torque only
D. prevent hunting and provide the starting torque
E. none of the above
In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then
In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then
A. the motor is said to be fully loaded
B. the torque generated is maximum
C. the excitation is said to be zero per cent
D. the excitation is said to be hundred per cent