Top 150+ Solved Synchronous Motors MCQ Questions Answer
Q. The operating speed of a synchronous motor can be changed to new fixed value by
a. changing the load
b. changing the supply voltage
c. changing frequency
d. using brakes
Q. A synchronous motor will always stop when
a. supply voltage fluctuates
b. load in motor varies
c. excitation winding gets disconnected
d. supply voltage frequency changes
Q. riunting in a synchronous motor takes place
a. when supply voltage fluctuates
b. when load varies
c. when power factor is unity
d. motor is under loaded
Q. The rotor copper losses, in a synchronous motor, are met by
a. d.c. source
b. armature input
c. motor input
d. supply lines
Q. The maximum power developed in a synchronous motor occurs at a coupling angle of
a. 30°
b. 60°
c. 90°
d. 180°
Q. When the stator windings are connected in such a fashion that the number of polesare made half, the speed of the rotor of a synchronous motor
a. remains same as the original value
b. decreases to half the original value
c. tends to becomes zero
d. increases to two times the original value
Q. In which of the following motors the stator and rotor magnetic field rotate at the same speed ?
a. Universal motor
b. Synchronous motor
c. Induction motor
d. Reluctance motor
Q. Synchronsizingpower of a synchronous machine is
a. direcly proportional to the synchronous reactance
b. inversely proportional to the synchronous reactance
c. equal to the synchronous reactance
d. none of the above
Q. Synchronous motors are
a. not-self starting
b. self-starting
c. essentially self-starting
d. none of the above
Q. The standard full-load power factor ratings for synchronous motors are
a. zero or 0.8 leading
b. unity or 0.8 lagging
c. unity or 0.8 leading
d. unity or zero
Q. A synchronous motor running with normal excitation adjusts to load increasesessentially by increase in
a. back e.m.f.
b. armature current
c. power factor
d. torque angle
Q. A synchronous motor has better power factor as compared to that of an equivalentinduction motor. This is mainly because
a. synchronous motor has no slip
b. stator supply is not required to produce magnetic field
c. mechanical load on the rotor remains constant
d. synchronous motor has large airgap
Q. A synchronous motor working at leading power factor can be used as
a. voltage booster
b. phase advancer
c. noise generator
d. mechanical synchronizer