Synchronous Motors Mcqs
Q.1: Synchronous motors are generally not self-starting because:;
A. the direction of rotation is not fixed&
B. the direction of instantaneous torque reverses after half cycle?
C. startes cannot be used on these machines(
D. starting winding is not provided on the machines0
Q.2: In case one phase of a three-phase synchronous motor is short-circuited the motor will____________?c
A. not start
B. run at 2/3 of synchronous speed
C. run with excessive vibrations
D. take less than the rated load
Q.3: A three-phase synchronous motor will have_____________?7
A. no slip-rings
B. one slip-ring
C. two slip-rings
D. three slip-rings
Q.4: When V is the applied voltage, then the breakdown torque of a synchronous motor varies as_________?c
A. V
B. V312
C. V2
D. 1/V
Q.5: The synchronous motor is not inherently self-starting because_______________?M
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 absentO
C. a rotating magnetic field does not have enough poles4
D. the rotating magnetic field is produced by only 50 Hz frequency currentsH
Q.6: An over-excited synchronous motor takes__________?2
A. leading current
B. lagging current
C. both and (b)
D. none of the above
Q.7: For V-curves for a synchronous motor the graph is drawn between:_______________?P
A. armature current and power factor!
B. terminal voltage and load factor
C. power factor and field current
D. field current and armature current"
Q.8: . In a synchronous motor which loss varies with load ?6
A. Windage loss
B. Bearing friction loss
C. Copper loss
D. Core loss
Q.9: The speed regulation of a synchronous motor is always___________?A
A. 1%
B. 0.5%
C. positive
D. zero
Q.10: A synchronous motor will always stop when:______________?9
A. supply voltage fluctuates
B. load in motor varies
C. excitation winding gets disconnected$
D. supply voltage frequency changes

Related Mcqs

All Subject Mcqs