MCQ on Synchronous motor – 1

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 1. The construction of a synchronous motor is similar to
(A) a series motor.
(B) an induction motor.
(C) an alternator.
(D) a shunt motor.

 2. Exciters of synchronous machines are
(A) synchronous machines.
(B) d.c. shunt machines.
(C) d.c. series machines.
(D) d.c. compound machines.

 3. In a synchronous motor, the slip rings are design to carry
(A) direct current.
(B) alternating current.
(C) no current.
(D) peak current.

 4. Synchronous motors are
(A) not-self starting.
(B) self-starting.
(C) essentially self-starting.
(D) none of the above.

 5. If one phase of a three-phase synchronous motor is short-circuited the motor will
(A) run at synchronous speed.
(B) fail to start.
(C) run with zurk.
(D) run at lower speed.

 6. A synchronous motor can develop synchronous torque
(A) when under loaded.
(B) while over-excited.
(C) only at synchronous speed.
(D) at startig.

 7. A three-phase synchronous motor will have
(A) no slip-rings.
(B) one slip-ring.
(C) two slip-rings.
(D) three slip-rings

 8. Which of the following motors is non-self starting ?
(A) D.C. series motor.
(B) synchronous motor.
(C) Squirrel cage induction motor.
(D) Wound round induction motor.

 9. If the field of a synchronous motor is underexcited, the power factor will be
(A) zero.
(B) unity.
(C) lagging.
(D) leading.

 10. A synchronous motor working at leading power factor can be used as
(A) alternator.
(B) voltage booster..
(C) phase advancer.
(D) phase reactor .

 11. An over excited synchronous motor can be used for
(A) capacitive loads.
(B) variable speed loads.
(C) power factor improvement.
(D) proving starting torque.

 12. The angle between the rotating stator flux and rotor poles is known as
(A) load angle.
(B) torque angle.
(C) synchronizing.
(D) power factor.

 13. The operating speed of a synchronous motor can be changed by
(A) changing the load.
(B) changing the supply voltage.
(C) changing frequency.
(D) changing exitation.

 14. Hunting 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.

 15. In a synchronous motor, the main function of using damping winding is to
(A) reduce armature reaction.
(B) prevent hunting only.
(C) provide starting torque only.
(D) prevent hunting and provide the starting torque.

 16. 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.

 17. Which of the following motor can also be run as a rotory converter?
(A) d.c. shunt motor.
(B) d.c. series motor.
(C) induction motor.
(D) synchronous motor.

 18. In a synchronous motor, damper windings are provided on
(A) stator frame.
(B) rotor shaft.
(C) pole faces.
(D) none of the above.

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