Synchronous Motor Multiple Choice Questions and Answers

6. Armature of a synchronous machine is kept fixed because

   A.Of reducing number of slip rings on the rotor

   B.Armature is associated with large power as compared to the field circuits

   C.Of difficulty of providing high voltage insulation on rotor

   D.All of the above reasons

7. The power factor of a synchronous motor is better than that of induction motor because

   A.Stator supply is relieved of responsibility of providing magnetic field

   B.Mechanical load on the motor can be adjusted

   C.Synchronous motor runs at synchronous speed

   D.Synchronous motor has large air gap

8. The mechanical displacement of the rotor with respect to the stator, in poly phase multipolar synchronous motors running at full load, is of the order of

   A.Zero-degree

   B.Two degrees

   C.Five degrees

   D.Ten degrees

9. Slip-rings in a synchronous motor carry

   A.Direct Current

   B.Alternating current

   C.No current

   D.All of the above

10. The efficiency of a properly designed synchronous motor will usually fall in range

   A.60 to 70%

   B.75 to 80%

   C.85 to 95%

   D.99 to 99.5%

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