Synchronous Motor Multiple Choice Quiz - Set 09 - ObjectiveBooks

# Practice Test: Question Set - 09

1. Which of the following resistances can be measured by conducting insulation resistance test on a synchronous motor?
(A) Phase to phase winding resistance
(B) Stator winding to earthed frame
(C) Rotor winding to earthed shaft
(D) All of the above

2. In a 3-phase, 4-pole, 50 Hz synchronous motor, the frequency, pole number and load torque all are halved. The motor speed will be
(A) 3000 r.p.m.
(B) 1500 r.p.m.
(C) 750 r.p.m.
(D) None of the above

3. Exciters of synchronous machines are
(A) D.C. shunt machines
(B) D.C. series machines
(C) D.C. compound machines
(D) Any of the above

4. A synchronous motor is running on a load with normal excitation. Now if the load on the motor is increased
(A) Power factor as well as armature current will decrease
(B) Power factor as well as armature current will increase
(C) Power factor will increase but armature current will decrease
(D) Power factor will decrease and armature current will increase

5. The speed regulation of a synchronous motor is always
(A) 1 %
(B) 0.5 %
(C) Positive
(D) Zero

6. 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%

7. The power factor of a synchronous motor is better than that of induction motor because
(A) Stator supply is relieved of responsibility of producing magnetic field
(C) Synchronous motor runs at synchronous speed
(D) Synchronous motor has large air gap

8. In a synchronous motor, damper windings are provided on
(A) Stator frame
(B) Rotor shaft
(C) Pole faces
(D) None of the above

9. In a synchronous motor it the back e.m.f. generated in the armature at no-load 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 percent
(D) The excitation is said to be hundred percent

10. The construction of a synchronous motor resembles
(A) A series motor
(B) An induction motor
(C) An alternator
(D) A rotary converter

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