Synchronous Motors MCQ Interview Questions - Set 10 - ObjectiveBooks

Synchronous Motors MCQ Interview Questions - Set 10

Practice Test: Question Set - 10

1. For power factor correction, synchronous motors operate at
    (A) No-load and greatly overexcited fields
    (B) No-load and under-excited fields
    (C) Normal load with minimum excitation
    (D) Normal load with zero excitation

2. Under which of the following conditions hunting of synchronous motor is likely to occur?
    (A) Periodic variation of load
    (B) Over-excitation
    (C) Overloading for long periods
    (D) Small and constant load

3. A synchronous machine with low value of short-circuit ratio has
    (A) Lower stability limit
    (B) High stability limit
    (C) Good speed regulation
    (D) Good voltage regulation

4. The back e.m.f. of a synchronous motor depends on
    (A) Speed
    (B) Load
    (C) Load angle
    (D) All of the above

5. 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

6. The angle between the rotating stator flux and rotor poles is called _________ angle.
    (A) Torque
    (B) Obtuse
    (C) Synchronizing
    (D) Power factor

7. When a 3-phase synchronous generator is supplying a zero power factor lagging load, the armature field affects the main field in the following way
    (A) Augments it directly
    (B) Directly opposes it
    (C) Cross-magnetizes it
    (D) None of the above

8. In a 3-phase synchronous motor, the negative phase sequence exists when the motor is
    (A) Supplied with unbalanced voltage
    (B) Under-loaded
    (C) Overloaded
    (D) None of the above

9. 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

10. The minimum armature current of the synchronous motor corresponds to operation at
    (A) Zero power factor leading
    (B) Unity power factor
    (C) 0.707 power factor lagging
    (D) 0.707 power factor leading

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