Electrical Machine - II (3150910) MCQs

MCQs of Synchronous & Auto Synchronous Motors

Showing 41 to 50 out of 68 Questions
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41.

If load angle of 4 pole synchronous motor is 8o electrical its value in mechanical degree is

(a)

2
(b)

4
(c)

8
(d)

16
Answer:

Option (b)

42.

In a synchronous motor, the synchronizing power comes into action when

(a)

Rotor speed is less than synchronous speed
(b)

Rotor speed is more than synchronous speed
(c)

Rotor speed is equal to synchronous speed
(d)

Rotor speed is either less or more than synchronous speed
Answer:

Option (d)

43.

In a 3-phase synchronous motor, the magnitude of field flux in study state condition 

(a)

Remains constant at all loads
(b)

Varies with speed
(c)

Varies with load
(d)

Varies with power factor
Answer:

Option (a)

44.

In a synchronous motor, Which method is/are used to perform magnetic locking (Starting)?

(a)

Induction Motor
(b)

Prime Mover or Pony Motor (Auxiliary motor - DC/AC)
(c)

Low Supply Frequency
(d)

All of these 
Answer:

Option (d)

45.

In which of the following motor, the stator and rotor magnetic field rotates at the same speed w.r.t. Sator?

(a)

Universal motor
(b)

Synchronous motor
(c)

Induction motor
(d)

Reluctance motor
Answer:

Option (b)

46.

A 3 phase synchronous motor is working at normal excitation, then the flux deficient in a circuit is ________

(a)

given by armature winding mmf
(b)

given by field winding mmf
(c)

supplied to armature winding mmf
(d)

supplied to field winding mmf
Answer:

Option (a)

47.

The excess flux in synchronous motor is neutralized by ________

(a)

armature winding by drawing demagnetizing component of the current from ac supply
(b)

armature winding by drawing magnetizing component of the current from ac supply
(c)

field winding by drawing demagnetizing component of the current from dc supply
(d)

field winding by drawing magnetizing component of the current from dc supply
Answer:

Option (a)

48.

The V-curves of synchronous motor is plotted between ________

(a)

Ia Vs If with constant shaft load
(b)

 If Vs Ia with constant shaft load
(c)

power factor vs If
(d)

power factor vs Ia
Answer:

Option (a)

49.

The inverse V-curves of synchronous motor is plotted between ________

(a)

armature current vs field current
(b)

field current vs power factor for variable shaft load
(c)

power factor vs field current for constant shaft load
(d)

terminal voltage vs power factor
Answer:

Option (c)

50.

When a constant power output is desired to maintain ________

(a)

Eb*sinδ is be maintained constant
(b)

Ia*cosθ is to be maintained constant
(c)

Eb*sinδ and Ia*cosθ are to be maintained constant
(d)

Eb*sinδ and Ia*sinθ are to be maintained constant
Answer:

Option (c)

Showing 41 to 50 out of 68 Questions
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