Electric Drives (3160919) MCQs

MCQs of Induction motor characteristics

Showing 41 to 50 out of 63 Questions
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41.

At no-load, the Iron loss of a 3-phase induction motor is

(a)

Practically Zero
(b)

Large
(c)

Small
(d)

None of the above
Answer:

Option (a)

42.

For higher efficiency of 3-phase induction motor, the slip should be

(a)

Unity
(b)

Large
(c)

As small as possible
(d)

Very large
Answer:

Option (c)

43.

A 3-phase induction motor is running at 2% slip. If the input to rotor is 1000 W, then mechanical power developed by the motor is

(a)

500 W
(b)

200 W
(c)

20 W
(d)

980 W
Answer:

Option (d)

44.

The approximate efficiency of a 3-phase, 50 Hz, 4-pole induction motor running at 1350 r.p.m. is

(a)

90%
(b)

60%
(c)

45%
(d)

100%
Answer:

Option (a)

45.

The field of an induction motor rotor rotates relative to the stator at

(a)

Rotor speed
(b)

Synchronous speed
(c)

Slip speed
(d)

Very low speed
Answer:

Option (b)

46.

The emf induced in the rotor of an induction motor is proportional to

(a)

Voltage applied to stator
(b)

Relative velocity between flux and rotor conductors
(c)

Both (a) and (b) above
(d)

Slip
Answer:

Option (c)

47.

The synchronous speed of an induction motor is defined as

(a)

 Natural speed at which a magnetic field rotates
(b)

The speed of a synchronous motor
(c)

The speed of an induction motor at no load
(d)

None of these
Answer:

Option (a)

48.

The slip frequency of an induction motor is

(a)

The frequency of rotor currents
(b)

The frequency of stator currents
(c)

Difference of the frequencies of the stator and rotor currents
(d)

Sum of the frequencies of the stator and rotor currents
Answer:

Option (a)

49.

With increase of load, the speed of induction motor operating in the stable region

(a)

Increases
(b)

Decreases
(c)

Remains constant
(d)

Increases and then becomes constant
Answer:

Option (b)

50.

When a polyphase induction motor is loaded

(a)

Increases and its frequency decreases
(b)

Increases and its frequency increases
(c)

Decreases and its frequency increases
(d)

Decreases and its frequency decreases
Answer:

Option (a)

Showing 41 to 50 out of 63 Questions
2 3 4 5 6 7