Electric Drives (3160919) MCQs

MCQs of Induction motor characteristics

Showing 31 to 40 out of 63 Questions
1 2 3 4 5 6
31.

The power supplied to a three-phase induction motor is 32 kW and the stator losses are 1200 Watt. If the slip is 5 percent. determine the rotor copper loss

(a)

2.8 kW
(b)

3.5 kW
(c)

4 kW
(d)

1.54 kW
Answer:

Option (d)

32.

Find the output power of the motor if friction and windage losses are 175 Watts

(a)

29.26 kW
(b)

28.51 kW
(c)

30.43 kW
(d)

14.56 kW
Answer:

Option (b)

33.

A 3 phase, 400-V, 50 Hz 4 pole induction motor is fed from a 3-phase supply and runs of 1425 rpm. The frequency of the rotor emf is

(a)

2.5 Hz
(b)

50 Hz
(c)

48 Hz
(d)

Zero
Answer:

Option (a)

34.

The rotor current in a 3-phase induction motor is ________ slip.

(a)

Directly proportional to
(b)

Inversely Proportional to
(c)

Independent
(d)

None of the above
Answer:

Option (a)

35.

A three-phase, four-pole, 50 Hz induction motor rotates at a full-load speed of 1470 rpm. The EMF measured between the slip-ring terminals when the rotor is not rotating is 200 V. The rotor windings are star connected and has resistance and stand-still reactance per phase of 0.1 Ω and 1.0 Ω. respectively. Then the rotor current on full load is

(a)

25 A
(b)

15.43 A
(c)

22.5 A
(d)

11.2 A
Answer:

Option (c)

36.

The starting torque of a 3-phase induction motor is _______________ supply voltage.

(a)

Independent of
(b)

Directly proportional
(c)

Directly proportional to square
(d)

Inversely proportional
Answer:

Option (c)

37.

The starting torque of an induction motor is maximum when rotor resistance per phase is ____________ rotor reactance/phase.

(a)

Equal to
(b)

Less than
(c)

More than
(d)

None of the above
Answer:

Option (a)

38.

The maximum torque of a 3-phase induction motor under running conditions is

(a)

Inversely proportional to the Rotor reactance at standstill
(b)

Inversely proportional to the supply voltage
(c)

Directly proportional to the Resistance
(d)

None of the above
Answer:

Option (a)

39.

The 3-phase induction motor is so designed that the rotor should have _____________ under running conditions.

 

(a)

High resistance
(b)

Low resistance
(c)

Large slip
(d)

High reactance
Answer:

Option (b)

40.

If a 3-phase induction motor is running at slip s, then, rotor copper loss is equal to.

(a)

(1 –  s) × Rotor Input
(b)

(1 + s) × Rotor input
(c)

s × Rotor input
(d)

s × stator input
Answer:

Option (c)

Showing 31 to 40 out of 63 Questions
1 2 3 4 5 6