Explore topic-wise MCQs in Electrical Machines.

This section includes 22 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Machines knowledge and support exam preparation. Choose a topic below to get started.

1.

If the induction motor connected to a power grid draws real power P and reactive power Q. If it is made to run as a generator, then P and Q will be?

A. negative, positive
B. positive, positive
C. positive, negative
D. negative, negative
Answer» B. positive, positive
Discussion
2.

As per the condition given, if a 3-phase squirrel-cage induction motor is operating at a slip of -0.05 then machine will?

A. draw mechanical strength and deliver electrical power to mains
B. draw electrical power from mains and deliver mechanical strength to shaft
C. draw electrical power from shaft and deliver mechanical strength through mains
D. any of the mentioned
Answer» B. draw electrical power from mains and deliver mechanical strength to shaft
Discussion
3.

A 3-phase induction machine is operating on 3-phase fixed frequency ac mains at a per unit slip of 1.5. Then which of the following statements follow the working condition?

A. I, IV
B. I, II
C. II, III
D. III, IVView Answer
Answer» B. I, II
Discussion
4.

A 3-phase, 400 V, 50 Hz delta connected induction motor has power factor of 0.35 when delivering 30% of its load. If it is star connected, then its?

A. p.f. increased and the stator current decreases
B. p.f. worsened and the stator current decreases
C. p.f. increased,and the stator current increases
D. p.f. does not change,and the stator current increase
Answer» B. p.f. worsened and the stator current decreases
Discussion
5.

Static capacitors are used to control power factor of slip ring induction motor only.

A. True
B. False
Answer» C.
Discussion
6.

In double cage induction motor, inner cage has ___________

A. small resistance and large reactance
B. high resistance and high reactance
C. small resistance and small reactance
D. high resistance and small reactance
Answer» B. high resistance and high reactance
Discussion
7.

Induction motor can be fed from ___________

A. either rotor or stator
B. stator
C. rotor
D. neither stator nor rotor
Answer» B. stator
Discussion
8.

If one of the three phases of the induction motor fails due to fault. The motor will ___________

A. stop and do permanent damage if it was running overloaded
B. continue running but will draw more current if it was operating at rated load
C. will not be affect the operation if light loaded
D. any of the mentioned
Answer» E.
Discussion
9.

If an unbalanced supply is fed to an induction motor, it will cause excessive heating of ____________

A. rotor
B. stator
C. rotor shaft
D. all of the mentioned
Answer» B. stator
Discussion
10.

Which tests are to be conducted to draw circle diagram for a given induction motor?

A. A, B, C
B. A, B
C. B, C
D. A,CView Answer
Answer» B. A, B
Discussion
11.

Choose the most appropriate option regarding the power factor control of the induction motor.

A. A: with capacitor
B. B: with capacitor
C. A: with capacitor, B: with capacitor
D. A: with no capacitor, B: with capacitor
Answer» B. B: with capacitor
Discussion
12.

The 3-phase induction motor operates at lagging power factor due to ________

A. II, III
B. I, II
C. II
D. I, II, IIIView Answer
Answer» B. I, II
Discussion
13.

IN_DOUBLE_CAGE_INDUCTION_MOTOR,_INNER_CAGE_HAS?$

A. small resistance and large reactance
B. high resistance and high reactance
C. small resistance and small reactance
D. high resistance and small reactance
Answer» B. high resistance and high reactance
Discussion
14.

A 3-phase, 400 V, 50 Hz delta connected induction motor has power factor of 0.35 when delivering 30% of its load. If it is star connected, then its$

A. p.f. increased and the stator current decreases
B. p.f. worsened and the stator current decreases
C. p.f. increased,and the stator current increases
D. p.f. does not change,and the stator current increase
Answer» B. p.f. worsened and the stator current decreases
Discussion
15.

Static_capacitors_are_used_to_control_power_factor_of_slip_ring_induction_motor_only.$

A. True
B. False
Answer» C.
Discussion
16.

If the induction motor connected to a power grid draws real power P and reactive power Q. If it is made to run as a generator, then P and Q will be

A. negative, positive
B. positive, positive
C. positive, negative
D. negative, negative
Answer» B. positive, positive
Discussion
17.

As per the condition below,

A.
B. draw mechanical strength and deliver electrical power to mains
C. draw electrical power from mains and deliver mechanical strength to shaft
Answer» B. draw mechanical strength and deliver electrical power to mains
Discussion
18.

A 3-phase induction machine is operating on 3-phase fixed frequency ac mains at a per unit slip of 1.5. Then machine is operating in generating mode.

A. True
B. False
Answer» C.
Discussion
19.

Induction motor can be fed fro?

A. either rotor or stator
B. stator
C. rotor
D. neither stator nor rotor
Answer» B. stator
Discussion
20.

Which of the following will not happen if one of the phases to the induction motor is not available?

A. Motor will start but operate at lower speed
B. It will hum but not start
C. It will continue to operate below 57.7% of rated load
D. External means are needed to make it run at rated speed
Answer» B. It will hum but not start
Discussion
21.

If one of the three phases of the induction motor fails due to fault. The motor will

A. stop and do permanent damage if it was running overloaded
B. continue running but will draw more current if it was operating at rated load
C. will not be affect the operation if light loaded
D. any of the mentioned
Answer» E.
Discussion
22.

If an unbalanced supply is fed to an induction motor, it will cause excessive heating of

A. rotor
B. stator
C. rotor shaft
D. All of the mentioned
Answer» B. stator
Discussion