Explore topic-wise MCQs in Electrical Machines.

This section includes 23 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.

While the operation of dc motor, there are sparkings at the commutation observed. These can be happening due to ________

A. under commutation
B. over commutation
C. too rapid reversal of the current
D. any of the mentioned
Answer» E.
Discussion
2.

Under commutation results ________

A. sparking at the trailing edge of brush
B. sparking at the leading edge of brush
C. sparking at the middle of brush
D. any of the mentioned
Answer» B. sparking at the leading edge of brush
Discussion
3.

The armature rotation in the dc machine and the magnetic field are independent of each other and obey laws of conservation of energy.

A. True
B. False
Answer» B. False
Discussion
4.

The brushes in dc machine are normally placed electrically in interpolar region to ________

A. make an angle of 90 deg. electrical
B. make an angle of 90 deg. mechanical
C. make an angle of 0 deg. electrical
D. none of the mentioned
Answer» B. make an angle of 90 deg. mechanical
Discussion
5.

For a four pole, 16 slot armature with two coil-side/slot having wave connected progressive winding has single turn coils. The commutator pitch for the machine should be ________

A. 1
B. -1
C. +1 and 1
D. none of the mentioned
Answer» B. -1
Discussion
6.

For a four pole, 16 slot armature with two coil-side/slot having lap connected progressive winding has single turn coils. Then number of commutator segment is?

A. 16
B. 32
C. 4
D. 8
Answer» B. 32
Discussion
7.

A 200 V dc machine working at rated speed. Voltage across the commutating terminals should ideally be ________

A. zero
B. 2 V
C. 1 V
D. 200 V
Answer» B. 2 V
Discussion
8.

Operation of a dc machine will ________

A. not be affected by commutating poles
B. be affected by commutating poles
C. be affected significantly upto 30% spread of commutating poles
D. none of the mentioned
Answer» B. be affected by commutating poles
Discussion
9.

Inductive kick causes ________

A. sparking at the brushes of the machine
B. similar problems when neutral phase shift takes place in the armature
C. large current to flow in the equalizer rings
D. none of the mentioned
Answer» B. similar problems when neutral phase shift takes place in the armature
Discussion
10.

What is Inductive kick?

A. reactance voltage in commutator segments
B. reactance voltage in shorted commutator segments
C. impulsive voltage in commutator segments
D. none of the mentioned
Answer» B. reactance voltage in shorted commutator segments
Discussion
11.

What is Commutator?

A. rotating segment to which brushes are attached
B. stationary segment to which rotating brushes are attached
C. rotating segment to which rotating brush segment is attached
D. any of the mentioned
Answer» B. stationary segment to which rotating brushes are attached
Discussion
12.

THE_BRUSHES_IN_DC_MACHINE_ARE_NORMALLY_PLACED_ELECTRICALLY_IN_INTERPOLAR_REGION,_TO?$

A. make an angle of 90 deg. electrical
B. make an angle of 90 deg. mechanical
C. make an angle of 0 deg. electrical
D. none of the mentioned
Answer» B. make an angle of 90 deg. mechanical
Discussion
13.

Under commutation results$

A. sparking at the trailing edge of brush
B. sparking at the leading edge of brush
C. sparking at the middle of brush
D. any of the mentioned
Answer» B. sparking at the leading edge of brush
Discussion
14.

The armature rotation in the dc machine and the magnetic field are independent of each other and obey laws of conservation of energy.$

A. True
B. False
Answer» B. False
Discussion
15.

While the operation of dc motor, there are sparkings at the commutation observed. These can be happening due to

A. under commutation
B. over commutation
C. too rapid reversal of the current
D. any of the mentioned
Answer» E.
Discussion
16.

For a four pole, 16 slot armature with two coil-side/slot having wave connected progressive winding has single turn coils. The commutator pitch for the machine should b?

A. 1
B. -1
C. +1 and 1
D. none of the mentioned
Answer» B. -1
Discussion
17.

For a four pole, 16 slot armature with two coil-side/slot having lap connected progressive winding has single turn coils. Then number of commutator segment is

A. 16
B. 32
C. 4
D. 8
Answer» B. 32
Discussion
18.

A 200 V dc machine working at rated speed. Voltage across the commutating terminals should ideally be

A. zero
B. 2 V
C. 1 V
D. 200 V
Answer» B. 2 V
Discussion
19.

Operation of a dc machine will

A. not be affected by commutating poles
B. be affected by commutating poles
C. be affected significantly upto 30% spread of commutating poles
D. none of the mentioned
Answer» B. be affected by commutating poles
Discussion
20.

Inductive kick causes

A. sparking at the brushes of the machine
B. similar problems when neutral phase shift takes place in the armature
C. large current to flow in the equalizer rings
D. none of the mentioned
Answer» B. similar problems when neutral phase shift takes place in the armature
Discussion
21.

Inductive kick is

A. reactance voltage in commutator segments
B. reactance voltage in shorted commutator segments
C. impulsive voltage in commutator segments
D. none of the mentioned
Answer» B. reactance voltage in shorted commutator segments
Discussion
22.

Commutator action is analogous to _________ in analog electronics.

A. full wave rectifier
B. half wave rectifier
C. comparator
D. amplifier
Answer» B. half wave rectifier
Discussion
23.

Commutator is a

A. rotating segment to which brushes are attached
B. stationary segment to which rotating brushes are attached
C. rotating segment to which rotating brush segment is attached
D. any of the mentioned
Answer» B. stationary segment to which rotating brushes are attached
Discussion