DC Machines Basics MCQs

Welcome to our comprehensive collection of Multiple Choice Questions (MCQs) on DC Machines Basics, a fundamental topic in the field of DC Machines. Whether you're preparing for competitive exams, honing your problem-solving skills, or simply looking to enhance your abilities in this field, our DC Machines Basics MCQs are designed to help you grasp the core concepts and excel in solving problems.

In this section, you'll find a wide range of DC Machines Basics mcq questions that explore various aspects of DC Machines Basics problems. Each MCQ is crafted to challenge your understanding of DC Machines Basics principles, enabling you to refine your problem-solving techniques. Whether you're a student aiming to ace DC Machines tests, a job seeker preparing for interviews, or someone simply interested in sharpening their skills, our DC Machines Basics MCQs are your pathway to success in mastering this essential DC Machines topic.

Note: Each of the following question comes with multiple answer choices. Select the most appropriate option and test your understanding of DC Machines Basics. You can click on an option to test your knowledge before viewing the solution for a MCQ. Happy learning!

So, are you ready to put your DC Machines Basics knowledge to the test? Let's get started with our carefully curated MCQs!

DC Machines Basics MCQs | Page 5 of 6

Discover more Topics under DC Machines

Q41.
How to avoid grooves in the commutation of DC machine with the help of brush?

a.

Brushes of opposite polarity should track each other

b.

Brushes of same polarity should track each other

c.

Brush position has no effect on the commutator grooving

d.

Brushes should not track each other

Discuss
Answer: (a).Brushes of opposite polarity should track each other
Q42.
Reason behind the rapid wear of brushes is __________

a.

Abrasion from dust

b.

Excessive spring pressure

c.

Rough commutator bars

d.

Abrasion from dust, excessive spring pressure and rough commutator bars

Discuss
Answer: (d).Abrasion from dust, excessive spring pressure and rough commutator bars
Q43.
For both lap and wave windings, what is the number of commutator bars equal to?

a.

Slots

b.

Armature conductors

c.

Winding elements

d.

Poles

Discuss
Answer: (c).Winding elements
Q44.
Spacing between the brushes for a 4-pole machine in terms of commutator segments for 12 conductor segments is _____

a.

48

b.

3

c.

2

d.

6

Discuss
Answer: (b).3
Q45.
Spacing between the brushes for a 4-pole machine in terms of commutator segments is equal to 6. What will be the number of armature slots?

a.

48

b.

3

c.

24

d.

6

Discuss
Answer: (c).24
Q46.
What is the range of the brush friction coefficients for medium category?

a.

0.40 and above

b.

0.22 to 0.40

c.

0.11 to 0.22

d.

0.08 to 0.11

Discuss
Answer: (b).0.22 to 0.40
Q47.
Specific resistance for a brush is given by _________

a.

R = (E * W * T) / (I * L)

b.

R = (E * W * I) / (T * L)

c.

R = (E * W * I) * (T * L)

d.

Doesn’t depend on E, W, T, I, L.

Discuss
Answer: (a).R = (E * W * T) / (I * L)
Q48.
How many poles to be used in DC machine if brushes are placed 4 commutator segments apart for 16 commutator segments?

a.

8

b.

12

c.

2

d.

4

Discuss
Answer: (d).4
Q49.
DC generators are disconnected/connected from/to the busbars only under the floating condition because ____________

a.

To avoid sudden loading of the prime mover

b.

To avoid burning of all switch contacts

c.

To avoid mechanical jerk to the shaft

d.

To avoid sudden loading of the prime mover, burning of all switch contacts and avoid mechanical jerking to the shaft

Discuss
Answer: (d).To avoid sudden loading of the prime mover, burning of all switch contacts and avoid mechanical jerking to the shaft
Q50.
In PMDC motors we use magnetic material with ___________

a.

Low residual flux

b.

Low coercivity

c.

High residual flux

d.

All magnetic materials

Discuss
Answer: (c).High residual flux
Page 5 of 6