DC Motors MCQs

Welcome to our comprehensive collection of Multiple Choice Questions (MCQs) on DC Motors, 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 Motors 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 Motors mcq questions that explore various aspects of DC Motors problems. Each MCQ is crafted to challenge your understanding of DC Motors 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 Motors 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 Motors. 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 Motors knowledge to the test? Let's get started with our carefully curated MCQs!

DC Motors MCQs | Page 7 of 13

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Q61.
Working range of the speed-torque characteristic, with increasing speed will ___________

a.

Reduce

b.

Increase

c.

Remain same

d.

Cannot comment

Discuss
Answer: (a).Reduce
Q62.
For speed x rpm, we get field current If₁ and for speed y rpm, we get the field current If₂. If y is greater than x then, ________________

a.

If₁ < f₂

b.

If₁ > If₂

c.

If₁ = If₂

d.

Cannot comment on If₁, If₂

Discuss
Answer: (b).If₁ > If₂
Q63.
400-V dc shunt motor takes a current of 5.6 A on no-load and 68.3 A on full-load. Armature reaction weakens the field by 3%. What is the ratio of full-load speed to no-load speed? Given: Ra = 0.18 Ω, brush voltage drop= 2 V, Rf = 200 Ω.

a.

1.2

b.

0.8

c.

1.4

d.

1

Discuss
Answer: (d).1
Q64.
In which of the following method, effect of armature reaction is more?

a.

Field weakening method

b.

Armature resistance control

c.

Same in both methods

d.

Cannot be determined

Discuss
Answer: (a).Field weakening method
Q65.
Which of the following DC motor has the poorest speed control?

a.

Differentially compounded motor

b.

Cumulatively compounded motor

c.

Shunt motor

d.

Series motor

Discuss
Answer: (d).Series motor
Q66.
In variable speed motor ____________

a.

Stronger commutating field is needed at low speed than at high speed

b.

Weaker commutating field is needed at low speed than at high speed

c.

Same commutating field is needed at low speed and at high speed

d.

Cannot be determined

Discuss
Answer: (b).Weaker commutating field is needed at low speed than at high speed
Q67.
The speed of a motor falls from 1200 rpm at no-load to 1050 rpm at rated load. The speed regulation of the motor is ____________

a.

12.36%

b.

14.28%

c.

16.77%

d.

18.84%

Discuss
Answer: (b).14.28%
Q68.
Which of the following is not the method of speed control in DC series motor?

a.

Diverter

b.

Tapped-field control

c.

Variable resistance in series with armature

d.

Series- parallel control

Discuss
Answer: (c).Variable resistance in series with armature
Q69.
For speed reversal, field control method is suitable.

a.

True

b.

False

c.

May be True or False

d.

Can't say

Discuss
Answer: (b).False
Q70.
For large motors what is the ratio of compensating winding is required for increasing the speed of the motor?

a.

2:1

b.

4:1

c.

6:1

d.

8:1

Discuss
Answer: (a).2:1
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