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# Test: Speed Control of DC Motors

## 10 Questions MCQ Test Electrical Machines | Test: Speed Control of DC Motors

Description
This mock test of Test: Speed Control of DC Motors for Electrical Engineering (EE) helps you for every Electrical Engineering (EE) entrance exam. This contains 10 Multiple Choice Questions for Electrical Engineering (EE) Test: Speed Control of DC Motors (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Speed Control of DC Motors quiz give you a good mix of easy questions and tough questions. Electrical Engineering (EE) students definitely take this Test: Speed Control of DC Motors exercise for a better result in the exam. You can find other Test: Speed Control of DC Motors extra questions, long questions & short questions for Electrical Engineering (EE) on EduRev as well by searching above.
QUESTION: 1

### The PWM control of DC motor varies

Solution:

In PWM technique duty ratio is a linear function with respect to speed.

QUESTION: 2

### Ward-Leonard system of system of speed control is not recommended for

Solution:

Ward-Leonard system of system of speed control is not recommended for constant speed operation.

QUESTION: 3

### Mark the wrong option. Which of the following cause and effect behaviour in speed control is correct when field resistance is increased.

Solution:

When field resistance is increased, emf actually decreases, not increases due to fall in flux.

QUESTION: 4

At a very low speed, increase in field resistance will

Solution:

At low speed increase in armature current caused by decrease in emf, will not be enough to compensate for decrease in flux in induced torque equation.

QUESTION: 5

Small DC motors have best speed control by

Solution:

For the small dc motors it is difficult to vary the speed using their field control.

QUESTION: 6

To implement armature voltage control, it must be ensured that

Solution:

It must be separately excited mahcine to implement the armature voltage control.

QUESTION: 7

Armature voltage control works for speeds _____ base speed and field resistance control works well for speed _____ base speed.

Solution:

For armature voltage control, armature current is increased so as to reduce speed below base speed. In field control flux is reduced so the speed would be above base speed.

QUESTION: 8

The torque limit of speed for a shunt motor

Solution:

The torque limit of the shunt motor remains constant till the base speed.

QUESTION: 9

A laboratory group was working with a set of 3-hp shunt DC motor. But there was a mistake that it was fused with a 0.3A fuse instead 3A fuse. Then it was started

Solution:

Due to the wrong usage of the fuse wire, it could not sustain the current and in few seconds it was blown off.

QUESTION: 10

Run-away for large DC machine is avoided by using

Solution:

The runaway in large machine is avoided by using compensating winding.