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DC Motor Speed Control - From Basic to Breakthroughs

Total questions: 10

Worksheet time: 5mins

Name
Class
Date
1.

Which of the following is a traditional method for controlling the speed of a DC motor?

a)

Using an inverter

b)

Adding resistance in the armature circuit

c)

Using a thyristor-based chopper

d)

Changing the polarity of the motor

2.

What effect does increasing the armature voltage have on the speed of a DC motor?

a)

It decreases the motor speed

b)

It increases the motor speed

c)

It has no effect on the motor speed

d)

It reverses the motor direction

3.

In a DC shunt motor, speed is primarily controlled by adjusting which of the following?

a)

The magnetic field strength

b)

The rotor resistance

c)

The load torque

d)

The supply voltage to the field windings

4.

What is the primary advantage of using chopper control in DC motor speed regulation?

a)

Lower cost

b)

Increased mechanical reliability

c)

High efficiency and precise control

d)

Simpler design compared to traditional methods

5.

In separately excited DC motors, how is the field flux controlled?

a)

By varying the load resistance

b)

By changing the field current

c)

By altering the armature voltage

d)

By adjusting the motor’s mechanical load

6.

Which control method is best suited for large variations in DC motor speed while maintaining high efficiency?

a)

Field flux control

b)

Armature resistance control

c)

Chopper control

d)

Mechanical load adjustment

7.

When controlling the speed of a DC motor by adding resistance to the armature circuit, what happens to the motor’s torque?

a)

Torque increases

b)

Torque remains constant

c)

Torque decreases

d)

Torque becomes unstable

8.

Thyristor-based speed control for DC motors is commonly used because it provides:

a)

High starting torque

b)

Smooth, stepless speed control

c)

Low efficiency in high-torque applications

d)

Constant speed control only

9.

Which of the following is a disadvantage of armature resistance control for DC motors?

a)

It leads to a decrease in efficiency

b)

It offers high torque at low speeds

c)

It provides smooth and continuous speed control

d)

It reduces motor size and cost

10.

What happens when you reduce the field current in a separately excited DC motor?

a)

Motor speed decreases

b)

Motor speed increases

c)

Motor torque increases

d)

Motor efficiency drops significantly