Introduction to Industrial Automation

Review Questions

  2.1.  What kind of materials can detect an inductive proximity switch and why?

  2.2.  How many categories of relays exist regarding to their use in industry? Explain each one of them.

  2.3. Is a thermal overload relay really a switch breaking a load circuit?

 2.4. Can a latching relay be considered as an electromechanical type of memory? If yes, how 

many bits of data can be stored in it? 

  2.5.  In your opinion, can the electronic level switch with immersed electrodes be used for detect-

ing the level of a tank containing kerosene?

  2.6. Explain if capacitive type proximity switches can detect metallic objects or not.

  2.7.  Describe two different ways to detect the end position of a pneumatic cylinder.

  2.8. What is the role of auxiliary relays in an automation system and what are the corresponding 

power relays?

A

B

Shaft

Rotating

code disk

Coding for

clockwise

rotation

Stationary disk

Coding for

counterclockwise

rotation

Coding track on disk

A

B

Z

A

B

Z

Encoder output

90 degrees

Phase

A

B

Phase

A

B

1

0

0

2

0

1

3

1

1

4

1

0

1

1

0

2

1

1

3

0

1

4

0

0