1. Electro-Pneumatics Module 1
Introduction to
Electro-pneumatics

2. Module Objectives
After the completion of this module, the student will be able to:
1- Explain all safety precaution when working with electro-pneumatics.
2- Explain the concept of signal flowing in electro-pneumatics.
3- Identify the advantages and disadvantages of the electro-pneumatics.

3. Module Contents 1. Introduction to electro-pneumatics
2. Signal flow in electro-pneumatics
3. Advantages of electro-pneumatic systems
4. Components of electro-pneumatic system
5. Safety and operation
6. Practical task
7. Practical task
8. Practical task

4. Uses of Electro-Pneumatics
Widely used in many areas of
Industrial automation.
Production,
assembly,
packaging systems
Examples of applications are:
Milk filling machine
Yogurt filling machine

5. Electro-Pneumatics It’s components are controlled by:
Electrical and electronic circuits.
Electronic and electromagnetic sensors,
Electrical switches
Industrial computers are used to replace the manual control of a pneumatic system.

6. Signal flow in electro-pneumatic control system

8. Signal flow
1. Signal input: usually generated from a sensor or a switch.
2. Signal processing: It is processed in the processing station such as OR gate, AND gate or time delay valve.
3. Signal output: the signal forms as a link between the signal control section and the power section
4. Command execution: it takes place at high power level either for:
High speed-fast ejection of product.
Apply high force as in power presses.

9. Advantages of electro-pneumatic systems
Greater reliability (Less moving parts subjected to wear).
Reduced installation complexity (Less components and hoses).
3. The control system can be easily modified and adapted (It is easier to change wiring and modify programs rather than changing mechanical components and hose networks).
4. Easy handling (less complexity).
5. Secure mounting (fewer hoses).
6. Environmentally-friendly coupling system (Less lubrication require).

10. Components of electro-pneumatic system
1. DC power supply. 2. Switches. 3. Relays. 4. Solenoid valves. 5. Sensor.

11. The DC power supply
It is used to reduce and convert the 230 V AC to a 24 V DC
It’s components are:
Transformer
Rectifier
Stabilizer

12. The DC power supply

13. Criteria for selecting power supplies
The magnitude of voltage and current it can supply.
How stable its output voltage or current is under varying load conditions.
Whether it provides continuous or pulsed energy.

14. Switches
They are installed in an electric circuit to connect or interrupt the electric current.
They are divided into:
1- Control switches: keep the selected position such as detent switches.
2. Push button switches: maintain the selected position as long as the switch is activated.

15. Types of switches to be discussed
Push button switches.
Detent switches.
Limit switches

16. Push button switches
They are activated manually and used connect or disconnect the electric current in he control circuit.
There are three typed of the push button switches:
Normally open contact (make)
Normally close contact (break)
Changeover contact (two way)

17. Normally open contact (make)
In this case the circuit is open if the switch is in its initial position
Pressing the pushbutton results in closing the circuit and then the current will flow to load.
When the plunger is released the spring will returns the switch to it initial position.

18. Normally close contact (break)
In this case the circuit is closed when the switch is in its initial position.
The circuit is interrupted by pressing the pushbutton..

19. Changeover contact (two way)
It combines the function of the normally open and normally closed.
They are used to close one circuit and open another circuit in one switching operation.
In the (ATHS) labs, these types of switches are combined in one switch block

20. Detent switches
These switches keep the selected position; the switch position remains unchanged until a new switch position is selected.
It is called detent switch or a latching switch.
They are designed to be as normally open, normally closed or changeover switches.
Symbol of N/C
detent Switch
Symbol of N/O
Detent Switch

21. Limit switches

22. Limit switches
The limit switch is actuated when a machine part or a work-piece is in a certain position. Normally, actuation is affected by a cam or cylinder piston.
They are normally changeover contacts.
The limit switch can be used in circuits according to one of the following:
Normally open switch
Normally closed switch
Changeover switch

23. Relays A relay is defined as an electromagnetically actuated switch.
When the voltage is applied to a solenoid coil terminals (A1, A2) will become an electromagnet which in turn attracts the contacts of the relay either closing or opening them.

24. Relays
The spring returns the contacts to the initial position immediately after disconnecting the voltage at the coil terminals.

25. Some advantages of a relay
It can be used to switch one or more contacts.
To switch a high current circuit with a low current circuit
Relay block
Relay
Symbol

26. Safety and operation
1. Pressurized air lines that become detached can cause accidents. Switch off pressure immediately. 2. First connect all tubing and secure before switching on the compressed air. 3. Cylinders may advance or retract as soon as the compressed air is switched on. 4. Do not operate the electrical limit switch manually during fault finding (use a tools only).

27. Safety and operation
5. Limit switches should be fixed in such a way that they contact the trip cam of the cylinder only in the determined direction. 6. Do not exceed the permissible working pressure. 7. Use only low voltages of ≤ 24 V. 8. Switch off the air and voltage supply before disconnecting the circuit.

28. Practical Task 1
Controlling an electric bulb lighting using different types of switches.
Background:
The student should know how to use the Pushbutton, detent and changeover switches that will be used to switch on/off a lamp using different circuit configurations.

29. Practical Task 1 Required components: 1- DC power supply (Fig. a)
2- Indicator unit (Fig. b)
3- Switch block (Fig. c)
4- Limit switch (Fig. d)
(a)
(b)
(c)
(d)

30. Practical Task 1 Procedures: Use a Push Button and a Detent Switch.
N.O NC

31. Practical Task 1 Procedures:
Use a limit Switch as a change over switch

32. Indirect control of a lamp using a pushbutton switch and a relay.
Background:
The relay is an electromagnetically operated switch; it will be used to indirectly control a 24V lamp through a pushbutton switch.
Required Components:
1- DC power supply
2- Indicator unit
3- Switch block
4- Relay block

33. Indirect control of a lamp using a pushbutton switch and a relay.
Connect with a Push Button and a relay (N/O) and (N/C) and press the push button. AND OBSERVE
(N/C) Relay
(N/O) Relay

34. Indirect control of a lamp using a Detent switch and a relay.
Connect with a Detent Sw. and a relay (N/O) and (N/C) and press the Detent Sw. AND OBSERVE

35. Practical Task 3 Opening/closing the flow in a pipeline
The double acting cylinder (1A) in the Figure is used to open and close the main valve in a pipeline. Draw an electro-pneumatic circuit to control the movement of cylinder (1A).

36. Solution-1 to Practical Task 3 with a double acting cylinder
Required components with a double acting cylinder:
Double – acting cylinder
5/2 way valve, double solenoid
Power supply
Switches

37. Solution-2 to Practical Task 3 with a double acting cylinder

40. Solution to Practical Task 3