Electropneumatic

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Electropneumatic

• Faculty of Electrical Electronics Engineering,
• University College of Engineering Technology
  Malaysia (KUKTEM).
• FKEE

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Chapter 4.0 Introduction to Electro pneumatic

• 4.1 An introduction to Electro pneumatic
• 4.2 Component in a control sequence
• 4.3 Power supply units
• 4.4 Switching contacts and type of
• actuation
• 4.5 Type of Actuation of switching
• elements
• 4.6 Electrical output devices

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4.1 An introduction to Electropneumatic

• Both pneumatic electropneumatic controllers
  have a pneumatic power section.
• In a pneumatic control, pneumatic components are
  used, that is various types of valves,
  sequencers, air barriers, etc.
• In an electro-pneumatic control the signal
  control section is made up of electrical
  components such as electrical input button,
  proximity switches, relays or PLC.

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Advantages of using Electropneumatic

• Replace tubing to wire
• Reduce the working area
• Sensor can be included in limited space
• Controller such as PLC can be included

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Pneumatic revision (cont..)

• Switching symbols for valves Pneumatic
  components are normally shown in the
  deenergized condition in circuit diagrams.

1. The valve switching position is shown by
square.
2. The number of square corresponds to the number
of switching positions.
3. Line indicate the flow path, arrows indicate
the direction of flow.
4. Closed ports are shown by two lines drawn at
right angles to one another.
5. The connecting lines for supply and exhaust
air are drawn outside the square.
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Pneumatic revision (cont..)

• Information about the type of valve can be
  established from the following features
• Number of ports
• Number of switching positions
• Port numbering
• The following applies to the numbering of the
  ports
• Air supply port 1
• Exhaust ports 3,5
• Working or outlet ports 2,4

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Pneumatic revision (cont..)
2/2 way valve, normally open position.
3/2 way valve, normally
closed position.
3/2 way valve, normally open position.
4/2 way valve flow from 1
to 2 from 4 to 3
5/2 way valve flow from 1 to 2 from 4 to 5
5/3 way valve mid position
closed
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4.2 Electropneumatic components
Electrical
Pneumatic
Electro pneumatic

• Input
• Pushbutton switch
• Roller limit switch
• Proximity sensor

• Single-acting cylinder
• Double-acting cylinder
• Rodless cylinder
• One way flow control valve
• Quick exhaust valve

• Input
• Pressure sensors

• Process
• Relay
• Timer relay
• Counter relay

• Output
• Lamp
• Buzzer

• Output
• Solenoid valve

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Elements of Control Chain
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4.3 Power Supply unit

• Power supply used to convert alternate current to
  direct current.- The signal control section of
  an electropneumatic controller is supplied
  with power via the electrical mains.- The
  individual assemblies of the power supply unit
  have the following task - The transformer
  reduces the operating voltage from 240V to 24V
  AC. - The rectifier convert the AC voltage into
  DC voltage. - The voltage rectifier is required
  to ensure that the electrical voltage
  remains constant regardless of the
  current flowing.

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4.4 Switching contacts and type of actuation
Normally-open contacts
Normally-closed contacts
Changeover contacts
Mechanically connected switch
Rotary switch with normally open contacts
manually actuated by turning
Push-button with normally open contacts manually
actuated by pushing
Limit switch with normally open or normally
closed contacts, mechanically actuated
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Switching Symbols for
Solenoid Coils and Relay
Electro-magnetically actuated on one side, with
spring return
Electro-magnetically actuated on both sides
Representation in electrical circuit diagrams
Solenoid valve
Electro-magnetically actuated, with pilot control
Contactor or relay with 3 normally open
contacts and 1 normally closed contact
Relay
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4.5 Type of actuation of Switching Elements
Frequently used types of actuation are -
Pushbuttons - Roller levers - Roller lever with
idle return
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4.6 Electrical Output Devices
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Chapter 5 Logic Function
What is LOGIC? Logic is conditions of inputs that
effects the output.

• In order to produce the required movements by
  pneumatic cylinders, it is often necessary to
  combine signals from several control elements
  through logic operation.
• There are 4 type of basic logic
• YES Logic (NO)
• NOT Logic (NC)
• AND Logic (AND)
• OR Logic (OR)

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5.1 The AND Logic Function
-Consists of at least 2 switching elements
connected in series-Can have 2 or more inputs. A
combination of switches and sensors may be
involved-The function is represented through a
logic symbol with two inputs and one output-Both
input must be present to switch the output.
Logic Symbol
Circuit connection
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5.2 The OR Logic Function

• Consists of at least 2 switching elements
  connected in parallelCan have 2 or more inputs.
  A combination of switches and sensors may be
  involved.The function is represented through a
  logic symbol with two inputs and one output.Only
  1 input signal needs to be present to switch the
  output.

Logic Symbol
Circuit connection
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Chapter 6 Solenoid valve with Pilot Control

• 6.1 Principle of a Solenoid Coil
• 6.2 3/2 Way Single Solenoid Valve
• 6.3 5/2 Way Single Solenoid Valve
• 6.4 5/2 Way Double Solenoid Valve

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6.1 Function principle of a Solenoid Coil

• When an electric current flow through a coil, a
  magnetic field is generated.

The following applies to the strength of the
magnetic field- Increasing the number of
windings increases the field- Increasing the
strength of the current increase the field-
Lengthening the coil reduces the field.
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Conversion of electrical signal into Pneumatic
signals

• If control system are using compressed air and
  electricity as working medium, converter system
  must be used.
• Solenoid valves convert electrical signals into
  pneumatic signals.
• Solenoid valve consist of
• A pneumatic valve
• A coil which switches the valve

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2/2-Way Solenoid Valve without Pilot Control
Normally-closed position, spring return

• Solenoid coil deenergized
• Port 1 is blocked.
• Port 2 is blocked.
• Exhausting is not possible.

• Solenoid coil energized
• The armature is raised.
• Compressed air flows from
• port 1 to port 2.

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Solenoid Valve with Pilot Control
Consist ofi) An electromagnetically-actuated
pilot control valveii) A pneumatically-actuated
main valve
Symbol for Pilot Control
In Comparison with solenoid valve without a pilot
control, solenoid valves with a pilot control are
distinguished byi) Lower force required to
actuate the armature.ii) Smaller dimensions of
the coil head.iii) Lower power consumption.Iv)
Less heat generated
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6.2 3/2 Way Single Solenoid Valve with Pilot
Control

• Normally-closed position, spring return, manual
  overrideSolenoid coil deenergized - Port 1 is
  blocked - Port 2 vented to port 3 - The pilot
  control channel is blocked by the armature
  seal on the valve side- The space above the
  valve piston is vented through the armature
  guide tube.

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3/2 Way Single Solenoid Valve with Pilot Control
(cont..)

• Solenoid coil energized - The armature is lifted
  and the armature seal on the coil side
  blocks the vent hole in the armature seal on
  the valve side opens the pilot control channel.
  - Compressed air from port 1 flows through the
  pilot control channel and actuates the valve
  piston - Port 3 is blocked and compressed air
  flows from port 1 to port 2.

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6.3 5/2 Way Single Solenoid Valve with Pilot
Control

• Spring returned, manual overrideSolenoid coil
  deenergized - Compressed air flows from port 1
  to 2. - Port 4 is vented to 5. - Port 3 is
  blocked. - The pilot control channel is blocked
  - The space above the valve piston is vented
  through the armature guide tube

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• Solenoid coil energized - The armature is
  lifted and the armature seal on the coil
  side blocks the vent hole in the armature
  guide tube, while the armature seal on the
  valve side opens the pilot control channel. -
  Compressed air from port 1 flows through the
  pilot control channel and actuates the valve
  piston. - Port 5 is blocked. - Compressed air
  flows from port 1 to port 4. - Port 2 is vented
  to port 3.

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See the differences
Valve locations
Deenergized
Energized
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6.4 5/2 Way Double Solenoid Valve with Pilot
Control

• Manual overrideSolenoid coil Y1 energized,
  solenoid coil Y2 deenergized.- The valve
  switches over.- Port 3 is blocked.- Compressed
  air flows from Port 1 to port 2.- Port 4 is
  vented to Port 5.

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Both Solenoid coil deenergized.- The valve
retrains its previous switching position.
Solenoid coil Y2 energized, solenoid coil Y1
deenergized- The valve switches over.- Port 5
is blocked.- Compressed air flows from port 1 to
port 4.- Port 2 is vented to port 3.