lab manual of pneumatics control

ELECTRO PNEUMATICS (Model No : VMPT - 302 LC)

Technical Reference

Version 1.0

Technical Clarification /Suggestion : / Technical Support Division,Vi Microsystems Pvt. Ltd.,Plot No :75,Electronics Estate,Perungudi,Chennai - 600 096,INDIA.Ph: 91- 44-24961852, 91-44-24963142Mail : [email protected],Web : www.vimicrosystems.com01 - 12 - 04 - 20

ELECTRO PNEUMATICS VMPT-302 LC

Vi Microsystems Pvt. Ltd., [ 1 ]

CHAPTER - 1

INTRODUCTION OF PNEUMATICS SYSTEM



1.1 APPLICATIONS OF PNEUMATICS

Pneumatics deals the use of compressed air, Most commonly, compressed air is used todo mechanical work-that is to produce motion and to generate forces. Pneumatic drives have thetask of converting the energy stored in compressed air into motion.

Cylinders are most commonly used for pneumatic drives. They are characterized by robustconstruction, a large range of types, simple installation and favorable price/performance. As aresult of these benefits, pneumatics is used in a wide range of applications.

Pneumatic linear cylinder and pneumatic swivel cylinder

Some of the many applications of pneumatics are

* Handling of work pieces(such as clamping, positioning, separating, stacking, rotating)

* Packaging* Filling* Opening and closing of doors (such as buses and trains)* Metal-forming (embossing and pressing)* Stamping

1.2 Signal and information

A signal is the representation of information the representation is by means of the value or valuepattern of the physical variable.



Signal/physical variable

0

1

7bar

5

4

32

Time

Pressure

Pointer position

Time

23

4

567

1

0

Informationa) Analog

0

1

23

6

7

54

8

0

1

765

4

32

Time

b) DigitalDisplay

Pressure3 bar

c) Binary

Yes 1

No 0 Time

PressureSupply

Pressure



Analog signal

An analog signal is a signal in which information is assigned point by point to a continuous valuerange of the signal parameter (DIN 19226. Part 5).

Application example

In the case of a pressure gauge, each pressure value (information parameter) is assigned aparticular display value ( = information). If the signal rises or falls, the information changescontinuously.

Digital signal

A digital signal is a signal with a finite number of value ranges of the information parameter. Eachvalue range is assigned a specific item of information (DIN 19226).

Application example

A pressure measuring system with a digital display shows the pressure in increments of 1 bar.There are 8 possible display values ( 0 to 7 bar) for a pressure range of 7 bar. That is, there eightpossible value ranges for the information parameter. If the signal rises or falls, the informationchanges in increments.

Binary Signal

A binary signal is a digital signal with only two value ranges for the information parameter. If thesignal rises or falls, the information changes in increments.

Application example

A control lamp indicates whether a pneumatic system is being correctly supplied with compressedair. If the supply pressure ( = signal is below 5 bar, the control lamp is off (0 status). If thepressure is above 5 bar, the control lamp is on ( 1status).

1.3 Signal flow in a control system

A controller can be divided into the functions signal input, signal processing signal output andcommand execution. The mutual influence of these functions is shown by the signal flow diagram.

* Signals from the signal input are logically associated (signal processing). Signalsfor signal input and signal process are low power signals. Both functions are partof the signal control section.

* At the signal output stage, signals are amplified from low power to high power.Signal output forms the link between the signal control section and the powersection.



* Command execution take place at a high power level-that is, in order to reach ahigh speed (such as for fast rejection of a workpiece form a machine) or to exerta high force (such as for a press). Command execution belongs to the powersection of a control system.

Signal flow in a control system The components in the circuit diagram of a purely pneumatic controller are arranged so that thesignal flow is clear. Bottom up: input elements (such as manually operated valves), logicalassociation elements (such as two-pressure valves), signal output elements (power valves, suchas 5/2 - way valves) and finally command execution (such as cylinders).

1.4 Pneumatic and Electro pneumatic control systems

Both pneumatic and electro pneumatic controllers have a pneumatic power section (see fig 1.4).The signal control section varies according to type.

* In a pneumatic control pneumatic components are used, that is, various types ofvalves, sequences, air barriers, etc.

* In an electro-pneumatic control the signal control section is made up of a electricalcomponents, for example with electrical input buttons, proximity switches, relays,or a programmable logic controller.

The directional control valves form the interface between the signal control section and thepneumatic power section in both types of controller.

Command execution

Signal output

Signal Processing

Signal inputPo

wer

Sign

al c

ontro

l se

ctio

nse

ctio

n



Fig. 1.4 Signal flow and components of a pneumatic control system.

SIGNAL OUTPUT

Final control elements Electropneumaticallyoperated directionalcontrol valves

controllers (PLCs)Programmable logicContactorsRelays

SIGNAL PROCESSING

Processing Elements

SIGNAL INPUT

Input ElementsPushbuttonsControl switchesLimit switchesReed switches

COMMAND EXECUTION

Optical displaysPneumatic motorsSwivel cylinderCylinder Power Components

Ind.proximity sensorsCap.proximity switchesLight barriersPressure-actuatedSwitches

SIGNAL FLOW Electropneumatic components

Pneu

mat

ic p

ower

sect

ion

Elec

trica

l sig

nal c

ontro

l sec

tion



1.5 The structure and mode of operation of an electro pneumatic controller

* The electrical signal control section switches the electrically actuated directional controlvalves.

* The directional control valves cause the piston rods to extend and retract.

* The position of the piston rods is reported to the electrical signal control section byproximity switches.

Fig.1.5 Structure of a modern electro pneumatic controller.



1.6 Advantages of electro pneumatic controllers

Electro pneumatic controllers have the following advantages over pneumatic control systems:

* Higher reliability (fewer moving parts subject to wear)

* Lower planning and commissioning effort. Particularly for complex controls

* Lower installation effort, particularly when modern components such as valveterminals are used

* Simpler exchange of information between several controllers.

Electro pneumatic controllers have asserted themselves in modern industrial practice and theapplication of purely pneumatic control systems is a limited to a few special applications



CHAPTER - 2FUNDAMENTALS OF ELECTRICAL

TECHNOLOGY



2.1 Direct current and alternating current

A simple electrical circuit consists of a voltage source, a load, and connection lines.

Physically, charge carriers electrons move through the electrical circuit via the electricalconductors from the negative pole of the voltage source to the positive pole. This motion ofcharge carriers is called electrical current. Current can only flow if the circuit is closed.

There are two types of current - direct current and alternating current:

* If the electromotive force in an electrical circuit is always in the same direction, thecurrent also always flows in the same direction. This is called direct current (DC) or a DCcircuit.

* In the case of alternating current or an AC circuit, the voltage and current changedirection and strength in a certain cycle.

Direct current

Time tCur

rent

1

Alternating current

Time tCur

rent

1



Fig. 2.1: DC circuit

Fig 2.1 shows a simple DC circuit consisting of a voltage source, electrical lines, a control switch,and a load (here a lamp).

Technical direction of flow

When the control switch is closed, current I flows via the load. The electrons move from thenegative pole to the positive pole of the voltage source. The direction of flow from quotes“positive” to” negative” was laid down before electrons were discovered. This definition is stillused in practice today. It is called the technical direction of flow.

2.2 Ohm’s Law

Electrical conductors

Electrical current is the flow of charge carriers in one direction. A current only flow in a materialif a sufficient number of free electrons are available. Materials that meet this criterion are calledelectrical conductors. The metals copper, aluminum and sliver are particularly good conductors.Copper is normally used for conductors in control technology.

Electrical resistance

Every material offers resistance to electrical current. This results when the free-moving electronscollide with the atoms of the conductor material, inhibiting their motion. Resistance is low inelectrical conductors. Materials with particularly high resistance are called insulators. Rubberand plastic-based materials are used for insulation of electrical wires and cables.

I

V=12V+-

H

S3

4



Source emf

The negative pole of a voltage source has a surplus of electrons. The positive pole has a deficit.This difference results in source emf (electromotive force).

Ohm’s law

Ohm’s law expresses the relationship between voltage, current and resistance. It states that in acircuit of given resistance, the current is proportional to the voltage, that is

* If the voltage increases, the current increases.* If the voltage decreases, the current decreases.

V = R . I

V = Voltage; Unit : Volt (V)R = Resistance; Unit : Ohm ()I = Current; Unit : Ampere (A)

Electrical Power

In mechanics, power can be defined by means of work. The faster work is done, the greater thepower needed. So power is “ work divided by time”.

In the case of a load in an electrical circuit, electrical energy is converted into kinetic energy (forexample electrical motor), light (electrical lamp), or heat energy (such as electrical heater,electrical lamp). The faster the energy is converted, the higher the electrical power so here, topower means converted energy divided by time. Power increases with current and voltage.

The electrical power of a load is also called its electrical power input.

P = V.IP = Power; Unit : Watt (W)V = Voltage; Unit : Volt (V)I = Current; Unit : Ampere (A)

Application example

Power of a coil

The solenoid coil of a pneumatic 5/2 - way valve is supplied with 24V DC. The resistance of thecoil is 60ohm. What is the power?

The current is calculated by means of ohm’s law:



I VR

V A 2460

0 4

.

The electrical power is the product of current and voltage:

P = V.I = 24V. 0.4 A = 9.6 W

2.3 Function of a solenoid

A magnetic field is induced when a current is passed through an electrical conductor. The strengthof the magnetic field is proportional to the current. Magnetic fields attract iron, nickel and cobalt.The attraction increases with the strength of the magnetic field.

Fig. 2.3: Electrical coil and magnetic lines of force

Structure of a solenoid

The solenoid has the following structure:

* The current-bearing conductor is wound around a coil. The overlapping of thelines of force of all loops increases the strength of the magnetic field resulting ina main direction of the field.

* An iron core is placed in the centre. When current flows, the iron is alsomagnetized. This allows a significantly higher magnetic field to be induced withthe same current (compared to an air-core coil)

Air-core coil Coil with iron core

and air gap



These two measures ensure that an solenoid exerts a strong force on ferrous (=containing iron)materials.

Applications of solenoids

In electro pneumatic controls, solenoids are primarily used to control the switching of valves,relays or contractor. This can be demonstrated using the example of the spring-return directionalcontrol valve:

* If current flows through the solenoid coil, the piston of the valve is actuated.

* If the current is interrupted, a spring pushes the piston back into its initial position.

Reactance in AC circuits

If a AC voltage is applied to a coil, an alternating current flows. This means that the current andmagnetic field are constantly changing. The change in the magnetic field induces a current in thecoil. The induced current opposes the current that induced the magnetic field. For this reason,a coil offers “resistance” to an alternating current. This is called reactance.

The reactance increases with the frequency of the voltage and the inductance of the coil.

Inductance is measured in Henry (H)

1 1 1H VSA

S

Reactance in DC circuits

In the case of DC circuits, the current, voltage and magnetic field only change when the currentis switched on. For this reason reactance only applies when the circuit is closed (switching on thecurrent)

In addition to reactance, the coil has ohmic resistance. This resistance applies both to AC circuitsand DC circuits.

2.4 Function of a capacitor

A capacitor consists of two metal plates with an insulating layer (dielectric) between them. If thecapacitor is connected to a DC voltage source closing the switch S1 in by this. If the circuit isthen interrupted, the charge remains stored in the capacitor. The larger the capacitance of acapacitor, the greater the electrical charge it can store for a given voltage.



Capacitance is measured in Farad (F):

If the charged capacitor is now connected to a load (closing switch S2 in Fig. 2.6), the capacitordischarges. Current flows through the load until the capacitor is fully.

Fig. 2.4: Function of a capacitor

2.5 Function of a diode

Diodes are electrical components that only allows current to flow in one direction

* In the flow direction, the resistance is so low that the current can flow unhindered.

* In the reverse direction, the resistance is so high that no current flows.

If a diode is inserted into a AC circuit, the current can only flow in one direction. The current isrectified.

The effect of a diode on an electrical circuit is comparable to the effect of a non-return valve ona pneumatic circuit.

1 1F ASV

Air-core coil

V

S1

mA

S2

mA

and air gapCoil with iron core

+ + + + + +

------



Fig. 2.5: Function a diode

2.6 Measurement in Electrical Circuits

Measurement

Measurement means comparing an unknown variable (such as the length of a pneumatic cylinder)with a known variable (such as the scale of a measuring tape). A measuring device (such as aruler) allows such measurements to be made. The (such as 30.4 cm)

V ~

R

I

Voltage V

Time t

Time t

Current I



Measurement in electrical circuits

Electrical current, voltages and resistance are normally measured with multimeters. These devicescan be switched between various modes:

* DC current and voltage, AC current and voltage

* Current, voltage and resistance.

The multimeter can only measure correctly if the correct mode is set. Devices for measuringvoltage are also called voltmeters. Devices for measuring current are also called ammeters.

Fig. 2.6: Multimeter

D C

-+0 10 20 4030

V

DC

AC PEAK HOLD

DATA/HOLD

RANGE

AUTO

OFF

V

mV

TTL

mA

A

A

FnF

+

-Cx

A mAA

400 mAMAX

COM

500V MAX 1000V 750V

TTLV

!

!

10A



Danger

* Before carrying out a measurement, ensure that voltage of the controller on whichyou are working does not exceed 24V!

* Measurements on parts of a controller operating at higher voltages (such as 230V)may only be carried out by persons with appropriate training or instruction.

* Incorrect measurement methods can result in danger to life.

* Please read the safety precautions in chapters 3 and 7!

Procedure for measurements on electrical circuits

Follow the following steps when making measurements of electrical circuits.

* Switch off voltage source of circuit.

* Set multimeter to desired mode. (Voltmeter or ammeter, AC or DC, resistance)

* When measuring DC voltage or current, check for correct polarity. (“+” probe ofdevice to positive pole of voltage source).

* Select largest range.

* Switch on voltage source.

* Observe pointer or display and step down to smaller range.

* Record measurement for greatest pointer deflection (smallest measuring range).

* For pointer instruments, always view from vertically above display in order toavoid parallax error.

2.7 Voltage Measurement

For voltage measurement, the measuring device (voltmeter) is connected in parallel to the load.The voltage drop across the load corresponds to the voltage drop across the measuring device.A voltmeter has an internal resistance. In order to avoid an inaccurate measurement, the currentflowing thought the voltmeter must be as small as possible, so the internal resistance of thevoltmeter must be as high as possible.



Fig. 2.7. Voltage measurement

2.8 Current Measurement

For current measurement, the measuring device (ammeter) is connected in series to the load. Theentire current flows through the device

Each ammeter has an internal resistance. In order to minimize the measuring error, the resistanceof the ammeter must be as small as possible.

Fig. 2.8 Current measurement

VoltmeterVV H

AmmeterA

V H



Resistance Measurement

The resistance of a load in a DC circuit can either be measured directly or indirectly.

* Indirect measurement measures the current through the load and the voltage across theload (Fig.2.9a). The two measurements can either be carried out simultaneously or oneafter the other. The resistance is then measured using ohm’s law.

* For direct measurement the load is separated from the rest of the circuit (Fig.2.9b). Themeasuring device (ohmmeter) is set to resistance measurement mode and connected to theterminals of the load. The value of the resistance is displayed.

If the load defective (for example, the magnetic coil of a valve is burned out), the measurementof resistance either results in a value of zero (short-circuit) or an infinitely high value (opencircuit).

Warning

The direct method must be used for measuring the resistance of a load in AC circuits.

Fig. 2.9. Measuring Resistance

Current I

H

A

V Voltage V V H

R=VI



Sources of error

Measuring device cannot measure voltage, current and resistance to any desired degree ofaccuracy. The measuring device itself influences the circuit it is measuring, and no measuringdevice can display a value precisely. The permissible display error of a measuring device is givenas a percentage of the upper limit of the effective range. For example, for a measuring devicewith an accuracy of 05, the display error must not exceed 0.5% of the upper limit of the effectiverange.

Application example

Display Error

A class 1.5 measuring device is used to the measure the voltage of a 9V battery. The range is setonce to 10V and once to 100V. How large is the maximum permissible display error for the twoeffective ranges?

Range Permissible display error Percentage error

10V10 15

100015V V. . .

0159

100 166%. . .V

100V100 15

10015V V. . . 15

9100 16 6%. . .

V

Table 2.1 : Calculating the display error

The example shows clearly that the permissible error is less for the smaller range. Also, the devicecan be read more accurately. For this reason, you should always set the smallest possible range.



CHAPTER - 3COMPONENTS AND ASSEMBLIES IN THEELECTRICAL SIGNAL CONTROL SECTION



3.1 Power supply unit

The signal control section of an electro pneumatic controller is supplied with power via theelectrical mains. The controller has a power supply unit for this purpose (see Fig. 3.1). Theindividual assemblies of the power supply unit have the following tasks:

* The transformer reduces the operating voltage. The mains voltage (i.e. 230V) is appliedto the input of the transformer. A lower voltage (i.e.24V) is available at the input.

* The rectifier converts the AC voltage into DC voltage. The capacitor at the rectifieroutput smooths the voltage.

* The voltage regulator at the output of the power supply unit is required to ensure that theelectrical voltage remains constant regardless of the current flowing.

Fig. 3.1 : Component parts of a power supply unit for an electro pneumatic controller.

Safety Precaution

* Because of the high input voltage, power supply units are part of the powerinstallation (DIN /VDE 100).

* Safety regulations for power installations must be observed.

* Only authorized personnel any work on power supply units.

TransformerRectifier

Stabilization

~ -

Powersupply unit



3.2 Push Button and control switches

Switches are installed in circuits to apply a current to a load or to interrupt the circuit. Theseswitches are divided into pushbuttons and control switches.

* Control switches are mechanically detented in the selected position. The switchposition remains unchanged until a new switch position is selected. Example;Light switches in the home.

* Push button switches only maintain the selected position as long as the switch isactuated (pressed). Example : Bell push.

Normally open contact (make)

In the case of a normally open contact, the circuit is open if the switch is in its initial position (not

actuated). The circuit is closed by pressing the push button - current flows to the load. When the

plunger is released, the spring returns the switch to its initial position, interrupting the circuit.



1.Actuator type (push button) 2.Switch element 3.Contact

Fig. 3.2: Normally open contact (make) - section and symbol

3.3 Normally closed contact (break)

In this case, the circuit is closed when the switch is in its initial position. The circuit is interruptedby pressing the pushbutton.

1. Actuator type (push button) 2. Contact 3. Switch element

Fig. 3.3: Normally open contact (break) - section and symbol



3.4 Changeover contact

The changeover contact combines the functions of the normally open and normally closedcontacts in one device. Changeover contacts are used to close one circuit and open another inone switching operation. The circuits are momentarily interrupted during changeover.

1. Actuator type (push button) 3. Switching element 2. Contact (Normally closed contact) 4. Contact (Normally open

contact)

Fig. 3.4 Changeover contact - section and symbol

3.5 Sensors for measuring displacement and pressure

Sensors have the task of measuring information and passing this on to the signal processing partin a form that can easily be processed. In electropnematic controllers, sensors are primarily usedfor the following purposes:

* No to detect the advanced and retracted end position of the piston rod in cylinderdrives

* To detect the presence and position of work pieces* To measure and monitor pressure

Limit switches

A limit switch is actuated when a machine part or workpiece is in certain position. Normally,actuation is effected by a cam. Limit switches are normally changeover contacts. They can then



be connected - as required - as normally open contact, normally closed contact or changeovercontact.

1. Guide pin 4. Compressing spring 7. Contact (Normallyopen contact)

2. Positive opening lever5. Bent leaf spring 8. Contact blade3. Housing 6. Contact pressure spring 9. Contact (normally

closed contact)

Fig. 3.5: Mechanical limit switch: construction and connection possibilities

3.6 Proximity switches

In contrast to limit switches, proximity switches operated contactlessly (non-contact switchingreliability).

The following types of proximity switch are differentiated:



* Reed switch * Inductive proximity switch* Capacitive proximity switch.* Optical proximity switch.

Reed switch

Reed switches are magnetically actuated proximity switches. They consist of two contact reedsin a glass tube filled with inert gas. The field of a magnet causes the two reeds to close. Allowingcurrent to flow. In reed switches that act as normally closed contacts, the contact reeds areclosed by small magnets. This magnetic field is overcome by the considerably stronger magneticfield of the switching magnets.

Reed switches have a long service life and a very short switching time (approx.0.2 ms). They aremaintenance-free, but must not be used in environments subject to strong magnetic fields (forexample in the vicinity of resistance welders).

Fig. 3.6. Reed switch (normally open contact)

3.7 Electronic sensors

Inductive, optical and capacitive proximity switches are electronic sensors. They normally havethree electrical contacts.

* Contact for supply voltage * Contact for ground.* Contact for output signal



In these sensors, no movable contact is switched instead, the output is either electricallyconnected to the supply voltage or to ground (= output voltage 0V).

Positive and negative switching sensors

There are two types of electronic sensor with regard to the polarity of the output voltage.

* In positive switching sensors, the output voltage is zero if no part is detected in theproximity. The approach of a workpiece or machine part leads to switch over of theoutput, applying the supply voltage.

* In negative switching sensors, the supply voltage is applied to the output if no part isdetected in the proximity. The approach of a workpiece or machine part leads to switchover of the output, switching the output voltage to 0V.

Inductive proximity sensors

An inductive proximity sensor consists of an electrical oscillator (1), a flip-flop (2) and anamplifier (3). When a voltage is applied, the oscillator generates a high-frequency alternatingmagnetic field that is emitted form the front of the sensor. If an electrical circuit is introduced intothis field, the oscillator is attenuated. The downstream circuitry, consisting of a flip-flop and anamplifier, evaluates the behavior of the oscillator and actuates the output.

Inductive proximity sensors can be used for the detection of all good electrical conductors(materials). In addition to metals, these include, for example, graphite.



Fig. 3.7 : Inductive proximity sensor

Schematic diagram

Metal Symbol

Function circuit diagram

1 2 3

Amplifier (3)Flip-flop (2)Oscillator (1)



3.8 Capacitive proximity sensor

A capacitive proximity sensor consists of a capacitor and an electrical resistance that togetherform an RC oscillator, and a circuit for evaluation of the frequency. An electrostatic field isgenerated between the anode and the cathode of the capacitor.

A stray field forms at the front of the sensor. If an object is introduced into this stray field formsat the front of the sensor. If an object is introduced into this stray field, the capacitance of thecapacitor changes. The oscillator is attenuated. The circuitry switches the output.

Capacitive proximity sensors not only react to highly conductive materials ( such as metal) butalso to insulators of high dielectric strength (such as plastics, glass, ceramics, fluids and wood).

Fig. 3.8: Capacitive proximity sensor

Optical proximity sensors use optical and electronic means for object detection. Red or infraredlight is used. Semiconductor light-emitting diodes (LEDs) are particularly reliable sources of redor infrared light. They are small and rugged, have a long service life and can be simply modulated.Photo diodes or photo transistors are used as a receiver. Red light has the advantage that the lightbeam can be seen during adjustment of the optical axes of the proximity switch. Polymer opticalfibers can also be used because of their low attenuation of light of this wavelength.

Optical Proximity sensor

Schematic diagram

Symbol

Function circuit diagram

1 2 3

Amplifier (3)Flip-flop (2)Oscillator (1)



Three different types of optical proximity switch are differentiated;

* One-way light barrier

* Reflective light barrier

* Diffuse reflective optical sensor.

3.9 Mechanical Pressure switch

In the mechanically actuated pressure switch, the pressure acts on a cylinder surface. If thepressure exerted exceeds the spring force of the return spring, the piston moves and operates thecontact set.

Fig. 3.9: piston-actuatedpressure switch

Diaphragm pressure switches are of increasing importance. Instead of actuating a mechanicalcontact, the output is switched electronically. Pressure or force sensitive sensors are attached tothe diaphragm. The sensor signal is evaluated by an electronic circuit. As soon as the pressureexceeds a certain value, the output is switched.



3.10 Relays and contactors

Construction of a relay

A relay is an electromagnetically actuated switch. When a voltage is applied to the solenoidcoil, an electromagnet field results. This causes the armature to be attracted to the coil core. Thearmature actuates the relay contacts, either closing or opening them, depending on the design.A return spring returns the armature to its initial position when the current to the coil isinterrupted.

1. Coil core 3. Relay coil 5. Insulation2. Return spring 4. Amature 6. Contact

Fig. 3.10 : Construction of a relay

A relay coil can switch one or more contacts. In addition to the type of relay described above,there are other types of electromagnetically actuated switch, such as the retentive relay, the timerelay, and the contactor.



Applications of relays

In electro pneumatic control systems, relays are used for the following functions:

* Signal multiplication

* Delaying and conversion of signals

* Association of information

* Isolation of control circuit from main circuit

In purely electrical controllers, the relay is also used for isolation of DC and AC circuits.

Retentive relay

The retentive relay responds to current pulses:

* The armature is energized when a positive pulse is applied.

* The armature is de-energized when a negative pulse is applied.

* If no input signal is applied, the previously set switch position is retained (retention).

The behavior of a retentive relay is analogous to that of a pneumatic double pilot valve, whichresponds to pressure pulses.

Construction and mode of operation

Electrically actuated directional control valves are switched with the aid of solenoids. They canbe divided into two groups:

* Spring-return valves only remain in the actuated position as long as current flows throughthe solenoid.

* Double solenoid valves retain the last switched position even when no current flowsthrough the solenoid.



Initial position

In the initial position all solenoids of an electrically actuated directional control valve are de-energized and the solenoids are inactive. A double solenoid valve has no clear initial position, asit does not have a return spring.

Port Designation

Directional control valves are also differentiated by the number of ports and the number ofswitching position. The valve designation results from the number of ports and positions, forexample:

* Spring-return 3/2-way valve

* 5/2-way double solenoid valve

The following section explains the construction and mode of operation of the major types ofvalve.

3.11 Directly controlled 3/2-way valve

Fig. 3.11 shows two cross-sections of a directly controlled electrically actuated 3/2-way valve.

* In its initial position, the working port 2 is linked to the exhaust port 3 by the slot in thearmature (see detail) (fig. 3.11a).

* If the solenoid is energized, the magnetic field forces the armature up against the pressureof the spring (Fig.3.11b). The lower sealing seat opens and the path is free for flow frompressure port 1 to working port 2. The upper sealing seat closes, shutting off the pathbetween port 1 and port 3.

* If the solenoid coil is de-energized, the armature is retracted to its initial position by thereturn spring (Fig. 3.11a). The path between port 2 and port 3 is opened and the pathbetween port 1 and port 2 closed. The compressed air is vented via the armature tube atport 3.



Manual override

The manual override a allows the path between port 1 and port 2 to be opened even if thesolenoid is not energized. When the screw is turned, the eccentric cam actuates the armature.Turning the screw back returns the armature to its initial position.

3.11a 3.11a

3.12 3/2 Way valve normally open

Fig. 3.12 shows an electrically actuated 3/2-way valve, normally open. Fig.3.12a shows the valvein its initial position, Fig. 3.12b actuated. Compared to the initial position of the closed valve (fig.3.12) the pressure and exhaust ports are reversed.



Fig 3.12 : 3/2-way valve with manual override (normally open)

3.13 Pilot controlled directional

In pilot controlled directional control valves, the valve piston is indirectly actuated.

* The armature of a solenoid opens or closes an air duct from port 1.

* If the armature is open, compressed air form port 1 actuates the valve piston.

* If the coil is de-energized, the armature is pressed against the lower sealing seat by thespring. The chamber of the upper side of the piston is vented(Fig. 3.13a).

* If the coil is energized, the solenoid pulls the armature down. The chamber on the upperside of the piston is pressurized (Fig. 3.13b)



Fig. 3.13 explains the mode of operation of the pilot control.

3.14 Pilot controlled 3/2-way valve

Fig. 3.14 shows two cross-sections of an electrically actuated pilot controlled 3/2-way valve.

* In its initial position, the piston surface is only subject to atmospheric pressure, so thereturn spring pushes the piston up (Fig. 3.14a, b) Ports 2 and 3 are connected.

* If the solenoid coil is energized, the chamber below the valve piton is connected topressure port 1. The force on the upper surface of the valve piston increases, pressing thepiston down. The connection between ports 2 and 3 is closed, the connection betweenports 1 and 2 opened. The valve remains in this position as long as the solenoid coil isenergized.

* If the solenoid coil is de-energized, the valve switches back to its initial position.

A minimum supply pressure (control pressure) is required to actuate the pilot controlled valveagainst the spring pressure. This pressure is given in the valve specifications and lies-dependingon type - in the range of about 2 to 3 bar.



Comparison of pilot controlled and directly actuated valves

The greater the flow rate of a directional control valve, the higher the flow.

In the case of a directly actuated valve, flow to the consuming device is released by the armature(see Fig. 4.2). In order to ensure a sufficiently large opening and sufficient flow rate, a relativelylarge armature is required. This in turn requires a large return spring - against which the solenoidmust exert a large force. This results in relatively large component size and high powerconsumption.

In a pilot controlled valve, flow to the consuming device is switched by the main stage (Fig.4.5).The valve piston is pressurized via the air duct. A relatively small airflow is sufficient, so thearmature can be comparatively small with low actuation force. The solenoid can also be smallerthan for a directly actuated valve. Power consumption and heat dissipation are lower.

The advantages with regard to power consumption, size of solenoids and heat dissipation haveled to almost exclusive use being made of pilot controlled directional control valve in electropneumatic control systems.

3.15 Pilot controlled 5/2-way valve

Fig. 3.15 shows the two switching positions of an electrically actuated pilot controlled 5/2-wayvalve.

* In its initial position, the piston is at the left stop (fig.3.15a). Port 1 and 2 and ports 4 and5 are connected.

* If the solenoid coil is energized, the valve spool moves to the right stop (Fig. 3.15b). Inthis position, ports 1 and 4 and 2 and 3 are connected.

* If the solenoid is de-energized, the return spring returns the valve spool to its initialposition.

* Pilot air is supplied via port 84.

1 3

2



Fig. 3.15 Pilot controlled 5/2-way solenoid valve



3.16 5/3-way valve with exhausted initial position

Fig. 4.8 shows the three switching positions of an electrically actuated, pilot controlled 5/3-way

valve.

* In its initial position, the solenoid coils are de-energized and the piston spool is held in the

mid-position by the two springs (Fig4.8a). Ports 2 and 3 and 4 and 5 are connected. Port

1 is closed.

* If the left solenoid coil is energized, the piston moves to its right stop (Fig.4.8b). Ports 1

and 4 and 2 and 3 are connected.

* If the right solenoid coil is energized, the piston moves to its left stop (Fig.4.8c). In this

position, ports 1 and 2 and 4 and 5are connected.

* Each position is held as long as the appropriate coil is energized. If neither coil is

energized, the valve returns to the initial mid-position.



Fig 3.16 Pilot-actuated 5/3-way double solenoid valve (mid-position exhausted)



CHAPTER - 4COMPONENTS LIST OF PNEUMATIC PANEL



Types of compressor

4.1 Air Compressor

The selection from the various types compressors available in dependent upon quality of air,pressure, quality and cleanliness and how dry the air should be. There are varying levels of thesecriteria depending on the types of compressor.

Reciprocating piston compressors

A piston compresses the air drawn in via an inlet valve. The air is passed on via an outletvalve. Reciprocating compressors are very common and provide a wide range of pressures anddelivery rates. For higher pressures multistage compression is used with intercooling betweeneach stage of compression.

The optimum range of pressures for reciprocating compressors are approximately:

up to 400 kPa (4 bar) Single stage

Types ofcompressor

piston compressorReciprocating Rotary piston

compressor Flow compressor

compressorDiaphragmPiston compressor Radial-flow Axial-flow

compressorcompressor

Sliding vane Twin-shaft screwcompressor compressor

Rootscompressor



up to 1500 kPa (15 bar) Double stage

over 1500 kPa (> 15 bar) Treble or multi stage

Also, it is possible but not necessarily economic to operate in the following ranges:

up to 1200 kPa (12 bar) Single stage

up to 3000 kPa (30 bar) Double stageover 3000 kPa (> 30 bar) Treble or multi stage

Diaphragm Compressor

The diaphragm compressor belongs to the reciprocating piston compressor group. Thecompressor chamber is separated from the piston by a diaphragm. The advantage of this is thatno oil can enter into the air flow from the compressor. The diaphragm compressor is thereforeused where oil is to be excluded from the air supply, for example in the food, pharmaceutical andchemical industries.

Rotary piston compressor

The rotary group of compressors use rotating elements to compress and increase thepressure of the air. During the compression process, the compression chamber is continuallyreduced.

Screw compressor

Two screw-shaped shafts (rotors) turn in opposite directions. The meshed profile of thetwo shafts causes the air to flow which is then compressed.

Flow compressor

These are particularly suitable for large delivery quantities. Flow compressors are madein axial or radial form. The air is made to flow by means of one or several turbine wheels. Thekinetic energy is converted into pressure energy. In the case of an axial compressor, the air is axialcompressor, the air is accelerated in the axial direction of flow by means of blades.



4.2 List of components

Air service unit

The air service unit is a combination of the following:

Compressed air filter (with water separated) Compressed air regulator Compressed air lubricator

However, the use of a lubricator does not need to be provided for in the power section of acontrol system unless necessary, since the compressed air in the control section does notnecessarily need to be lubricated.

The correct combination, size and type of these elements are determined by the application andthe control system demand. An air service unit is fitted at each control system in the network toensure the quality of air for each individual task.

Compressed air filter

The compressed air filter has the job of removing all contaminants from the compressedair flowing through it as well as water which has already condensed. The compressed air entersthe filter bowl through guide slots. Liquid particles and larger particles of dirty are separatedcentrifugally collection in the lower part of the filter bowl. The collected condensate must bedrained before the level exceeds the maximum condensate mark, as it will otherwise be re-entrained in the air stream.

The purpose of the regulator is to keep the operating pressure of the system (secondary pressure)virtually constant regardless of fluctuations in the line pressure (primary pressure) and the airconsumption.

Compressed air lubricator

The purpose of the lubricator is to deliver a metered quantity of oil mist into a leg of thedistribution system when necessary for the operation of the pneumatic system.



4.3 3/2 PUSH BUTTON VALVE

This valve consists of three ports and two states. The valve is controlled by a push button andspring force. When the push button is depressed, the internal piston moves, allowing pressurizedair to pass from ports P to A. At this stage the valve is active. Upon release of the push button,the spring force moves the internal piston, there by terminating the air flow from ports P to A, andreturns to the initial position. Air from port A is exhausted through port R.

3/2 NC ROLLER VALVE

This valve consists of three ports and two states. The valve is controlled by a roller headand spring force. When an external force activates the roller head, the piston moves, compactingthe spring force and allowing the flow of pressurized air from ports P to A. When the roller headis de-activated, the spring force causes the valve to return to the initial position. Air flow fromports P to A will terminated and Air is exhausted to atmosphere via the exhaust port R

5/2 Single Pilot Operated Spring Return Valve

This valve consists of five ports and two states. The valve is controlled by pilot air anda spring. Pressurized air enters the valve through port P. If the controller at port X is active, thepiston will move and air flow will be established between ports P and B. When the controller atport X is deactivated, the spring expands, terminating the air flow between ports P and B, thereby establishing air flow between Ports P and A.



5/2 Double Pilot Operated Valve

This valve consists of five ports and two states. The valve is controlled at both ends bypilot air, which are controlled by some controller

Pressurized air enters the valve through port P. If the controller at port X is active, the piston willmove and air flow will be established between ports P and B. If the controller at port Y is active,the piston will move and airflow will be established between Ports P and A.

Shuttle valve (or gate)

This component is a control unit, which has two input ports, and one output port. Eitherof the input ports must be active for the output port to operate. The output Port A is active (haspressure) when pressure is applied to one or both P input ports.

Flow Control Valve

These valves are used to regulate air flow in a pneumatic systems (example to control thepiston speeds of the cylinders). As pneumatic pressure as well as the velocity of the piston aredirectly proportional to the amount of flow of air, so we can control all these parameter by justcontrolling the flow The air can flow only via the cross section which is adjustable by means ofthe throttle screw.



One-way flow control valve

In the case of the one-way flow control valve, the air flow is throttled in one directiononly. A check valve blocks the flow of air in the bypass leg and the air can flow only through theregulated cross-section. In the opposite direction, the air can flow freely through the openedcheck valve. These valves are used for speed regulation of actuators and if possible, should bemounted directly on the cylinder.

Quick Exhaust Valve

Quick Exhaust Valves are used when lengthy return times is to be avoided, particularly withsingle acting cylinder. The simple idea behind it, is to allow cylinder to return in its maximumspeed by reducing resistance to flow of the exhausting air, by expelling the air to atmosphere nearto cylinder via a large orifice opening.



Manifold

The manifold conducts pressurized air flow from the main pressure line and distributes it

to the various components connected to it. Generally Port A is the port used for the inlet of

pressurized air flow from the input component. The rest Ports B, C, D, and E are used to direct

pressurized air to the components. There is no restriction on the component that certain port

should act as inlet, it is user choice that any port can be used as inlet and rest as outlets.

A B C D E A B C D E

Two pressure valve

The two pressure valve is switched based on the compressed air entering into both input

connections 1 and leaving via an output connection 2. Should both input connections being

receiving compressed air, the connection with the lower pressure takes precedence and is put out

(AND function).

2



CHAPTER - 5APPLICATION AND SYMBOLS FORDIRECTIONAL CONTROL VALVES



2

1 3

1

2

12

12

1031

2

1431

4 2

5 314

24

1

14

4 2

5 31

12

12

1 35

24

14

12

1 35

24

14

24

1 314 12

121435

4 2

1

Valve type Symbol

Pilot controlled spring return 2/2-way valve

Pilot controlled spring return 3/2-way valve,

normally closed

Pilot controlled spring return 3/2-way valve,

normally open


return 5/2-way valvePilot controlled spring


exhausted or pressurized)(normally closed,

Pilot controlled 4/2-way double solenoid valve

double solenoid valvePilot controlled 5/2-way

Shut-off function

Single-acting cylinders

Switching compressed air on and off

or swivel cylindersDouble-acting linear

Double-acting linear or swivel cylinders

stop, with specialwith intermediate

requirements regardingbehavior in event of

power failure.

Double-acting linear or swivel cylinders

Applications



CHAPTER - 6PERFORMANCE DATA OF SOLENOID COILS



6.1 Performance data of solenoid coils

An electrically actuated directional control valve can be equipped with various different solenoidcoils. The valve manufacturer usually offers one or more series of solenoid coils for each type ofdirectional control valve, with connection dimensions to match the valve. The choice of solenoidcoil is made on the basis of the electrical performance data (Table 4.4)

Coil type DC Voltage AC Voltage

Voltages Normal Special

12V,24V,42V,48Von request

24V, 42V, 110V, 230V, 50Hz on request

Voltage fluctuation Max.±10% Max.±10%

Frequency fluctuation - Max.±5% at nominal voltage

Power consumption fornormal voltages

4.1 Wat 12V4.5 Wat 24V

Pickup : 7.5VAHold : 6VA

Power factor - 0.7

Duty cycle 100% 100%

Degree of protection IP65 IP 65

Cable conduit fitting PG9 PG9

Ambient temperature 5 - 40°C

Medium temperature 10 - 60°C 10 - 60° C

Average pickup time 10ms 10msTable 4.4 Performance data of DC and AC solenoid calls (Festo)

6.2 Specification of operating voltage

The voltage specification in Table 4.4 relates to the voltage supplied to the solenoid coils. Thesolenoid coils are chosen to match the signal control section of the electro pneumatic controlsystem. If the signal control section operates with a DC voltage of 24V, for example, thecorresponding type of coil should be chosen.

To ensure proper operation of the solenoid coil, the voltage supplied to it from the signal controlsection must be within certain limits for the 24V coil type, the limits are as follows:

Minimum Voltage : Vmin = 24V. (100% - 10%) = 24V.0.9 = 21.6V

Maximum Voltage : Vmax = 24V. (100% + 10%) = 24V.1.1 = 26.4V

If the signal control section operates with Ac voltage and there fore AC solenoid coils are used,



the frequency of the AC voltage must be within a specified range. For the AC coils described inthe table, frequencies up to 5% above or below 50Hz are permissible; in other words thepermitted frequency range is between 47.5 and 52.5 Hz.

6.3 Electrical connection of solenoid coils

The solenoid coil of a directional control valve if connected to the signal control section of anelectro pneumatic control system via a two-core cable.

There is a removable plug connector between the cable and the solenoid. When the connectoris inserted it is screwed down to protect the plug contacts against the ingress of dust and water.The type of plug connector and cable conduit fitting are specified in the technical documentationfor the solenoid coil (such as PG9 in table 4.4)

6.4 Protective circuit of a solenoid coil

The electric circuit is opened or closed by a contact in the signal control section of the controlsystem. When the contact is opened, the current through the solenoid coil suddenly decays. Asa result of the rapid change in current intensity, in conjunction with the inductance of the coil, avery high voltage is induced briefly in the coil. Arcing may occur at the opening contact. Evenafter only a short operating time, this leads to destruction of the contact. A protective circuit istherefore necessary.

Fig. 4.13 shows the protective circuit for a DC coil. While the contact is closed, current I1 flowsthrough the solenoid and the diode is de-energized (fig. 6.4 a). When the contact is opened, theflow of current in the main circuit is interrupted (Fig. 6.5b). The circuit is now closed via thediode. In that way the current can continue flowing through the coil until the energy stored inthe magnetic field is dissipated.

As a result of the protective circuit, current IM is no longer subject to sudden decay, instead itis continuously reduced over a certain length of time the induced voltage peak is considerablylower, ensuring that the contact and solenoid coil are not damaged.



Fig. 6.4 (a), (b) : Protective circuit of a solenoid coil

Auxiliary Functions

In addition to the protective circuit required for operation of the valve, further auxiliary functionscan be integrated in the cable connection, for example:

* Indicator lamp (lights up when the solenoid is actuated)

* Switching delay (to allow delayed actuation)

+24V

0V

i1

DI =0I=IM 1

MI =ID

1i = 0

0V

+24V

MI



6.5 Adapters and cable sockets

The protective circuit and auxiliary functions are integrated either into the cable socket or in theform of adapter inserts i.e. illuminating seal (Fig. 4.14). Appropriate adapters and cable socketsmust be chosen to match the voltage at which the signal control section operates (for example24V DC).



Class of protection

Plugs, sockets and adapters are sealed in order to prevent either dust or moisture from entering

the plug connection. If the adapter, solenoid coil and valve have different classes of protection,

the lowest of the three classes of protection applies to the assembled valve, coil and cable conduit.

Explosion protection

If it is intended to use electrically actuated directional control valves in an environment subject

to explosion hazards, special solenoid coils approved for sch applications are required; these have

molded cables.



CHAPTER - 7 APPLICATION OF ELECTRO PNEUMATIC

SYSTEM



A lifting device transfers work pieces from the one roller conveyor or to another a differentheight. The task is to carry out the project engineering for the associated electro pneumaticcontrol system.

A positional sketch of the lifting device is shown in fig. 5.2. There are three pneumatic drives;

* Drive 1A lifts the workpieces.

* Drive 2A pushes the workpieces onto the upper roller conveyor.

* Drive 3A is used as a stopper, for releasing and interrupting this supply of workpieces.

Fig 5.2 : Positional sketch of the lifting device



Note

The packages first have to be separated to be fed singly; this is done at an upstream facility. Theoptical proximity switch B6 is not taken into account for the purposes of further projectengineering of the lifting device.

7.1 Drives for the lifting device

Cylinder 1A requires a stroke of 500mm and a force of at least 600N, cylinder 2A a stroke of250mm and a force of at least 400 N. Cylinder 3A requires a stroke of 20 mm and a force of40N. On cylinders 1A and 2A the advance and retract speeds of the piston rods need to bevariable. The control system must allow soft braking of drives 1A and 2A.

To prevent the possibility of secondary damage, in the event of an electrical power failure thepiston rods for cylinders 1A and 2A are to be braked immediately and remain at a standstill. Thepiston rod of the stopper cylinder 3A is meant to extend in these circumstances. Movement cycle of the lifting device

The movement cycle of the lifting device is described in Table 5.2 (see positional sketch, Fig. 5.2).It comprises four steps.

Step Movement pistonrodcylinder A

Movement pistonrodcylinder 2A

Movement pistonrodcylindr 3A

End of step, stepenabling condition

comments

1 None None Retract B5 triggered (packagepresent)

Open device

2 Advance None Advance 1B2 triggered Lift package

3 None Advance None 2B2 triggered Push outpackage

4 Retract Retract None 1B1, 2B1 triggered Retract drives toinitial position

Table 7.1 : Movement cycle of the lifting device



7.2 Operator Control

The control system of the lifting device must enable the device to be run in a continuous cycle(continuous operation). A single cycle operating mode is also necessary in which the sequenceis processed precisely once.

The operator control equipment for the system must conform to the relevant standards (seesection 7.4). The control panel for the lifting device is shown in Fig.5.3.

The following operating functions are specified in more detail in relation to the lifting device:

* “EMERGENCY STOP”: When this is actuated, not only the electrical power supply, alsothe pneumatic power supply must be shut down.

* “Reset” : This returns the system to the initial position, i.e, the piston rods of cylinders 1Aand 2A retract, the piston rod of cylinder 3A extends.

* “Continuous cycle OFF”: This stops the continuous cycle process. If there is already aworkpiece in the device, it is transferred to the upper roller conveyor. The piston rods ofcylinders 1A and 2A retract. The device is subsequently in its initial position.

Main switch EMERGENCY STOPEMERGENCY STOP

Automatic

Continous cycle on cycle start

Single

cycle offContinous

Manual Reset



Ambient conditions

The lifting device is used in a production shop in which the temperature fluctuates between 15 and35 degrees centigrade. The pneumatic components of the power section and the electricalconnections of the valves are to be dust-tight and splash-proof. The electrical components of thesignal control section are installed in a control cabinet and must conform to the relevant safetyregulations.

Power supply

The following power supply networks are available:

* Compressed air network (P = 0.6 Mpa = 6 bar)

* Electrical network (V = 230 VAC)

The electrical signal control section and the main circuit are to be operated with 24V DC. Apower supply unit therefore needs to be provided to supply this voltage.

7.3 Overall conceptual design of the control system

The signal processing aspect of the lifting device is implemented as a relay control system. Inview of the small number of drive units, the valves are mounted separately.

As the linear guides of the lifting platform and of the pushing device are already part of thestation, cylinders without integrated guides are used. Double-acting cylinders are used for drives1A and 2A. Drive 3A takes the form of a single - acting stopper cylinder.

Selection of cylinders

The cylinders are chosen on the basis of the requirements in terms of force and stroke, usingcatalogues obtained from pneumatics manufacturers. On account of the required drive force,cylinder 1A must have a piston diameter of at least 40mm, and cylinder 2A a piston diameter ofat least 40mm, and cylinder 2A a piston diameter of at least 32mm.

To ensure soft braking, cylinders with integrated adjustable end position cushioning are used fordrives 1A and 2A. The following cylinders would be suitable, for example:

* Cylinder 1A : Festo DNGUL-40-500-PPV-A

* Cylinder 2A : Festo DNGUL-32-250-PPV-A

A stopper cylinder is used for drive 3A; it is extended if the compressed air supply fails. Thisrequirement is met by a Festo STA-32-20-P-A type cylinder, for example



Selection of directional control valves for the control chain

In order to obtain the required behavior for drives 1A and 2A in the event of a power failure, thevalves used are spring-centered 5/3-way valves with a closed mid-position. As the movementsof the piston rods are relatively slow, valves of a comparatively small nominal size are adequate.Valves with 1/8-inch ports are used to match the smaller of the two cylinders directional controlvalves of the festo MEH-5/3G-1/8 type would be suitable, for example.

A spring-return 3/2-way valve of the Festo MEH-3/2-1/8 type is used for actuation of stoppercylinder 3A.

Pressure Sequence valve

The supply of compressed air for all three control chains must be shut off as soon as the electricalpower supply fails or an EMERGENCY STOP is triggered. An additional, electrically actuated,spring-return 3/2-way valve is therefore necessary which enables the supply of compressed aironly when the electrical power supply is functioning properly and no EMERGENCY STOPdevice has been actuated. In order to ensure that there is adequate flow, a Festo CPE14-M1H-3GL-1/8 type valve is used.

Speed regulation

The advance and retract speeds of drives 1A and 2A are regulated by means of exhaust air flowcontrol. Function connectors reduce tubing work, because they are screwed directly into thecylinder bore. The type of connectors required are those with a one-way flow control function,for example festo GRLA-1/4 (cylinder 1A) or GFLA-1/8 (cylinder 2A).

Selection of proximity switches

The proximity switches are selected to match the cylinders. It makes sense to use positive-switching sensors. For example, inductive sensors of type SMTO-1-PS-K-LED-24 are suitablefor cylinders 1A and 2A, and type SMT-8-PS-KL-LED-24 for cylinder 3A.

For controlling the device (see movement sequence) two proximity switches are needed for eachof cylinders 1A and 2A in order to detect the forward and retracted end positions. In the case ofcylinder 3A it is sufficient to have one sensor to detect the forward end position.

Positive-switching optical sensors, for example festo type SOEGRT-M18-PS-K, are used todetect whether there is a workpiece ahead of the stopper cylinder or on the lifting platform.

Allocation table for the lifting device

The subsequent steps of the project design process are made easier by listing the cylinders,solenoids, sensors, control elements and indicators (Table 5.3). Components belonging to anindividual control chain are shown on the same line of the table.



Advance Retract Other OtherRetractAdvance

1M1

2M1

Cyl.1A

Cyl.2A

Cyl.3A

Comp.air

2M2

1M2

3M1 -

-

-

0M1

1B2

2B2

3B1

1B1

2B1

B5

S1

S2

S3

S4

S5

S6

S8

S7

Control chain 1

Control chain 2

Control chain 3

Pressure sequence valve

Package on lifting platform

Emergency stop (Normally

Manual (MAN)

Main switch

closed contact)

Automatic (AUT)

Reset

Continous cycle ON

Single cycle START

Continous cycle OFF

Drive/function Actuated solenoid Proximity switch

ControlElement Comments



7.4 Displacement - step diagram for the lifting device

The displacement-step diagram for the lifting device is shown in Fig. 5.4. it illustrates the stepsin which the piston rods of the three cylinders advance and retract, and when the proximityswitches respond.

Fig.5.4: Displacement-step diagram for the lifting device.

Cylinder 1A

1 2 3 4 5=1

1B2

2B2

3B1

1B1

2B1

1B1 ^ 2B1 ^ 3B1

S7S6

S4 (AUT)

B5

1

0

1

1

0

0

Cylinder 2A

Cylinder 3A



CHAPTER - 8SAFETY MEASURES FOR ELECTROPNEUMATIC CONTROL SYSTEMS



Numerous protective measures are necessary in order to ensure that electro pneumatic controlsystems can be safely operated.

One source of danger is moving parts of machines and equipment. On a pneumatic press, forexample, care must be taken to prevent the operator’s fingers or hands from being trapped. Fig8.0 provides an overview of sources of danger and suitable protective measures.

Fig.8.0 Moving parts of machines and equipment: sources and danger and protectivemeasures

8.1 Source of danger

Electric current is another source of danger. The dangers and protective measures relating to

electric current are summarized in Fig 8.1.

Dangers from moving parts of machines and equipment(Cylinder, axes, grippers, suction cups, clamping devices,

presses, workpieces, etc.)

Protection byenclosure/covering

CageGrid

Warning lightssignalling devices

control andProtection by

EMERGENCY STOPTwo-hand safety control Setup procedure

unsupervised startup

Protection bysignal processing

measuresProtection against



Fig 8.1 Electric current: Sources of danger and protective measures

8.2 Safety rules

In order to provide the best possible safeguards for operating personnel, various safety rules andstandards must be observed when designing electro pneumatic control systems. The key standardsdealing with protection against the dangers of electric current are listed below.

* Protection measures for Electrical Power Installations up to 1000V (DIN VDE 0100).

* Specifications for Electrical Equipment and Safety of Machines (DIN/EN 60204).

* Degrees of protection of Electrical Equipment (DIN-VDE 470-1). When a person touches a live part, an electric circuit is completed. An electric current flowsthrough the person’s body.

Dangers from components through which electric current flows(Power supply units, sensors, signal processing, components

solenoid coils of dielectrical control valves)

Protection against contact with high

Safety extra-low voltage Main switch with

repair workmaintenance andProtection during

interclocking dust/foreign bodiesProtection against

Protection ofelectrical equipment

against environmentalinfluences

voltage

Covering/housingAdequate distanceGrounding

Protection againstwater/moisture



8.3 Effect of electric current on the human body

The effect of electric current on the human body increases with the intensity of the current andwith the length of time in contact with the current. The effects are grouped according to thefollowing threshold values.

* Below the threshold perception, electric current has no effect on the human body tohuman health.

* Above the let-go threshold muscles become cramped and functioning of the heart isimpaired.

* Above the threshold of non-fibrillation, the effects are cardiac arrest or ventricular.

* Up to the let-go threshold, electric current is perceived but there is no danger fibrillation,cessation of breathing and unconsciousness. There is an acute risk to life.

The threshold of perception, let-go threshold and non-fibrillation threshold are plotted in fig foralternating current with a frequency of 50 Hz. This corresponds to the frequency of the electricalsupply network. For direct current, the threshold values for endangering human beings are slightlyhigher.

Electrical resistance of the human body

The human body offer resistance to the flow of current. Electric current may enter the bodythrough the hand, for example: it then flows through the body to reemerge at another point (suchas the feet-see fig). Accordingly, the electrical resistance RM of the human body (Fig ) is formedby a series circuit comprising the entry resistance R01 the internal resistance R1 and the exitresistance R02 (Fig ). It is calculated using the following formula:

R R R RM 01 1 02

The contact resistances R01 and R02 vary greatly depending on the contact surface and themoistness and thickness of the skin. This affects the total resistance RM. It may range betweenthe following extremes.

* Less than 1000 ohms (large contact surfaces, wet, sweaty skin)

* Several million ohms (point contact, very dry, thick skin)



02R

R1

01R~

I

G

RE

ILR

RM~U

G

I

~

MR



8.4 Variables influencing the risk of accident

The current I through the human body is dependent on the source voltage V, the resistance RLof the electric line, the resistance RM of the person and the resistance RE of the ground (Fig). Itis calculated as follows:

I VR R RL M E

According to this formula, a high current, i.e. a high level of danger, is obtained in the followingcircumstances:

* When touching an electrical conductor carrying a high voltage V(Such as a conductor in the electrical supply network, 230V AC)

* When touching a conductor at a low contact resistance R0 and consequently lowresistance RM (such as with large contact surfaces, sweaty skin, wet clothing)

Danger zones with AC voltage (frequency 50Hz/60 Hz)

Tim

e t

0

10

20

50

1000

500

200

100

2000

5000

10000

ms

0.1 0.2 0.5 1 2 5 10 20 50 100 200 500 mA 2000

Current I

1 2 3 4

Threshold of non-fibrillation

Let-gothreshold

perceptionThreshold of



CHAPTER - 9COMPONENTS DESCRIPTION OF ELECTRO PNEUMATIC

TRAINER



1. 3/2 – way valve with pushbutton actuator N.C. assy.:

* Design: directly actuated, one side, with return spring. * Pressure range: (-0.9 – 8 bar) * Nominal Flow rate 1 ..2: 60 l/min

2. Quick-exhaust valve assy.:

* Quick-exhaust valve with built-in silencer. * Design: Pop pet valve * Pressure range: (0.5 – 10 bar) * Nominal flow rate 1 …2: 960 l/min * Nominal flow rate 2… 3: 1100 l/min.

3. 3/2-way roller lever Valve Act. N.C. assy.: The roller lever valve is actuated when the roller lever is pressed, for example by the cam of a cylinder. After release of the roller lever, the valve is returned to its initial position by as return spring.

* Design: Pop pet valve, directly actuated, one side with return spring. * Pressure range: (-0.9 to 8 bar) * Nominal flow rate 1…2: 80 l/min.

* Nominal flow rate 1 .. 4: 500 l/min.* Response time: Optimum.

4. 5/2 –way Single Pilot Valve with Assembly:

The pneumatic single piloted valve is actuated by pneumatic signals, and following removal ofthe signal is returned to its initial position by a return spring.

* Design: Directly actuated, one side with return spring. * Pressure range: (0 to 10 bar) * Nominal flow rate 1…2: 500 l/min.

* Nominal flow rate 1.... 4: 500 l/min.* Response time: Optimum

5. 5/2 Double Pilot Valve with Assembly:

The pneumatic double pilot valve is reversed by pneumatic signals form alternate sides. Thecircuit state is retained after removal of the signal until the next counteracting signal.

* Design: Directly actuated, both sides



* Pressure range: (0 – 10 bar) * Nominal flow rate 1…2: 500 l/min.

* Nominal flow rate 1 .. 4: 500 l/min.* Response time: Optimum.

6. Shuttle valve (OR) assy.:

The shuttle valve is switched through to the output by applying compressed air to one of the inputs (OR function).

* Design: OR gate (shuttle valve) * Pressure range: (1 – 10 bar) * Nominal flow rate 1…2: 500 l/min.

7. Dual-pressure valve (AND):

The dual-pressure valve is switched through to the output by applying compressed air to bothof the inputs (AND function).

* Design: AND gate (dual-pressure valve) * Pressure range: (1 – 10 bar) * Nominal flow rate 1…2: 550 l/min.

8. Time-delay valve / adjust N.C. assy.:

The time delay can be set with an adjusting screw (infinitely variable).

* Design – Return Spring. * Pressure range - (2.5 – 8 bar) * Nominal flow rate 1…2 - 92 l/min. * Delay – 30s

9. One-way flow control valve assy.:

The one-way flow control valve is a combination of flow control valve and a non-return valve. The cross-section of the restrictor can be set by means of a knurled screw.

* Design – Combined flow control valve. * Pressure range - (0.5 – 10 bar) * Nominal flow rate 0 – 220 LPM.



10. Single-acting cylinder assy.: * Design – Piston cylinder * Operating Pressure – 10 bar * Stroke length – Maximum 50 mm * Thrust at (6bar) – 169 N * Spring return force minimal – 13.65N

11. Double-acting cylinder assy.:

* Design – Piston cylinder * Operating Pressure – 10 bar * Stroke length – Maximum 100 mm * Thrust at (6bar) – 188.5 N * Return Thrust at (6 bar) – 158. 3 N

12. Manifold assy.: Manifold with six (2x3) self-closing non-return valves. A common manifold (QS – 6x6 = multiple connector) for plastic tubing allows supply of compressed air to the control via six Individual ports (QS-4 for plastic tubing PUN 4 x 0.75).

13. Filter regulator with gauge assy. With Lubricator:

* Filter control valve with pressure gauge, start-up valve, quick push-pull connectors and quick couplings, mounted on a swivel support. * The filter with water separator removes dirt, pipe sinter, rust and condensed water. * The pressure control valve regulates the supply air pressure to the set operating pressure and compensates pressure fluctuations. The filter bowl has a condensate drain valve. * The start-up valve / shut off valve ventilates and vents the entire control. The 3/2 way valve is actuated by a rotary button. * Design – Sintered filter * Nominal flow rate – 750 l/min * Input Pressure – Maximum (16 bar) * Output pressure – Maximum (12 bar) * Grade of filtration – 40 m * Condensate quantity – 22 c.cm.

* Connector – G 1/8

14. Plastic tubing:

* PUN 6 x 1 * Exterior diameter – 6 mm



* Interior diameter – 4 mm. * Blue – 15m

15. T – connectors(4):

These shall be for branching of the tubes for making circuitry.

16. 5/2 way Hand lever valve:

* ¼ Hand lever valve with * Flow – 1600 l/min * Work pressure – (0 – 8 bar)

17. Read Switch, Electronic with cylinder attachment:

The proximity switch consists of a sensor, the mounting kit, and the cable. This proximity switchgives a signal when it detects a magnetic field. The status is indicated by a LED.

* Switching voltage – 10 –30 VDC* Switching Current – Maximum 200mA* Switching power – 6w* Switch accuracy - ±0.1mm.

18. 3/2 way Single Solenoid Valve with LED, NC:

The status is indicated by an LED on the housing. The valve is equipped with a manual override.The electrical connections feature polarity reversal protection for the LED and the suppressorcircuit.

Pneumatic Technical data:

* Design – Spool valve, pilot controlled, with return spring. * Pressure range – 250 – 800 kPa (2.5 – 8 bar)

* Response time at 600 kPa (6 basr) – On: 20 ms, Off: 30ms* Nominal flow rate 1 .. 2 – 500 l/min.

* Electrical Technical Data:# Power Consumption – 1.5 W# Duty Cycle – 100%

19. 5/2 way Single Solenoid valve, with LED:

The status is indicated by an LED on the housing. The valve is equipped with a manual override.The electrical connections feature polarity reversal protection for the LED and the suppressorcircuit.




* Design – Spool valve, pilot controlled, with return spring. * Pressure range – 250 – 800 kPa (2.5 – 8 bar)

* Response time at 600 kPa (6 basr) – On: 20 ms, Off: 30ms* Nominal flow rate 1 .. 2 and 1 .. 4 – 500 l/min.* Electrical Technical Data:

# Power Consumption – 1.5 W# Duty Cycle – 100%

20. 5/2 way Double Solenoid valve, with LED:

The statuses are indicated by an LED on the housing. The valve is equipped with two manualoverride. The electrical connections feature polarity reversal protection for the LED and thesuppressor circuit.


* Design – Spool valve, with pilot control. * Pressure range – 150 – 800 kPa (1.5 – 8 bar)

* Response time at 600 kPa (6 bar) – 10 ms* Nominal flow rate 1 .. 2 and 1 .. 4 – 500 l/min.

* Electrical Technical Data:# Power Consumption – 1.5 W# Duty Cycle – 100%

21. Hand Sliding Valve: * 3/2 way valve * 1/8” – G thread * Flow – 0- 400 l/min Working Pressure – (0-8 bars)



CHAPTER - 10EXPERIMENTAL SECTION



BASIC PNEUMATIC SECTION



EXPERIMENT - 1

CIRCUIT DIAGRAM

Single acting cylinder

AND Gate

1 12

2

1 3 31

2

3/2 Push button valve 3/2 Push button

FRL

Compressor

Component Description

Number Description1 Compressed air supply

Air service unit, simplified representation1

Single acting cylinder 1

Two pressure valve1

3/2 Push button valve2



EXPERIMENT - 1

CONTROL THE SINGLE ACTING CYLINDER USING TWO WAY PRESSURE VALVE

Aim

To construct a pneumatic circuit to control the single acting cylinder control by Two-waypressure valve.

Apparatus Required

Compressor airFRLTwo-way pressure valveSingle acting cylinder

Procedure

1. Draw the circuit diagram.2. Connect the compressor air supply to FRL unit.3. Any two of the outputs of FRL unit directly connected to 3/2 push button valve inlet

first and second.4. Both 3/2 push button valves outputs to give AND Gate input.5. Check the all circuit.6. Open the hand slide valve. The air passes in both 3/2 pushbutton valves input port.7. When both push button is press the cylinder should be activated.

Truth table

Input 1 Input 2 Output

ONOFFOFFON

ONOFFONOFF

ONOFFOFFOFF

Result

The pneumatic circuit of two way pressure valve was simulated.



EXPERIMENT - 2

CIRCUIT DIAGRAM


OR Gate

1 12

2

1 3 31

2

3/2 Push button valve 3/2 Push button

FRL

Compressor




Single acting cylinder 1


Shuttle valve1



EXPERIMENT - 2

FOR USING OR GATE CONTROL TO SINGLE ACTING CYLINDERAim

To construct a pneumatic circuit to control the single acting cylinder.

Apparatus Required

Compressor airTube3/2 push button valveShuttle valveSingle acting cylinder

Procedure

1. Draw the circuit diagram.

2. Connect the compressor air supply to FRL unit.

3. Any two of the output of FRL unit to first 3/2 push button valve inlet and second 3/2push button valve inlet.

4. Both 3/2 push button valves outputs to give shut the valve inlet ports.

5. Check the all circuits.

6. Open the hand slide valve. The air passes in both 3/2 push button valve inlets.

7. Press any one push button valve. The cylinder will be activated.

Truth table

Input 1 Input 2 Output

OFFONOFFON

OFFOFFONON

OFFONONON

Result

Thus the single acting cylinder controlled by OR Gate.



EXPERIMENT - 3

CIRCUIT DIAGRAM

Double acting cylinter

3

24

FRL

Compressor

1

2


Double acting cylinder

1 Air service unit, simplified representation

Compressed air supply1DescriptionNumber


55/2 Single pilot valve

31

2

3/2 Push button valve

5/2 Single Pilot valve

1



EXPERIMENT - 3

FOR USING 5/2 SINGLE PILOT VALVE, CONTROL TO DOUBLE ACTING CYLINDER

Aim

To construct a pneumatic circuit to control the single acting cylinder.

Apparatus Required

Compressor air

FRL


5/2 single pilot valve

Air tube

Procedure



3. Connect any one of the outputs o FRL unit to 5/2 single pilot valve inlet port 1.

4. Again one of the outputs of FRL unit to connect to any to 3/2 push button valve inlet.

5. 3/2 push button valve output connect to 5/2 double pilot valve (port 12).

6. Both outputs of 5/2 double valve directly connected to double acting cylinder.

7. When is press 3/2 push button valve the cylinder will be activated.

Result

The direct control of a double acting cylinder was simulated.



EXPERIMENT - 4

CIRCUIT DIAGRAM


3

24

FRL

Compressor

1

2


3/2-Push button valve

1 5/2 Double Pilot valve

Compressed air supply1DescriptionNumber


55/2 Double pilot valve

31

2



2

1 33/2 Push button valve



EXPERIMENT - 4

DOUBLE ACTING CYLINDER CONTROL BY USING 5/2 DOUBLE PILOT VALVE

Aim

To construct a pneumatic circuit to control the double acting cylinder using 5/2 double pilotvalve.

Apparatus required

Compressor

Air tube

3/2 push button valve

5/2 double pilot valve

FRL unit

Procedure



3. Two outputs of FRL unit directly connected to 3/2 push button valves inlets. The bothoutputs connected to double pilot (Port 12, Port 14).

4. 3/2 double pilot outputs (2, 4) are connect to double acting cylinder.

5. Check for all circuit.

6. Observe the working of cylinder.

Result

Thus the double acting cylinder controlled by 5/2 double pilot valve.



EXPERIMENT - 5

CIRCUIT DIAGRAM

Double acting

CompressorFRL

12

3

W2W1

3

2

1

4

5

3

12

W2

3/2 Roller lever valve


One way flow




Number Description1 Compressor

5/2 Double pilot valve1

3/2 Roller lever valve2 Flow control valve21

W1

control valve

cylinder



EXPERIMENT - 5

CONTINUOS RECIPROCATING OF DOUBLE ACTING CYLINDER CONTROL THE 5/2 DOUBLE PILOT VALVE

Aim

To construct a circuit to control the forward return stroke of a double acting cylinder by pilotpressure.

Apparatus required

Air compressor.Air tube.Double acting cylinder.3/2 roller lever valve.5/2 double pilot valve and flow control valve. Procedure


2. Connect compressor air supply to FRL unit.

3. Connect any one of the outputs of FRL unit to 5/2 direction control unit port 1.

4. Connect port 4 of DCV to blank end of the double acting cylinder.

5. Connect the output of FRL unit to the input of two 3/2 roller lever valves to give pilotpressure for 5/2 double pilot valve.

6. The output of the two roller valves are connected to the either side of the 5/2 double pilotvalve properly.

7. When the FRL valves is opened the higher pressure air enters the blank end of the cylinderthrough DCT and the piston moves forward.

8. At the end of the forward stroke the piston rod pressure the roller valve. The output ofroller valve is sent to double acting cylinder to change the position.

9. Now the high pressure air from FRL unit is sent to rod end of the double acting cylinderthrough the second position of the DCV the piston retracts.

10. At the end of the return stroke the roller valve is pressed. The output of the roller valveis sent to DC change the piston. This is repeated until the FRL valve is closed.

Result

The continuos reciprocating of double acting cylinder was simulated.



EXPERIMENT - 6

CIRCUIT DIAGRAM

Double acting

CompressorFRL

12

3

W2W1

3

2

1

4

5

3

12

W2



One way flow control valve


Distance rule




3/2 way roller lever valve

1 Double acting cylinder

32

11 Single acting cylinder



W3 W3

21

3

3/2 Roller lever valvecylinder



EXPERIMENT - 6

STUDY THE CIRCUIT USING (A+B-A-B)Aim

To design a circuit for the sequence A+B-A-B.

Apparatus Required

Compressor

FRL




3/2 Roller lever valve.

Air tube

Procedure


2. Connect the compressor air to FRL unit

3. Are both outputs of FRL unit connected to all components.

4. Test your all circuits.

5. You will open the hand slide valve.

6. Observe the working of cylinders.

Result

The circuit diagram for the sequence is drawn and executed.



ELECTRO PNEUMATIC SECTION



Mechanical Circuit Electrical Circuit

Material Description

Number Description

1 Compressed air supply


1 3/2-way valve, pneumatically operated


1 Electrical connection 24V


1 Pushbutton (make)

1 Valve solenoid


31

2

FRL

Compressor

S1

3/2 Single solenoid valve

S1

Push button switch

Solenoid coil

0V

3

14

24V



EXPERIMENT - 1

Controlling the single acting cylinder using electrically.

AIM

To construct a pneumatic circuit to control the single acting cylinder electrically using push buttonswitch.

APPARATUS REQUIRED

Compressor, FRL, solenoid coil, electrical trainer, single acting cylinder and batch card.

PROCEDURE


2. Electro controller gives - voltage to pneumatic panel.

3. Input of push button is getting from solenoid valve output.

4. Connect the air supply to FRL unit.

5. Check all the connections carefully

6. Test the circuit.

7. Observe the working of the cylinder using the 3/2 single solenoid valve.

Result

Thus the movement of single acting cylinder was carried out using the 3/2 single solenoid valve.





Number Description

2 Pushbutton (make)



2 Valve solenoid



1 5/2 way valve


SPDT - Single Pole Double Through


W1

2

5 3

FRL

Compressor

4

W2

1 5/2 Double solenoid valve

W1 W2

24V 24V

solenoid coil

0V 0V

SPDT



EXPERIMENT - 2

Actuation of double acting cylinder using 5/2 double solenoid valve through SPDT switch.

AIM

To develop a electro pneumatic circuit to actuate a double acting cylinder.

APPARATUS REQUIRED

Compressor, FRL, Electrical controller, 5/2 Double solenoid valve, SPDT switch and Data Card.

PROCEDURE

1. Provide power supply to the pneumatic trainer from control trainer by interfacing 24V +and -

2. Using the SPDT switch energize the corresponding solenoid valve to get the desiredmovement in the cylinder.

3. Design and draw the pneumatic circuit.

4. Supply the Air to FRL unit.

5. Assemble all the components.

6. Check all the connections carefully.


8. Observe the working of the cylinder using the 5/2 double solenoid valve.

Result

Thus the movement of the double acting cylinder was carried out using the 5/2 DCV.




Designation Description

1 Pushbutton (make)



1 Valve solenoid



1 5/2 way valve



W1

2

5 3

FRL

Compressor

4

15/2 Single pilot valve

W1

+24V

0V

Electrical circuitMechanical circuit

13

4

Push button switch

Solenoid coil



EXPERIMENT - 3

Electrically control Double acting cylinder using pushbutton switch.

AIM

To construct a pneumatic circuit to control the single acting cylinder electrically using push buttonswitch.

APPARATUS REQUIRED

Compressor, FRL, 5/2 Double solenoid valve, electrical trainer, single acting cylinder and Batchcard.

PROCEDURE

1. Draw the circuit diagram and connect the air supply to FRL unit.

2. Connect the electrical circuit from 24V DC source to ON/OFF switch.

3. Solenoid are connected to the pushbutton switch.

4. When the solenoid is given a signal by a push button switch. DCV is activated to doubleacting cylinder.

5. When off button is pressed the signal solenoid are cut and the solenoids are de-energizedand the DCV comes to the original position.

RESULT

Thus the double acting cylinder is controlled electrically operated switch.




Number Description

1 Distance rule



1 Air service unit, FRL

1 3/2-Single solenoid coil


1 Pushbutton (make)

1 Relay with switch-on-delay


1 Make switch


31

2

FRL

Compressor

S1


T1

Push button switch

On delay timer

0V

3

14

24VPneumatic circuit diagram

A1

A25 S1

S1

3

3

Make switch

4

Solenoid coil

Electrical circuit diagram

2

3



EXPERIMENT - 4

Actuation of single acting cylinder using Time delay valve used to on delay timer.

AIM

To develop an electro pneumatic circuit for actuation of single acting cylinder using timer.

APPARATUS REQUIRED

Compressor Air, FRL, Time delay valve, electrical controller, single acting cylinder, 3/2 singlesolenoid valve and Batch card.

PROCEDURE

1. Provide power supply to electrical controller by interfacing the +ve to +ve and -ve to -ve.

2. Provide power supply to pneumatic trainer from electrical controller by interfacing 24 +veto +ve and -ve to -ve.

3. Using the SPDT switch energize the corresponding solenoid to get the desired movementof the cylinder.

4. Actual the time delay circuit.

5. From dime delay give connection to single along cylinders to actual cylinder according totime set.

6. Design and draw the pneumatic circuit.

7. Connect the air supply.


9. Observe the working of the cylinder.

Result

Thus the movement of single acting cylinder was carried out using time delay.





Number Description




1 3/2-way valve with pushbutton


1 Pushbutton (make)


1 Make switch

1 Valve solenoid

1 Relay with switch-off delay


31

2

FRL

Compressor

S1


T1

Push button switch

Off delay timer

0V

3

4

24V

A1

A25

S1

T1

3

Make switch

4

Solenoid coil

3

12 3



EXPERIMENT - 5

Actuation of single acting cylinder using OFF delay Timer.

AIM

To develop an electro pneumatic circuit for actuation of a single acting cylinder using OFF delayTimer.

APPARATUS REQUIRED

Compressor Air, FRL, 3/2single acting cylinder, electrical controller, single acting cylinder, Timer,Batch chord.

PROCEDURE

1. Provide power supply to pneumatic trainer from electrical controller by inter facing 24+and 24-.

2. Provide 24V power supply to timer.

3. Any one of the output of FRL unit direct connect to 3/2 single solenoid valve.

4. Single solenoid valve out put is connect to single acting cylinder.

5. Give +24V and -24V in Timer.

6. Output of Timer connected to solenoid coil.

7. Check the all circuit.

8. Observe the working of cylinder.

9. Observe the working circuit.

Result

Thus the movement of single acting cylinder was carried out using time delay.



Mechanical Circuit


Electrical Circuit

Flow control valve

W2

Q2Q1

Compressor


W1

2

5 3

FRL

4

15/2 Double solenoid valve

DescriptionNumber

1 CompressorFRL15/2 Double Solenoid Valve1Flow control valve1

Double acting cylinder1Proximity sensor1Solenoid coils1

0V

4

32

1+24V

Solenoid CoilSolenoid Coil

W2

Q2

W1Sensor

Proximity

Q1



EXPERIMENT - 6

Continuos actuation of double acting cylinder using magnetic proximity sensor.

AIM

To construct a pneumatic circuit to control the double acting cylinder electrically using magneticproximity sensor.

APPARATUS REQUIRED

Compressor Air, FRL, 5/2 double solenoid valve electrical controller, sensor, double actingcylinder and flow control valve.

PROCEDURE

1. Draw the circuit diagram

2. Connect the circuit diagram in all components.

3. Connect air supply to FRL unit.

4. Connect the electrical circuit from electrical controller to panel [24+ and 24-)

5. Connect from proximity sensor output to 5/2 double solenoid valve input.

6. Check all circuit in panel.


8. Observe the working in double acting cylinder activated.

Result

Thus the movement of double acting cylinder was carried out using the magnetic proximitysensor.



Mechanical Circuit

Electrical Circuit Material

Description


Flow control valve

S3S1

2

5 3

4

FRL

Compressor



5/2 Double solenoid valve 1

4

35

2

S2 S4

P1 P2 P4P3

DescriptionNumber

1 Compressed air supply1 Air service unit, simplified

2 Double acting cylinder1 5/2 Way valve2 One-way flow control valve

representation

1 5/2-way valve, with selection switch

Electrical connection 0V14 Pushbutton (make)

Valve solenoid41 Electrical connection 24V

S1 S2 S3 S4

+24V

0V

Solenoid coil

4

3

1 2

3 4 5 6 7

3 3 3

4 4 4



EXPERIMENT - 7

Simulation of Electrically sequencing circuit using a double acting cylinder and miniature cylinder.

AIM

To simulate the electrically sequencing circuit using Push button switch.

APPARATUS REQUIRED

Compressor Air, FRL, 5/2 Double solenoid valve, electrical controller, double acting cylinder,Miniature cylinder then batch card.

PROCEDURE

1. Draw the circuit diagram

2. Connect the mechanical circuit in panel.

3. To give the wiring connection as for as above the diagram.

4. Check for all circuit.


6. Observe the working of the cylinders.

RESULT

Thus the sequence of double acting cylinders was carried out using push button switch.



Mechanical Circuit

Electrical Circuit


Flow control valve

S3S1

2

5 3

4

FRL

Compressor



5/2 Double solenoid valve 1

4

35

2

S2 S4

P1 P2 P4P3

SensorProximity

P3

S1

Solenoid Coil

0V

4

321+24V

S2

P2

4

P4

S3

4

S4

P1

ProximitySensor

876Push button switch

5

DescriptionNumber

1 Compressed air supply1 Air service unit, simplified

2 Double acting cylinder1 5/2 Way valve2 One-way flow control valve

representation

1 5/2-way valve, with selection switch

Electrical connection 0V1

4 Magnetic proximity switchValve solenoid4

2 Distance rule

Electrical connection 24V1



EXPERIMENT - 8

AIM

Study the circuit A+B+A-B- using electrically magnetic sensor proximity.

APPARATUS REQUIRED

Compressor Air, FRL, electrical controller, double acting cylinder, 5/2 Double solenoid valveMagnetic proximity switch, miniature cylinder.

PROCEDURE

1. Draw the electrical circuit and mechanical circuit.

2. Provide power supply to electrical controller by interfacing the 24+ve to +24ve andnegative voltage.

3. Any one output is push button have direct connected to electro pneumatic panel +24V or-24V. This push button should be on.

4. To give the wiring connection as fox as above the diagram.

5. Check for all circuit connection.

6. Connect the air supply to FRL unit.


8. Observe the working of the cylinders auto material reciprocating of circuit in A+B+A-B.

Result

Thus the movement of double acting cylinder were carried out using the circuit A+B+A-B.

lab manual of pneumatics control

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