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Pneumatic Systems for Engineers

This document discusses pneumatic systems and components used in automatic control systems. It describes the basic elements of an automatic control system, including input sensors, output actuators, and controllers. A key type of controller discussed is a programmable logic controller (PLC), which uses programmable memory to store instructions to implement functions like logic, sequencing, timing, and counting to control machines and processes. Examples provided include using a PLC to control the operation of an automatic drilling machine.

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parth bhardwaj
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164 views4 pages

Pneumatic Systems for Engineers

This document discusses pneumatic systems and components used in automatic control systems. It describes the basic elements of an automatic control system, including input sensors, output actuators, and controllers. A key type of controller discussed is a programmable logic controller (PLC), which uses programmable memory to store instructions to implement functions like logic, sequencing, timing, and counting to control machines and processes. Examples provided include using a PLC to control the operation of an automatic drilling machine.

Uploaded by

parth bhardwaj
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Chapter: 4 Introduction to Pneumatic Systems and Components

Topics:
1. Basic Requirements for Pneumatic System
2. Applications
3. Pneumatic fundamentals
4. Construction, working principle and operation of pneumatic power transmission
system components:
a. Power source
b. FRL unit
c. Actuators
d. Control valves like DCV, FCV, PCV, time delay, quick exhaust, twin
pressure, shuttle valve.

Introduction
 What type of task might a control system handle?
 To control a sequence of events, maintain some variable constant, or follow
some prescribed change.
 Example: Control system for an automatic drilling machine.

Why Automatic Control is required?

 To improve the quality and lower the cost of production.


 To increase the production rate.
 To attain optimal performance.
 To relieve the drudgery of many routine, repetitive manual operations:
 Metal matching sequences
 Product assembly lines
 Batch chemical processes
Profitability usually depends on productivity and automation is a means towards greater
productivity

Basic Elements of Automatic Control System


 Input Sensors: Convert physical phenomena (for example, position) to electrical
signal.
 Output Actuators: Convert electrical signal to a physical action, for example, air
valve or motor.
 Controller: Using the measurements, calculates control actions. Major Types of
Controllers are:
 Programmable Logic Control (PLC): Developed initially out of Automotive
Industry. Distributed Control System (DCS): Employed in the Chemical Industry.
 DCS and PLC systems are merging into one device called Programmable
Electronic System (PES).
1.1 Controllers
A control system might be required to control a sequence of events, maintain some
variable constant, or follow some prescribed change. Lets us have a look at two such
control systems. Automatic drilling machine[1]

Figure 1.1: an automatic drilling machine [1]

A Control Circuit

Figure 1.2: A control circuit [2].

A controller circuit for automatic drilling machine is shown in Fig 1.2 where
opening/closing of the switch deactivates/activates the relay and thus Turn OFF/ON the
motor and causes the drill to rotate/steady.
Another switch could activate a relay and switch on the current to a pneumatic or
hydraulic valve, which results in pressure being switched to drive a piston in a cylinder
and so results in the work piece being pushed into the required position.
For controlling the number of items packed into a packing case, we could likewise wire
up electrical circuits involving sensors and motors. However, the controller circuits we
devised for these two situations would be different.
Thus, when the rules used for the control actions are changed, the wiring has to be
changed.

1.1.1 The Programmable Logic Controller


A programmable logic controller (PLC) (Fig.1.3) is a special form of microprocessor
based controller. It uses programmable memory to store instructions to implement
functions such as Logic, Sequencing, Timing, Counting, and Arithmetic in order to
control machines and processes.

Fig.1.3: A programmable logic controller[1].

References

1. Bolton, William. Programmable logic controllers. 5th edition, Newnes.


2. https://www.mobileautomation.com.au/plc-industrial-application/
3. https://www.polytechnichub.com/application-programmable-logic-controller-plc/
4. https://www.quora.com/What-are-application-of-PLC
5. https://www.sanfoundry.com/plc-program-operate-drilling-parts

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