Industrial Automation: What is Automation?, History of Automation, Manual Control, Pneumatic Control, Hard wired logic control, Electronic Control using Logic Gates, Programmable Logic Controllers, Advantages of PLCs, Industrial Automation Components, Sensors ( Field Instruments ), Widely used Sensors ( Field Instruments ) and Leading Manufacturers in Sensors ( Field Instruments )

 Industrial Automation

•Automation is encompassing virtually every walk of life.

•Automation solutions are required right from agricultural to space technology.

•Plant Automation is the necessity for the manufacturing industry to survive in today’s globally competitive market.

What is Automation?

Automation is basically the delegation of human control function to technical equipment for

Increasing productivity

Increasing Quality

Reducing Cost

Increasing safety in working conditions

History of Automation

Pneumatic Control.

Hard wired logic Control.

Electronic Control using Logic Gates.

Programmable Logic Controller.

Manual Control.

Manual Control

All the actions related to process control are taken by the operators.


•Likely human errors and consequently its effect on quality of final product.

•The production, safety, energy consumption and usage of raw material are all subject to the correctness and accuracyof human action.

Pneumatic Control

Industrial automation, with its machine and process control,had its origin in the1920s with the advent of “Pneumatic Controllers”.

Actions were controlled by a simple manipulation of pneumatic valves, which in turn were controlled by relay sand switches.


•Bulkyand Complex System.

•Involves lot of rework to implement control logic.

•Longer project time.

Hard wired logic control

Thecont actor and Relays together with hardware timers and counters were used in achieving the desired level of automation


•Bulky panels

•Complex wiring

•Longer project time

•Difficult maintenance and trouble shooting

Electronic Control using Logic Gates

In1960s with the advent of electronics,the logic gates started replacing the relays and auxiliary contactors in the control circuits. The hardware timers & counters were replaced by electronic timers.


•Reduced space requirements.

•Energy saving.

•Less maintenance & greater reliability.

•Change sin control logic not possible.

•More project time.

Programmable Logic Controllers

10In 1970s with the coming of microprocessors and associated peripheral chips, the whole process of control and automation underwent a radical change.

Instead of achieving the desired control or automation through physical wiring of control devices, in PLC it is achieved through a program or say software.

The programmable controllers have in recent years experienced an unprecedented growth as universal element in Industrial Automation.

It can be effectively used in applications ranging from simple control like replacing small number of relays to complex automation problems

Advantages of PLCs

Reduced space

Energy saving

Ease of maintenance


Greater life & reliability

Tremendous flexibility

Shorter project time

Easier storage, archiving and documentation

Industrial Automation Components

• Field Instruments.

• Control Hardware.

• Control Software.

Sensors ( Field Instruments )

Sensors with transmitters are the field devices placed in the field who actually sense the parameter and send the analog signal to the control hardware.

The analog signals used are Ohm (RTD), mV(Thermocouple), 4-20 mA, +/-10 V, etc

Widely used Sensors ( Field Instruments )

RTD : Output in Ohms (Temperature)

Thermocouples : Output in mV (Temperature)

Pressure Transmitters : 4-20mA, 0-10 V …..

Flow Transmitter : 4-20mA, 0-10 V …..

Level Transmitter : 4-20mA, 0-10 V …..

Conductivity meter : 4-20mA, 0-10 V …..

Density meter : 4-20mA, 0-10 V …..

pH transmitter : 4-20mA, 0-10 V …..

Leading Manufacturers in Sensors ( Field Instruments )

Fisher Rosemount.


Anderson & Housers.



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