PLC,SCADA And HMI

CHAPTER 1

COMPANY PROFILE

Wonder System is a dedicated team of “Automation -Design” (Hardware,

Software & Systems) engineers, capable of, and committed to understand

customer requirements, translate them to feasible design specification, develop

performing solutions, validate, and help deploy to the end uses. Wonder system

excellence in automation design services makes it a technology innovator and

trusted partner for system engineering services. It provides intensive practical

training. It believes in providing 50% theory and 50%practical.Wonder system

is known for providing quality products which is effective in upgrading the

knowledge and skills set of the student. Wonder system also provides exposure

to the industrial environment to students and introduce to latest technology

trends.

Wonder Systems India, being system integrator for SSD Drives division of

Parker Hannifin Corporation (formerly Eurotherm Drives), UK and Italy offers

complete Engineering & cost effective solutions, covering Design Concepts,

Assembly, Supply, Commissioning and Field services for various Industrial

applications

For the customers, it means:

Shortened Time-To Market

Cost Efficiency

Certainty of Outcome

Highest Quality

1.1 OBJECTIVE OF AUTOMATION TRAINING

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PLC,SCADA And HMI

To train a new generation of skilled workers for service maintenance,

programming operation of new range of machines and equipments being

introduced for industrial and commercial use.

To upgrade the skills of existing industrial workers through short term

specialized courses in newly emerging Hi-Tech Area of industry.

To provide diagnostic and development curriculum design and high live

dialectic support for training system as well as industrial consultancy facilities.

1.2 PARTNERS

BHARAT ISPAT UDYOG

GIAN STEEL ROLLING MILLS

GOLDEN STRIPS LTD

ALLIED RECYCLING LTD

KASHMIR STEELS LTD

HIM ALLOYS LTD

C.P. ROLLING MILLS PVT. LTD

VIJAY STEEL LTD.

1.3 INTERNATIONAL PARTNERS

STEEL MASTERS LTD, TANZANA

GALAXY PROMOTERS, NIGERIA

RAZAQUE STEEL, PAKISTAN

ACCURATE STEEL MILLS,KENYA

1.4 APPLICATIONS

Wonder Systems India, being System Integrators for PARKER SSD Drives (formerly

Eurotherm Drives), UK and SAEL, Italy offer complete Engineering & cost effective

solutions, covering Design Concepts, Assembly, Supply, Commissioning and Field

services for various Industrial applications.

Hot Strip Mills

TMT Mills

Bar Mills

Tube Mills

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Cold Rolling Mills

PVC Extrusion mills

Paper Mill

Drawing mills

Cable industries

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PLC,SCADA And HMI

CHAPTER 2

INTRODUCTION TO AUTOMATION

2.1 Definition Of Automation

It is define as the replacement of muscular and mental efforts of human being

by the use of hydraulic, pneumatic, electrical and electronics component or it

is the use of machines, control system and information technologies to

optimize productivity in the production of goods and delivery of services.

Automation plays an increasingly important role in the world economy and in

daily experience.

The dictionary defines automation as “the technique of making

an apparatus ,a process, or a system operate automatically.”

We define automation as “ the creation and application of technology to monitor and

control the production and delivery of products and services.”

Using our definition, the automation profession includes “everyone involved in the

creation and application of technology to monitor and control the production and

delivery of products and services”; and the automation professional is “any individual

involved in the creation and application of technology to monitor and control the

production and delivery of products and services.”

Automation provides benefits to virtually all of industry. Here are some examples:

Manufacturing , including food and pharmaceutical, chemical and petroleum,

pulp and paper

Transportation , including automotive, aerospace, and rail

Utilities , including water and wastewater, oil and gas, electric power, and

telecommunications

Defence

Facility operations , including security, environmental control, energy

management, safety, and other building automation and many others

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PLC,SCADA And HMI

Automation crosses all functions within industry from installation, integration, and

maintenance to design, procurement, and management. Automation even reaches into

the marketing and sales functions of these industries.

Automation involves a very broad range of technologies including robotics and

expert systems,telemetry and communications, electro-optics, Cyber security, process

measurement and control, sensors, wireless applications, systems integration, test

measurement, and many, many more.

2.2 Current Emphasis In Automation

Currently, for manufacturing companies, the purpose of automation has shifted

from increasing productivity and reducing costs, to broader issues, such as

increasing quality and flexibility in the manufacturing process.

2.3 Need For Automation

Economic advantage through increased ‘Productivity’.

Reduced labour costs.

Savings in supervision

Reduction in operating cost.

Improved accuracies with consistency of quality parameters.

Safety concerns – Automation of component handling for hazardous process.

Elimination of human errors.

Suitable for mass production with better material handling.

Flexible with zero set-up change time.

2.4 Criteria For Automation

Inaccessible areas of operation.

Component handling difficult because of size.

Process ‘critical to quality’ of end product & calls for no manual intervention.

Influence of process time i.e. Process time smaller than manual load / unload

time.

Enhancement of productivity and reduction in operator fatigue.

Elimination of wrong loading – Requirement of Fool proofing.

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Safety concerns, hazardous process.

2.5 Safety Issues Of Industrial Automation:-

One safety issue with automation is that while it is often viewed as a way to minimize

human error in a system, increasing the degree and levels of automation also

increases the consequences of error. For example, The Three Mile Island nuclear

event was largely due to over-reliance on "automated safety" systems.

Unfortunately, in the event, the designers had never anticipated the actual

failure mode which occurred, so both the "automated safety “systems and their

human overseers were inundated with vast amounts of largely irrelevant

information. With automation we have machines designed by (fallible) people

with high levels of expertise, which operate at speeds well beyond human

ability to react, being operated by people with relatively more limited education (or

other failings, as in the Bhopal disaster or Chernobyl disaster). Ultimately, with

increasing levels of automation over ever larger domains of activities, when

something goes wrong the consequences rapidly approach the catastrophic. This is

true for all complex systems however, and one of the major goals of safety

engineering for nuclear reactors, for example, is to make safety mechanisms as simple

and as foolproof as possible (see safety engineering and passive safety).

2.6 Automation Tools

Different types of automation tools exist.

ANN - Artificial neural network

DCS - Distributed Control System

HMI - Human Machine Interface

LIMS - Laboratory Information Management System

MES - Manufacturing Execution System

PAC - Programmable automation controller

PLC - Programmable Logic Controller

SCADA - Supervisory Control and Data Acquisition

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2.7 Advantages Of Automation

Increased productivity

Improved quality

Improved robustness of product

Economy improvement

Time saving

Reduce human efforts

Low power consumption

More accuracy

2.8 Limitation Of Automation

Current technology is unable to automate all the desired tasks.

As a process becomes increasingly automated, there is less and less labor to be

saved or quality improvement to be gained. This is an example of both

diminishing returns and the logistic function.

Similar to the above, as more and more processes become automated, there are

fewer remaining non-automated processes. This is an example of exhaustion of

opportunities.

Unemployment rate increases due to machines replacing humans and putting those

humans out of their jobs.

Technical Limitation: Current technology is unable to automate all the desired tasks

Security Threats/Vulnerability: An automated system may have limited level of

intelligence; hence it is most likely susceptible to commit error.

Unpredictable development costs: The research and development cost of automating a

process may exceed the cost saved by the automation itself.

High initial cost: The automation of a new product or plant requires a huge initial

investment in comparison with the unit cost of the product, although the cost of

automation is spread in many product batches of things.

CHAPTER 3

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PROGRAMMABLE LOGIC CONTROLLER

3.1 Introduction

Automation of many different processes, such as controlling machines, basic

relay control, motion control, process control is done through the use of small

computers called a programmable logic controller (PLC). This is actually a

control device that consists of a programmable microprocessor, and is

programmed using a specialized computer language.

3.2 What is PLC

A Programmable Logic Controller, PLC, or Programmable Controller is an electronic

device used for Automation of industrial processes, such as control of machinery

on factory assembly lines.  A programmable controller is a digitally operating

electronic apparatus which uses a programmable memory for the internal storage of

instructions for implementing specific functions, such as logic, sequencing, timing,

counting and arithmetic, to control various machines or processes through digital or

analog input/output devices. Unlike general purpose computers, the PLC is designed

for multiple inputs and output arrangements, extended temperature ranges,

immunity to electrical noise, and resistance to vibrations and impacts. Programs to

control machine operation are typically stored in battery-backed or non-

volatile memory. A PLC is an example of a real time system since output results are

produced in response to input conditions within a bounded time, otherwise unintended

operation  results. A programmable logic controller (PLC) is a digital commuter used

for automation of electro mechanical process.

Such as control of machinery on factory assembly line, Amusement rides, Lighting

fixture, Lifts, Ovens, Furness. DC MOTAR ACTUATOR, SOLENOID, ALARM,

HEATING ELEMENTS etc. The switching voltage cans 12v, 24v, 110v, 240

voltages. In many case the PLC cannot switch on the device directly because of high

current. PLC are used in many industries, it is designed for multiple inputs and output

arrangement.

A programmable logic controller (PLC) or programmable controller is a

digital computer used for automation of electromechanical processes, such as

control of machinery on factory assembly lines, amusement rides, or lighting

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PLC,SCADA And HMI

fixtures. PLC’s are used in many industries and machines, such as packaging

and semiconductor machines. Unlike general-purpose computers, the PLC is

designed for multiple inputs and output arrangements, extended temperature

ranges, immunity to electrical noise, and resistance to vibration and impact.

Programs to control machine operation are typically stored in battery-backed or

non-volatile memory. A PLC is an example of a real time system since output

results must be produced in response to input conditions within a bounded time,

otherwise unintended operation will result.

A modern programmable logic controller is usually programmed in any one of

several languages, ranging from ladder logic to Basic or C. Typically, the

program is written in a development environment on a personal computer (PC),

and then is downloaded onto the programmable logic controller directly through

a cable connection. Programmable logic controllers contain a variable number

of Input/output (I/O) ports the programmable logic controller circuitry monitors

the status of multiple sensor inputs, which control output.

Fig.3.1 Programmable logic controller (PLC)

A PLC is user friendly, microprocessor-based specialized computer that carries

out control functions of many types and levels of complexity. Its purpose is to

monitor crucial process parameters and adjust process

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PLC,SCADA And HMI

A programmable logic controller (PLC) is a solid state device designed to

perform logic functions previously accomplished by electromechanical

relays. operations accordingly.

The design of a PLC is similar to that of a computer. Basically, the PLC is an

assembly of solid state digital logic elements designed to make logical

decisions and provide outputs. Programmable logic controllers are used for the

control and operation of manufacturing process equipment and machinery.

3.3 PLC Origin

The PLC was invented in response to the needs of the American automotive

manufacturing industry. Programmable controllers were initially adopted by

the automotive industry where software revision replaced the re-wiring of

hard-wired control panels when production models changed.

Before the PLC, control, sequencing, and safety interlock logic for

manufacturing automobiles was accomplished using hundreds or thousands of

relays, cam timers, and drum sequencers and dedicated closed-loop

controllers. The process for updating such facilities for the yearly model

change-over was very time consuming and expensive, as the relay systems

needed to be rewired by skilled electricians.

In 1968 GM Hydramatic (the automatic transmission division of General

Motors) issued a request for proposal for an electronic replacement for hard-

wired relay systems.

The winning proposal came from Bedford Associates of Bedford,

Massachusetts. The first PLC, designated the 084 because it was Bedford

Associates' eighty-fourth project, was the result. Bedford Associates started a

new company dedicated to developing, manufacturing, selling, and servicing

this new product: Modicon, which stood for Modular Digital Controller. One

of the people who worked on that project was Dick Morley, who is considered

to be the "father" of the PLC. The Modicon brand was sold in 1977 to Gould

Electronics, and later acquired by German Company AEG and then by French

Schneider Electric, the current owner.

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One of the very first 084 models built is now on display at Modicon's

headquarters in North Andover, Massachusetts. It was presented to Modicon

by GM, when the unit was retired after nearly twenty years of uninterrupted

service. Modicon used the 84 moniker at the end of its product range until the

984 made its appearance.In short:

Developed to replace relays in the late 1960s

Costs dropped and became popular by 1980s

Now used in many industrial designs

3.4 PLC History

12 K of memory and 1024 I/O points. The Hydramatic Division of the

General Motors Corporation specified the design criteria for the first

programmable controller in 1968 Their primary goal To eliminate the high costs

associated with inflexible relay-controlled systems,

The controller had to be designed in modular form, so that sub-assemblies could

be removed easily for replacement or repair.

The control system needed the capability to pass data collection to a central

system.

The system had to be reusable.

The method used to program the controller had to be simple, so that it could be

easily understood by plant personnel.

3.5 Programmable Controller Development

1968 Programmable concept developed

1969 Hardware CPU controller, with instructions, 1 K of memory and

128 I/O

points .

1974 Use of several (multi) processors within a PLC - timers and

counters;arthimetic operation.

1976 Remote input/output systems introduced

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1977 Microprocessors - based PLC introduced

1980 Intelligent I/O modules developed Enhanced communications

facilities

3.6 Programming

Early PLCs, up to the mid-1980s, were programmed using proprietary

programming panels or special-purpose programming terminals, which often

had dedicated function keys representing the various logical elements of PLC

programs. Programs were stored on cassette tape cartridges. Facilities for

printing and documentation were very minimal due to lack of memory capacity.

The very oldest PLCs used non-volatile magnetic core memory.

3.7 Functionality

The functionality of the PLC has evolved over the years to include sequential

relay control, motion control, process control, distributed control systems and

networking. The data handling, storage, processing power and communication

capabilities of some modern PLCs are approximately equivalent to desktop

computers. PLC-like programming combined with remote I/O hardware, allow a

general-purpose desktop computer to overlap some PLCs in certain

applications.

3.8 Architecture Of PLC

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Fig 3.2 Architecture of PLC

Fig 3.3 Componenets of PLC

3.8.1 Parts Of PLC

Power Supply: PLC requires 24V switch mode power supply for its operation.

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MCU: Its full form is microcontroller unit. It is the processor of PLC. It is

basically the brain of PLC. It performs various control operations of PLC.

Inputs And Outputs: PLC has a set of isolated inputs and isolated outputs.

Different PLC’s have different number and different type of inputs and outputs.

Like in Micrologix 1000 we have total number of 6 inputs and 4 outputs whereas in

Micrologix 1100 we have 10 inputs and 6 outputs.

Expansion Port: In PLC there is an expansion port which is used for the addition

of any other equipment with PLC. For example analog cards.

Memory Module: The memory module in PLC is used for the storage of program

in PLC for future use.

Communication Port: The communication ports are used in PLC to communicate

with the computer. In PLC there are two types of communication ports i.e. RS 232

comport and Ethernet port.

Display: In some of the PLC’s there is display screen which is available on the

PLC. This display screen is used as human machine interface i.e. it provides good

visualization of operation running on PLC.

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3.9 Pin Diagram

Fig3.4 PLC Pin Diagram.

3.9.1 Inputs And Outputs Of PLC

PLC programs are made up of a combination of the "gates" together with inputs,

outputs, timers, counters, internal memory bits, analog inputs, analog outputs,

mathematical calculations, comparators etc.

3.9.1.1Inputs

These are the physical connections from the real world to the PLC. They can be limit

switches, push buttons, and sensors, anything that can "switch" a signal on or off. The

voltages of these devices are usually, but not always, 24 Volt DC. Manufacturers make

inputs that can accept a wide range of voltages both ac and dc. It should be

remembered that an input will be ON,"status 1", when the voltage is present at the input

connection and OFF, "status 0", when the voltage is no longer present at the input

connection.

3.9.1.1.1 Types Of Inputs Of PLC

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User Type: These are the inputs and outputs that are physically present and

are practical to the inputs and outputs of the PLC.

Bit Type: These are the inputs and outputs that are not physically present and

are functional in the PLC only. These inputs/outputs are basically used to drive

each other in the ladder logic programming.

XIC (Examine if closed):

XIO (Examine if open):

Tb3.2 XIO Truth table

3.9.1.2 Outputs

These are the connections from the PLC to the real world. They are used to

switch solenoids, lamps, contactors etc on and off. Again they are usually 24

Volt DC, either relay or transistor, but can also be 115/220 Volt AC.

3.9.1.2.1 Types Of PLC Outputs

Relay type output

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I/

P

O/P

0 0

1 1

I/

P

O/P

0 1

1 0

PLC,SCADA And HMI

Transistor type output

TRIAC type output

3.10 PLC Manufactures

SIEMENS

ALLEN BRADLEY

GENERAL ELECTRICAL

MITSUBISHI

SCHENIDER

ABB

TOSHIBA

L N T

UNITRONICS

COTRUST

3.11 How The PLC Operates

Fig 3.5 Operation of PLC

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3.12 Ladder Logic

Ladder logic is the main programming method used for PLCs. As mentioned

before, ladder logic has been developed to mimic relay logic. The decision to

use the relay logic diagrams was a strategic one. By selecting ladder logic as

the main programming method, the amount of retraining needed for engineers

and tradespeople was greatly reduced.

Modern control systems still include relays, but these are rarely used for logic.

A relay is a simple device that uses a magnetic field to control a switch.

Objectives

Know general PLC issues

To be able to write simple ladder logic programs

Understand the operation of a PLC

PLC History

Ladder Logic and Relays

PLC Programming

PLC Operation

3.13 Basic Ladder Logic Symbols

Normally open contact Passes power (ON) if coil driving the

contact is ON (closed) Allen-Bradley calls it XIC - eXamine

If Closed

Normally closed contact Passes power (ON) if coil driving

the

contact is off (open) Allen-Bradley calls it XIO - eXamine If

Open

Output or coil If any left-to-right path of inputs passes

power,

output is energized Allen-Bradley calls it OTE - OuTput

Energize

Not Output or coil If any left-to-right path of inputs passes

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power, output is de-energized

For Example

Eg.1.There is only 1 output & 4 inputs. If I1 & I2 simultaneously pressed then

Q1 output ON & if I3 & I4 is simultaneously pressed then Q1 OFF.

Types of PLC’s and their Programming

1. Simple programs with NO and NC

a. If a 1st detent button is pressed then the 4 indicators will glow and if the 3 rd

and 4th detent button is pressed then the 2nd and 3rd output will goes off and the

remaining will goes on.

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Using Memory Bit:

a. When only 1st , 3rd, 5th input is pressed then only the 1st output will glow and

when 2nd ,4th, 6th input is pressed then only that output will goes off.

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Program Using Timer:

a. When 1st input is pressed then the 1st output will glow after the time delay of

5 seconds and when that 1st output goes on then again after 5 sec delay 2nd

output will glow but 1st output will goes off.

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In GE-Fanuc Program Using Timer And Counter Is

a. When the momentary push button is pressed then the 4 outputs will goes on

after 5 seconds.

b. There is one timer and counter , when the counter takes 5 pulses then after that

the timer starts and after 5 seconds the 1st output will goes on.

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a. There are two counters when the 1st counter takes 5 pulses then the 1st output

will glow and when 2nd counter takes 6 pulses then that output will goes off.

b. Addition and Multiplication of two numbers.

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3.14 PLC Advantages & Disadvantages

Flexibility: One single Programmable Logic Controller can easily run

many machines.

Correcting Errors:. Correcting errors in PLC is extremely short and

cost effective.

Space Efficient: Today's Programmable Logic Control memory is

getting bigger and bigger this means that we can generate more and

more contacts, coils, timers, sequencers, counters and so on. We can

have thousands of contact timers and counters in a single PLC.

Imagine what it would be like to have so many things in one panel.

Low Cost: Prices of Programmable Logic Controlers vary from few

hundreds to few thousands. This is nothing compared to the prices of

the contact and coils and timers that you would pay to match the same

things. Add to that the installation cost, the shipping cost and so on.

Testing: A Programmable Logic Control program can be tested and

evaluated in a lab. The program can be tested, validated and corrected

saving very valuable time.

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Visual observation: When running a PLC program a visual operation

can be seen on the screen. Hence troubleshooting a circuit is really

quick, easy and simple.

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CHAPTER 4

COMPARISION AND MATH INSTRUCTIONS IN

PLC PROGRAMMING

4.1 Comparison Instruction

A comparison instruction compares values of data. Depending on the data to

be compared it returns true or false logic. They are controlling instructions and

can be used any-where in a ladder logic program, except at the right-most

position of a rung. Some of the comparison instructions are as follows:

• Equal (EQU)

• Not Equal (NEQ)

• Less Than (LES)

• Less Than or Equal (LEQ)

• Greater Than (GRT)

• Greater Than or Equal (GEQ)

• Comparison (CMP)

• Limit (LIM)

4.1.1 EQU [Equal]

This input instruction is true when Source A = Source B.

The EQU instruction compares two user specified values. If the values are

equal, it allows rung continuity. The rung goes true and the output is energized

You must enter a word address for Source A. You can enter a program

constant or a word address for Source B.

4.1.2 NEQ [Not Equal]

Use the NEQ instruction to test whether two values are not equal.

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If Source A and Source B are not equal, the instruction is logically true. If the

two values are equal, the instruction is logically false.

Source A must be a word address.

Source B can be a word address or program constant

4.1.3 LES [Less Than]

This conditional input instruction tests whether one value (Source A) is less

than another (Source B).

If the value at Source A is less than the value at Source B, the instruction is

logically true.

If the value at Source A is greater than or equal to the value at Source B, the

instruction is logically false.

Enter a word address for Source A. Enter a constant or a word address for

Source B.

4.1.4 LEQ [Less Than or Equal]

This conditional input instruction tests whether one value (source A) is less

than or equal to another (source B).

If the value at source A is less than or equal to the value at source B, the

instruction is logically true.

If the value at source A is greater than the value at source B, the instruction is

logically false.

4.1.4 GRT [Greater Than]

This input instruction compares two user specified values.

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If the value stored in Source A is greater than the value stored in Source B, it

allows rung continuity. The rung will go "true" and the output will be

energized (provided no other instructions affect the rung's status).

If the value at Source A is less than or equal to the value at Source B, the

instruction is logically false.

4.1.5 GEQ [Greater Than or Equal To]

If the value stored in Source A is greater than or equal to the value stored in

Source B, it allows rung continuity. The rung will go true and the output will

be energized (provided no other instructions affect the rung's status).

If the value at Source A is less than the value at Source B, the instruction is

logically false.

4.1.6 LIM [Limit Test]

Use the LIM instruction to test for values within or outside a specified range,

depending on how you set the limits.

The instruction is true when the Test value is between the limits or is equal to

either limit.

If the Test value is outside the limits, the instruction is false.

4.2 Math Instructions

Mathematical functions are controlled instructions which retrieve one or more

values, perform an operation and store the result in memory. In a ladder logic

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program, when its rung is true, the mathematical operation is performed.

Commonly used math instructions include:

ADD (value,value,destination) - add two values

SUB (value,value,destination) - subtract

MUL (value,value,destination) - multiply

DIV (value,value,destination) – divide

Eg.1. Press start push button value stored in some memory word is added with

another value in the memory & resulted value is the multiplied by some another

value in other memory words.

4.2.1 Basic Logic Instructions

AND INSTRUCTION

OR INSTRUCTION

NAND INSTRUCTION

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NOT INSTRUCTION

X-OR INSTRUCTION

X-NOR INSTRUCTION

4.2.1.1The NOT function

The simplest of all logic functions is the NOT gate. 

It's sole function in life is to invert of flip the logic state.  So an input of 1 will

come out as a 0 and vica versa.  Shown below is a truth table (it doesn't lie)

showing all possible inputs and the resulting logical output.

INPUT OUTPUT

1 0

0 1

Tb4.1 NOT Truth table

The ladder logic equivalent for a NOT function looks like a normal contact but

with a slash through it.

4.2.1.2The AND function

The AND gate is associated with the following symbol that can have any

number of inputs but only one output.  

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The truth table below shows that the output is only turned on when all the

inputs are true that is 1.  An easy way to remember this is AND works like

multiplication operation.

INPUT A INPUT B OUTPUT

0 0 0

0 1 0

1 0 0

1 1 1

Tb 4.2 AND Truth Table

The ladder logic equivalent for an AND function looks like two normal contacts

side

by side.

4.2.1.3The OR function

Last but not least the OR gate is associated with the following symbol that also

can have any number of inputs but only one output.  

INPUT A INPUT B OUTPUT

0 0 0

0 1 1

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1 0 1

1 1 1

Tb4.3 OR Truth Table

The ladder logic equivalent for an OR function looks like two normal contacts

on top of each other

4.2.1.4Combining AND or OR with NOT 

The NOT gate might not look like much help if you haven't programmed much

but you'll find yourself actually using it frequently.  It's very common to use it

in combination with AND and OR.  So the engineering gods decided to make

some symbols for these combinations. 

Putting the NOT and AND gates together forms the NAND gate.  The truth

table below shows that it is simply an inverted output of the AND gate.

A little circle (or if you like, a bubble) at the end of a AND gate is used to

signify the NAND function.  It's symbol and corresponding ladder logic are

shown below.  Now pay close attention to the ladder logic because the contacts

are in parallel and not in series like the AND function.

4.3 Basic instructions

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Positive Logic (most PLCs follow this convention)

True = logic 1 = input energized.

False = logic 0 = input NOT energized.

Negative Logic

True = logic 0 = input NOT energized

False = logic 1 = input energized.

Normally Open

This instruction is true (logic 1) when the hardware input (or internal relay

equivalent) is energized.

Normally Closed

This instruction is true (logic 1) when the hardware input (or internal relay

equivalent) is NOT energized.

Output Enable

(OTE) - Output Enable.

This instruction mimics the action of a conventional relay coil.

On Timer

(TON) - Timer ON.

Generally, ON timers begin timing when the input (enable) line goes true, and

reset if the enable line goes false before setpoint has been reached. If enabled

until setpoint is reached then the timer output goes true, and stays true until the

input (enable) line goes false.

Off Timer

(TOF) - Timer OFF.

Generally, OFF timers begin timing on a true-to-false transition, and continue

timing as long as the preceding logic remains false. When the accumulated

time equals setpoint the TOF output goes on, and stays on until the rung goes

true.

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Up Counter

(CTU)

This instruction is used to count the event in increasing order.For instance it is

used in car parking to count the no. of cars entered.Sometimes we want to

continue a process after no. of times an event happens ,at that situation we

make use of up counter .

Down Counter

(CTD)

This instruction is used to count the no. of events in reverse or decreasing

order.For instance in car parking system to count the no. of cars leaving the

space we make use of down counter.

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PLC,SCADA And HMI

CHAPTER 5

HMI( HUMAN MACHINE INTERFACE)

5.1Introduction

A Human-Machine Interface or HMI is the apparatus which presents process

data to a human operator, and through which the human operator controls the

process.

An HMI is usually linked to the SCADA system's databases and software

programs, to provide trending, diagnostic data, and management information

such as scheduled maintenance procedures, logistic information, detailed

schematics for a particular sensor or machine, and expert-system

troubleshooting guides.

The HMI system usually presents the information to the operating personnel

graphically, in the form of a mimic diagram. This means that the operator can

see a schematic representation of the plant being controlled.The Human

Machine Interface (HMI) includes the electronics required to signal and

control the state of industrial automation equipment. These interface products

can range from a basic LED status indicator to a 20-inch TFT panel with

touchscreen interface. HMI applications require mechanical robustness and

resistance to water, dust, moisture, a wide range of temperatures, and, in some

environments, secure communication. They should provide Ingress Protection

(IP) ratings up to IP65, IP67, and IP68. The unique capacitive Atmel®

QTouch technology, Atmel SAM9 microprocessors, and Atmel

CryptoAuthentication™ devices enable designers to meet these requirements

and more, with an optimized BOM.

5.2Features and Benefits

Supports high source and sink output IO capabilities up to 60mA for direct drive

of LEDs.

High-speed PWM units enable LED dimming and screen back lighting.

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PLC,SCADA And HMI

Robust touch technology provides reduced wear and increased product lifetime.

Due to its superior field penetration, Atmel Touch technology will operate

through 6mm thick, non-conductive surfaces.

The excellent signal-to-noise ratio of the Atmel QMatrix™ touch technology

makes the design immune to water, moisture, or dust and enables operators to

use gloves.

Capacitive touch eases design of full hermetic or sealed products, while power

efficiency minimizes heat dissipation.

Free Atmel QTouch software library on the Atmel microcontroller lets

designers avoid the cost of an additional component.

The Atmel touch spread spectrum frequency implementation helps designers

meet electro-magnetic emission requirements.

The Atmel industrial microprocessor product portfolio with integrated LCD,

combined with the Atmel QTouch technology, are the ideal candidates for

your next control panel design.

The Atmel CryptoAuthentication family of hardware security devices provides

cost effective solutions for authenticated and encrypted communications

between HMI and industrial equipment.

5.3 Definition

The HMI quality may be defined by the system utility (usefulness), in terms of

the user tasks, obtained by task analysis . This is in contrast with automated

systems, for which the quality is typically defined by attributes such as

performance, reliability and recovery costs of the system units.[1] Unlike

automated systems, for which the system utility depends primarily on the

system availability, performance and reliability, the utility of the HMI

interaction is affected mainly by the user’s performance and reliability, in

the context of the user’s expectations.

HMI stands for Human Machine Interface and is the means by which a human

operator will interact with a process controller. Put very simply, the Human

Machine Interface is the process controller’s input/output mechanism for

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PLC,SCADA And HMI

humans. Unless the process being controlled is entirely automated, some form

of HMI will be required.

A human will depend on the output of the HMI to provide feedback about the

current state of a particular industrial process. This may be as simple as

reassuring the human that an automated process is running or has completed

correctly, or that specific parameters are operating inside required limits. The

HMI output is usually a visual display of some kind (e.g. alphanumeric

characters or graphical images) but can also include audible feedback and

alarms.

The HMI will also allow a range of inputs by providing interaction controls

such as dials, push buttons or, in a more advanced HMI, a touch screen

display. These controls allow processes to be started, stopped, adjusted or

programmed as necessary.

5.4 HMI Devices

LED Indicators and Mechanical Switches are a leading HMI for industrial

applications, and Atmel AVR® and AT91SAM microcontrollers offer a

variety of benefits.

Capacitive Touch Technology for HMI helps protect industrial interface

modules, while increasing design flexibility and enhancing look and feel.

Industrial Control Panels with LCD Displays provide the operator an

efficient, flexible way to monitor and control increasingly complex automated

processes.

Hardware Security Products protect firmware integrity from tampering to

assure continuous and reliable performance.

5.5 Attributes of the HMI quality

Performance. The time it takes for the users to evaluate the system state and

decide what to do next is typically higher by an order of magnitude than the

system response time. Instead of measuring the system response time, we

should measure the time elapsed from the moment the user decides to perform

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PLC,SCADA And HMI

a task until its completion. Typically, most of the elapsed time is wasted

because the user fails to follow the operational procedures, attempting to

recover from unwanted system response to unexpected actions. Systems

Engineering should regard user productivity, rather than system performance.

Reliability. The operators Failure rate (MTBF) is about 10% of the overall

operation time, higher by several orders of magnitude than that of the system.

Instead of measuring component failure rates, such as by MTBF, we should

measure operational failure rates, such as the rate of almost-accidents due to

user errors. This is especially true for safety-critical systems, in which the

costs of an accident are much higher than those of maintenance. Operational

reliability is the key to task performance.

Resilience. The interaction may go out of sync, namely, the system might get to

an exceptional state. The exceptional states include failure of a system unit, or

the result of a user’s action that does not match the interaction protocol .

Resilience engineering methods may be applied to resume normal operation

after getting to the exceptional state. Task-oriented System Engineering

enables definition of an interaction protocol. The STAMP model may be used

to constrain the system operation according to the protocol.

Recovery costs. The operators' mean time to repair (MTTR) is about 50% of

the overall operation time, higher by several orders of magnitude than that of

the system. Instead of measuring maintenance costs, such as by MTTR, we

should measure the time it takes for the users to recover from system failures.

Logic. An application that is logical in its internal design and produces accurate

results may nevertheless be difficult to use. The reason for this is that logic is

not absolute. It is subjective, it is task related, and it changes over time.

Typically, it applies to the internals of the application. Therefore, the user has

difficulty following the developer’s logic.

5.6 The Importance of the HMI When Selecting a Process Controller

Choosing the right HMI can be as important as considering the capabilities of

the process controller behind it. The most obvious effect of a particular type of

HMI will be on the ease of use of the product. A Human Machine Interface

which is easy to understand and gives clear options to end users will produce

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PLC,SCADA And HMI

fewer errors, as well as a more pleasant user experience. A manufacturer

which consistently provides an easy to use product will benefit in terms of

future orders and recommendations to other customers. A manufacturer whose

products may perform very well on a technical level, will find themselves

losing business if their end users experience difficulty and frustration when

using the product, or if the rate of user error is negatively impacting on a

client’s business.

The choice of HMI will also have an impact on the real cost of the product for

the end user.

An easier to use HMI means lower training costs. It also potentially means that

less skilled personnel will be able to operate the product effectively. In

addition, user errors can result in significant losses to a business in terms of

time and materials wasted. So while one type of HMI may appear to be

significantly cheaper in terms of the component costs, a more advanced HMI

may well be more cost-effective when in the longer term.

There are also cost benefits for manufacturers directly. It has been mentioned

in other articles that a process controller with integrated HMI already offers

manufacturers significant cost benefits in terms of reduced labour costs to

integrate controllers with a separate HMI, as well as potentially faster

development times. But there are other benefits of choosing a built-in HMI.

Products which are easy to use generate fewer support requests to

manufacturers. And advanced HMI’s can reduce product obsolescence and

make it easier and cheaper to upgrade or refresh a product range. A powerful

PLC with HMI, for example, may well have spare capacity, which can be

utilised in the future to add features and capabilities but without changing the

hardware components. And if that PLC also has a built-in HMI which allows

new screens to be added easily, or existing screens to be refreshed with new

graphics or colour schemes, it becomes much cheaper to create a “new”

product. Finally, an advanced HMI which can be easily used by a greater range

of people offers the possibility of creating products which could have a

customer base of many thousands, rather than a handful of very specialised

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PLC,SCADA And HMI

industrial customers. An example of this potential is the HiFri fat-free frying

system which uses the Unitronics Vision 570 PLC, and features a built-in

advanced HMI, consisting of a 5.7 inch colour touch screen.

 5.7 How to select the right PLC

Given the importance of the Human Machine Interface and the significant

variation in type of HMI available, how do you go about choosing the right

one for your application?

Correct selection requires analysis both of the back end process control

requirements as usual (what I/O’s are needed, required accuracy levels etc),

and of the context in which it is to be used. This means defining the user’s task

in terms of what information the operator needs at different stages of the

process and what user actions are needed at different points of the task.

This will indicate the complexity of the information that needs to be

represented at any one time, including the number of items of information,

whether they are numerical or text values, and whether a graphical

representation would be helpful.

It is also useful to define the expected level of knowledge of a user, which will

help define how much contextual information needs to be provided by the

display. A highly skilled user who already understands the process can

exercise knowledge and memory to make informed decisions about what to do

in response to a particular value (e.g. a lab technician monitoring a value

relating to an experiment he is running). But a less skilled or novice user will

not have this knowledge and must be given contextual information and

context-sensitive options in order to prevent errors (e.g. a restaurant employee

operating a frying machine).

It is also essential to analyse the type of errors that are possible as a result of

incorrect user behaviour, and the consequences of those errors. The more

serious the consequences the more it is essential that the choice of HMI should

allow the chance of error to be minimised or prevented altogether. A high-risk

application is the most likely to require a context-sensitive user interface

solution involving an advanced HMI with touch screen.

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PLC,SCADA And HMI

Once these factors (task complexity, user knowledge and error risk) are clear,

it then makes sense to base your choice on the best HMI to meet these user

requirements. It is then a relatively straightforward task to check that the PLC

behind the HMI has the necessary capabilities to deal with the technical side of

the process.

As always, Tecnologic can provide expert advice to help you choose the best

process controller for your application. We can discuss your application

requirements by phone, or arrange a site visit as necessary. We can also

provide candidate models on a sale or return basis, allowing your design team

to fully assess both the back end and HMI capabilities

Fig 5.1 HMI

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PLC,SCADA And HMI

Two components are needed in a human machine interface. The first is an input. A human

user needs some way to tell the machine what to do, to make requests of the machine, or to

adjust the machine. Examples of input devices include keyboards, toggles, switches, touch

screens, joysticks, and mice. All of these devices can be utilized to send commands to a

system or even an interlinked set of systems.

The interface also requires an output, which allows the machine to keep the human user

updated on the progress of commands, or to execute commands in physical space. On a

computer, for example, users have a screen which can display information. A robot, on the

other hand, may move in response to commands and store data on a hard drive so that people

can see how the robot responds, learns, and navigates the world. Outputs can also include

things as simple as status lights which alert people when toggles or switches have been

activated.

The technology behind the human machine interface is constantly improving. Researchers

have developed interfaces which can be controlled with the mind, for example, seeing

applications for this technology among stroke patients and other people with severely

restricted modes of communication. Likewise, outputs have become much more sophisticated

over time.

As many people have noted, a poorly designed human machine interface can be extremely

frustrating. On one end of the scale, the interface may be buggy or nonfunctional, causing

difficulty because it does not work as intended. On the other end of the scale, the interface

works, but it is designed in such a way that it is confusing and challenging to operate because

it is not intuitive for users. The art of designing intuitive interfaces requires a deep

understanding of how humans interact with their environment and an awareness of the

psychology of designing interfaces in a way which will be accessible to a broad spectrum of

humans. What works for an engineer in a human machine interface, for example, might not

be as easy for a member of the general public.

The user interface (also known as human computer interface or man-machine interface

(MMI)) is the aggregate of means by which people—the users—interact with the system a

particular machine, device, computer program or other complex tool. The user interface

provides means of:

Input, allowing the users to manipulate a system.

Output, allowing the system to indicate the effects of the users' manipulation.

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PLC,SCADA And HMI

The design of a user interface affects the amount of effort the user must expend to

provide input for the system and to interpret the output of the system, and how much

effort it takes to learn how to do this. Usability is the degree to which the design of a

particular user interface takes into account the human psychology and physiology of

the users, and makes the process of using the system effective, efficient and

satisfying.

5.8 How To Connect An HMI With PC

The terminal of HMI can be connected with PC either by USB or Ethernet port.

You must have to enter the panel address of your HMI in your browser (Internet Explorer,

Mozilla firebox etc.)You can also transfer programmed by pen drive.

For USB

The panel view component has a USB port to support communication with USB.

You must first install ALLEN BRADLEY Panel view USB remote NDIS network

device driver on your computer. The default address of Allen Bradley HMI is

169.254.2542.

For Ethernet

For Ethernet first install the drivers. The default address of single Allen Bradley

HMI is 169.254.2542. If you install more than one HMI in the circuit then the

address start from 169.254.0.0 to 169.254.255.255.

Fig5.2 An HMI Controlled System

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PLC,SCADA And HMI

CHAPTER 6

DC/AC Motors And Drives

6.1 DC Motors

DC motors have been used in industrial applications for years. Coupled with a

DC drive, DC motors provide very precise control. DC motors can be used with

conveyors, elevators, extruders, marine applications, material handling, paper,

plastics, rubber, steel, and textile applications to name a few.

Fig 6.1 DC Motor

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PLC,SCADA And HMI

6.2 Construction

DC motors are made up of several major components which include the following:

• Frame

• Shaft

• Bearings

• Main Field Windings (Stator)

• Armature (Rotor)

• Commutator

• Brush Assembly

Of these components, it is important to understand the electrical characteristics of the main

field windings, known as the stator, and the rotating windings, known as the armature. An

understanding of these two components will help with the understanding of various functions

of a DC Drive.

Basic Construction The relationship of the electrical components of a DC motor is

shown in the following illustration. Field windings are mounted

on pole pieces to form electromagnets. In smaller DC motors the

field may be a permanent magnet. However, in larger DC fields

the field is typically an electromagnet. Field windings and pole

pieces are bolted to the frame. The armature is inserted between

the field windings. The armature is supported by bearings and end

brackets (not shown). Carbon brushes are held against the

commutator.

Armature The armature rotates between the poles of the field windings.

The armature is made up of a shaft, core, armature windings,

and a commutator. The armature windings are usually form

wound and then placed in slots in the core.

Armature, the part of an electric generator or motor that

contains the main current-carrying winding. The armature

usually consists of a coil of copper wire wound around an iron

or steel core. The coil and core are placed in a magnetic field

produced by one or more permanent magnets or

electromagnets. If the armature in a generator or motor is

designed to rotate, it is called a rotor; if it is a stationary part, it 45

PLC,SCADA And HMI

is called a stator

Fig 6.2 Armature

6.3 DC Motor Operation

Magnetic Fields There are two electrical elements of a DC motor, the field

windings and the armature. The armature windings are made

up of current carrying conductors that terminate at a

commutator. DC voltage is applied to the armature windings

through carbon brushes which ride on the commutator.

In small DC motors, permanent magnets can be used for the

stator. However, in large motors used in industrial applications

the stator is an electromagnet. When voltage is applied to stator

windings an electromagnet with north and south poles is

established. The resultant magnetic field is static (non-

rotational). For simplicity of explanation, the stator will be

represented by permanent magnets in the following

illustrations.

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PLC,SCADA And HMI

Fig 6.3 motor

Magnetic Fields A DC motor rotates as a result of two magnetic fields

interacting with each other. The first field is the main field that

exists in the stator windings. The second field exists in the

armature. Whenever current flows through a conductor a

magnetic field is generated around the conductor.

Right-Hand Rule for Motors A relationship, known as the right-hand rule for motors, exists

between the main field, the field around a conductor, and the

direction the conductor tends to move. If the thumb, index

finger, and third finger are held at right angles to each other and

placed as shown in the following illustration so that the index

finger points in the direction of the main field flux and the third

finger points in the direction of electron flow in the conductor,

the thumb will indicate direction of conductor motion. As can

be seen from the following illustration, conductors on the left

side tend to be pushed up. Conductors on the right side tend to

be pushed down. This results in a motor that is rotating in a

clockwise direction. You will see later that the amount of force

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PLC,SCADA And HMI

acting on the conductor to produce rotation is directly

proportional to the field strength and the amount of current

flowing in the conductor

.

Fig 6.4 Electron flow

According to right hand rule

Thumb points to direction of conductor motion

Index finger points to magnetic field

Middle finger points to current

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PLC,SCADA And HMI

Armature Field An armature, as we have learned, is made up of many coils and

conductors. The magnetic fields of these conductors combine to

form a resultant armature field with a north and south pole. The

north pole of the armature is attracted to the south pole of the

main field. The south pole of the armature is attracted to the

north pole of the main.

This attraction exerts a continuous torque on the armature. Even

though the armature is continuously moving, the resultant field

appears to be fixed. This is due to commutation

Fig 6.5 Armature Field

In the following illustration of a DC motor only one armature conductor is shown. Half of the

conductor has been shaded black, the other half white. The conductor is connected to two segments

of the commutator.

In position 1 the black half of the conductor is in contact with the negative side of the DC applied

voltage. Current flows away from the commutator on the black half of the conductor and returns to the

positive side, flowing towards the commutator on the white half.

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PLC,SCADA And HMI

Fig 6.6 forward current flow

In position 2 the conductor has rotated 90°. At this position the conductor is lined up with the

main field. This conductor is no longer cutting main field magnetic lines of flux; therefore, no

voltage is being induced into the conductor. Only applied voltage is present. The conductor coil

is short-circuited by the brush spanning the two adjacent commutator segments. This allows

current to reverse as the black commutator segment makes contact with the positive side of

the applied DC voltage and the white commutator segment makes contact with the negative

side of the applied DC voltage.

Fig 6.7 reverse current flow

As the conductor continues to rotate from position 2 to position 3 current flows away

from the commutator in the white half and toward the commutator in the black half.

Current has reversed direction in the conductor. This is known as commutation.

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PLC,SCADA And HMI

Fig 6.8 Commutation

6.4 Types of DC Motors

The field of DC motors can be a permanent magnet, or electromagnets connected in

series, shunt, or compound.

6.4.1 Permanent Magnet Motors : The permanent magnet motor uses a magnet to supply

field flux. Permanent magnet DC motors have excellent starting

torque capability with good speed regulation. A disadvantage of

permanent magnet DC motors is they are limited to the amount of

load they can drive. These motors can be found on low

horsepower applications. Another disadvantage is that torque is

usually limited to 150% of rated torque to prevent

demagnetization of the permanent magnets.

Fig 6.9 Permanent Magnet Motor

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PLC,SCADA And HMI

6.4.2 Series Motors: In a series DC motor the field is connected in series with the

armature. The field is wound with a few turns of large wire

because it must carry the full armature current. A

characteristic of series motors is the motor develops a large

amount of starting torque. However, speed varies widely

between no load and full load. Series motors cannot be used

where a constant speed is required under varying loads.

Additionally, the speed of a series motor with no load

increases to the point where the motor can become damaged.

Some load must always be connected to a series-connected

motor. Series-connected motors generally are not suitable for

use on most variable speed drive applications.

Fig 6.10 Series Motor

6.4.3 Shunt Motors : In a shunt motor the field is connected in parallel (shunt) with

the armature windings. The shunt-connected motor offers good

speed regulation. The field winding can be separately excited or

connected to the same source as the armature. An advantage to a

separately excited shunt field is the ability of a variable speed

drive to provide independent control of the armature and field.

The shunt-connected motor offers simplified control for

reversing. This is especially beneficial in regenerative drives.

Fig 4.11 Shunt Motor

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PLC,SCADA And HMI

Compound Motors Compound motors have a field connected in series with the

armature and a separately excited shunt field. The series field

provides better starting torque and the shunt field provides

better speed regulation.

Fig 6.11 Compound Motor

6.5 Basic DC Drives

SIMOREG drives are designed for connection to a three-phase. AC supply.

They, in turn, .supply the armature and field of Variable speed DC motors.

SIMOREG drives can be selected for connection to 230, 400, 460, 575, 690,

830, and 950 VAC, making them suitable for global use.

Siemens SIMOREG.DC MASTER 6RA70drives are available upto 1000.HP at

500.VDC in standard model drives.In addition drives can be paralleled,

extending the range up to 6000.HP Siemens. SIMOREG drives have wide

range of microprocessor-controlled internal parameters to control DC motor

operation.

Fig 6.13 DC Drive SIMOREG.6RA70

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PLC,SCADA And HMI

6.5.1 Power Modules. The.SIMOREG.6RA70 is available in a power module and

base drive panels.The power module contain the control

electronics and power components necessary to control

drive operation

and the associated DC motor.

6.5.2 Base Drive Panels. The base drive panel consists of the power module mounted on a

base panel with line fuses, control transformer and contactor.This design allows for easy

mounting and connection of power cables..

6.5.2 High Horsepower Designs. High horsepower designs are also available with ratings

upto

14,000amps.These drives have input ratings upto 700VAC

&

an operate motors with armature ratings upto 750VDC.

Fig4.14 Drive Panel

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PLC,SCADA And HMI

Fig 6.15 High Horsepower Panel

6.6 Converting AC to DC:

6.6.1 Thyristor. A primary function of a DC drive,such as the SIMOREG

6RA70

DC MASTER is to convert AC voltage into a variable DC

voltage It is necessary to vary to DC voltage in order to

control the speed of a DC motor.A thyristor is one type of

device commonly used to convert AC to DC.A thyristor

consists of an anode ,cathode and a gate.

Fig6.16 Thyristor Symbol

6.6.2 AC to DC Conversion. The thyristor provides a convenient method of converting

AC voltage to a variable DC voltage for use in controlling

the speed of a DC motor.In this example the gate is

momentarily applied when AC input voltage is at the top of

the sinewave.The thyristor will conduct until the input’s

sinewave crosses zero. At this point the anode is no longer

positive with respect to the cathode and the thyristor shuts

off.The result is a half-wave rectified.DC.The amount of

rectified DC voltage can be controlled by timing the input

to the gate.Applying current on the gate at the beginning of

the sinewave result in a higher average voltage applied to

the motor.Applying current on the gate later in the

sinewave results in a lower average voltage applied to the

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PLC,SCADA And HMI

motor.

6.7 Basic Drive Operation:-

6.7.1Controlling a DC Motor. A thyristor bridge is a technique commonly used to

control the speed of a DC motor by varying the DC

voltage.Examples of how a DC rectifier bridge

operates are given on the next few pages.The actual

values for a given load speed and motor vary.

It is important to note that the voltage applied to a DC

motor be no greater than the rated nameplate.Armature

windings are commonly wound for 500 VDC The control

logic in the drive must be adjusted to limit available DC

voltage to 0-500 VDC.Likewise the shunt field must be

limited to the motor’s nameplate value.

Fig 6.17 Siemens Drive

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PLC,SCADA And HMI

Basic Operation A DC drive supplies voltage to the motor to operate at a

desired speed. The motor draws current from this power

source in proportion to the torque (load) applied to the

motor shaft.

Fig 6.18 Drive Operation

6.8 Application Examples The Siemens SIMOREG.6RA70 DC MASTER drives are designed to handle the most

challenging applications. The following examples are just some of applications the SIMOREG

can be used on:

Winders/Coilers. DCmotors offer superior characteristics at low speed for

winder and coiler operation and performance.In winder

applications maintaining tension at standstill is a very

important operation.DC motors offer a wide speed range at

rated torque.On many winder applications that run in an

extended speed range a smaller horsepower .DC motor

could do the same job as a larger horsepower AC motor.

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PLC,SCADA And HMI

Fig 6.19 Winder

Crane/hoist:

Fig6.20 Crane

Marine Applications. DC drives offer several advantages in marine applications.

Compact sizing is one of the biggest advantages.DC

drives also adapt well from generator supplies such as

found in the marine industry.

Extruding. Extruding is a price competitive industry.DC offers in the

60 to 1000 HP range which is commonly used in extruding

Application.

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PLC,SCADA And HMI

6.9 AC DRIVES

6.9.1 What Is An AC Drive?

The word "drive" is used loosely in the industry. It seems that people involved primarily in the

world of gear boxes and pulleys refer to any collection of mechanical and electro-mechanical

components, which when connected together will move a load, as a "drive". When speaking to

these people, an AC drive may be considered by them as the variable frequency inverter and

motor combination. It may even include the motor's pulley - I am not sure.

People in the electrical field and electrical suppliers usually refer to a variable frequency inverter

unit alone, or an SCR power module alone (when discussing DC drives) as the "drive" and the

motor as the "motor".

Manufacturers of variable frequency drives (VFD) used to refer to the drive as just that, a

"variable frequency drive". More manufacturers are referring to their drive as an "adjustable

speed AC drive". To make matters worse when a motor is included in the package it may be

referred to as an "adjustable speed AC drive system".

A variable frequency drive is an adjustable speed drive. Adjustable speed drives include all

types; mechanical and electrical.

The main power components of an AC drive, have to be able to supply the required level of

current and voltage in a form the motor can use. The controls have to be able to provide the user

with necessary adjustments such as minimum and maximum speed settings, so that the drive can

be adapted to the user's process. Spare parts have to be available and the repair manual has to be

readable. It's nice if the drive can shut itself down when detecting either an internal or an

external problem. It's also nice if  the drive components are all packaged in a single enclosure to

aid in installation but that's about it

. Fig 6.21 Main Power Circuit Of AC Drive

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PLC,SCADA And HMI

6.9.2Where does the real action happen in a AC drive system?

Above is a cross-sectional view a motor rotor and field magnetic core. Looking from the side

would look something like a looking at a can.

We can add magnets (and torque) to our drive system by using a motor with a core that is either

longer, larger in cross-sectional diameter, or some combination of both.

A Side Note About Fishing, Electro-magnets, Current, and Magnetic Conductivity

When we go fishing we put bait on a hook and throw it in water knowing that according to

generally accepted theory, a hungry fish will sooner or later, bite. Well the truth is we don't

know why the fish bite. No one to date, has talked to a fish (well maybe a few people talk to

fish). The fact the we get hungry and therefore fish must too, seems like a safe assumption. But

it doesn't really matter because we do know that putting bait on a hook will get fish into the boat.

Magnetism and electricity are the same way. We have some well accepted theories that we can

use to explain how magnets can move our load but no one really knows what magnetism and

electricity are (regardless of what they say). When it comes to using magnetic force to move our

load, how it works just doesn't matter. We do know that it works. We have even noticed a few

peculiar things.

We have noticed that when you wrap a coil of wire around a piece of iron and apply electric

current the piece of iron becomes magnetic. We call this an electro-magnet. 

Fig 6.22 Coil With Iron Core

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Important Motor Formula

Synchronous RPM" is the RPM the motor would run if the rotor did not slip.

All AC induction motors slip.

AC Generator

If a magnet is passed along the coils, an electric current is generated in each

of the three phases. In fact, there is little difference between AC generator

and motor field windings. 

The faster you move the magnet the higher the AC output frequency. Variable frequency drives

control the frequency electronically.

AC Motor

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4.10 AC Frequency Drive

AC Frequency Drive is a drive which convert the incoming frequency of ac supply into

desired

frequency to make the desired change in speed of motor.

AC Frequency Drive:

Plenum rated drive

Efficient Energy $aving algorithm

PI control with inverse, square root and differential control via two feedback

capability

Sleep and Snooze function for optimum energy savings

Built-in kW-hour and kW display

Communication interface for Johnson Controls Metasys N2, Siemens APOGEE

FLN, LonWorks as well as Modbus.

Belt failure detection with or without sensor

Display of process parameters in engineering units

Multi-parameter display

Wide voltage range: 380 to 480 VAC

Static auto-tuning for faster commissioning

Copy function for faster parameter loading

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Complete motor protection

12 pulse ready, unique low harmonic design

Motor Speed The speed and horsepower of an application

must be known when selecting a motor and

drive. Given the velocity in feet per minute (FPM)

of the conveyor belt, the diameter in inches ofthe

driven pulley, and the gear ratio (G) between the

motor and driven pulley, the speed of the motor

can be determined. The following formula is used

to calculate conveyor speed.

A variable frequency drive is an adjustable speed drive. Adjustable speed drives include

all types; mechanical and electrical. A variable frequency drive is an adjustable speed

drive. Adjustable speed

drives include all types; mechanical and electrical.

"A good AC drive technician understands the operation of the variable speed drive and

the functions

of its components.

An outstanding AC drive technician also understands the effects of the load on the drive

and the

effects of the drive on the load."

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CHAPTER 7

SCADA

7.1 INTRODUCTION

SCADA (supervisory control and data acquisition) is a type of industrial

control system (ICS). Industrial control systems are computer-controlled systems

that monitor and control industrial processes that exist in the physical world.

SCADA systems historically distinguish themselves from other ICS systems by

being large-scale processes that can include multiple sites, and large distances.

These processes include industrial, infrastructure, and facility-based processes, as

described below:

Industrial processes include those of manufacturing, production, power generation ,

fabrication , and refining, and may run in continuous, batch, repetitive, or discrete

modes.

Infrastructure processes may be public or private, and include water treatment and

distribution, wastewater collection and treatment, oil and gas pipelines, electrical

power transmission and distribution, wind farms, civil defense siren systems, and

large communication systems.

Facility processes occur both in public facilities and private ones, including

buildings, airports, ships, and space stations. They monitor and control heating,

ventilation, and air conditioning systems (HVAC), access, and energy

consumption.

Widely used in industry for Supervisory Control and Data Acquisition of

industrial processes, SCADA systems are now also penetrating the experimental physics

laboratories for the controls of ancillary systems such as cooling, ventilation, power

distribution, etc.

More recently they were also applied for the controls of smaller size particle

detectors such as the L3 muon detector and the NA48 experiment, to name just two

examples at CERN.

SCADA systems have made substantial progress over the recent years in terms of

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functionality, scalability, performance and openness such that they are an alternative

to in house development even for very demanding and complex control systems as

those of physics experiments.

7.2Communication Requirements Of SCADA

SCADA systems are indispensable in the operation and control of interconnected power

systems.SCADA requires two-way communication channels between the Master

Control Centre and Remote Control Centre.

Fig 7.1 SCADA Communication

Traditionally, the SCADA systems were used by the operators in scanning mode,

providing data regarding generating stations, Generating units, Transformer sub-stations

etc. Traditional hard wired SCADA systems were arranged to perform several

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functions to supplement Automatic Control and Protection Systems.

All the protective relays and most of the control relays and control systems are

necessary for automatic control of generating stations and transmission systems even

when the supervisory control is used. Only initiating devices may be different or

omitted with fully automatic SCADA control. For example, tap changing may be

initiated either by the sub- section control room operator or by the automatic voltage

control relays connected in the protection panel of the transformer.

With traditional SCADA systems, the function of protection and control were

segregated. Controls systems were arranged to keep the values of controlled quantities

within target limits. Protection equipment was arranged for sounding alarms and for

tripping circuit- breakers. With the recent revolution in microprocessor technology, the

size, performance and cost of digital automation systems have become acceptable

in commercial installation.

7.3 Common system components

A SCADA system usually consists of the following subsystems:

Remote terminal units (RTUs) connect to sensors in the process and converting

sensor signals to digital data. They have telemetry hardware capable of sending

digital data to the supervisory system, as well as receiving digital commands from

the supervisory system. RTUs often have embedded control capabilities such as

ladder logic in order to accomplish boolean logic operations.

Programmable logic controller (PLCs) connect to sensors in the process and

converting sensor signals to digital data. PLCs have more sophisticated embedded

control capabilities, typically one or more IEC 61131-3 programming languages,

than RTUs. PLCs do not have telemetry hardware, although this functionality is

typically installed alongside them. PLCs are sometimes used in place of RTUs as

field devices because they are more economical, versatile, flexible, and

configurable.

A Telemetry system is typically used to connect PLCs and RTUs with control

centers, data warehouses, and the enterprise. Examples of wired telemetry media

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used in SCADA systems include leased telephone lines and WAN circuits.

Examples of wireless telemetry media used in SCADA systems include satellite

(VSAT), licensed and unlicensed radio, cellular and microwave.

A Data Acquisition Server is a software service which uses industrial protocols to

connect software services, via telemetry, with field devices such as RTUs and

PLCs. It allows clients to access data from these field devices using standard

protocols.

A human–machine interface or HMI is the apparatus or device which presents

processed data to a human operator, and through this, the human operator

monitors and interacts with the process. The HMI is a client that requests data

from a Data Acquisition Server.

A Historian is a software service which accumulates time-stamped data, boolean

events, and boolean alarms in a database which can be queried or used to populate

graphic trends in the HMI. The Historian is a client that requests data from a Data

Acquisition Server.

SCADA is used as a safety tool as in lock-out tag-out

A supervisory (computer) system, gathering (acquiring) data on the process and

sending commands (control) to the process.

Communication infrastructure connecting the supervisory system to the remote

terminal units.

Various process and analytical instrumentation

7.4 Hardware solutions

SCADA solutions often have Distributed Control System (DCS) components. Use

of "smart" RTUs or PLCs, which are capable of autonomously executing simple

logic processes without involving the master computer, is increasing. A

standardized control programming language, IEC 61131-3 (a suite of 5

programming languages including Function Block, Ladder, Structured Text,

Sequence Function Charts and Instruction List), is frequently used to create

programs which run on these RTUs and PLCs. Unlike a procedural language such

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as the C programming language or FORTRAN, IEC 61131-3 has minimal training

requirements by virtue of resembling historic physical control arrays. This allows

SCADA system engineers to perform both the design and implementation of a

program to be executed on an RTU or PLC. A Programmable Automation

Controller (PAC) is a compact controller that combines the features and

capabilities of a PC-based control system with that of a typical PLC. PACs are

deployed in SCADA systems to provide RTU and PLC functions. In many

electrical substation SCADA applications, "distributed RTUs" use information

processors or station computers to communicate with digital protective relays,

PACs, and other devices for I/O, and communicate with the SCADA master in

lieu of a traditional RTU.

Since about 1998, virtually all major PLC manufacturers have offered integrated

HMI/SCADA systems, many of them using open and non-proprietary

communications protocols. Numerous specialized third-party HMI/SCADA

packages, offering built-in compatibility with most major PLCs, have also entered

the market, allowing mechanical engineers, electrical engineers and technicians to

configure HMIs themselves, without the need for a custom-made program written

by a software programmer. The Remote Terminal Unit (RTU) connects to

physical equipment. Typically, an RTU converts the electrical signals from the

equipment to digital values such as the open/closed status from a switch or a

valve, or measurements such as pressure, flow, voltage or current. By converting

and sending these electrical signals out to equipment the RTU can control

equipment, such as opening or closing a switch or a valve, or setting the speed of

a pump.

7.5Supervisory station

The term supervisory station refers to the servers and software responsible for

communicating with the field equipment (RTUs, PLCs, SENSORS etc.), and then

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to the HMI software running on workstations in the control room,ss or elsewhere.

In smaller SCADA systems, the master station may be composed of a single PC.

In larger SCADA systems, the master station may include multiple servers,

distributed software applications, and disaster recovery sites. To increase the

integrity of the system the multiple servers will often be configured in a dual-

redundant or hot-standby formation providing continuous control and monitoring

in the event of a server failure.

7.6 Operational philosophy

For some installations, the costs that would result from the control system failing

are extremely high. Hardware for some SCADA systems is ruggedized to

withstand temperature, vibration, and voltage extremes. In the most critical

installations, reliability is enhanced by having redundant hardware and

communications channels, up to the point of having multiple fully equipped

control centres. A failing part can be quickly identified and its functionality

automatically taken over by backup hardware. A failed part can often be replaced

without interrupting the process. The reliability of such systems can be calculated

statistically and is stated as the mean time to failure, which is a variant of Mean

Time Between Failures (MTBF). The calculated mean time to failure of such high

reliability systems can be on the order of centuries

7.7 Communication infrastructure and methods

SCADA systems have traditionally used combinations of radio and direct wired

connections, although SONET/SDH is also frequently used for large systems such

as railways and power stations. The remote management or monitoring function

of a SCADA system is often referred to as telemetry Some users want SCADA

data to travel over their pre-established corporate networks or to share the network

with other applications. The legacy of the early low-bandwidth protocols remains,

though.

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SCADA protocols are designed to be very compact. Many are designed to send

information only when the master station polls the RTU. Typical legacy SCADA

protocols include Modbus RTU, RP-570, Profibus and Conitel. These

communication protocols are all SCADA-vendor specific but are widely adopted

and used. Standard protocols are IEC 60870-5-101 or 104, IEC 61850 and DNP3.

These communication protocols are standardized and recognized by all major

SCADA vendors. Many of these protocols now contain extensions to operate over

TCP/IP. Although the use of conventional networking specifications, such as

TCP/IP, blurs the line between traditional and industrial networking, they each

fulfill fundamentally differing requirements

With increasing security demands , there is increasing use of satellite-based

communication. This has the key advantages that the infrastructure can be self-

contained (not using circuits from the public telephone system), can have built-in

encryption, and can be engineered to the availability and reliability required by the

SCADA system operator. Earlier experiences using consumer-grade VSAT were

poor. Modern carrier-class systems provide the quality of service required for

SCADA

RTUs and other automatic controller devices were developed before the advent of

industry wide standards for interoperability. The result is that developers and their

management created a multitude of control protocols.

Recently, OLE for process control (OPC) has become a widely accepted solution

for intercommunicating different hardware and software, allowing communication

even between devices originally not intended to be part of an industrial network.

7.8 Alarm Handling

Alarm handling is based on limit and status checking and performed in the data servers.

More complicated expressions (using arithmetic or logical expressions) can be

developed by creating derived parameters on which status or limit checking is

then performed. The alarms are logically handled centrally, i.e., the information only

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exists in one place and all users see the same status (e.g., the acknowledgement), and

multiple alarm priority levels (in general many more than 3 such levels) are supported.

It is generally possible to group alarms and to handle these as an entity (typically

filtering on group or acknowledgement of all alarms in a group). Furthermore, it is

possible to suppress alarms either individually or as a complete group. The filtering of

alarms seen on the alarm page or when viewing the alarm log is also possible at least on

priority, time and group. However, relationships between alarms cannot generally be

defined in a straightforward manner. E-mails can be generated or predefined actions

automatically executed in response to alarm conditions.

7.9Logging/Archiving

The terms logging and archiving are often used to describe the same facility.

However, logging can be thought of as medium-term storage of data on disk,

whereas archiving is long-term storage of data either on disk or on another

permanent storage medium. Logging is typically performed on a cyclic basis,

i.e., once a certain file size, time period or number of points is reached the data

is overwritten. Logging of data can be performed at a set frequency, or only

initiated if the value changes or when a specific predefined event occurs.

Logged data can be transferred to an archive once the log is full. The logged

data is time-stamped and can be filtered when viewed by a user. The logging of

user actions is in general performed together with either a user ID or station ID.

There is often also a VCR facility to play back archived data

7.10 ApplicationsThe following development tools are provided as

standard:

A graphics editor, with standard drawing facilities including freehand, lines,

squares circles, etc. It is possible to import pictures in many formats as well as

using predefined symbols including e.g. trending charts, etc. A library of generic

symbols is provided that can be linked dynamically to variables and animated as

they change. It is also possible to create links between views so as to ease

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navigation at run-time.

2.A data base configuration tool (usually through parameter templates). It is

in general possible to export data in ASCII files so as to be edited through an

ASCII editor or Excel.

A scripting language

An Application Program Interface (API) supporting C, C++, VB

A Driver Development Toolkit to develop drivers for hardware that is not

supported by the SCADA product.

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CHAPTER 8

PROJECT

8.1 INTRODUCTION TO PROJECT: TRAFFIC LIGHTS

With the increasing speed of life, the demand to perform tasks at a higher speed is

being laid out too. In today’s world more emphasis is being laid on working with

machines so that man labour can be decreased .Automation is the best way to

reduce man’s labour especially in industries. So there is need to develop more and

more industrial project which depends upon machines not on man. In industries

there are many operations which is not suitable for the human body. So to avoid the

accidents, industries emphasis on automation to perform hazardous operations.

Similarly,Traffic lights are necessary part of our daily life. If we not follow the

traffic rules then the traffic cannot be controlled.Many kinds of accidents would

occur.Thats why we need Traffic lights to control the Jams and to save the Human

beings.

8.2Steps to make the project:

Click on the on the icon of Siemens PLC software called LOGO!SOFT.

Fig.8.1 Icon of LOGO!SOFT

Then this main window of the software opens.

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Fig 8.2 Main Window

Then we select the File option to make the new project –Ladder diagrams as shown

in the below figure

Fig.8.3 Making a new file

After this selection following window pops up before us,in which we can see all

the contacts ,timers. Counters and many more functions using which we make

the programs.

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Fig.8.4Main window view

To make the single pole traffic light program we use Normally open

(NO),Normally

closed (NC) and Timers to give the proper timing to the lights to glow.

Normally open contact Passes power (ON) if coil driving the contact is ON

(closed)

Fig.8.5 Normally open symbol

Normally closed contact Passes power (ON) if coil driving the contact is off

(open).

Fig.8.6 Normally close symbol

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Output or coil If any left-to-right path of inputs passes power, output is energized.

Fig.8.7 Coil symbol

ON Delay Timer counts the time in seconds .It is called ON delay timer because it

starts after the given value of time is passed.

For setting the time we click on the timer then this window opens and we cn set the

time according

to our need.

Fig8.8How to give the timer time

We can use the contacts and Timers we bring them on the screen by dragging them.

And then make the program for the single pole Traffic light system as shown in the

following dig.

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Fig 8.9 Single pole Traffic light

As we see we have given time for Red Light to glows for 60 sec,Yellow for 40

sec,Green for 100 sec with the help of timers.

Then we click connect the program to the power bus (F3) to see the output as

shown in the following dig.

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Fig 8.10 program output

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CONCLUSION

A Programmable Logic Controller(PLC) is a device that was invented to replace

the necessary sequential relay circuit for machine control. A person knowlegde in

relay logic system can master the major PLC functions.

These are used extensively in nuclear reactor building and security control

system.It is a reliable compare to other systems.These may be used to run a

vibot.By using the PLC application logic we can control the air locks logic

controlpanel of reactor building.these PLcs we used in many “Real World”

applications.so using these PLCs nuclear reactor building doors namely main air

locks and emergency airlocks.

A Human-Machine Interface or HMI is the apparatus which presents process data

to a human operator, and through which the human operator controls the process.

The user interface (also known as human computer interface or man-machine

interface (MMI)) is the aggregate of means by which people—the users—interact

with the system a particular machine, device and computer program.

SCADA (supervisory control and data acquisition) is a type of industrial control

system (ICS). Industrial control systems are computer-controlled systems that

monitor and control industrial processes that exist in the physical world. It is useful

in various process.

Industrial processes include those of manufacturing, production, power generation ,

fabrication , and refining, and may run in continuous, batch, repetitive, or discrete

modes. Infrastructure processes may be public or private, and include water

treatment and distribution, wastewater collection and treatment, oil and gas

pipelines, electrical power transmission and distribution, wind farms, civil defense

siren systems, and large communication systems.

Drives are used to control the frequency, speed and torque of motors. It is used in

various industries in like paper mill,lifts,water supply distribution etc.

All these devices are the main requirements to make the operations automatic.

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Automation involves a very broad range of technologies including robotics and expert

systems, telemetry and communications, electro-optics, Cyber security, process

measurement and control, sensors, wireless applications, systems integration, test

measurement, and many, many more.

New opportunities are emerging in the automation field. It has a wide scope.

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REFERENCES:

www.google.com

www.electrical.com

www.drivesys.com

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