AUTOMATIC VOLTAGE CONTROL OF TRANSFORMER USING MICROCONTROLLER AND SCADA

M.G. COLLEGE OF ENGINEERING VANDITHADAM, THIRUVALLAM, THIRUVANANTHAPURAM-695027

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

NOVEMBER 2013

PROJECT REPORT

ON

AUTOMATIC VOLTAGE CONTROL OF

TRANSFORMER USING MICROCONTROLLER

AND SCADA

Submitted in partial fulfillment of the requirements of the award of B.Tech on

Electrical and Electronics Engineering

of the Cochin University of Science and Technology(CUSAT)

Submitted by:

AJESH JACOB(19113203)

TABLE OF CONTENTS

SL NO: CHAPTERS PAGE NO:

1 INTRODUCTION 1

2 WAY OF STUDY 3

3 PARAMETERS CONSIDERING

4

3.1 ANALOG PARAMETERS:

5

3.2 LOGIC PARAMETER: 5

4 FUNCTIONAL BLOCK DIAGRAM 5

4.1 MAIN HARDWARES 5

4.1.1 MICROCONTROLLER 5

4.1.2 RS232 5

4.1.3 TEMPERATURE SENSOR 5

4.1.4 DUAL FULL BRIDGE DRIVER 6

5 SOFTWARES 6

5.1 LAB VIEW 6

6 CIRCUIT DIAGRAM 7

7 SCADA 8

8 ESTIMATION OF PROJECT 8

9 CONCLUSION 9

REFERENCE 9

LIST OF FIGURES

FIG NO CONTENT PAGE NO

1. FUNCTIONAL BLOCK DIAGRAM 5

2. CIRCUIT DIAGRAM 7

1

AUTOMATIC VOLTAGE CONTROL OF

TRANSFORMER USING MICROCONTROLLER

AND SCADA

Ajesh Jacob(19113203)

S7,Department of Electrical and Electronics Engineering

MG COLLEGE OF ENGINEERING

ABSTRACT: A tap changer control operates to connect appropriate tap position of winding

in power transformers to maintain correct voltage level in the power transmission and

distribution system. Automatic tap changing can be implemented by using µC. This improved

tap-changing decision and operational flexibility of this new technique make it attractive for

deployment in practical power system network. This paper deals with the implementation of

µC based tap changer control practically, using special purpose digital hardware as a built-in

semiconductor chip or software simulation in conventional computers. Two strategies are

suggested for its implementation as a software module in the paper. One is to integrate it with

the supervisory system in a substation control room operating in a LAN environment. In this

configuration, the parallel transformers can be controlled locally. The other is to integrate it

into the SCADA (Supervisory Control and Data Acquisition) system, which allows the

transformers to be monitored and controlled remotely over a wide area of power-network. The

implementation of µC based tap changer control needs interfacing between the power system

and the control circuitry. µC s may need to interact with people for the purpose of

configuration, alarm reporting or everyday control.

A human-machine interface (HMI) is employed for this purpose. 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.

CHAPTER 1

INTRODUCTION There are vast opportunities to improve energy use efficiency by eliminating waste through

process optimization. Applying today’s computing and control equipment and techniques is one

of the most cost-effective and significant opportunities for larger energy users to reduce their

energy costs and improve profits. An Energy Management Information System (EMIS) is an

important element of a comprehensive energy management program. It provides relevant

information to key individuals and departments that enable them to improve energy performance.

Today it is normal for companies, particularly in process sectors, to collect huge amounts of real-

2

time data from automated control systems, including microcontrollers, Supervisory Control and

Data Acquisition (SCADA), etc. The captured data is shared and analysed in an orderly and

precise way that identifies problem areas and provides solutions, this mass of data is merely

information overload. Advances in information technology (IT), defined here as the use of

computers to collect, analyses, control and distribute data, have developed rapidly. It is now

common for managers and operators to have access to powerful computers and software. Today

there are a number of techniques to analyses the factors that affect efficiency, and models are

automatically generated based on “what if” scenarios in order to improve decisions to be taken.

The paper shows a very advanced technology for handling automatically more than 200 digital

and analogue (i/p and o/p) parameters via intelligent monitoring and controlling system.

However, load management is the process of scheduling the loads to reduce the electric energy

consumption and or the maximum demand. It is basically optimizing the processes/loads to

improve the system load factor. Load-management procedures involve changes to equipment

and/or consumption patterns on the customer side. There are many methods of load management

which can be followed by an industry or a utility, such as load shedding and restoring, load

shifting, installing energy-efficient processes and equipment, energy storage devices, co-

generation, non-conventional sources of energy, and reactive power control Meeting the peak

demand is one of the major problems now facing the electric utilities. With the existing

generating capacity being unmanageable, authorities are forced to implement load shedding in

various sectors during most of the seasons. Load shifting will be a better option for most

industries. Load shifting basically means scheduling the load in such a way that loads are

diverted from peak period to off-peak periods, thereby shaving the peak and filling the valley of

the load curve, so improving the load factor .To encourage load shifting in industries, and

thereby to reduce peak demand automatically, Also, power quality is of major concern to all

types of industries, especially those operating with critical machinery and equipments. Poor

quality of power leads to major problems like break-downs, production interruptions, excess

energy consumption etc. Modern industries require automation of their operation enabling them

to produce quality products and also for mass production. The conventional systems are being

replaced by modern Power Electronic systems, bringing a variety of advantages to the users.

Classic examples are DC & AC Drives, UPS, soft starters, etc. Power Quality Alarming and

Analysis provides a comprehensive view into a facility's electrical distribution system. Power

Quality can be monitored at the electrical mains or at any critical feeder branch in the

distribution system such as described here. Devices in this category typically provide all of the

parameters found in basic devices, plus advanced analysis capabilities [7]-[8]. These advanced

analysis capabilities include using waveform capture to collect and view waveform shape and

magnitude, providing harmonic analysis graphs, collection and storage of events and data, and

recording single or multiple cycle waveforms based on triggers such as overvoltage or transients.

With the ever-increasing use of sophisticated controls and equipment in industrial, commercial,

and governmental facilities, the continuity, reliability, and quality of electrical service has

become extremely crucial to many power users. Electrical systems are subject to a wide variety

3

of power quality problems which can interrupt production processes, affect sensitive equipment,

and cause downtime, scrap, and capacity losses. Momentary voltage fluctuations can disastrously

impact production . the proposed modified intelligent monitoring and controlling system will

introduce monitoring, alarming, controlling, and power quality mitigation based on data

collected and analyzed from the system.

OBJECTIVES: The original system can afford the following features:

- Complete information about the plant (circuit breakers status, source of feeding, and level of

the consumed power).

- Information about the operating values of the voltage, operating values of the transformers,

operating values of the medium voltage, load feeders, operating values of the generators. These

values will assist in getting any action to return the plant to its normal operation by minimum

costs.

- Information about the quality of the system (harmonics, current, voltages, power factors,

flickers, etc.). These values will be very essential in case of future correction.

- Recorded information such case voltage spikes, reducing the voltage on the medium or current

interruption.

- implementation of µC based tap changer control practically, using special purpose digital

hardware as a built-in semiconductor chip or software simulation in conventional computers.

CHAPTER 2

WAY OF STUDY

Searching for a new trend topic

Select the topic

Sketching the block diagram

List out the components needed

Googling the properties of each components

Select the apt components

Rough sketching the circuit diagram

Calculating the cost of project

4

Plan to study the software part

Correcting the circuit by designing the values of components

Implementing the circuit

Presenting the project

CHAPTER 3

PARAMETERS CONSIDERING;

3.1 ANALOG PARAMETERS:

1. Incoming Voltage

2. Bus Voltage

3. 3 - Feeder Current

4. Max Bus Current

5. Incoming Current

6. Power

7. Active Power

8. Power Factor

9. Frequency

3.2. LOGIC PARAMETER:

1. over Heat Protection

2. Flame Identification

3. Trespassing Identification

5

CHAPTER 4

FUNCTIONAL BLOCK DIAGRAM

4.1 MAIN HARDWARES 4.1.1.MICROCONTROLLER: The PIC16F87XA is a low power CMOS 8-bit microcontroller

based on the AVR enhanced RISC architecture by executing powerful instructions clock cycle,

achieves through PIC16F87XA puts approaching 1MIPS/MHz allowing the system designer to

optimize power consumption versus processing speed.

4.1.2. RS-232: In telecommunications, RS-232 is a standard for serial data communication.

.interconnection between a DTE (Data terminal equipment) and a DCE(Data Circuit-terminating

Equipment).it is commonly used in computer serial ports. is commonly used in computer serial

ports.

4.1.3. TEMPERATURE SENSOR: The Temperature sensor detector is designed for the

security practice. This sensor buffers a piezoelectric transducer. As the transducer is displaced

from the mechanical neutral axis, bending creates strain within the piezoelectric element and

generates voltages. When vibration Temperature sensor alarm recognizes temperature it sends a

signal to either control panel developed a new type of Omni-directional high sensitivity security

vibrational temperature detector with Omni-directional detection.

6

4.1.4. DUAL FULL BRIDGE DRIVER: The L298 is an integrated monolithic circuit in a 15-

lead Multi-watt and PowerSO20 packages. It is a high voltage, high current dual full-bridge

driver designed to accept standard TTL logic levels and drive inductive loads such as relays,

solenoids, DC and stepping motors. Two enable inputs are provided to enable or disable the

device independently of the input signals. The emitters of the lower transistors of each bridge are

connected together and the corresponding external terminal can be used for the connection of an

external sensing resistor. An additional supply input is provided so that the logic works at a

lower voltage.

CHAPTER 5

SOFTWARE

5.1. Lab VIEW: (short for Laboratory Virtual Instrument Engineering Workbench) is a

system-design platform and development environment for a visual programming language from

National Instruments. The graphical language is named "G" (not to be confused with G-code).

Originally released for the Apple Macintosh in 1986, LabVIEW is commonly used for data

acquisition, instrument control, and industrial automation on a variety of platforms including

Microsoft Windows, various versions of UNIX, Linux, and Mac OS X. The programming

language used in LabVIEW, also referred to as G, is a dataflow programming language.

Execution is determined by the structure of a graphical block diagram (the LV-source code) on

which the programmer connects different function-nodes by drawing wires. These wires

propagate variables and any node can execute as soon as all its input data become available.

Since this might be the case for multiple nodes simultaneously, G is inherently capable of

parallel execution. Multi-processing and multi-threading hardware is automatically exploited by

the built-in scheduler, which multiplexes multiple OS threads over the nodes ready for

executions.

In terms of performance, LabVIEW includes a compiler that produces native code for the CPU

platform. The graphical code is translated into executable machine code by interpreting the

syntax and by compilation. The LabVIEW syntax is strictly enforced during the editing process

and compiled into the executable machine code when requested to run or upon saving. In the

latter case, the executable and the source code are merged into a single file. The executable runs

with the help of the LabVIEW run-time engine, which contains some precompiled code to

perform common tasks that are defined by the G language. The run-time engine reduces compile

time and also provides a consistent interface to various operating systems, graphic systems,

hardware components, etc. The run-time environment makes the code portable across platforms.

Generally, LabVIEW code can be slower than equivalent compiled C code, although the

differences often lie more with program optimization than inherent execution speed. Libraries

with a large number of functions for data acquisition, signal generation, mathematics, statistics,

signal conditioning, analysis, etc., along with numerous graphical interface elements are

7

provided in several LabVIEW package options. The number of advanced mathematic blocks for

functions such as integration, filters, and other specialized capabilities usually associated with

data capture from hardware sensors is immense. In addition, LabVIEW includes a text-based

programming component called MathScript with additional functionality for signal processing,

analysis and mathematics. MathScript can be integrated with graphical programming using

"script nodes" and uses a syntax that is generally compatible with MATLAB.

CHAPTER 6

CIRCUIT DIAGRAM

8

CHAPTER 7

SCADA FOR POWER SYSTEM AUTOMATION

Automation of power distribution system has increasingly been adopted by power utilities

worldwide in recent years. As part of its efforts to provide a more reliable supply to the customer

and to enhance operational efficiency. The automation of the power system can be achieved by

SCADA. It is a boon to the automation concept of dynamic technology. SCADA refers to

“SUPERVISORY CONTROL&DATA ACQUISITION”. This paper presents the approach

adopted in implementing the SCADA system and the benefits accrued through incorporating

system. Electric power distribution system is an important part of electric power system in

delivery of electricity to consumers. Electric power utilities worldwide are increasingly adopting

the computer aided monitoring, control and management of electric power distribution system to

provide better service to electric consumers. Therefore research and development activities

worldwide are being carried out to automate the electric power distribution system utilizing

recent advancement in the area of information technology and data communication system. This

paper reports the present and past status of the research and development activities in the area of

electric power distribution automation both in developed as well as in developing countries. The

information given in this paper is useful to electric power distribution utilities and academicians

involved in research and development activities in the area of power distribution automation.

Even public sectors like TNEB has installed SCADA for monitor & control ninety-five

substations in the CHENNAI metro for this, We are trying to reproduce SCADA in a computer

based SCADA system equipped with automated generation control function is proposed. To

supervise and control the generation and transmission system as well as to cater for their

increasing sophistication in system operation and coordination. In order to serve such a high

number of RTU by a control centre and to avoid any communication bottleneck at the master

station, a distributed system approach is suggested.

CHAPTER 8

ESTIMATION OF PROJECT

SL NO PURPOSES PRICE RATE

1 programming 5000/-

2 Layout designing 3000/-

3 components 5000/-

4 Circuit designing 3000/-

5 others 5000/-

6 Total 21,000/-

9

CHAPTER 9

CONCLUSION This paper deals with the implementation of µC based tap changer control practically, using

special purpose digital hardware as a built-in semiconductor chip or software simulation in

conventional computers. Two strategies are suggested for its implementation as a software

module in the paper. One is to integrate it with the supervisory system in a substation control

room operating in a LAN environment. In this configuration, the parallel transformers can be

controlled locally. The other is to integrate it into the SCADA (Supervisory Control and Data

Acquisition) system, which allows the transformers to be monitored and controlled remotely

over a wide area of power-network. The implementation of µC based tap changer control

needs interfacing between the power system and the control circuitry. µC s may need to

interact with people for the purpose of configuration, alarm reporting or everyday control.

REFERENCE

[1] M. R. Mcrae, R. M. Seheer and B. A. Smith, "Integrating Load Management Programs into Utility

Operations and Planning with a Load Reduction Forecasting System," IEEE Trans., Vol PAS-104, No. 6, pp.

1321- 1325, June 1985.

[2] C. W. Gellings, "Interruptible Load Management into Utility Planning", IEEE Trans. Vol.PAS-104, No.8,

pp.2079-2085, August 1985[3] C. W. Gellings, A. C. Johnson and P. Yatcko, "Load Management Assessment

Methodology at PSE&G", IEEE Trans.,Vol. PAS-101, No.9, pp. 3349-3355, September,1982.

[4] C. Alvarez, R.P. Malhame, A. Gabaldon, “A class of models for load management application and

evaluation revisited”, IEEE Transaction on Power Systems, Vol. 7, No. 4, pp. 1435, Novemebr-1992.

[5] L Ma Isaksen and N.W. Simons, “Bibliography and load management”, IEEE Transactions on Power

Apparatus and Systems 1981: PAS-100(5):1981.

[6] J.N. Sheen et al, “TOU pricing of electricity for load management in Taiwan power company”, IEEE Trans

on Power Systems 1994.

[7] Meier, Alexandra von (2006). Electric Power Systems: A Conceptual Introduction. John Wiley & Sons, Inc.

ISBN 978-0-471-17859.

[8] Kusko, Alex; Marc Thompson (2007). Power Quality in Electrical Systems. McGraw Hill. ISBN 978-

0071470759.

[9] M.M. Eissa. Demand Side Management Program Evaluation Based on Industrial and Commercial Field

Data. Energy Policy 39 (October, 2011) 5961–5969.

SUBSTATION AUTOMATION USING µC AND SCADA 2014

DEPT. OF EEE, MG COLLEGE OF ENGINEERING 1

CHAPTER 1

INTRODUCTION

There are vast opportunities to improve energy use efficiency by eliminating waste through

process optimization. Applying today’s computing and control equipment and techniques is

one of the most cost-effective and significant opportunities for larger energy users to reduce

their energy costs and improve profits. An Energy Management Information System (EMIS)

is an important element of a comprehensive energy management program. It provides relevant

information to key individuals and departments that enable them to improve energy

performance. Today it is normal for companies, particularly in process sectors, to collect huge

amounts of real-time data from automated control systems, including Programmable Logic

Controllers (PLCs), Supervisory Control and Data Acquisition (SCADA), etc. The captured

data is shared and analysed in an orderly and precise way that identifies problem areas and

provides solutions, this mass of data is merely information overload. Advances in information

technology (IT), defined here as the use of computers to collect, analyse, control and distribute

data, have developed rapidly. It is now common for managers and operators to have access to

powerful computers and software. Today there are a number of techniques to analyse the

factors that affect efficiency, and models are automatically generated based on “what if”

scenarios in order to improve decisions to be taken. The paper shows a very advanced

technology for handling automatically, digital and analogue (i/p and o/p) parameters via

intelligent monitoring and controlling system.

A tap changer control operates to connect appropriate tap position of winding in power

transformers to maintain correct voltage level in the power transmission and distribution

system. Automatic tap changing can be implemented by using µC. This improved tap-changing

decision and operational flexibility of this new technique make it attractive for deployment in

practical power system network. This paper deals with the implementation of µC based tap

changer control practically, using special purpose digital hardware as a built-in semiconductor

chip or software simulation in conventional computers. Two strategies are suggested for its

implementation as a software module in the paper. One is to integrate it with the supervisory

system in a substation control room operating in a LAN environment. In this configuration, the

parallel transformers can be controlled locally. The other is to integrate it into the SCADA

(Supervisory Control and Data Acquisition) system, which allows the transformers to be

monitored and controlled remotely over a wide area of power-network. The implementation of

µC based tap changer control needs interfacing between the power system and the control

circuitry. µC s may need to interact with people for the purpose of configuration, alarm

reporting or everyday control.

A human-machine interface (HMI) is employed for this purpose. 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.



However, load management is the process of scheduling the loads to reduce the electric energy

consumption and or the maximum demand. It is basically optimizing the processes/loads to

improve the system load factor. Load-management procedures involve changes to equipment

and/or consumption patterns on the customer side. There are many methods of load

management which can be followed by an industry or a utility, such as load shedding and

restoring, load shifting, installing energy-efficient processes and equipment, energy storage

devices, co- generation, non-conventional sources of energy, and reactive power control

Meeting the peak demand is one of the major problems now facing the electric utilities.

With the existing generating capacity being unmanageable, authorities are forced to implement

load shedding in various sectors during most of the seasons. Load shifting will be a better

option for most industries. Load shifting basically means scheduling the load in such a way

that loads are diverted from peak period to off-peak periods, thereby shaving the peak and

filling the valley of the load curve, so improving the load factor .To encourage load shifting in

industries, and thereby to reduce peak demand automatically, Also, power quality is of major

concern to all types of industries, especially those operating with critical machinery and

equipment. Poor quality of power leads to major problems like break-downs, production

interruptions, excess energy consumption etc. Modern industries require automation of their

operation enabling them to produce quality products and also for mass production. The

conventional systems are being replaced by modern Power Electronic systems, bringing a

variety of advantages to the users. Classic examples are DC & AC Drives, UPS, soft starters,

etc. Power Quality Alarming and Analysis provides a comprehensive view into a facility's

electrical distribution system. Power Quality can be monitored at the electrical mains or

at any critical feeder branch in the distribution system such as described here. Devices in

this category typically provide all of the parameters found in basic devices, plus advanced

analysis capabilities. These advanced analysis capabilities include using waveform capture to

collect and view waveform shape and magnitude, providing harmonic analysis graphs,

collection and storage of events and data, and recording single or multiple cycle waveforms

based on triggers such as overvoltage or transients. With the ever-increasing use of

sophisticated controls and equipment in industrial, commercial, and governmental facilities,

the continuity, reliability, and quality of electrical service has become extremely crucial

to many power users. Electrical systems are subject to a wide variety of power quality problems

which can interrupt production processes, affect sensitive equipment, and cause downtime,

scrap, and capacity losses. Momentary voltage fluctuations can disastrously impact production.

the proposed modified intelligent monitoring and controlling system will introduce

monitoring, alarming, controlling, and power quality mitigation based on data collected

and analysed from the system.



CHAPTER 2

AUTOMATION

2.1 INTRODUCTION

The word ‘Automation’ is derived from Greek words “Auto” (self) and “Matos” (moving).

Automation therefore is the mechanism for systems that “move by it”. However, apart from

this original sense of the word, automated systems also achieve significantly superior

performance than what is possible with manual systems, in terms of power, precision and speed

of operation.

2.2 DEFINITION

Automation is a set of technologies that results in operation of machines and systems without

significant human intervention and achieves performance superior to manual operation.

AUTOMATION PYRAMID

2.1.1SENSORS AND ACTUATORS LAYERS:

This layer is closest to the process and machines, used to translate signals so that signals can be derived

from processes for analysis and decisions and hence control signals can be applied to the processes.

This forms the base layer of the pyramid also called ‘level 0’ layer.



2.1.2 AUTOMATIC CONTROL LAYER:

This layer consists of automatic control and monitoring systems, which drive the actuators

using the process information given by sensors. This is called as ‘level 1’ layer.

2.1.3 SUPERVISORY CONTROL LAYER:

This layer drives the automatic control system by setting target/goal to the controller.

Supervisory Control looks after the equipment, which may consist of several control loops.

This is called as ‘level 2’ layer.

2.1.4 PRODUCTION CONTROL LAYER:

This solves the decision problems like production targets, resource allocation, task allocation

to machines, maintenance management etc. This is called ‘level 3’ layer.

2.1.5 ENTERPRISE CONTROL LAYER:

This deals less technical and more commercial activities like supply, demand, cash flow,

product marketing etc. This is called as the ‘level 4’ layer.

2.3 TYPES OF AUTOMATION

Automation systems can be categorized based on the flexibility and level of integration in

manufacturing process operations. Various automation systems can be classified as follows

2.3.1 FIXED AUTOMATION:

It is used in high volume production with dedicated equipment, which has a fixed set of

operation and designed to be efficient for this set. Continuous flow and Discrete Mass

Production systems use this automation. e.g. Distillation Process, Conveyors, Paint Shops,

Transfer lines etc.

A process using mechanized machinery to perform fixed and repetitive operations in order to

produce a high volume of similar parts.

2.3.2 PROGRAMMABLE AUTOMATION:

It is used for a changeable sequence of operation and configuration of the machines using

electronic controls. However, non-trivial programming effort may be needed to reprogram the

machine or sequence of operations. Investment on programmable equipment is less, as

production process is not changed frequently. It is typically used in Batch process where job

variety is low and product volume is medium to high, and sometimes in mass production also.

e.g. in Steel Rolling Mills, Paper Mills etc.



2.3.3 FLEXIBLE AUTOMATION:

It is used in Flexible Manufacturing Systems (FMS) which is invariably computer

controlled. Human operators give high-level commands in the form of codes entered into

computer identifying product and its location in the sequence and the lower level changes are

done automatically. Each production machine receives settings/instructions from computer.

These automatically loads/unloads required tools and carry out their processing instructions.

After processing, products are automatically transferred to next machine. It is typically used in

job shops and batch processes where product varieties are high and job volumes are medium

to low. Such systems typically use Multi purpose CNC machines, Automated Guided Vehicles

(AGV) etc.

2.3.4 INTEGRATED AUTOMATION:

It denotes complete automation of a manufacturing plant, with all processes functioning

under computer control and under coordination through digital information processing. It

includes technologies such as computer-aided design and manufacturing, computer-aided

process planning, computer numerical control machine tools, flexible machining systems,

automated storage and retrieval systems, automated material handling systems such as robots

and automated cranes and conveyors, computerized scheduling and production control. It may

also integrate a business system through a common database. In other words, it symbolizes full

integration of process and management operations using information and communication

technologies. Typical examples of such technologies are seen in Advanced Process Automation

Systems and Computer Integrated Manufacturing (CIM).



CHAPTER 3

SCADA

SCADA systems are widely used in industry for Supervisory Control and Data

Acquisition of industrial processes. Companies that are members of standardisation committees

(e.g. OPC, OLE for Process Control) and are thus setting the trends in matters of IT technologies

generally develop these systems. As a matter of fact, they 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 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. This paper describes SCADA systems in terms of their architecture, their

interface to the process hardware, the functionality and application development facilities they

provide. Some attention is paid to the industrial standards to which they abide, their planned

evolution as well as the potential benefits of their use.

3.1 ARCHITECTURE

This section describes the common features of the SCADA products that have been

evaluated at CERN in view of their possible application to the control systems of the LHC

detectors.

3.1.1 HARDWARE ARCHITECTURE

One distinguishes two basic layers in a SCADA system: the "client layer" which caters for

the man machine interaction and the "data server layer" which handles most of the process

data control activities. The data servers communicate with devices in the field through process

controllers. Process controllers, e.g. PLCs, are connected to the data servers either directly or

via networks or fieldbuses that are proprietary (e.g. Siemens H1), or non-proprietary (e.g.

Profibus). Data servers are connected to each other and to client stations via an Ethernet

LAN.



3.1.2 SOFTWARE ARCHITECTURE

The products are multi-tasking and are based upon a real-time database (RTDB)

located in one or more servers. Servers are responsible for data acquisition and handling (e.g.

polling controllers, alarm checking, calculations, logging and archiving) on a set of parameters,

typically those they are connected to.



CHAPTER 4

PROPOSED BLOCK DIAGRAM



CHAPTER 5

PROPOSED FUNCTIONAL BLOCK DESCRIPTION

5.1 MICROCONTROLLER:

The PIC16F87XA is a low power CMOS 8-bit microcontroller based on the AVR

enhanced RISC architecture by executing powerful instructions clock cycle, achieves through

PIC16F87XA puts approaching 1MIPS/MHz allowing the system designer to optimize power

consumption versus processing speed.

Special Features:-

Flash memory : 14.3 Kbytes(8192 words)

Data SRAM : 368 bytes

Data EEPROM : 256 bytes

Self- reprogrammable under software control

In – Circuit serial Programming via two pins(5v)

Watchdog timer with on-chip RC oscillator

Programmable code protection

Power –saving sleep mode

Selectable oscillator options

In – circuit Debug via two pins

Figure 1



5.2 RS-232 :

In telecommunications, RS-232 is a standard for serial data communication.

.interconnection between a DTE (Data terminal equipment) and a DCE(Data Circuit-

terminating Equipment).it is commonly used in computer serial ports. is commonly used in

computer serial ports.

5.3 TEMPERATURE SENSOR:

The Temperature sensor detector is designed for the security practice. This sensor

buffers a piezoelectric transducer. As the transducer is displaced from the mechanical neutral

axis, bending creates strain within the piezoelectric element and generates voltages. When

vibration Temperature sensor alarm recognizes temperature it sends a signal to either control

panel developed a new type of Omni-directional high sensitivity security vibrational

temperature detector with Omni-directional detection.

5.4 Lab VIEW:

Short for Laboratory Virtual Instrument Engineering Workbench) is a system-design

platform and development environment for a visual programming language from National

Instruments. The graphical language is named "G" (not to be confused with G-code). Originally

released for the Apple Macintosh in 1986, LabVIEW is commonly used for data acquisition,

instrument control, and industrial automation on a variety of platforms including Microsoft

Windows, various versions of UNIX, Linux, and Mac OS X. The programming language used

in LabVIEW, also referred to as G, is a dataflow programming language. Execution is

determined by the structure of a graphical block diagram (the LV-source code) on which the

programmer connects different function-nodes by drawing wires. These wires propagate

variables and any node can execute as soon as all its input data become available. Since this

might be the case for multiple nodes simultaneously, G is inherently capable of parallel

execution. Multi-processing and multi-threading hardware is automatically exploited by the

built-in scheduler, which multiplexes multiple OS threads over the nodes ready for

executions.

In terms of performance, LabVIEW includes a compiler that produces native code for the CPU

platform. The graphical code is translated into executable machine code by interpreting the

syntax and by compilation. The LabVIEW syntax is strictly enforced during the editing process

and compiled into the executable machine code when requested to run or upon saving. In the

latter case, the executable and the source code are merged into a single file. The executable

runs with the help of the LabVIEW run-time engine, which contains some precompiled code

to perform common tasks that are defined by the G language. The run-time engine reduces

compile time and also provides a consistent interface to various operating systems, graphic

systems, hardware components, etc. The run-time environment makes the code portable across

platforms. Generally, LabVIEW code can be slower than equivalent compiled C code, although

the differences often lie more with program optimization than inherent execution speed.

Libraries with a large number of functions for data acquisition, signal generation, mathematics,



statistics, signal conditioning, analysis, etc., along with numerous graphical interface

elements are provided in several LabVIEW package options. The number of advanced

mathematic blocks for functions such as integration, filters, and other specialized capabilities

usually associated with data capture from hardware sensors is immense. In addition, LabVIEW

includes a text-based programming component called MathScript with additional functionality

for signal processing, analysis and mathematics. MathScript can be integrated with graphical

programming using "script nodes" and uses a syntax that is generally compatible

with MATLAB.

5.5 DUAL FULL BRIDGE DRIVER:

The L298 is an integrated monolithic circuit in a 15- lead Multi-watt and PowerSO20

packages. It is a high voltage, high current dual full-bridge driver designed to accept standard

TTL logic levels and drive inductive loads such as relays, solenoids, DC and stepping motors.

Two enable inputs are provided to enable or disable the device independently of the input

signals. The emitters of the lower transistors of each bridge are connected together and the

corresponding external terminal can be used for the connection of an external sensing resistor.

An additional supply input is provided so that the logic works at a lower voltage.

5.6 STEPPER MOTOR

This motor based on the input from PIC will rotates the shaft of auto-transformer and

changes the tapping i.e. at low voltages the shaft is rotated in the clockwise direction and stepup

the voltage level to the required voltage level and vice versa. This in turn is added to the

external power and transmitted out.

Figure 2



5.7 POWER SUPPLY

A voltage regulator is designed to automatically maintain a constant voltage level in

the circuit. Here the voltage regulator IC 7805 is used to reduce the high dc voltage to 5V. it is

a member of 78xx series of fixed linear voltage regulator ICs. The voltage source in a circuit

may have fluctuations and would not give the fixed voltage output. The maintains the output

voltage at a constant value. The xx in 78xx indicates the fixed output voltage it is designed to

provide. 7805 provides +5V regulated power supply. Capacitors of suitable values can be

connected at input and output pins depending upon the respective voltage levels.

Figure 3



CHAPTER 6

MODIFIED FUNCTIONAL BLOCK DIAGRAM



CHAPTER 7

MODIFIED BLOCK DIAGRAM DESCRIPTION

7.1 TRI TAPPED TRANSFORMER

Transformer converts AC electricity from one voltage to another with little loss of

power. Transformers works only with AC and this is one of the reasons why mains electricity

is AC. Step up transformers increase voltage, step down transformers reduce voltage. The input

coil is called primary and output coil is called secondary, There is no electrical connection

between two coils; instead they are linked by an alternating magnetic field created in the soft

iron core of the transformer.

Transformers wastes very little power so the power out is almost equal to the power in.

Not that as voltage is stepped down current is stepped up. The ratio of the number of turns on

each coil, called the turns ratio, determines the ratio of the voltages. A step down transformers

has a large number of turns on its primary which is connected to the high voltage mains supply,

and a small number of turns on its secondary coil to give a low output voltage.

7.2 Bi –PASS RELAY SECTION:

The microcontroller continuously monitors the status of 3 lines originating from Port

A. Whenever any lines fails, the controller came to know that and it activates the corresponding

relay in the bypass circuit to bypass line. The relays detect the abnormal conditions in the

electrical circuits by constantly measuring the electrical quantities which are different under

normal and fault conditions. The electrical quantities which may change under fault conditions

are voltages, current, frequency, and phase angle. Through the changes in one or more of these

quantities, the faults signal their presence, type and location to the protective relays.

7.3 RELAY

Relay is an electromagnetic device which is used to isolate two circuits electrically and

connect them magnetically. They are very useful devices and allow one circuit to switch

another one while they are completely separate. They are often used to interface an electronic

circuit (working at a low voltage) to an electrical circuit which works at very high voltage. For

example, a relay can make a 5V DC battery circuit to switch a 230V AC mains circuit. Thus a

small sensor circuit can drive, say, a fan or an electric bulb. A relay can be divided into two

parts: input and output. The input section has a coil which generates magnetic field when a

small voltage from an electronic circuit is applied to it. This voltage is called the operating

voltage. Commonly used relays are available in different configuration of operating voltages

like 6V, 9V, 12V, 24V etc.



The output section consists of contactors which connect or disconnect mechanically. In a basic

relay there are three contactors: normally open (NO), normally closed (NC) and common

(COM). At no input state, the COM is connected to NC. When the operating voltage is applied

the relay coil gets energized and the COM changes contact to NO. Different relay

configurations are available like SPST, SPDT, and DPDT etc., which have different number of

changeover contacts. By using proper combination of contactors, the electrical circuit can be

switched on and off.

7.4 CRYSTAL OSCILLATOR

A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance

of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise

frequency. This frequency is commonly used to keep track of time (as in quartz wristwatches),

to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for

radio transmitters and receivers. The most common type of piezoelectric resonator used is the

quartz crystal, so oscillator circuits designed around them became known as "crystal

oscillators."

Quartz crystals are manufactured for frequencies from a few tens of kilohertz to tens of

megahertz. More than two billion (2×109) crystals are manufactured annually. Most are used

for consumer devices such as wristwatches, clocks, radios, computers, and cellphones. Quartz

crystals are also found inside test and measurement equipment, such as counters, signal

generators, and oscilloscopes. A crystal is a solid in which the constituent atoms, molecules,

or ions are packed in a regularly ordered, repeating pattern extending in all three spatial

dimensions.

Almost any object made of an elastic material could be used like a crystal, with

appropriate transducers, since all objects have natural resonant frequencies of vibration. For

example, steel is very elastic and has a high speed of sound. It was often used in mechanical

filters before quartz. The resonant frequency depends on size, shape, elasticity, and the speed

of sound in the material. High-frequency crystals are typically cut in the shape of a simple,

rectangular plate. Low-frequency crystals, such as those used in digital watches, are typically

figure. 4 Single pole double throw switch



cut in the shape of a tuning fork. For applications not needing very precise timing, a low-cost

ceramic resonator is often used in place of a quartz crystal. When a crystal of quartz is properly

cut and mounted, it can be made to distort in an electric field by applying a voltage to an

electrode near or on the crystal. This property is known as piezoelectricity. When the field is

removed, the quartz will generate an electric field as it returns to its previous shape, and this

can generate a voltage. The result is that a quartz crystal behaves like a circuit composed of an

inductor, capacitor and resistor, with a precise resonant frequency.

Quartz has the further advantage that its elastic constants and its size change in such a

way that the frequency dependence on temperature can be very low. The specific characteristics

will depend on the mode of vibration and the angle at which the quartz is cut (relative to its

crystallographic axes).[8] Therefore, the resonant frequency of the plate, which depends on its

size, will not change much, either. This means that a quartz clock, filter or oscillator will remain

accurate. For critical applications the quartz oscillator is mounted in a temperature-controlled

container, called a crystal oven, and can also be mounted on shock absorbers to prevent

perturbation by external mechanical vibrations.

7.5 RESISTORS

A resistor is a passive two-terminal electrical component that implements electrical

resistance as a circuit element. The current through a resistor is in direct proportion to the

voltage across the resistor's terminals. Thus, the ratio of the voltage applied across a resistor's

terminals to the intensity of current through the circuit is called resistance. This relation is

represented by Ohm's law: where I is the current through the conductor in units of amperes, V

is the potential difference measured across the conductor in units of volts, and R is the

resistance of the conductor in units of ohms. More specifically, Ohm's law states that the R in

this relation is constant, independent of the current.

Resistors are common elements of electrical networks and electronic circuits and are

ubiquitous in electronic equipment. Practical resistors can be made of various compounds and

films, as well as resistance wire (wire made of a high-resistivity alloy, such as nickel-chrome).

Resistors are also implemented within integrated circuits, particularly analog devices, and can

also be integrated into hybrid and printed circuits.

7.6 CAPACITORS

A capacitor (formerly known as condenser) is a passive two-terminal electrical

component used to store energy in an electric field. The forms of practical capacitors vary

widely, but all contain at least two electrical conductors separated by a dielectric (insulator);

for example, one common construction consists of metal foils separated by a thin layer of

insulating film. Capacitors are widely used as parts of electrical circuits in many common

electrical devices.



CHAPTER 8

CIRCUIT DIAGRAM



CHAPTER 9

WORKING

We are about to control and monitor the different parameters of a substation particularly

voltage, current ,frequency power ,heat or temperature developed in a transformer. Controlling

includes the voltage restoration ; whenever the voltage level fails, the tapings of the transformer

is being selected by relay switching and for the protection from the over voltage relay trip

switch is employed from over heating of transformer , cooling arrangements are automatically

enhanced.

9.1 MEASUREMENT OF PARAMETERS

9.1.1 VOLTAGE:

Voltage coming to the back feeder is measured by selecting a low voltage taping from

the transformer which will provide an output voltage in the range 0 to 3 V, which is fed to the

ADC port of the microcontroller which converts the analogue voltage to its corresponding

digital signal.

9.1.2 CURRENT:

So as to obtain the current flowing through the load a current dividing circuit ie; the

circuit consisting of a known value highly rated resistance connected in series to the load

produces a small voltage drop across the resistance , which is fed to the ADC of the

microcontroller , with the known value of voltage and resistance we can calculate the current

flowing in the load , which is computed internally in the ALU of the microcontroller.

9.1.3 FREQUENCY :

Frequency is defined as the number of oscillations per second , frequency of the supply

can be found out by inputing a low voltage signal from the supply to the COUNTER/TIMER

pin of the microcontroller after setting the pin to COUNTER mode .The signal voltage is fed

to the COUNTER pin with a comparator as an interfacing device ,which generates only

discrete signals of digital high or digital low ie; the continuous input AC sine wave is

converted to discrete pulses hence with the help of a counter in the microcontroller we can

count the number of digital high or digital low signals occurring in a second,there by we can

measure the frequency.

9.1.4 TEMPERATURE

Temperature developed at the transformer is measured using a temperature sensor

LM35 which produces an analogues voltage for every change of 1oC ,this voltage is fed to the

ADC port of the microcontroller which generates the equivalent digital signal of the

temperature from corresponding analog voltage.



9.2 CONTROLLING

Using SCADA we are controlling and monitoring the parameters from the GUI screen of the

computer with a tool LabVIEW ,for the controlling and monitoring it is necessary to transfer

the parameter and control signal data from the host to the server and vice versa .Here a zigbee

module is used for the transfer of parameters and control signal data, according to the data and

value of different parameters the relays will be switched automatically based on different

conditions provided for the regulation and protection.



CHAPTER 10

VIRTUAL INSTRUMENT

10.1 FRONT PANNEL



10.2 BLOCK DIAGRAM



CHAPTER 11

MICROCONTROLLER

To realize this project we used two microcontrollers for two kind of applications; to

design the solar tracker and soar power synchronizer. For both applications PIC16F876

microcontrollers arte used. This chapter deals about the microcontroller.

About PIC16F786

PIC is a family of modified Harvard architecture microcontrollers made by Microchip

Technology, derived from the PIC1650 originally developed by General Instrument's

Microelectronics Division. The name PIC initially referred to "Peripheral Interface Controller"

PICs are popular with both industrial developers and hobbyists alike due to their low cost, wide

availability, large user base, extensive collection of application notes, availability of low cost

or free development tools, and serial programming (and re-programming with flash memory)

figure. 5 Pin out diagram of PIC16F786



capability. They are also commonly used in educational programming as they often come with

the easy to use 'pic locator' software. Some of its features are,

High-Performance RISC CPU:

Only 35 single-word instructions to learn

All single-cycle instructions except for program branches, which are two-cycle

Operating speed: DC – 20 MHz clock input, DC – 200 ns instruction cycle

Up to 8K x 14 words of Flash Program Memory, Up to 368 x 8 bytes of Data Memory

(RAM), Up to 256 x 8 bytes of EEPROM Data Memory

Pin out compatible to other 28-pin or 40/44-pin

Peripheral Features:

Timer0: 8-bit timer/counter with 8-bit prescaler

Timer1: 16-bit timer/counter with prescaler, can be incremented during Sleep via

external crystal/clock

Timer2: 8-bit timer/counter with 8-bit period register, prescaler and postscaler

Two Capture, Compare, PWM modules

o Capture is 16-bit, max. resolution is 12.5 ns

o Compare is 16-bit, max. resolution is 200 ns

o PWM max. resolution is 10-bit

Synchronous Serial Port (SSP) with SPI™

(Master mode) and I2C™ (Master/Slave)

Universal Synchronous Asynchronous Receiver

Transmitter (USART/SCI) with 9-bit address

detection

Parallel Slave Port (PSP) – 8 bits wide with

external RD, WR and CS controls (40/44-pin only)

Brown-out detection circuitry for Brown-out Reset (BOR)

Analog Features:

10-bit, up to 8-channel Analog-to-Digital

Converter (A/D)

Brown-out Reset (BOR)

Analog Comparator module with:

o Two analog comparators

o Programmable on-chip voltage reference

(VREF) module

o Programmable input multiplexing from device

inputs and internal voltage reference

O Comparator outputs are externally accessible



11.1 CONFIGURING THE PORTS

PIC16F876 consists of 3 ports. This is from PORTA to PORTC. Different ports have

different number of bits. PORTA has 6 bits from PORTA0 toPORTA5. PORTB and PORTC

has 8-bits each. Some pins of theses I/O ports are multiplexed with an alternate function of

peripheral features on the device. In general when a peripheral is enabled, that pin may not be

used as a general I/O pin. Now let’s looks deeper about how a port can be configured as input

or output. Here it is enabled only the two I/O ports, PORT A and PORT B. PORTA is

configured as an analog port while the PORTB is configured as a digital port, to interface with

the LCD module.

11.1.1 PORT A

PORTA is a 6-bit wide, bidirectional port. The corresponding data direction register is

TRISA Setting a TRISA bit (= 1) will make the corresponding PORTA pin an input (i.e., put

the corresponding output driver in a High-Impedance mode). Clearing a TRISA bit (= 0) will

make the corresponding PORTA pin an output (i.e. put the contents of the output latch on the

selected pin). Reading the PORTA register reads the status of the pins, whereas writing to it

will write to the port latch. All write operations are read-modify-write operations. Therefore, a

write to a port implies that the port pins are read, the value is modified and then written to the

port data latch. Pin RA4 is multiplexed with the Timer0 module clock input to become the

RA4/T0CKI pin. The RA4/T0CKI pin is a Schmitt Trigger input and an open-drain output. All

other PORTA pins have TTL input levels and full CMOS output drivers. Other PORTA pins

are multiplexed with analog inputs and the analog V REF input for both the A/D converters

and the comparators. The operation of each pin is selected by clearing/setting the appropriate

control bits in the ADCON1 and/or CMCON registers.

On a Power-on Reset, these pins are configured as analog inputs and read as ‘0’. The

comparators are in the off (digital) state.

The TRISA register controls the direction of the port pins even when they are being

used as analog inputs. The user must ensure the bits in the TRISA register are maintained set

when using them as analog inputs.

Initialization of PORTA



BLOCK DIAGRAM OF RA3:RA0

7.2.2 PORT B

PORTB is an 8-bit wide, bidirectional port. The corresponding data direction

register is TRISB. Setting a TRISB bit (= 1) will make the corresponding PORTB pin

an input (i.e., put the corresponding output driver in a High-Impedance mode). Clearing

a TRISB bit (= 0) will make the corresponding PORTB pin an output (i.e., put the

contents of the output latch on the selected pin). Three pins of PORTB are multiplexed

with the In-Circuit Debugger and Low-Voltage Programming function: RB3/PGM,

RB6/PGC and RB7/PGD.

figure. 6 Internal block diagram of the analog Pins RA0 to RA3



C H A P T E R 1 2

L A B V I E W

1 2 . 1 INTRODUCTION

LabVIEW (short for Laboratory Virtual Instrumentation Engineering Workbench)

is a platform and development environment for a visual programming language from

National Instruments. The graphical language is named "G". Originally released for the

Apple Macintosh in 1986, LabVIEW is commonly used for data acquisition, instrument

control, and industrial automation on a variety of platforms including Microsoft Windows,

various flavors of UNIX, Linux, and Mac OS X. The latest version of LabVIEW is version

LabVIEW 2013. Visit National Instruments at www.ni.com.

The code files have the extension “.vi”, which is an abbreviation for “Virtual Instrument”.

LabVIEW offers lots of additional Add-Ons and Toolkits.

12.2 DATAFLOW PROGRAMMING

The programming language used in LabVIEW, also referred to as G, is a dataflow

programming language. Execution is determined by the structure of a graphical block

diagram (the LV-source code) on which the programmer connects different function-nodes

by drawing wires. These wires propagate variables and any node can execute as soon as all

its input data become available. Since this might be the case for multiple nodes

simultaneously, G is inherently capable of parallel execution. Multi-processing and multi-

threading hardware is automatically exploited by the built-in scheduler, which multiplexes

multiple OS threads over the nodes ready for execution.

12.3 GRAPHICAL PROGRAMMING

LabVIEW ties the creation of user interfaces (called front panels) into the development

cycle. LabVIEW programs/subroutines are called virtual instruments (VIs). Each VI has

three components: a block diagram, a front panel, and a connector panel. The last is used to

represent the VI in the block diagrams of other, calling VIs. Controls and indicators on the

front panel allow an operator to input data into or extract data from a running virtual

instrument. However, the front panel can also serve as a programmatic interface. Thus a

virtual instrument can either be run as a program, with the front panel serving as a user

interface, or, when dropped as a node onto the block diagram, the front panel defines the

inputs and outputs for the given node through the connector pane. This implies each VI can

be easily tested before being embedded as a subroutine into a larger program.

The graphical approach also allows non-programmers to build programs simply by

dragging and dropping virtual representations of lab equipment with which they are already

familiar. The LabVIEW programming environment, with the included examples and the

documentation, makes it simple to create small applications. This is a benefit on one side, but

http://www.ni.com/



there is also a certain danger of underestimating the expertise needed for good quality "G"

programming. For complex algorithms or large-scale code, it is important that the

programmer possess an extensive knowledge of the special LabVIEW syntax and the

topology of its memory management. The most advanced LabVIEW development systems

offer the possibility of building stand-alone applications. Furthermore, it is possible to create

distributed applications, which communicate by a client/server scheme, and are therefore

easier to implement due to the inherently parallel nature of G-code.

12.4 BENEFITS

One benefit of LabVIEW over other development environments is the extensive

support for accessing instrumentation hardware. Drivers and abstraction layers for many

different types of instruments and buses are included or are available for inclusion. These

present themselves as graphical nodes. The abstraction layers offer standard software

interfaces to communicate with hardware devices. The provided driver interfaces save

program development time. The sales pitch of National Instruments is, therefore, that even

people with limited coding experience can write programs and deploy test solutions in a

reduced time frame when compared to more conventional or competing systems. A new

hardware driver topology (DAQmxBase), which consists mainly of G-coded components

with only a few register calls through NI Measurement Hardware DDK (Driver Development

Kit) functions, provides platform independent hardware access to numerous data acquisition

and instrumentation devices. The DAQmxBase driver is available for LabVIEW on

Windows, Mac OS X and Linux platforms.

This document introducing the following themes:

Start using LabVIEW

o The LabVIEW Environment

o Front Panel and Block Diagram

o Palettes: Control Palette, Functions Palette, Tools Palette

o Data Types

o Property Nodes

Sub VIs

Loops and Structures

Troubleshooting and Debugging

Working with Data

o Arrays

Array

Functions

o Cluster

Working with Strings



Error Handling

Working with Projects using Project Explorer

Design Techniques

o Shift Register

o State Machine

o Multiple Loops

User Interface

Plotting Data

Deployment: Building Executable Applications (.exe)

Introduction to Add Ons and Toolkits

o Briefly explanations…

o More detail about Control and Simulation Toolkit in later chapter

Introduction to DAQ - Data Acquisition

o MAX – Measurement and Automation Explorer

o NI-DAQmx

Quick Reference with Keyboard Short-cuts

12.5 THE LABVIEW ENVIRONMENT

LabVIEW programs are called Virtual Instruments, or VIs, because their appearance

and operation imitate physical instruments, such as oscilloscopes and multimeters. LabVIEW

contains a comprehensive set of tools for acquiring analyzing, displaying, and storing data,

as well as tools to help you troubleshoot your code.

When opening LabVIEW, you first come to the “Getting Started” window.

Figure 7



In order to create a new VI, select “Blank VI” or in order to create a new LabVIEW project,

select“Empty project” When you open a blank VI, an untitled front panel window appears. This

window displays the front panel and is one of the two LabVIEW windows you use to build a

VI. The other window contains the block diagram. The sections below describe the front panel

and the block diagram.

12.6 FRONT PANEL

When you have created a new VI or selected an existing VI, the Front Panel and the

Block Diagram for that specific VI will appear.

Figure 8

In LabVIEW, you build a user interface, or front panel, with controls and indicators.

Controls are knobs, push buttons, dials, and other input devices. Indicators are graphs,

LEDs, and other displays.

You build the front panel with controls and indicators, which are the interactive input

and output terminals of the VI, respectively. Controls are knobs, push buttons, dials, and

other input devices. Indicators are graphs, LEDs, and other displays. Controls simulate

instrument input devices and supply data to the block diagram of the VI. Indicators simulate

instrument output devices and display data the block diagram acquires or generates.



12.7 BLOCK DIAGRAM

After you build the user interface, you add code using VIs and structures to control

the front panel objects. The block diagram contains this code. In some ways, the block

diagram resembles a flowchart.

Figure 9

After you build the front panel, you add code using graphical representations of functions to

control the front panel objects. The block diagram contains this graphical source code. Front

panel objects appear as terminals, on the block diagram. Block diagram objects include

terminals, subVIs, functions, constants, structures, and wires, which transfer data among

other block diagram objects.



CHAPTER 13

TRANSFORMER

A transformer is a device that transfers electrical energy from one circuit to another

through inductively coupled conductors — the transformer's coils or "windings". Except for

air-core transformers, the conductors are commonly wound around a single iron-rich core, or

around separate but magnetically-coupled cores. A varying current in the first or "primary"

winding creates a varying magnetic field in the core of the transformer. This varying magnetic

field induces a varying electromotive force (EMF) or "voltage" in the "secondary" winding.

This effect is called mutual induction.

If a load is connected to the secondary, an electric current will flow in the secondary winding

and electrical energy will flow from the primary circuit through the transformer to the load. In

an ideal transformer, the induced voltage in the secondary winding is in proportion to the

primary voltage and is given by the ratio of the number of turns in the secondary to the number

of turns in the primary as follows:

By appropriate selection of the ratio of turns, a transformer thus allows an alternating

current (AC) voltage to be "stepped up" by making NS greater than NP, or "stepped down" by

making NS less than NP.

Transformers come in a range of sizes from a thumbnail-sized coupling transformer hidden

inside a stage microphone to huge units weighing hundreds of tons used to interconnect

portions of national power grids. All operate with the same basic principles, although the range

of designs is wide. While new technologies have eliminated the need for transformers in some

electronic circuits, transformers are still found in nearly all electronic devices designed for

household ("mains") voltage. Transformers are essential for high voltage power transmission,

which makes long distance transmission economically practical.

13.1 BASIC PRINCIPLES

The transformer is based on two principles: firstly, that an electric current can produce

a magnetic field (electromagnetism) and secondly that a changing magnetic field within a coil

of wire induces a voltage across the ends of the coil (electromagnetic induction). Changing the

current in the primary coil changes the magnitude of the applied magnetic field. The changing

magnetic flux extends to the secondary coil where a voltage is induced across its ends.

A simplified transformer design is shown in figure 10. A current passing through the

primary coil creates a magnetic field. The primary and secondary coils are wrapped around a

core of very high magnetic permeability, such as iron; this ensures that most of the magnetic

field lines produced by the primary current are within the iron and pass through the secondary

coil as well as the primary coil.



Figure:10 An ideal step-down transformer showing magnetic flux in the core.

Induction Law

The voltage induced across the secondary coil may be calculated from Faraday's law of

induction, which states that:

where VS is the instantaneous voltage, NS is the number of turns in the secondary coil and Φ

equals the magnetic flux through one turn of the coil. If the turns of the coil are oriented

perpendicular to the magnetic field lines, the flux is the product of the magnetic field strength

B and the area A through which it cuts. The area is constant, being equal to the cross-sectional

area of the transformer core, whereas the magnetic field varies with time according to the

excitation of the primary. Since the same magnetic flux passes through both the primary and

secondary coils in an ideal transformer, the instantaneous voltage across the primary winding

equals

Taking the ratio of the two equations for VS and VP gives the basic equation for stepping up or

stepping down the voltage

http://en.wikipedia.org/wiki/File:Transformer3d_col3.svg



13.2 IDEAL POWER EQUATION

Figure11: The ideal transformer as a circuit element

If the secondary coil is attached to a load that allows current to flow, electrical power

is transmitted from the primary circuit to the secondary circuit. Ideally, the transformer is

perfectly efficient; all the incoming energy is transformed from the primary circuit to the

magnetic field and into the secondary circuit. If this condition is met, the incoming electric

power must equal the outgoing power.

Pincoming = IPVP = Outgoing = ISVS

Giving the ideal transformer equation

If the voltage is increased (stepped up) (VS > VP), then the current is decreased (stepped

down) (IS < IP) by the same factor. Transformers are efficient so this formula is a reasonable

approximation.

The impedance in one circuit is transformed by the square of the turns ratio. For

example, if an impedance ZS is attached across the terminals of the secondary coil, it appears

to the primary circuit to have an impedance of . This relationship is reciprocal, so

that the impedance ZP of the primary circuit appears to the secondary to be .

http://en.wikipedia.org/wiki/File:Transformer_under_load.svg



13.3 DETAILED OPERATION

The simplified description above neglects several practical factors, in particular the

primary current required to establish a magnetic field in the core, and the contribution to the

field due to current in the secondary circuit.

Models of an ideal transformer typically assume a core of negligible reluctance with

two windings of zero resistance.When a voltage is applied to the primary winding, a small

current flows, driving flux around the magnetic circuit of the core. The current required to

create the flux is termed the magnetizing current; since the ideal core has been assumed to have

near-zero reluctance, the magnetizing current is negligible, although still required to create the

magnetic field.

The changing magnetic field induces an electromotive force (EMF) across each

winding. Since the ideal windings have no impedance, they have no associated voltage drop,

and so the voltages VP and VS measured at the terminals of the transformer, are equal to the

corresponding EMFs. The primary EMF, acting as it does in opposition to the primary voltage,

is sometimes termed the "back EMF". This is due to Lenz's law which states that the induction

of EMF would always be such that it will oppose development of any such change in magnetic

field.



CHAPTER 14

PROGRAM CODE

#include "E:\scada_substatn\main.h"

#include <lcd.c>

#include <stdlib.h>

#use rs232(baud=9600,xmit=pin_c6,rcv=pin_c7)

float volt=0,amp=0;

float ad_out1=0,ad_out2=0;float freq=0,temp=0;

float i=1.5;

float var=49.0;

void low_volt();

void high_volt();

void norm_volt();

void main()

{

set_tris_d(0x00);

set_tris_b(0x00);

set_tris_c(0x00);

setup_adc(adc_clock_internal);

setup_adc_ports(all_analog);

lcd_init();

output_b(0);

output_c(0);

output_d(0);

setup_timer_0(rtcc_ext_l_to_h);

while(1)

{

set_timer0(0);



freq=0;

delay_ms(1100);

freq=get_timer0();

set_adc_channel(0);

delay_us(50);

ad_out1=read_adc();

set_adc_channel(1);

delay_us(50);

ad_out2=read_adc();

set_adc_channel(2);

delay_us(50);

temp=read_adc();

temp=(temp*500)/1023;

volt=ad_out1/220;

amp=ad_out2/27.6;

lcd_putc('\f');

lcd_gotoxy(1,1);

printf(lcd_putc,"Volt:%2.2f",80*volt);

lcd_gotoxy(1,2);

printf(lcd_putc,"Current:%2.1f A",amp);

delay_ms(2000);

freq=48.2+(freq/48.6);

lcd_putc('\f');

lcd_gotoxy(1,1);

printf(lcd_putc,"Frequncy:%2.1f",freq);

lcd_gotoxy(1,2);

printf(lcd_putc,"Temp:%2.1f",temp);

printf("%2.1f%1.2f%1.1f%2.1f",temp,volt,amp,freq);

if(temp>=38.0)



{

output_high(pin_c0);

}

if(temp<38.0)

{

output_low(pin_c0);

}

if(volt<=2.7){

high_volt();

}

if((volt>2.7 )&&(volt <=3.5))

{

norm_volt();

}

if(volt>3.5){

low_volt();

}

if(amp>4)

{

output_high(pin_b3);

delay_ms(1000);

output_low(pin_c1);

output_low(pin_c2);

delay_ms(100);

}

if(amp<=4.0)

{

output_low(pin_b3);





delay_ms(300);

}

}

}

void low_volt()

{

output_b(0x05);

delay_ms(400);

}

void norm_volt()

{

output_b(0x00);

delay_ms(400);

}

void high_volt()

{

output_b(0x03);

delay_ms(400);

}



CHAPTER 15

PCB LAYOUT

PCB 3-D LAYOUT



CHAPTER 16

PCB DESIGN

16.1 PCB PREPARATION TECHNIQUE:

You need to generate a positive (copper black) UV translucent artwork film. You will

never get a good board without good artwork, so it is important to get the best possible quality

at this stage. The most important thing is to get a clear sharp image with a very solid opaque

black. Nowadays, artwork is drawn using either a dedicated PCB CAD program or a suitable

drawing/graphics package. It is absolutely essential that your PCB software prints holes in the

middle of pads, which will act as center marks when drilling. It is virtually impossible to

accurately hand-drill boards without these holes. When defining pad and line shapes, the

minimum size recommended for via (through linking holes) for reliable results is 50 mil,

assuming 0.8mm drill size;1 mil (1/1000)th of an inch. You can go smaller with smaller drill

sizes, but through linking will be harder. 65mil round or square pads for normal components

and DIL ICs, with 0.8mm hole, will allow a 12.5 mil, down to 10 mil if you really need to.

Centre-to-Centre Spacing of 12.5 mil tracks should be 25 mil — slightly less may be possible

if your printer can manage it. Take care to preserve the correct diagonal track-track spacing on

mitered corners; grid is 25 mil and track width 12.5 mil. The artwork must be printed such that

the printed side is in contact with the PCB surface when exposing, to avoid blurred edges. In

practice, this means that if you design the board as seen from the component side, the bottom

(solder side) layer should be printed the ‘correct’ way round, arid the top side of a double-

sided board must be printed mirrored.

16.2. MEDIA:

Artwork quality is very dependent on both the output device and the media used. It is not

necessary to use a transparent artwork medium — as long as it is reasonably translucent to UV,

its fine-less translucent materials may need a slightly longer exposure time. Line definition,

black opaqueness and toner/ink retention are much more important. Tracing paper has good

enough UV translucency and is nearly as good as drafting film for toner retention. It stays

flatter under laser-printer heat than polyester or acetate film. Get the thickest you can find as

thinner stuff can crickle. It should be rated at least 90 gsm; 120 gsm is even better but harder

to find. It is cheap and easily available from office or art suppliers.

16.3. OUTPUT DEVIES:

Laser printers offer the all-round solution. These are afford able, fast, and good quality. The

printer used must have at least 600dpi resolution for all but the simplest PCBs, as you will

usually be working in multiples of 0.06cm (40 tracks per inch). 600 dpi divides into 40, so you

get consistent spacing and line width. It is very important that the printer produces a good solid

black with no toner pinholes. If you’re planning to buy a printer for PCB use, do some test

prints on tracing paper to check the quality first. If the printer has a density control, set it to the



blackest. Even the best laser printers don’t generally cover large areas well, but usually this

isn’t a prob1em as long as fine tracks are solid. When using tracing paper or drafting film,

always use manual paper feed and set the straightest possible paper output path to keep the

artwork as flat as possible and minimize jamming. For small PCBs, you can usually save paper

by cutting the sheet in half. You may need to specify a vertical offset in your PCB software to

make it print on the right part of the page. Some laser printers have poor dimensional accuracy,

which can cause problems for large PCBs. But as long as any error is linear, it can be

compensated by scaling the printout in software. Print accuracy is likely to be noticeable

problem when it causes misalignment of the sides on double sided PCBs-this can usually be

avoided by careful arrangement of the plots on the page to ensure the error is the same on both

layers; for example, choosing whether to mirror horizontally or vertically when reversing the

top-side artwork

16.4 EXPOSURE:

The photo resist board needs to be exposed to UV light through the artwork, using a UV

exposure box. UV exposure units can easily be made using standard fluorescent lamp ballasts

and UV tubes. For small PCBs, two or four 8-watt, 30.5cm tubes will be adequate. For larger

(A3) units 38cm tubes are ideal. To determine the tube-to-glass spacing, place a sheet of tracing

paper on the glass and adjust the distance to get the most even light level over the surface of

the paper. Even illumination is a lot easier to obtain with 4-tube units. The UV tubes you need

are sold as replacements for UV exposure units, ‘black light’ tubes for disco lighting, etc. These

look white, occasionally black/blue when off, and light up with a light purple. Do not use short-

wave UV lamps like EPROM eraser tubes and germicidal lamps that have clear glass, because

these emit short-wave UV which can cause eye and skin damage. A timer that switches off the

UV lamps automatically is essential, and should allow exposure times from 2 to 10 minutes in

15- to 30-second increments. It is useful if the timer has an audible indication when the timing

period has completed. Place the two sheets together with the toner sides facing, and carefully

line them up, checking all over the board area for correct alignment, using the holes in the pads

as a guide. A light box is very handy here, but exposure can also be done with daylight by

holding the sheets on the surface of a window. If printing errors have caused slight mis-

registration, align the sheets to average the errors across the whole PCB, to avoid breaking pad

edges or tracks when drilling. When these are correctly aligned, staple the sheets together on

two opposite sides, about 10 mm from the edge of the board, forming a Sleeve or envelope.

The gap between the board edge and staples is important to stop the paper distorting at the

edge. Use the smallest stapler you can find, so that the thickness of the staple is not much more

than that of the PCB. Expose each side, covering up the top side with a reasonably light-proof

soft Cover when exposing the underside. Be very careful when turning the board Over, to avoid

the laminate slipping inside the artwork and ruining the alignment .After exposure, you can

usually see a faint image of the pattern in the Photosensitive layer. much essential for surface

mount boards. Unless you have access to a roller tinning machine, chemical tinning is the only

option.



16.5. DRILLING:

If you have fiberglass (FR4) board, you must use tungsten carbide drill bits. Fiberglass eats

normal high-speed steel (HSS) bits very rapidly, although HSS drills are all right for odd larger

sizes (>2mm). Carbide drill bits are expensive and the thin ones snap very easily. When using

carbide drill bits below 1 mm, you must use a good vertical drill stand —you will break drill

very quickly without one. Carbide drill bits are available as straight-shank or thick (sometimes

called ‘turbo’) shank. In straight shank, the whole bit is the diameter of the hole, and in thick

shank, a standard-size (typically about 3.5 mm) shank tapers down to the hole size. The

straight- shank drills are usually preferred because they break less easily and are usually

cheaper. The longer thin section provides more flexibility. Small drills for PCB use usually

come with either a set of collets of various sizes or a 3-jaw chuck. Sometimes the 3-jaw chuck

is an optional extra and is worth getting for the time it saves on changing collets. For accuracy,

however, 3-jaw chucks aren’t brilliant, and snl.aii drill sizes below 1 mm quickly form grooves

in the jaws, preventing good grip. Below 1 mm, you should use collets, and buy a few extra of

the smallest ones; keeping one collet per drill size, as using a drill in a collet will open it out

and it no longer grips smaller drills well. You need a good strong light on the board when

drilling, to ensure accuracy. A dichroic halogen lamp, under-run at 9V to reduce brightness,

can be mounted on a microphone gooseneck for easy positioning. It can be useful to raise the

working surface about 15cm above the normal desk height for more comfortable viewing. Dust

extraction is nice, but not essential—an occasional blew does the trick! A foot-pedal control to

switch the drill ‘off’ and ‘on’ is very convenient, especially when frequently changing bits.

Avoid hole sizes less than 0.8 mm unless you really need them. When making two identical

boards, drill them both together to save time. To do this, carefully drill a 0.8mm hole in the pad

near each corner of each of the two boards, getting the center as accurate as possible. For larger

boards, drill a hole near the center of each side as well. Lay the boards on top of each other and

insert a 0.8mm track pin in two opposite corners, using the pins as pegs to line the PCBs up.

Squeeze or hammer the pins into the boards, and then into the remaining holes. The two PCBs

are now ‘nailed’ together accurately and can be drilled together

.



16.6. CUTTING:

A small guillotine is the easiest way to cut fiberglass laminate. Ordinary saws (band

saws, jigsaws, and hacksaws) will be blunted quickly unless these are carbide-tipped, and the

dust can cause sink irritation. A carbide tile-saw blade in a jigsaw might be worth a try. It’s

also easy to accident ally scratch through the protective film when sawing, causing photo resist

scratches and broken tracks on the finished board. A sheet-metal guillotine is also excellent for

cutting boards, provided the blade is fairly sharp. To make cut-outs, drill a series of small holes,

punch out the blank, and file to size. Alternatively, use a fretsaw or small hacksaw, but be

prepared to replace blades often. With practice it’s possible to do corner cutouts with a

guillotine but you have to be very careful that you don’t over-cut!

16.7. SOLDERING:

Soldering is the joining together of two metals to give physical bonding and good

electrical Conductivity. It is used primarily in electrical and electronic circuitry. Solder is a

combination of metals, which are solid at normal room temperatures and become liquid at

between 180 and 200°C. Solder bonds well to various metals, and extremely well to copper.

Soldering is a necessary skill you need to learn to successfully build electronics circuits. It is

the primary way how electronics components are connected to circuit boards, wires and

sometimes directly to other components. To solder you need a soldering iron. A modem basic

electrical soldering iron consists of a heating element, a soldering bit (often called the tip), a

handle and a power cord. The heating element can be either a resistance wire wound around a

ceramic tube, or a thick film resistance element printed onto a ceramic base. The element is

then insulated and placed into a metal tube for strength and protection. This is then thermally

insulated from the handle. The heating element of soldering iron usually reaches temperatures

of around 370 to 400°C (higher than needed to melt the solder). The soldering bit is a specially

shaped piece of copper plated with iron and then usually plated with chrome or iron. The tip

planting makes it very resistant to aggressive solders and fluxes.

The strength or power of a soldering iron is usually expressed in Watts. Irons generally used in

electronics are typically in the range 12 to 25 Watts. Higher powered iron will not run hotter,

but it will have more power available to quickly replace heat drained from the iron during

soldering. Most irons are available in a variety of voltages; 12V, 24V, 115V and 230V are the

most popular. Today most laboratories and repair shops use soldering irons, which operate at

24V (powered by isolation transformer supplied with the soldering iron or by a separate low

voltage outlet). You should always use this low voltage where possible as it is much safer. For

advanced soldering work (like very tiny very sensitive electronic components), you will need

a soldering iron with temperature control. In this type of soldering irons the temperature may

be usually set between 200⁰C and 450⁰C. Many temperature-controlled soldering irons

designed for electronics have a power rating of around 40 to 50 watt. They will heat fast and

give enough power for operation, but are mechanically small (because the temperature

controller stops them from overheating when they are not used).



You will occasionally see gas-powered soldering irons which use butane rather than the mains

electrical supply to operate. They have a catalytic element which once warmed up continues to

glow hot when gas passes over them. Gas-powered soldering irons are designed for occasional

“on the spot” use for quick repairs, rather than for main stream construction or assembly

work.You need to be careful in soldering because most electronic components are fragile, and

heat sensitive. Usually our biggest concern is heat. Low enough soldering temperature and

short enough soldering time keeps components in good shape. Electronic components are

designed so that they can take high temperatures on their contacts/ wires for some time without

damage (to withstand the soldering). Prolonged exposure to high temperature will heat up

when inside of the component can cause damage to it. Currently, the best commonly available,

workable, and safe solder alloy is 63/ 37. That is, 63% lead, 37% tin. It is also known as eutectic

solder. Its most desirable characteristics is that its solids (“pasty”) state, and its liquid state

occur at the same temperature — 361⁰F. The combination of 63% lead and 37% tin melts at

the lowest possible temperature. Nowadays there is a tendency to move to use lead free solders,

but it will takes years until they will catch on normal soldering work. Lead free solders are

nowadays available, but they are generally more expensive and/or harder to work on than

traditional solders that have lead in them.There are certain safety measures which you should

keep in mind when soldering. The tin material used in soldering contains dangerous substances

like lead (40-60% of typical soldering tins are lead and lead is poisonous). Also the various

from the soldering flux can be dangerous. While it is true that lead does not vaporize at the

temperatures at which soldering is typically done, particulate matter is dangerous as fumes

would be in terms of poisoning and there is particulate lead present to some extend in the fumes

from your flux When soldering keep the room well ventilated and use a small fan or fume trap.

A proper fume trap or a fan will keep the most pollution away from your face. Professional

electronics workshops use expensive fume extraction systems to protect their workers (needed

for working safety reasons). Those fume extraction devices have a special filter, which filters

out the dangerous fumes. If you can connect a duct to the output from the trap to the outside,

that would be great. Always wash hands prior to smoking, eating, drinking or going to the

bathroom. When you handle soldering tin, your hands will pick up lead, which needs to be

washed out from it before it gets to your body. Do not eat or drink or smoke whilst working

with soldering iron. Do not place cups, glasses or a plate of food near your working area. Wash

also the table sometimes. As you solder, at times there will be bit of spitting and Sputtering. If

you look you will see tiny balls of solder that shoot out and can be found on your soldering

table. The soldering iron will last longer with proper care before and during use wipe the bit

on a damp sponge. Most bench stands incorporate a sponge for this purpose. When using a

new bit apply solder to it as it heats up. Always keep a hot iron in bench stand, or suspended

by the hook, when not in use. Turn of the iron when you do not use it. Periodically remove the

bit and clear away any oxide build up. Regularly check the mains lead for burns or other

damage (change mains lead if necessary).



CHAPTER 17

SOLDERING

All components are first tested. The leads of all components are

cleared by rubbing with an abrasive. The PCB is also cleaned by scratching off the varnish

layer at the selected point. The lead of the component to be soldered is applied with some flux

to remove any remaining oxide coating. Soldering is a process in which two or more metal

items are joined together by melting and flowing a filler metal (solder) into the joint, the filler

metal having a lower melting point than the work piece. Soldering differs from welding in that

soldering does not involve melting the work pieces.

There are three forms of soldering, each requiring progressively higher temperatures and

producing an increasingly stronger joint strength:

1. Soft soldering, which originally used a tin-lead alloy as the filler metal,

2. silver soldering, which uses an alloy containing silver,

3. Brazing which uses a brass alloy for the filler.

The alloy of the filler metal for each type of soldering can be adjusted to modify the melting

temperature of the filler. Soldering appears to be a hot glue process, but it differs from gluing

significantly in that the filler metals alloy with the work piece at the junction to form a gas and

liquid tight bond. Soft soldering is characterized by having a melting point of the filler metal

below approximately 400 0 C (752 0F), whereas silver soldering and brazing use higher

temperatures, typically requiring a flame or carbon arc torch to achieve the melting of the filler.

Soft solder filler metals are typically alloys that have liquids temperatures below 350 0C.

In this soldering process, heat is applied to the parts to be joined, causing the solder to melt and

to bond to the work pieces in an alloying process called wetting. In stranded wire, the solder is

drawn up into the wire by capillary action in a process called 'wicking'. Capillary action also

takes place when the work pieces are very close together or touching. The joint strength is

dependent on the filler metal used. Soldering produces electrically-conductive, water- and gas-

tight joints. There is evidence that soldering was employed up to 5000 years ago in

Mesopotamia.



CHAPTER 18

BILL OF MATERIALS

Table 18.1 : Bill Of Materials

COMPONENTS QTY PRICE

PIC16877A

ZIGBEE MODULE

SEVEN SEGMENT DISPLAY

ADAPTER

TRANSFORMER

RELAY

LED

ASSEMBLE BOARD

PCB BOARD

RESISTORS

CRYSTAL

TOTAL

1

2

1

1

2

5

2

2

1

2

1

600

3000

20

200

500

200

10

200

300

2

35

5067



CHAPTER 19

CONCLUSION

This paper deals with the implementation of µC based tap changer control practically,

using special purpose digital hardware as a built-in semiconductor chip or software

simulation in conventional computers. Two strategies are suggested for its implementation

as a software module in the paper. One is to integrate it with the supervisory system in a

substation control room operating in a LAN environment. In this configuration, the parallel

transformers can be controlled locally. The other is to integrate it into the SCADA

(Supervisory Control and Data Acquisition) system, which allows the transformers to be

monitored and controlled remotely over a wide area of power-network. The implementation

of µC based tap changer control needs interfacing between the power system and the control

circuitry. µC s may need to interact with people for the purpose of configuration, alarm

reporting or everyday control.