This Thesis is submitted in Partial Fulfillment for the Requirement of the Degree of Bachelor of Science in

Electrical & Electronic EngineeringCourse Code: EEE-499

Instant Power Supply ( IPS) System with Load Priority

Prepared By:1. Full Name : Susanta Kumar Paul ID # 103-092-511

2. Full Name : A.S.M. Fokrul Hasan ID # 103-032-511

3. Full Name : Md. Abdus Salam ID # 103-050-511

4. Full Name : Mohammad Nazir Hasan ID # 093-005-511

5. Full Name : Sunirmol Biswas ID # 103-115-511

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Instant Power Supply ( IPS) System with Load Priority

A thesis report submitted to the department of EEE, Atish Dipankar Biggayan O Projokti

Bishawbiddaloy for partial fulfillment of the Degree of B.Sc in Electrical and Electronic

Engineering.

Submitted By:

1. Full Name : Susanta Kumar Paul ID # 103-092-511

2. Full Name : A.S.M. Fokrul Hasan ID # 103-032-511

3. Full Name : Md. Abdus Salam ID # 103-050-511

4. Full Name : Mohammad Nazir Hasan ID # 093-005-511

5. Full Name : Sunirmol Biswas ID # 103-115-511

Supervised By: Signature:

Marzia Hoque Date:

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It is here by declared that no part of this thesis bearers the copyright violation and no plagiarism opted during the course of material preparation. The entire works has been planned and carried out under the thesis supervisor of the honorable faculty member Marzia Hoque department of Electrical and Electronic Engineering, Atish Dipankar Biggayan O Projokti Bishawbiddaloy, Dhaka, Bangladesh.

The content of this thesis is submitted by the group

1. Full Name : Susanta Kumar Paul ID # 103-092-511

2. Full Name : A.S.M. Fokrul Hasan ID # 103-032-511

3. Full Name : Md. Abdus Salam ID # 103-050-511

4. Full Name : Mohammad Nazir Hasan ID # 093-005-511

5. Full Name : Sunirmol Biswas ID # 103-115-511

Only for the fulfillment of the course of “Instant Power Supply (IPS) System With

Load Priority ” . And no part of this is used anywhere for the achievement of any

academic

Degree or Certificate .

Full Name : Susanta Kumar Paul Full Name: A.S.M. Fokrul HasanID NO # 103-092-511 ID NO # 103-032-511 Department of EEE Department of EEE

Full Name :Md. Abdus Salam Full Name : Mohammad Nazir Hasan ID NO # 103-050-511 ID NO # 093-005-511Department of EEE Department of EEE

Full Name : Sunirmol Biswas

ID NO # 103-115-511Department of EEE

Certificate

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This is to certify that the B.Sc. thesis entitled Instant Power Supply (IPS) System With Load Priority. submitted by this group

1. Full Name : Susanta Kumar Paul ID # 103-092-511

2. Full Name : A.S.M. Fokrul Hasan ID # 103-032-511

3. Full Name : Md. Abdus Salam ID # 103-050-511

4. Full Name : Mohammad Nazir Hasan ID # 093-005-511

5. Full Name : Sunirmol Biswas ID # 103-115-511

The thesis represents an independent and original work on the part of the candidates.

The research work has not been previously formed the basis for the award of any Degree,

Diploma, Fellowship or any other discipline.

The whole work of this thesis has been planned and carried out by this group under

the supervision and guidance of the faculty members of Atish Dipankar Biggayan O

Projokti Bishawbiddaloy, Bangladesh.

Name of the Supervisor

Marzia Hoque

Department of Electrical and Electronic Engineering

Atish Dipankar Biggayan O Projokti Bishawbiddaloy

12.11.2013

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Faculty of Engineering

Department of EEE

Atish Dipankar Biggayan O Projokti Bishawbiddaloy

Dhaka, Bangladesh.

Subject: Letter of transmittal .

Dear Sir,

With due respect, we should like to inform you that is a great pleasure for us to submit the final

project on “Instant Power Supply (IPS) System With Load Priority” for Department of

Electrical and Electronic Engineering as requirement bachelor degree/ program. This project

provided us with a practical exposure to the overall working environment and very good

experience which is prevailing in to professional life. We came to know about many things

regarding the current world on the concept of Electronic Development. We have tried to our best

to put through effort for the preparation of this report. Any short coming or fault may arise as our

unintentional mistake we will whole heartily welcome for any clarification and suggestion about

any view and conception disseminated through this project.

We hope and strongly believe that this project will meet the requirement as well as satisfying your

purpose. We will available for any further classification in this regard.

Sincerely Yours,

1. Full Name : Susanta Kumar Paul ID # 103-092-511

2. Full Name : A.S.M. Fokrul Hasan ID # 103-032-511

3. Full Name : Md. Abdus Salam ID # 103-050-511

4. Full Name : Mohammad Nazir Hasan ID # 093-005-511

5. Full Name : Sunirmol Biswas ID # 103-115-511

Atish Dipankar Biggayan O Projokti Bishawbiddaloy

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Department of Electrical and Electronic Engineering

APPORAVAL SHEET

This project Title is “Instant Power Supply System with Load Priority” has been

submitted to the following respected members of the Board of Examiners of the

Department of Electrical and Electronic Engineering in partial fulfillment of the

requirements of the degree of Bachelor of Department of Electrical and Electronic

Engineering by the following students.

1. Full Name : Susanta Kumar Paul ID # 103-092-511

2. Full Name : A.S.M. Fokrul Hasan ID # 103-032-511

3. Full Name : Md. Abdus Salam ID # 103-050-511

4. Full Name : Mohammad Nazir Hasan ID # 093-005-511

5. Full Name : Sunirmol Biswas ID # 103-115-511

As the supervisor I have approved this paper for submission.

Mazia Hoque Md. Imam Hossain Project Supervisor & Lecturer Senior Lecturer & CoordinatorDepartment of EEE Department Of EEE Atish Dipankar Biggayan O Atish Dipankar Biggayan O Projokti Bishawbiddaloy Projokti Bishawbiddaloy

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ACKNOWLEDGEMENT

At first we would like to thank our Supervisor Marzia Hoque (Lecturer, ADBOPB)

for giving us the opportunity to work to under his supervision, the endless hours of help,

Suggestions, Advice and Support to keep us on track during the development of this thesis.

We also want to express gratitude to Mr. Md. Imam Hossain for his support during our

work on this thesis.

Last, but not the least, we would like to thank our parents and family for making it possible

for us to study and for their constant help and support.

12 November 2013 The Authors

Dhaka

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ABSTRACT

Instant power supply system with load priority (IPS) can be used in the period of the load shedding. In this work such device is developed while connecting the load of the IPS right after the load shedding system after face load function. Moreover few loads might be important than others. That’s why priority based power supply is implemented in this thesis work using electromechanical switches or relays or electronic components such as Transistor, Rectifier, MOSFET, Resistor etc. We also used a power transformer and a control transformer.

In each chapter deals with a specific aspect and explaining the logic principles of its subject and the goes on to present the reader with a wide range of practical application circuit.

Although every care has been taken in preparing thesis.

TABLE OF CONTENTS

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Contents Page No

Cover Page 01 Initial Page 02 Declaration 03 Certificate 04 Transmittal 05 Approval Sheet 06 Acknowledgement 07 Abstract 08 Table of Contents 09 List of Table 11 List of Figure 11

CHAPTER 01: Introduction Page No

1.1 Introduction 131.2 Installed Capacity and Maximum Generation 13 1.3 Current Situation and Future Projection of Electricity

Demand, Generation and Load Shedding 14 1.4 Consumption of Electricity by Category 16

1.5 Causes of Electricity 161.5.1 High Gas Dependency 171.5.2 Lack of timely Implementation of Allocated Money 171.5.3 Political Reason 17

1.5.4 Over population 171.6 Solution 18

CHAPTER 02: Instant Power Supply

2.1 Introduction 20 2.2 Specification 20 2.3 Principle of Operation 21 2.4 Block Diagram of operation 22 2.5 List of the Component 23 2.6 Circuit Diagram of Oscillation 25 2.7 Load Priority 25 2.8 Result 26

CHAPTER 03 Components

3.1 Transformer 273.2 Basic principles 273.3 Induction law 283.4 The real transformer 30 3.5 Leakage flux 303.6 Equivalent circuit 313.7 Basic transformer parameters

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and construction 32

3.8 Energy losses 343.9 Transformer losses arise from 343.10 Core form and shell form transformers 353.11 Construction 363.12 Construction 383.13 Windings 393.14 Cooling 403.15 Insulation drying 423.16 Bushings 423.17 Classification parameters 423.18 Types 433.19 Oscillator Circuit 443.20 The Power Circuit 453.21 Rectifier 463.22 Types of Rectifiers 463.23 The Half – Wave Rectifier 463.24 The Full Wave Rectifiers 473.25 The full wave bridge rectifier 483.26 DC Power Supply 483.27 Battery 493.28 Batteries work 503.29 Electron Flow 503.30 Batteries 513.31 Titanium Batteries 513.32 Disposable Lithium Batteries 513.33 Rechargeable Batteries 523.34 Integrated Circuit 523.35 Transistor 533.36 Bipolar Junction Transistors 533.37 Transistors Work 543.38 Transistor Gain 553.39 Transistor work as an amplifier 563.40 The Transistor as an Amplifier 563.41 DC and AC quantities 563.42 Transistor amplification 57

CHAPTER 04: Discussions and Conclusions

4.1 Advantage 594.2 Disadvantage 594.3 Future Improvement 59 References 60

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LIST OF TABLE Table: 01 Installed Capacity and Maximum Generation 13

Table: 02 System Specification 20 Table: 03 List of components 23 to 24

Table: 04 Result 26

LIST OF FIGURE

Fig:1.1 Growth rate of Installed Capacity and Maximum Generation between 2000-01 and 2010-2011 14

Fig: 1.2 Current Situation and Future Projection of Electricity Demand, Generation and Load Shedding 15

Fig: 1.3 Growth rate of Demand, Generation and Load Shedding 15Fig: 1.4 Consumption of Electricity by Category (MKWH) and their

Corresponding Growth Rate from 2000-01 to 2007-08 16Fig:2.1 Block Diagram of IPS 22Fig: 2.2 PWM inverter circuit 25Fig: 3.1 Ideal transformer circuit diagram 27Fig: 3.2 Ideal transformer and induction law 29Fig: 3.3 Leakage flux of a transformer 30Fig: 3.4 Real transformer equivalent circuit 31Fig: 3.5 Power transformer over-excitation condition caused by

decreased frequency; flux (green), iron core’s magnetic characteristics (red) and magnetizing current (blue) 33

Fig: 3.6 Core form = core type; shell form = shell type 35Fig: 3.7 Laminated core transformer showing edge of

laminations at top of photo 36Fig: 3.8 Power transformer inrush current caused by residual flux at

switching instant; flux (green), iron core’s magnetic characteristics (red) and magnetizing current (blue) 37

Fig: 3.9 Laminating the core greatly reduces eddy-current losses 38Fig: 3.10 Windings are usually arranged concentrically to minimize

flux leakage. Main article: Windings 39Fig: 3.11 Cooling System 40Fig: 3.12 Transformer 43Fig: 3.13 PCB Layout of Oscillator Circuit 44Fig: 3.14 PCB layout of Power Circuit 45Fig: 3.15 Diode 46Fig: 3.16a Half wave rectifier Circuit 46Fig: 3.16b Half wave rectifier 47Fig: 3.17a Center – tapped full wave rectifier 47Fig: 3.17b. Output of full wave rectifier 48Fig:3.18 The full wave bridge rectifier. 48Fig: 3.19a DC Power Supply 49Fig: 3.19b Output voltage 50Fig: 3.20 Battery construction 50Fig: 3.21 integrated circuit (IC) 52Fig. 3.22 Construction of Transistor 53

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Fig. 3.23a Clickon Transistor 54Fig. 3.23b Terminals of a Transistor 54Fig. 3.24 Current Flow of a Transistor 55Fig. 3.25 Simple Transistor Circuit 55Fig. 3.26 Transistor Application 57Fig. 3.27 Wave diagram 58

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CHAPTER 01

Introduction

1.1 Introduction

IPS stands for “Instant Power Supply”. It is an electrical device that can provide electricity when the main supply is not available. IPS is the ideal solution for continuous power supply facilities during load shedding. A general IPS consists of a charger circuit, a battery, an oscillator circuit and an output circuit. The charger circuit charges the battery properly by using the main supply when it is ON. When the main supply is not available then the battery supplies the power. In Bangladesh we observed that there are far difference of installed capacity and maximum generation of electricity that we recite here. We also discus the consumption of electricity by category and how can we overcame this situation.

1.2 Installed capacity and the maximum generation

In Fiscal Year (FY) 2000-01, the total installed capacity was 4005 MW and the maximum generation was 3033 MW. Both the installed capacity and maximum generation have slightly increased over the time. The installed capacity as well as the maximum generation has increased with a decreasing rate as compared to the FY 2002-03 . The growth rate of the installed capacity was higher in the FY 2010-11 (11.38 percent) whereas, the growth rate of maximum generation was higher in the FY 2007-08 (11.08 percent).

Table 1: Installed Capacity and Maximum Generation [1]

The total installed capacity was 4005 MW in the FY 2000-01 which has

increased to 6685 MW in the FY 2010-11 (13 June, 2011)[1] with an annual increasing rate of 6.62 percent. However, the maximum generation was 3033 MW in FY 2000-01 which has increased to 4699 MW in the FY 2010-11 (13 June, 2011) with an annual increasing rate of 5.49 percent (Figure 1). The annual increasing rate of maximum generation (5.49 percent) is lower than that of the installed capacity (6.62 percent) between the FY 2000-01 and 2010-2011. This is resulted from the poorer productivities of older power plants. Beside this, due to the shortage of gas supply, some power plants are unable to utilize their generation capacity

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Fiscal YearBangladesh

Installed Capacity

(MW)

Growth Rate (%)

Maximum Generation (MW)

Growth Rate (%)

2000-01 4005 - 3033 -2001-02 4230 5.62 3218 6.102002-03 4710 11.35 3458 7.462003-04 4710 0 3622 4.742004-05 5025 6.69 3751 3.562005-06 5275 4.98 3812 1.632006-07 5262 -0.25 3718 -2.472007-08 5262 0 4130 11.082008-09 5803 10.28 4162 0.772009-10 5978 3.02 4606 10.672010-11 (13 June, 2011)

6658 11.38 4699 2.02

Fig:1.1 Growth rate of Installed Capacity and Maximum Generation between2000-01 and 2010-2011

1.3 Current Situation and Future Projection of Electricity Demand, Generation and Load Shedding

The real demand for electricity could not be met due to the shortage of available generation

capacity. A good number of generation units have become very old and have been operating at a much-

reduced capacity. As a result, their reliability and productivity are also poor. Beside this, due to the

shortage of gas supply, some power plants are unable to utilize their usual generation capacity. Therefore,

there is an increase in the load-shedding over the years. The average maximum demand for electricity was

3970 MW in 2007 which has increased to 4833 MW in 2011 (May, 2011) with an average increasing rate

of 216 MW per annum. Under the business as usual scenario, the average demand might stand at 5696

MW by 2015. On the other hand, the average generation was 3378 MW in 2007 which has increased to

4103 MW in 2011 (May, 2011) with an annual average increasing rate of 181 MW. Continuation of this

rate indicates that the average generation would be 4828 MW by 2015, which is far away from the vision

of 11500 MW generations by 2015. This increased demand over generation has resulted in increased load

shedding (Figure 2). Additionally, the average load shedding has increased to 656 MW in 2011 (May,

2011) with an average increasing rate of 35 MW per year starting from 2007. If this increasing rate

remains the same, the average load shedding might be stood at 795 MW by 2015 [1].

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Fig: 1.2 Current Situation and Future Projection of Electricity Demand, Generation and Load Shedding.

It is also observed that the demand for electricity has been increased with a rate of 5.43 percent per

year whereas, the generation of electricity has been increased with a rate of 5.37 percent per year between 2007 and 2011. The lower increasing rate of generation (5.37 percent) than that of the demand (5.43 percent) has accelerated the rate of load shedding which has been increased at a rate of 6.72 percent per annum during the same period. [1]

Fig: 1.3 Growth rate of Demand, Generation and Load Shedding

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1.4 Consumption of Electricity by Category

The consumption pattern of electricity varies according to different categories. The consumption of electricity at all categories has increased every year . Except in the year 2005-06, almost all the times after 2001-02, the consumption pattern of electricity at the domestic level increased with a decreasing rate. The same result is also found in the case of commercial services. However, except in the year 2005-06, in industrial services and other services, the consumption pattern has also been increasing with a decreasing rate from the year 2003-04. The consumption rate of electricity of all the service categories was highest in the year 2005-06 . The main reason for which the consumption pattern increased with a decreasing rate is the lower generation of electricity over the demand. Although, the consumption pattern of different sectors has increased over the years but it was lower than that the expected . The annual rate of increase between 2000-01 and 2007-08 was the highest at the commercial services which was 15.6 percent, followed by domestic services (13.8 percent), industrial services (13.3 percent) and other services (6.4 percent).

Fig: 1.4 Consumption of Electricity by Category (MKWH) and their Corresponding Growth Rate from 2000-01 to 2007-08

1.5 Causes of Electricity Crisis

Although the government has taken several initiatives for reducing the crisis of electricity, yet the crisis persists. This is mainly due to the problems associated with high gas dependency, improper privatization policy, lack of satisfactory and timely implementation of allocated money, political reasons and over population.

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1.5.1 High Gas Dependency

The most important reason at the moment is that the government is unable to ensure the supply of natural gas, the main primary fuel which is used to produce electricity. The Shortage of available gas supply creates a struggling situation of electricity generation. Still, 83 percent of the total electricity used to be generated by natural gas. Many power plants are idle due to the shortage of gas supply. This has resulted in the lower generation of electricity. On the other hand, unprecedented delay in finalizing a coal policy makes it difficult to generate the expected level of electricity. Government remains silent about the exploration and exploitation of coal, which is cheaper and safer in generating electricity.

1.5.2 Lack of timely Implementation of Allocated Money

The government has given highest priority to the development in the power sector which has been reflected in the allocation of the annual development program (ADP). The total allocation in the power sector was Tk. 7145.28 crore for the fiscal year 2011-12. Over the last few years there was a significant gap between the allocation and the implementation of ADP in the power sector. Considering the last fiscal year, it has been observed that only 29 percent of the allocated ADP had been implemented during the first eight months of that fiscal year. It means that another 71 percent have to be implemented within the next four months of that fiscal year. When a huge amount of allocated money is required to implement, there exist corruptions. That is why the lack of timely implementation has reduced the proper development in the sector of electricity, in fact, in the generation of electricity.

1.5.3 Political Reason

In Bangladesh, the governments come and go and the issue of electricity remains a struggling one. The politicians are very much interested in covering a lot of areas without thinking the existing generation in order to win the mind of the voters. This may bear information about the huge coverage of the electricity but in reality, it creates crisis. This type of politics makes the crisis more acute.

1.5.4 Over Population

There has been an increase in the demand for electricity in the recent years as a result of industrial development and population growth. One of the common matters in the country is over population, which creates a lot of problem in the various development sectors. More population means more consumption of electricity. Population is increasing but the generation of electricity is not increasing as required. After all, there is an improvement in the life style of the citizen in the country. With the improvement of the people’s life standard, the demand for electricity has also increased. As the generation has increased with a slower rate than that of the demand for electricity, the crisis of electricity is on the rise.

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1.6 Solution

Instant Power Supply (IPS) IPS stands for “Instant Power Supply”. It is an electrical device that can provide electricity when

the main supply is not available. IPS is the ideal solution for continuous power supply facilities during mains failure. A general IPS consists of a charger circuit, a battery, an oscillator circuit, Overload protection circuit and an output step by step Lode sharing circuit. The charger circuit charges the battery properly by using the main supply when it is ON. When the main supply is not available then the battery supplies the power.

Solar Energy

Solar Energy can be a great source for solving power crisis in Bangladesh. Bangladesh is situated between 20.30 and 26.38 degrees north latitude and 88.04 and 92.44 degrees east which is an ideal location for solar energy utilization. At this position the amount of hours of sunlight each day throughout a year .The highest and the lowest intensity of direct radiation in W/m². In a recent study conducted by Renewable Energy Research Centre, it is found that average solar radiation varies between 4 to 6.5 kWhm-2 day-1 and maximum amounts of radiation are available in the month of March-April and minimum in December-January. So from the above figure and discussion we can say that there is a good prospect of harnessing solar power in Bangladesh. Moreover, in the rural areas where there is no electricity connection, photovoltaic technology can be a blessing. Although, the installment cost of solar systems in the house is very much costly, but once installed it can give service up to 20-25 years with proper maintenance. Moreover, in the northern territories of Bangladesh where the solar intensity is very high, solar thermal power plant can be installed. For both photovoltaic technology and solar thermal technology, Bangladesh is at a perfect location. In fact, Bangladesh government has recently taken many steps to encourage people to use photovoltaic energy. Almost every newly built apartment buildings are now using solar panels along with the grid connection to get support during the load shedding period. Even in the rural areas, some NGO’s have been working to provide solar panels to the villagers in a cheap price.

Biogas

Natural resources in the form of fossil fuels are the raw materials from which electrical energy is generated and the day to day life of the people of today’s world is solely dependent on the electrical energy in this present world. Scientists around the world have already indicated that our natural reserve of gas is decreasing day by day and the time is not too far when we will have no natural gas resource. Although previously it was believed that Bangladesh has plenty amount of gas, but recent study has shown that natural gas reserve of Bangladesh is not sufficient to meet the daily cooking purpose of the people for next few decades, let alone generation of electricity. However, waste materials produced from natural day to day life usage and also from animal wastes, can be good sources of energy in this purpose and can help to meet the electricity demand by generating electricity through biogas. Many countries around the world are now paying their attention to biogas because of its environment friendly technology and as a supplement for the gradually decreasing fossil fuel reserves. Many countries now-a-days are producing electricity from biogas. Some of them are using biogas technology in mass production of electricity rather than using it in a distributed ways around the country. In Bangladesh biogas is still a relatively new technology. In most of the places it is used to generate electricity to meet the household

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demands. But an agro-based country like Bangladesh produces huge amount of waste materials. Converting these waste materials into energy is economically advantageous as well as helpful to solve the issue of power crisis. In Bangladesh, recycling industry wastes raises a total of 436 t/d of material recovery. Moreover, 3,054 t/d of wastes is expected to be collected in 2015 and cumulative disposal volume is estimated at about 9 million tones by the end of 2015 . This huge amount of waste, most of which are computable and have very good fermentation property can be easily used to produce electricity as well as the generated gas can be used for the cooking purpose. Waste to energy technology can be a huge asset for a developing country like Bangladesh. Although some small farms and houses in the rural areas are using wastes produced from their livestock to produce electricity for daily purposes, it should be used commercially to produce electricity in the areas where there is still no electricity from the national grid. It will help the people of these areas to meet their demand of electricity and the government and the companies related to this technology can earn money which is also beneficial.

Generator

In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric current to flow through an external circuit. The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine.,[1] a hand crank, compressed air, or any other source of mechanical energy. Generators provide nearly all of the power for electric power grids.

The reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators have many similarities. Many motors can be mechanically driven to generate electricity and frequently make acceptable generators.

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CHAPTER-02

Instant Power Supply (IPS)

2.1 Introduction

Instant Power Supply ( IPS ) stands for “It is an electrical device that can provide electricity when the main supply is not available. IPS is the ideal solution for continuous power supply facilities during mains failure. A general IPS consists of a charger circuit, a battery, an oscillator circuit and an output circuit. The charger circuit charges the battery properly by using the main supply when it is ON. When the main supply is not available then the battery supplies the power. The system has many distinct features over the conventional generators. It is fully automatic. It does not require any fuel as like a generator needs. It also does not produce any sound pollution like a generator does. It is the precession IPS designed according to our power line Condition. The IPS those are available in the market has some limitations such as. [2]

Unstable or unregulated output voltage

Battery longibility is small

High cost

To overcome above shortcomings an initiative was taken to design such an IPS that will give a stable output and its battery will serve for a long time compared to the conventional IPS. It will also be available at comparatively low cost .

2.2 System Specification

Table: 02 System Specification

Serial number Features Specifications

1 Main voltage 220 V, 50 Hz

2 Low voltage Battery power supply 12V DC

3 Temperature range 0-80 Deg. F.

4 Output range 220V – 240V

5 Power 200 watt

6 Back up time Battery dependent

7 Use Tube light & fan

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2.3 Principle of Operation

The simplified block diagram of designed IPS is shown in Fig. 1.This Transformer is Step down is

voltage range. Primary 220 V AC & secondary 12-0-12 V. The 220V AC supply is applied to the input

(step up) transformer 12-0-12 V AC from input transformer is then enters in to the rectifier bridge which

this power convert that DC to AC. Instant Power supply DC battery 12 voltage converting to the AC

amplification high voltage 230 V 50Hz. output. Transformer 12 to 15V AC used to charge a 12V battery

through the charger control circuit 12V AC supply to the Power circuit this converts 12V DC. This 12V

AC is then amplified and transmitted to the output (step up) transformer. 220V AC supply is achieved

from the output transformer.

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2.4 Block Diagram of IPS

Fig:2.1 Block Diagram of IPS

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2.5 List of components

Table : 03 List of Components

Resistors DiodeR1 3K9,1/4W R49 3K3,1/4W D1 5.6V,Zener D21 1N4007R2 10K,1/4W R50 10K,1/4W D2 1N4007 D22 1N4007R3 100K, 1/4W R51 6K8,1/4W D3 1N4007 D23 1N4007R4 3k3, 1/4W R52 2K2,1/4W D4 1N4007 D24 1N4007R5 100k, 1/4W R53 1K, 1/4W D5 1N4148 D25 1N4007R6 10k, 1/4W R54 47ohm,1W D6 1N4148 D26 1N4007R7 10k, 1/4W R55 1K, 1/4W D7 1N4148 D27 1N4007R8 330k, 1/4W R56 10K, 1/4W D8 1N4007 D28 1N4007R9 10k, 1/4W R57 3K3, 1/4W D9 1N4007 D29 1N4007R10 2k2, 1/4W R58 220K,1/4W D10 1N4148 D30 1N4007R11 10k, 1/4W R59 220K,1/4W D11 1N4007 D31 1N4007R12 10k, 1/4W R60 3K3, 1/4W D12 1N4007 D32 1N4007R13 10k, 1/4W R61 3K3, 1/4W D13 1N4007 D33 1N4007R14 3k3, 1/4W R62 1K, 1/4W D14 1N4007 D34 1N4007R15 10k, 1/4W R63 680ohm D15 1N4007 D35 1N4007R16 10k, 1/4W R64 10K, 1/4W D16 1N4007 D36 1N4007R17 100k, 1/4W R65 1K, 1/4W D17 1N4007 D37 1N4007R18 4k7, 1/4W R66 33K, 1/4W D18 1N4007 D38 1N4007R19 4k7, 1/4W R67 D19 1N4148 D39 1N4007R20 1k, 1/4W R68 1K, 1/4W D20 1N4007R21 100k, 1/4W R69 470, 1/4WR22 10ohm,1/4W R70 47K, 1/4W Wire wound ResistorR23 56k, 1/4W R71 22K, 1/4W 20ohm/20W Wire would ResistorR24 4k7, 1/4W R72 22K, 1/4W 1ohm/20W Wire would ResistorR25 10k, 1/4W R73 47K, 1/4W PresetR26 10k, 1/4W R74 330K,1/4W VR1 4K7 Charging CutR27 10k, 1/4W R75 4K7, 1/4W VR2 4K7 Charging Ampere Adj.R 28 47k, 1/4W R76 10K, 1/4W VR3 4K7 Freq. Fine tuneR29 47k, 1/4W R77 10K, 1/4W VR4 4K7 PWMR30 10k, 1/4W R78 1K, 1/4W VR5 20K Freq. Adj.R31 10ohm,1/4W R79 100K,1/4W VR6 20K OverloadR32 2k2, 1/4W R80 56K, 1/4W VR7 4K7 Low BatteryR33 6k8, 1/4W R81 22K, 1/4W LEDS R34 680, 1/4W R82 4K7, 1/4W LED REDR35 4k7, 1/4W R83 22K, 1/4W LED REDR36 47k, 1/4W R84 1K, 1/4W LED GREENR37 10k, 1/4W R85 1K, 1/4W LED GREENR38 10k, 1/4W R86 1K, 1/4W LED YELLOWR39 6k8, 1/4W R87 47K, 1/4W CapacitorR40 10k, 1/4W R88 22K, 1/4W CA1 0.1 µf,100VR41 22k, 1/4W R89 1K, 1/4W CA2 1000 µf,35VR42 220k, 1/4W R90 10K, 1/4W CA3 1000 µf,35V

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R43 10K, 1/4W R91 10K, 1/4W CA4 0.1 µf,100V

Resistors ResistorsR44 3K3, 1/4W R47 100K, 1/4W RA1 1K RA12 220 OhmR45 470K, 1/4W R48 2K2, 1/4W RA2 1K RA13 100KR46 2K2, 1/4W RA3 10K RA14 22 Ohm

RA4 2K2 RA15 22 OhmCapacitor RA5 10K RA16 22Ohm

C1 4.7MFd,63V C23 0.022MFd,1KV RA6 22 Ohm RA17 10KC2 4.7MFd,63V C24 0.1MFd,100KpF RA7 22 Ohm RA18 10KC3 4.7MFd,63V C25 2.2MFd,63V RA8 22 Ohm RA19 2K2C4 4.7MFd,63V C26 220MFd,40V RA9 10K RA20 1KC5 0.47MFd,63V C27 0.1MFd,100KpF RA10 10K RA21 1KC6 0.1MFd,100KpF C28 0.1MFd,100KpF RA11 100K RA22 10KC7 1MFd,63V C29 0.1MFd,100KpFC8 0.1MFd,100KpF C30 0.1MFd,100KpF ICC9 47Md,63V C31 47Md,63V IC-1 LM324N (OP-AMP)C10 1MFd,63V C32 47Md,63V IC-2 SG3524N / SG3525A (PWM)C11 0.1MFd,100KpF C33 10MFd63V IC-3 MOC3021 (OPTO-COUPLER)C12 0.1MFd,100KpF C34 47Md,63V IC-4 LM324 N (OP-AMP)C13 47Md,63V C35 10MFd63V IC-5 4N35 (OPTO-COUPLER)C14 4.7Md,63V C36 0.1MFd,100KpF IC-6 4N35 (OPTO-COUPLER)C15 0.1MFd,100KpF C37 10MFd63V IC-7 LM339 (OP-AMP)C16 10MFd,63V C38 10MFd63V IC-8 LM7812 (12V REGULATOR)C17 2.2MFd,63V C39 47Md,63V IC-9 LM7812 (12V REGULATOR)C18 2.2MFd,63V C40 0.1MFd,100KpFC19 0.1MFd,100KpF C41 10MFd63V SCR C20 47Md,63V C42 0.1MFd,100KpF SCR-1 TYN604/612C21 0.1MFd,100KpF C43 100MFd,50V SCR-2 TYN604/612C22 0.1MFd,100KpF C44 100MFd,50V

TransistorT1 BC557 (PNP)T2 BC557 (PNP)T4 BC547 (NPN)T5 BC547 (NPN)T8 BC557 (PNP)T10 XL08/8T169 (SCR)T11 BD140/2N6107 (PNP)T12 BC547 (NPN)T13 BC547 (NPN)T14 BC551 (PNP)T15 BC557 (PNP)T16 BC557 (PNP)T17 BC557 (PNP)

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2.6 Circuit Diagram of IPS Oscillation

Fig: 2.2 Circuit Diagram of IPS

2.7 Load priority

Load priority means the load where is necessary to apply the power immediately .In this thesis we

can try to develop one thing that in the period of the power failing or load shading the IPS backup the

power supply but not at a time every room. By the selection of us 1st time backup drawing room or kitchen

room and then other room. To apply this process the IPS longevity would be higher than the normal IPS,

which has not this load priority system. After all we think this system is effective and acceptable to us.

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2.8 Result

The designed IPS circuit worked properly. Detail result is as follows

Table: 04 Result

Input Transformer

Primary Input 220V, 50 HzSecondary Output 12-0-12 V, 50 Hz.

The Charger Circuit

Input 12V, 50 Hz.Output 13.5V DC. (Approximately) The Battery.Input 13.5V DCOutput 12V DC

Oscillator Circuit

Input 12V DC.Output 5 V, 50 Hz.

Output Transformer

Step-up Transformer Primary Input 12-0-12 V, 50 Hz.Secondary Output 220V, 50 Hz

This thesis work was planed in a systematic way. The total activities were performed step by step.

At first the whole system was outlined in a block diagram and then circuits of different sections of the

block were designed and tested. Finally all the circuits were arranged and connected properly and then

tested. Firstly, the charger circuit was designed. A 12-0-12 V AC supply was given to the circuit by a step

down transformer and an output of approximately 13.5V DC was obtained at the output of voltage

regulator LM7812. There was a little voltage drop of about 1.5V across the circuit. Then a 12V DC

battery was connected to the charge circuit.

After that, the oscillator circuit has been designed. To test it a 12V DC supply was applied and proper

oscillation was observed by the help of an oscilloscope. An output of approximately 12 V, 50 Hz was

obtained. It was always difficult to obtain a pure AC output. The output of the oscillator circuit was then

applied to the output step up transformer through output transistors and an output of 220V, 50 Hz was

acquired. By increasing the number of the output transistors power of the designed circuit can be

enhanced.

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CHAPTER-03

Components

3.1 Transformer

A transformer is a static electrical device that transfers energy by inductive coupling between its winding circuits. A varying current in the primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic flux through the secondary winding. This varying magnetic flux induces a varying electromotive force (emf) or voltage in the secondary winding. Transformers can be used to vary the relative voltage of circuits or isolate them, or both.

Transformers range in size from thumbnail-sized used in microphones to units weighing hundreds of tons interconnecting the power grid. A wide range of transformer designs are used in electronic and electric power applications. Transformers are essential for the transmission, distribution, and utilization of electrical energy.[4]

3.2 Basic principles

The ideal transformer

Fig: 3.1 Ideal transformer circuit diagram

Consider the ideal, lossless, perfectly-coupled transformer shown in the circuit diagram at right having primary and secondary windings with NP and NS turns, respectively.

The ideal transformer induces secondary voltage ES =VS as a proportion of the primary voltage VP = EP and respective winding turns as given by the equation

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,

where,

- VP/VS = EP/ES = a is the voltage ratio and NP/NS = a is the winding turns ratio, the value of these ratios being respectively higher and lower than unity for step-down and step-up transformers,

- VP designates source impressed voltage,- VS designates output voltage, and,- EP & ES designate respective emf induced voltages.

Any load impedance connected to the ideal transformer’s secondary winding causes current to flow without losses from primary to secondary circuits, the resulting input and output apparent power therefore being equal as given by the equation

.

Combining the two equations yields the following ideal transformer identity

.

This formula is a reasonable approximation for the typical commercial transformer, with voltage ratio and winding turns ratio both being inversely proportional to the corresponding current ratio. The load impedance is defined in terms of secondary circuit voltage and current as follows

.

The apparent impedance of this secondary circuit load referred to the primary winding circuit is governed by a squared turns ratio multiplication factor relationship derived as follows

.

3.3 Induction law

The transformer is based on two principles: first, that an electric current can produce a magnetic field and second 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 magnetic flux that is developed. The changing magnetic flux induces a voltage in the secondary coil. Referring to the two figures here, 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, usually iron,[d] so that most of the magnetic flux passes through both the primary and secondary coils. Any secondary winding connected load causes current and voltage induction from primary to secondary circuits in indicated directions.

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Fig: 3.2 Ideal transformer and induction law

The voltage induced across the secondary coil may be calculated from Faraday’s law of induction, which states that:

where Vs = Es is the instantaneous voltage, Ns is the number of turns in the secondary coil, and dΦ/dt is the derivative of the magnetic flux Φ through one turn of the coil. If the turns of the coil are oriented perpendicularly to the magnetic field lines, the flux is the product of the magnetic flux density 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 above two equations gives the same voltage ratio and turns ratio relationship shown above, that is,

.

The changing magnetic field induces an emf across each winding. [8] The primary emf, acting as it does in opposition to the primary voltage, is sometimes termed the counter emf. This is in accordance with Lenz’s law, which states that induction of emf always opposes development of any such change in magnetic field. As still lossless and perfectly-coupled, the transformer still behaves as described above in the ideal transformer.

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3.4 The real transformer

Real transformer deviations from ideal

The ideal model neglects the following basic linear aspects in real transformers:

Core losses collectively called magnetizing current losses consisting of:

Hysteresis losses due to nonlinear application of the voltage applied in the transformer core

Eddy current losses due to joule heating in core proportional to the square of the transformer’s applied voltage.

Whereas the ideal windings have no impedance, the windings in a real transformer have finite non-zero impedances in the form of:

Joule losses due to resistance in the primary and secondary windings.

Leakage flux that escapes from the core and passes through one winding only resulting in primary and secondary reactive impedance.

3.5 Leakage flux

Main article: Leakage inductance

Fig: 3.3 Leakage flux of a transformer

The ideal transformer model assumes that all flux generated by the primary winding links all the turns of every winding, including itself. In practice, some flux traverses paths that take it outside the windings. Such flux is termed leakage flux, and results in leakage inductance in series with the mutually coupled transformer windings.[9] Leakage flux results in energy being alternately stored in and discharged from the magnetic fields with each cycle of the power supply. It is not directly a power loss (see Stray losses below), but results in inferior voltage regulation, causing the secondary voltage to not be directly proportional to the primary voltage, particularly under heavy load. Transformers are therefore normally designed to have very low leakage inductance. Nevertheless, it is impossible to eliminate all leakage flux because it plays an essential part in the operation of the transformer. The

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combined effect of the leakage flux and the electric field around the windings is what transfers energy from the primary to the secondary. In some applications increased leakage is desired, and long magnetic paths, air gaps, or magnetic bypass shunts may deliberately be introduced in a transformer design to limit the short-circuit current it will supply. Leaky transformers may be used to supply loads that exhibit negative resistance, such as electric arcs, mercury vapor lamps, and neon signs or for safely handling loads that become periodically short-circuited such as electric arc welders.

Air gaps are also used to keep a transformer from saturating, especially audio-frequency transformers in circuits that have a DC component flowing through the windings. Knowledge of leakage inductance is for example useful when transformers are operated in parallel. It can be shown that if the percent impedance (Z) and associated winding leakage reactance-to-resistance (X/R) ratio of two transformers were hypothetically exactly the same, the transformers would share power in proportion to their respective volt-ampere ratings (e.g. 500 KVA unit in parallel with 1,000 KVA unit, the larger unit would carry twice the current). However, the impedance tolerances of commercial transformers are significant. Also, the Z impedance and X/R ratio of different capacity transformers tends to vary, corresponding 1,000 KVA and 500 KVA units’ values being, to illustrate, respectively, Z ~ 5.75%, X/R ~ 3.75 and Z ~ 5%, X/R ~ 4.75

3.6 Equivalent circuit Explain

Referring to the diagram, a practical transformer’s physical behavior may be represented by an equivalent circuit model, which can incorporate an ideal transformer.[22]

Winding joule losses and leakage reactance’s are represented by the following series loop impedances of the model:

Primary winding: RP, XP

Secondary winding: RS, XS.

In normal course of circuit equivalence transformation, RS and XS are in practice usually referred to the primary side by multiplying these impedances by the turns ratio squared, (NP/NS) 2 = a2.

Fig: 3.4 Real transformer equivalent circuit

Core loss and reactance is represented by the following shunt leg impedances of the model.

Core or iron losses: RC

Magnetizing reactance: XM.

RC and XM are collectively termed the magnetizing branch of the model.

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Core losses are caused mostly by hysteresis and eddy current effects in the core and are

proportional to the square of the core flux for operation at a given frequency. The finite permeability core requires a magnetizing current IM to maintain mutual flux in the core. Magnetizing current is in phase with the flux, the relationship between the two being non-linear due to saturation effects. However, all impedances of the equivalent circuit shown are by definition linear and such non-linearity effects are not typically reflected in transformer equivalent circuits.[23] With sinusoidal supply, core flux lags the induced emf by 90°. With open-circuited secondary winding, magnetizing branch current I0 equals transformer no-load current.

The resulting model, though sometimes termed ‘exact’ equivalent circuit based on linearity assumptions, retains a number of approximations.[22] Analysis may be simplified by assuming that magnetizing branch impedance is relatively high and relocating the branch to the left of the primary impedances. This introduces error but allows combination of primary and referred secondary resistances and reactance’s by simple summation as two series impedances.

Transformer equivalent circuit impedance and transformer ratio parameters can be derived from the following tests: Open-circuit test, short-circuit test, winding resistance test, and transformer ratio test.

3.7 Basic transformer parameters and construction

Effect of frequency

Transformer universal emf equation

If the flux in the core is purely sinusoidal, the relationship for either winding between its rms voltage Erms of the winding, and the supply frequency f, number of turns N, core cross-sectional area a in m2 and peak magnetic flux density Bpeak in Wb/m2 or T (tesla) is given by the universal emf equation:

If the flux does not contain even harmonics the following equation can be used for half-cycle average voltage Eavg of any wave shape.

The time-derivative term in Faraday’s Law shows that the flux in the core is the integral with respect to time of the applied voltage. Hypothetically an ideal transformer would work with direct-current excitation, with the core flux increasing linearly with time. In practice, the flux rises to the point where magnetic saturation of the core occurs, causing a large increase in the magnetizing current and overheating the transformer. All practical transformers must therefore operate with alternating (or pulsed direct) current.

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The emf of a transformer at a given flux density increases with frequency. By operating at

higher frequencies, transformers can be physically more compact because a given core is able to transfer more power without reaching saturation and fewer turns are needed to achieve the same impedance. However, properties such as core loss and conductor skin effect also increase with frequency. Aircraft and military equipment employ 400 Hz power supplies which reduce core and winding weight. Conversely, frequencies used for some railway electrification systems were much lower (e.g. 16.7 Hz and 25 Hz) than normal utility frequencies (50 – 60 Hz) for historical reasons concerned mainly with the limitations of early electric traction motors. As such, the transformers used to step-down the high over-head line voltages (e.g. 15 kV) were much heavier for the same power rating than those designed only for the higher frequencies.

Fig: 3.5 Power transformer over-excitation condition caused by decreased frequency; flux (green), iron core’s magnetic characteristics (red) and magnetizing current (blue).

Operation of a transformer at its designed voltage but at a higher frequency than intended will lead to reduced magnetizing current. At a lower frequency, the magnetizing current will increase. Operation of a transformer at other than its design frequency may require assessment of voltages, losses, and cooling to establish if safe operation is practical. For example, transformers may need to be equipped with ‘volts per hertz’ over-excitation relays to protect the transformer from overvoltage at higher than rated frequency.

One example of state-of-the-art design is traction transformers used for electric multiple unit and high speed train service operating across the, country border and using different electrical standards, such transformers’ being restricted to be positioned below the passenger compartment. The power supply to, and converter equipment being supply by, such traction transformers have to accommodate different input frequencies and voltage (ranging from as high as 50 Hz down to 16.7 Hz

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and rated up to 25 kV) while being suitable for multiple AC asynchronous motor and DC converters & motors with varying harmonics mitigation filtering requirements.

Large power transformers are vulnerable to insulation failure due to transient voltages with high-frequency components, such as caused in switching or by lightning.

3.8 Energy LossesAn ideal transformer would have no energy losses, and would be 100% efficient. In practical

transformers, energy is dissipated in the windings, core, and surrounding structures. Larger transformers are generally more efficient, and those rated for electricity distribution usually perform better than 98%.

Experimental transformers using superconducting windings achieve efficiencies of 99.85%. The increase in efficiency can save considerable energy, and hence money, in a large heavily loaded transformer; the trade-off is in the additional initial and running cost of the superconducting design.

As transformer losses vary with load, it is often useful to express these losses in terms of no-load loss, full-load loss, half-load loss, and so on. Hysteresis and eddy current losses are constant at all loads and dominate overwhelmingly at no-load, variable winding joule losses dominating increasingly as load increases. The no-load loss can be significant, so that even an idle transformer constitutes a drain on the electrical supply and a running cost. Designing transformers for lower loss requires a larger core, good-quality silicon steel, or even amorphous steel for the core and thicker wire, increasing initial cost so that there is a trade-off between initial cost and running cost (also see energy efficient transformer).

3.9 Transformer losses arise from:

i)Winding joule losses

Current flowing through winding conductors causes joule heating. As frequency increases, skin effect and proximity effect causes winding resistance and, hence, losses to increase.

ii) Hysteresis lossesEach time the magnetic field is reversed, a small amount of energy is lost due to hysteresis within the core. According to Steinmetz’s formula, the heat energy due to hysteresis is given by

,

hysteresis loss is thus given by

where, f is the frequency, η is the hysteresis coefficient and βmax is the maximum flux density, the empirical exponent of which varies from about 1.4 to 1 .8 but is often given as 1.6 for iron.

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iii) Eddy current losses

Ferromagnetic materials are also good conductors and a core made from such a material also constitutes a single short-circuited turn throughout its entire length. Eddy currents therefore circulate within the core in a plane normal to the flux, and are responsible for resistive heating of the core material. The eddy current loss is a complex function of the square of supply frequency and inverse square of the material thickness Eddy current losses can be reduced by making the core of a stack of plates electrically insulated from each other, rather than a solid block; all transformers operating at low frequencies use laminated or similar cores.

iv) Stray losses

Leakage inductance is by itself largely lossless, since energy supplied to its magnetic fields is returned to the supply with the next half-cycle. However, any leakage flux that intercepts nearby conductive materials such as the transformer’s support structure will give rise to eddy currents and be converted to heat. There are also radiative losses due to the oscillating magnetic field but these are usually small.

3.10 Core form and shell form transformers

Fig: 3.6 Core form = core type; shell form = shell type

Closed-core transformers are constructed in ‘core form’ or ‘shell form’. When windings surround the core, the transformer is core form; when windings are surrounded by the core, the transformer is shell form. Shell form design may be more prevalent than core form design for distribution transformer applications due to the relative ease in stacking the core around winding coils. Core form design tends to, as a general rule, be more economical, and therefore more prevalent, than shell form design for high voltage power transformer applications at the lower end of their voltage and power rating ranges (less than or equal to, nominally, 230 kV or 75 MVA). At higher voltage and power ratings, shell form transformers tend to be more prevalent. Shell form design tends to be 35 | P a g e

preferred for extra high voltage and higher MVA applications because, though more labor intensive to manufacture, shell form transformers are characterized as having inherently better kVA-to-weight ratio, better short-circuit strength characteristics and higher immunity to transit damage.

3.11 Construction

Laminated steel cores

Fig: 3.7 Laminated core transformer showing edge of laminations at top of photo

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Fig: 3.8 Power transformer inrush current caused by residual flux at switching instant; flux (green), iron core’s magnetic characteristics (red) and magnetizing current (blue).

Transformers for use at power or audio frequencies typically have cores made of high permeability silicon steel. The steel has a permeability many times that of free space and the core thus serves to greatly reduce the magnetizing current and confine the flux to a path which closely couples the windings. Early transformer developers soon realized that cores constructed from solid iron resulted in prohibitive eddy current losses, and their designs mitigated this effect with cores consisting of bundles of insulated iron wires. Later designs constructed the core by stacking layers of thin steel laminations, a principle that has remained in use. Each lamination is insulated from its neighbors by a thin non-conducting layer of insulation. The universal transformer equation indicates a minimum cross-sectional area for the core to avoid saturation.

The effect of laminations is to confine eddy currents to highly elliptical paths that enclose little flux, and so reduce their magnitude. Thinner laminations reduce losses,[45] but are more laborious and expensive to construct. Thin laminations are generally used on high-frequency transformers, with some of very thin steel laminations able to operate up to 10 kHz.

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Fig: 3.9 Laminating core greatly reduces eddy-current losses

One common design of laminated core is made from interleaved stacks of E-shaped steel sheets capped with I-shaped pieces, leading to its name of 'E-I transformer'. Such a design tends to exhibit more losses, but is very economical to manufacture. The cut-core or C-core type is made by winding a steel strip around a rectangular form and then bonding the layers together. It is then cut in two, forming two C shapes, and the core assembled by binding the two C halves together with a steel strap. They have the advantage that the flux is always oriented parallel to the metal grains, reducing reluctance.

A steel core's remanence means that it retains a static magnetic field when power is removed. When power is then reapplied, the residual field will cause a high inrush current until the effect of the remaining magnetism is reduced, usually after a few cycles of the applied AC waveform. Overcurrent protection devices such as fuses must be selected to allow this harmless inrush to pass. On transformers connected to long, overhead power transmission lines, induced currents due to geomagnetic disturbances during solar storms can cause saturation of the core and operation of transformer protection devices.

Distribution transformers can achieve low no-load losses by using cores made with low-loss high-permeability silicon steel or amorphous (non-crystalline) metal alloy. The higher initial cost of the core material is offset over the life of the transformer by its lower losses at light load.

3.12 Solid coresPowdered iron cores are used in circuits such as switch-mode power supplies that operate

above mains frequencies and up to a few tens of kilohertz. These materials combine high magnetic permeability with high bulk electrical resistivity. For frequencies extending beyond the VHF band, cores made from non-conductive magnetic ceramic materials called ferrites are common. Some radio-

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frequency transformers also have movable cores (sometimes called 'slugs') which allow adjustment of the coupling coefficient (and bandwidth) of tuned radio-frequency circuits.

3.13 Windings

Fig: 3.10 Windings are usually arranged concentrically to minimize flux leakage. Main article: Windings

The conducting material used for the windings depends upon the application, but in all cases the individual turns must be electrically insulated from each other to ensure that the current travels throughout every turn.[52] For small power and signal transformers, in which currents are low and the potential difference between adjacent turns is small, the coils are often wound from enamelled magnet wire, such as Formvar wire. Larger power transformers operating at high voltages may be wound with copper rectangular strip conductors insulated by oil-impregnated paper and blocks of pressboard.

Cut view through transformer windings. White: insulator. Green spiral: Grain oriented silicon steel. Black: Primary winding made of oxygen-free copper. Red: Secondary winding. Top left: Toroidal transformer. Right: C-core, but E-core would be similar. The black windings are made of film. Top: Equally low capacitance between all ends of both windings. Since most cores are at least moderately conductive they also need insulation. Bottom: Lowest capacitance for one end of the secondary winding needed for low-power high-voltage transformers. Bottom left: Reduction of leakage inductance would lead to increase of capacitance.

High-frequency transformers operating in the tens to hundreds of kilohertz often have windings made of braided Litz wire to minimize the skin-effect and proximity effect losses. Large power transformers use multiple-stranded conductors as well, since even at low power frequencies non-uniform distribution of current would otherwise exist in high-current windings. Each strand is individually insulated, and the strands are arranged so that at certain points in the winding, or throughout the whole winding, each portion occupies different relative positions in the complete conductor. The transposition equalizes the current flowing in each strand of the conductor, and reduces

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eddy current losses in the winding itself. The stranded conductor is also more flexible than a solid conductor of similar size, aiding manufacture.

The windings of signal transformers minimize leakage inductance and stray capacitance to improve high-frequency response. Coils are split into sections, and those sections interleaved between the sections of the other winding.

Power-frequency transformers may have taps at intermediate points on the winding, usually on the higher voltage winding side, for voltage adjustment. Taps may be manually reconnected, or a manual or automatic switch may be provided for changing taps. Automatic on-load tap changers are used in electric power transmission or distribution, on equipment such as arc furnace transformers, or for automatic voltage regulators for sensitive loads. Audio-frequency transformers, used for the distribution of audio to public address loudspeakers, have taps to allow adjustment of impedance to each speaker. A center-tapped transformer is often used in the output stage of an audio power amplifier in a push-pull circuit. Modulation transformers in AM transmitters are very similar.

Dry-type transformer winding insulation systems can be either of standard open-wound 'dip-and-bake' construction or of higher quality designs that include vacuum pressure impregnation (VPI), vacuum pressure encapsulation (VPE), and cast coil encapsulation processes.[54] In the VPI process, a combination of heat, vacuum and pressure is used to thoroughly seal, bind, and eliminate entrained air voids in the winding polyester resin insulation coat layer, thus increasing resistance to corona. VPE windings are similar to VPI windings but provide more protection against environmental effects, such as from water, dirt or corrosive ambients, by multiple dips including typically in terms of final epoxy coat.

3.14 Cooling

Fig: 3.11 Cooling System

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Cutaway view of liquid-immersed construction transformer. The conservator (reservoir) at top

provides liquid-to-atmosphere isolation as coolant level and temperature changes. The walls and fins provide required heat dissipation balance.See also: Arrhenius equation

To place the cooling problem in perspective, the accepted rule of thumb is that the life expectancy of insulation in all electric machines including all transformers is halved for about every 7°C to 10°C increase in operating temperature, this life expectancy halving rule holding more narrowly when the increase is between about 7°C to 8°C in the case of transformer winding cellulose insulation. Small dry-type and liquid-immersed transformers are often self-cooled by natural convection and radiation heat dissipation. As power ratings increase, transformers are often cooled by forced-air cooling, forced-oil cooling, water-cooling, or combinations of these. Large transformers are filled with transformer oil that both cools and insulates the windings. Transformer oil is a highly refined mineral oil that cools the windings and insulation by circulating within the transformer tank. The mineral oil and paper insulation system has been extensively studied and used for more than 100 years. It is estimated that 50% of power transformers will survive 50 years of use, that the average age of failure of power transformers is about 10 to 15 years, and that about 30% of power transformer failures are due to insulation and overloading failures. Prolonged operation at elevated temperature degrades insulating properties of winding insulation and dielectric coolant, which not only shortens transformer life but can ultimately lead to catastrophic transformer failure With a great body of empirical study as a guide, transformer oil testing including dissolved gas analysis provides valuable maintenance information. This can translate in a need to monitor, model, forecast and manage oil and winding conductor insulation temperature conditions under varying, possibly difficult, power loading conditions. Building regulations in many jurisdictions require indoor liquid-filled transformers to either use dielectric fluids that are less flammable than oil, or be installed in fire-resistant rooms. Air-cooled dry transformers can be more economical where they eliminate the cost of a fire-resistant transformer room.

The tank of liquid filled transformers often has radiators through which the liquid coolant circulates by natural convection or fins. Some large transformers employ electric fans for forced-air cooling, pumps for forced-liquid cooling, or have heat exchangers for water-cooling. An oil-immersed transformer may be equipped with a Buchholz relay, which, depending on severity of gas accumulation due to internal arcing, is used to either alarm or de-energize the transformer. Oil-immersed transformer installations usually include fire protection measures such as walls, oil containment, and fire-suppression sprinkler systems. Another protection means consists in fast depressurization systems which are activated by the first dynamic pressure peak of the shock wave, avoiding transformer explosion before static pressure increases. Many explosions are reported to have been avoided thanks to this technology.

Polychlorinated biphenyls have properties that once favored their use as a dielectric coolant, though concerns over their environmental persistence led to a widespread ban on their use Today, non-toxic, stable silicone-based oils, or fluorinated hydrocarbons may be used where the expense of a fire-resistant liquid offsets additional building cost for a transformer vault. PCBs for new equipment was banned in 1981 and in 2000 for use in existing equipment in United Kingdom. Legislation enacted in Canada between 1977 and 1985 essentially bans PCB use in transformers manufactured in or imported into the country after 1980, the maximum allowable level of PCB contamination in existing mineral oil transformers being 50 ppm.

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Some transformers, instead of being liquid-filled, have their windings enclosed in sealed,

pressurized tanks and cooled by nitrogen or sulfur hexafluoride gas. Experimental power transformers in the 500-to-1,000 kVA range have been built with liquid nitrogen or helium cooled superconducting windings, which, compared to usual transformer losses, eliminates winding losses without affecting core losses.

3.15 Insulation dryingConstruction of oil-filled transformers requires that the insulation covering the windings be

thoroughly dried of residual moisture before the oil is introduced. Drying is carried out at the factory, and may also be required as a field service. Drying may be done by circulating hot air around the core, or by vapor-phase drying (VPD) where an evaporated solvent transfers heat by condensation on the coil and core.

For small transformers, resistance heating by injection of current into the windings is used. The heating can be controlled very well, and it is energy efficient. The method is called low-frequency heating (LFH) since the current is injected at a much lower frequency than the nominal of the power grid, which is normally 50 or 60 Hz. A lower frequency reduces the effect of the inductance in the transformer, so the voltage needed to induce the current can be reduced. The LFH drying method is also used for service of older transformers

3.16 BushingsLarger transformers are provided with high-voltage insulated bushings made of polymers or

porcelain. A large bushing can be a complex structure since it must provide careful control of the electric field gradient without letting the transformer leak oil.

3.17 Classification parametersTransformers can be classified in many ways, such as the following:

Power capacity: From a fraction of a volt-ampere (VA) to over a thousand MVA.

Duty of a transformer: Continuous, short-time, intermittent, periodic, varying.

Frequency range: Power-frequency, audio-frequency, or radio-frequency.

Voltage class: From a few volts to hundreds of kilovolts.

Cooling type: Dry and liquid-immersed - self-cooled, forced air-cooled; liquid-immersed - forced oil-cooled, water-cooled.

Circuit application: Such as power supply, impedance matching, output voltage and current stabilizer or circuit isolation.

Utilization: Pulse, power, distribution, rectifier, arc furnace, amplifier output, etc..

Basic magnetic form: Core form, shell form.

Constant-potential transformer descriptor: Step-up, step-down, isolation.

General winding configuration: By EIC vector group - various possible two-winding combinations of the phase designations delta, wye or star, and zigzag or interconnected star;[j] other - autotransformer, Scott-T, zigzag grounding transformer winding

Rectifier phase-shift winding configuration: 2-winding, 6-pulse; 3-winding, 12-pulse; . . . n-winding, [4]*6-pulse; polygon; etc..

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3.18 Types

A) Construction of Core

I) Core type

II ) Shell Type

III) Spiral Type

B) Application

I) Power transformer

II) Distribution Transformer

III)Auto Transformer

IV) Instrument Transformer :

ia) Current transformer

ib) Potential Transformer

C) Structure Type

I) Indoor Type Transformer

II) Outdoor Type Transformer

III) Pole mounted Transformer

D) Frequency Type

I) Audio frequency Transformer

II) Radio frequency Transformer

Fig: 3.12 Transformer

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3.19 Oscillator Circuit ( PWM )

Generally, an electronic circuit that produces a repetitive electronic signal is known as an electronic oscillator . More precisely, an oscillator is a circuit that generates a repetitive wave form of fixed amplitude and frequency without any external input signal. Basically the function of an oscillator is to generate alternating current or voltage wave form . Generally Oscillators are characterized by the frequency of their output signal. An audio oscillator produces frequencies in the audio range, about 16 Hz to 20 kHz. An RF oscillator produces signals in the radio frequency (RF) range of about 100 kHz to 100 GHz. A low-frequency oscillator (LFO) is an electronic oscillator that generates a frequency below ≈20 Hz. Oscillators that produce a high-power AC output from a DC supply are usually termed as inverters.[3]

Fig: 3.13 PCB Layout of Oscillator Circuit

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3.20 The Power Circuit

A type of circuit that carries power to electrical loads is called the power circuit. In other words the part of an electronic circuit that controls the output of the circuit is known as the power circuit. A power circuit is generally a proper combination of incoming main power, few transistors and output transformer. It often carries high voltages to the load. In the designed circuit a power push-pull amplifier is used consists of transistors Q1 and Q2.

Fig: 3.14 PCB layout of Power Circuit

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3.21 Rectifier

One of the very important applications of diode is in DC power supply as a rectifier to convert AC into DC. DC Power supply is the important element of any electronic equipment. This is because it provides power to energize all electronic circuits like oscillators, amplifiers and so on. In electronic equipments, D.C. Power supply is must. For example, we can’t think of television, computer, radio, telephone, mobile as well as measuring instruments like multi-meter etc. Without DC power supply. The reliability and performance of the electronic system proper design of power supply is necessary. The first block of DC power supply is rectifier. Rectifier may be defined as an electronic device used to convert ac voltage or current into unidirectional voltage or current. Essentially rectifier needs unidirectional device. Diode has unidirectional property hence suitable for rectifier. Rectifier broadly divided into two categories: Half wave rectifier and full wave rectifier. Diodes are unilateral devices, that is, they conduct current in one direction but block it in the opposite direction. They will have a voltage drop of 0.2 – 0.3 V or 0.6 – 0.7 V when they are conducting depending on the materials they are made of, Germanium or Silicon, respectively. The direction of the current is from anode to cathode. Cathodes are usually indicated with a painted band. [6]

Fig: 3.15 Diode.

3.22 Types of Rectifiers

There are two basic types of rectifiers: half wave rectifiers and full wave rectifiers. Half wave rectifiers, as the name suggests convert half of the AC wave to DC power using as few as a single diode. Full wave rectifiers convert the full AC wave and can use as few as two diodes. There are variations on both of these types of rectifiers such as the full wave bridge rectifier, which uses four diodes

3.23 The Half – Wave Rectifier:

Fig: 3.16a Half wave rectifier Circuit

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Fig: 3.16b Half wave rectifier [6]

When the input signal is positive (between t1 and t2, t3 and t4, etc.), the diode is forward biased and conducts current. When the input signal is negative (between t2 and t3, t4 and t5, etc.), the diode is reverse biased and does not conduct current. Hence the output waveform Vout is obtained. This is called “half rectified sine wave”.

3.24 The Full Wave Rectifiers

1)The center – tapped full wave rectifier.

Fig: 3.17a Center – tapped full wave rectifier

During the positive half cycle of the input signal, the diode D1 is forward biased and the diode D2 is reverse biased. Hence the current flows through D1 and R. During the negative half cycle of the input signal, the diode D1 is reverse biased and the diode D2 is forward biased. Hence the current flows through D2 and R. Thus, the voltage obtained across R is full wave rectified as seen is Figure 3.8a

Fig: 3.17b. Output of full wave rectifier.

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3.25 The full wave bridge rectifier.

Fig:3.18 The full wave bridge rectifier.

During the positive half cycle of the input signal, the diodes D1 and D2 are forward biased, and D3 and D4 are reverse biased. So, the current flows from A to B over diode D1, to C over R, to D over diode D2, and back to A over the secondary windings of transformer. During the negative half cycle, the diodes D3 and D4 are forward biased, and D1 and D2 are reverse biased. So, the current flows from F to D and B over D4, to C over R, to A over D3, and back to F over the secondary winding. Thus, the waveform shown in Figure 7.6 is again obtained. Since in each case, the current has to go through two diodes, there is a voltage drop in the bridge equal to two diodes drops.

3.26 DC Power Supply

Fig: 3.19a DC Power Supply

If a capacitor is added to the output of the rectifier circuit, the half rectified or the full rectified voltage will charge the capacitor. Hence, depending on the load resistor, a voltage which is almost dc

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will be obtained. From a to b, the capacitor is charged, from b to c, the capacitor is discharged, because the load resistor R draws current.

Fig: 3.19b Output voltage

3.27 Battery

The common battery is a device that changes chemical energy to electrical energy. Dry cells are widely used in toys, flashlights, portable radios, cameras, hearing aids, and other devices in common use. A battery consists of an outer case made of zinc (the negative electrode), a carbon rod in the center of the cell (the positive electrode), and the space between them is filled with an electrolyte paste. In operation the electrolyte, consisting of ground carbon, manganese dioxide, sal ammoniac, and zinc chloride, causes the electrons to flow and produce electricity.

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Fig: 3.20 Battery construction[6]

3.28 Batteries work

Electricity is the flow of electrons through a circuit or conductive path like a wire. Batteries have three parts, an anode (-), a cathode (+), and the electrolyte. The cathode and anode (the positive and negative sides at either end of a smaller battery) are hooked up to an electrical circuit.

3.29 Electron Flow

The chemical reactions in the battery causes a build up of electrons at the anode. This results in an electrical difference between the anode and the cathode. You can think of this difference as an unstable build-up of the electrons. The electrons wants to rearrange themselves to get rid of this difference. But they do this in a certain way. Electrons repel each other and try to go to a place with fewer electrons. In a battery, the only place to go is to the cathode. But, the electrolyte keeps the electrons from going straight from the anode to the cathode within the battery. When the circuit is closed (a wire connects the cathode and the anode) the electrons will be able to get to the cathode. In this example, the electrons go through the wire, lighting the light bulb along the way. This is one way of describing how electrical potential causes electrons to flow through the circuit. However, these electrochemical processes change the chemicals in anode and cathode to make them stop supplying electrons. So there is a limited amount of power available in a battery. When a battery is recharged, the

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direction of the flow of electrons is changed, The electrochemical processes happen in reverse, and the anode and cathode are restored to their original state and can again provide full power. Batteries are used in many places such as in flashlights, cars, PCs, laptops, portable MP3 players and cell phones. A battery is essentially a can full of chemicals that cause chemical reactions that produce electrons. Looking at any battery, there are generally two terminals. One terminal is marked (+), or positive, while the other is marked (-), or negative. In an AA, C or D cell (normal flashlight batteries), the ends of the battery are the terminals. In a large car battery, there are two heavy lead posts that act as the terminals. Electrons collect on the negative terminal of the battery. If a wire is connected between the negative and positive terminals, the electrons will flow from the negative to the positive terminal as fast as it can wear out the battery quickly and possibly cause an explosion.

Inside the battery, a chemical reaction produces the electrons. The speed of electron production by this chemical reaction (the battery's internal resistance) controls how many electrons can flow between the terminals. Electrons flow from the battery into a wire, and must travel from the negative to the positive terminal for the chemical reaction to take place. That is why a battery can sit on a shelf for a year and still have plenty of power - unless electrons are flowing from the negative to the positive terminal, the chemical reaction does not take place. Once the wire is connected, the chemical reaction begins.

3.30 Batteries

The first battery recorded was created by Alessandro Volta in 1800. To create the battery, he made a stack by alternating layers of zinc, blotting paper soaked in salt water, and silver.

3.31 Titanium Batteries

Batteries containing titanium technology should provide better power in most devices using a lot of power. It is claimed that they work well in high-tech devices such asMP3 & portable CD players, and smoke detectors and flashlights

3.32 Disposable Lithium Batteries

Lithium batteries are primary cell batteries that have lithium metal or lithium compounds as an anode. Depending on the design and chemical compounds used, lithium cells can produce voltages from 1.5V to about 3V, twice the voltage of an ordinary zinc-carbon battery or alkaline cell. Lithium batteries are used in many portable consumer electronic devices, and are widely used in industry. They are recommended as a best buy by consumer groups.

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3.33 Rechargeable Batteries

The nickel-cadmium battery gives the longest cycle life of any currently available battery (over 1,500 cycles), but has low energy density compared with some of the other chemistries. Batteries using older technology suffer from memory effect, but this has been reduced drastically in modern batteries. Cadmium is toxic to most life forms, so it poses environmental concerns. Its chemical composition is nickel for the cathode and cadmium for the anode. It is used in many domestic applications, but is being superseded by Li-ion and Ni-MH types.

3.34 Integrated CircuitAn integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a

microchip) is a set of electronic circuits on one small plate ("chip") of semiconductor material, normally silicon. This can be made much smaller than a discrete circuit made from independent components.

Integrated circuits are used in virtually all electronic equipment today and have revolutionized the world of electronics. Computers, mobile phones, and other digital home appliances are now inextricable parts of the structure of modern societies, made possible by the low cost of producing integrated circuits.

ICs can be made very compact, having up to several billion transistors and other electronic components in an area the size of a fingernail. The width of each conducting line in a circuit (the line width) can be made smaller and smaller as the technology advances; in 2008 it dropped below 100 nanometers and in 2013 it is expected to be in the tens of nanometers

Fig: 3.21 integrated circuit (IC) [5]

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3.35 Transistor

A Transistor is an semiconductor which is a fundamental component in almost all electronic devices. Transistors are often said to be the most significant invention of the 20th Century. Transistors have many uses including switching, voltage/current regulation, and amplification - all of which are useful in renewable energy applications. A transistor controls a large electrical output signal with changes to a small input signal. This is analogous to the small amount of effort required to open a tap (faucet) to release a large flow of water. Since a large amount of current can be controlled by a small amount of current, a transistor acts as an amplifier A transistor acts as a switch which can open and close many times per second.

3.36 Bipolar Junction Transistors

The most common type of transistor is a bipolar junction transistor. This is made up of three layers of a semi-conductor material in a sandwich. In one configuration the outer two layers have extra electrons, and the middle layer has electrons missing (holes). In the other configuration the two outer

layers have the holes and the middle layer has the extra electrons. Layers with extra electrons are called N-Type, those with electrons missing called P-Type. Therefore the bipolar junction transistors are more commonly known as PNP transistors and NPN transistors respectively. Bipolar junction transistors are typically made of silicon and so they are very cheap to produce and purchase.

Fig. 3.22 Construction of Transistor[5]

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3.37 Transistors Work

A bipolar junction transistor has three terminals - Base, Collector, and Emitter corresponding to the three semi-conductor layers of the transistor. The weak input current is applied to the inner (base) layer. When there is a small change in the current or voltage at the inner semiconductor layer (base), a rapid and far larger change in current takes place throughout the whole transistor.

Fig. 3.23a Clickon Transistor

Fig. 3.23b Terminals of a Transistor

Pictured above is a schematic diagram of the more common NPN transistor. Below is an illustration of the same transistor using water rather than electricity to illustrate the way it functions:

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Fig. 3.24 Current Flow of a Transistor

The illustration (from satcure-focus.com) shows pipework with three openings B (Base), C (Collector), and E (Emitter). The reservoir of water at C is the supply voltage which is prevented from getting though to E by a plunger. If water is poured into B, it pushes up the plunger letting lots of water flow from C to E. If even more water is poured into B, the plunger moves higher, and the flow of water from C to E increases. Therefore, a small input current of electricity to the Base leads to a large flow of electricity from the Collector to the Emitter.

3.38 Transistor Gain

Looking at the water analogy again, if it takes 1 litre of water per minute poured into B to control 100 litres of water per minute flowing from C to E, then the Gain (or amplification factor) is 100. A real transistor with a gain of 100 can control 100mA of current from C to E with an input current of just 1mA tothe base (B).If the output power (current x voltage) are more than 1 Watt a Power Transistor must be used. These let much more power flow through, and require a larger controlling input current.

Fig. 3.25 Simple Transistor Circuit

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Pictured above is a very simple circuit which demonstrates the use of transistors. When a finger

is placed in the circuit where shown, a tiny current of around 0.1mA flows (assuming a finger resistance of 50,000 Ohms). This is nowhere near enough to light the LED which needs at least 10mA. However the tiny current is applied to the Base of the transistor where it is boosted by a factor (gain) of around 100 times and the LED light The most common type of transistor is a bipolar junction transistor. This is made up of three layers of a semi-conductor material in a sandwich. In one configuration the outer two layers have extra electrons, and the middle layer has electrons missing (holes). In the other configuration the two outer layers have the holes and the middle layer has the extra electrons.

3.39 How does a transistor work as an amplifier?

We know that in a transistor we have three types of regions: EMITTER, COLLECTOR, BASE, and we know that emitter is highly doped, so charge carriers are very high, so resistance is very less, and on the other side collector is moderately doped so charge carriers are less, so resistance is very high. So from the above concept we conclude that in a transistor current is flowing from low resistance to high resistance. for example the 100 electrons are moving from emitter to base, in base only some (4 electrons) of the electrons are neutralized, and remaining 96 electrons are moved to collector terminal through high resistance path. so now same current flowing through high resistance so voltage amplified.

3.40 The Transistor as an Amplifier– Amplification is the process of linearly increasing the amplitude of an electrical signal.

– A transistor can act as an amplifier directly using the gain,

– Keep in mind that when a transistor is biased in the active (linear) region, the BE junction has a low resistance due to forward bias and the BC junction has a high resistance due to reverse bias.

3.41 DC and AC quantities– Amplifier circuits have both ac and dc quantities.

– Capital letters are used will be used for both ac and dc currents.

– Subscript will be capital for dc quantities.

– Subscript will be lowercase for ac quantities.

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3.42 Transistor amplification

– A transistor amplifies current because the collector current is equal to the base current multiplied by the current gain,

– Base current (IB) is small compared to IC and IE.

– Thus, IC is almost equal to IE.

– Consider the following circuit.

Fig. 3.26 Transistor Application

– An ac voltage, Vin, is superimposed on the dc bias voltage VBB.

– DC bias voltage VCC is connected to the collector through the collector resistance, RC.

– The ac input voltage produces an ac base current, which results in a much larger ac collector current.

– The ac collector current produces an ac voltage across RC, thus producing an amplified, but

inverted, reproduction of the ac input voltage in the active region.

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Fig. 3.27 Wave

– The forward biased base-emitter junction present low resistance to the ac wave.

– This internal ac emitter resistance is designated r’e.

Ie ? Ic = Vb/ r’e

– The ac collector voltage, Vc = IcRC.

– Since Ie ? Ic, the ac collector voltage is Vc ? IeRC.

– Vb can be considered the transistor ac input voltage where Vb = Vin – IbRB.

– Vc can be considered the transistor ac output voltage.

– The ratio of Vc to Vb is the ac voltage gain, Av, of the transistor circuit.

Av = Vc/Vb

– Substituting IeRC for Vc and Ie r’e for Vb yields

Av = Vc/Vb ? (IeRC)/(Ie r’e) = RC/ r’e

– Thus, amplification depends on the ratio of RC and r’e.

– RC is always considerably larger in value than r’e, thus the output voltage is larger than the input voltage.

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4.1 Advantage :

1. The time of load shading automatically get power back. 2. Easy Installation.3. Low maintenance cost.4. Possible to get proper voltage on the basis of capacity.5. Noiseless operation.

4.2 Disadvantage

1. Due to charging power loss.2. Making cost high.3. Power backup time limited.4. Without charging it is work less.

4.3 Future Improvement

We are committed to increase the batter performance of this project. In our country the most of the people use this IPS. In charging period it consume much power. As a result it is burden to the power supply authority. So not only in this item we may use the solar panel. If we can use this solar panel we must save our valuable natural Gas, Petrol, Diesel etc.

4.4 Conclusions

In this Thesis program, we can understand the contraction of IPS and know how can it works. We also understand it’s various components. We should take care in the period of making and using of this project.

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References

[1] electricity_scenario.pdf Page 13[2] http://www.powercombd.com/products/72-instant-power-supply-ips Page 20[3] http://en.wikipedia.org/wiki/Electronic_oscillator Page 44[4] http://en.wikipedia.org/wiki/Transformer Page 27[5] Steve Krar Page 53[6] Wikipedia, the free encyclopedia. Page 50

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