ABSTRACT
The AVR is automatic voltage regulator and it is a device which is used to regulate or stabilize electrical power supply for electrical or electronic appliances
In this project, therefore, we are interested in the construction of this all important device. Furthermore, we shall discuss the techniques, processes, switching stages and then the working principle of the automatic voltage regulator
Chapter one of this project dwells on the introduction of the project topic. It also talks about the objectives of the project, bringing to mind what we intend to achieve at the end
Chapter two of the project reviews the research works that have been carried out by some other people in this study area. It also discusses on some of the components used in this project
Chapter three gives a detailed account of the basic construction and the operation of the AVR. It also highlights on some other components used, discussing their working principles using both the circuit and block diagrams
Chapter four of this project draws the conclusion and consequently gives the recommendation on how to better the operation of the AVR. It also includes the references and articles consulted in the course of this project.
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TABLE OF CONTENTS
Certification page                                                  i
Abstract                                                               ii
Acknowledgement                                           iii
Dedication                                                     iv
Table of content                                             v-vi
CHAPTER ONE
1.1 Introduction to automatic voltage regulator  1-3
1.2 Objectives of the project                           3-4
CHAPTER TWO
2.0 Literature review                                       5-7
2.1 Some of the components used                    8
2.2 Resistors                                                  8-9
2.3 Capacitors                                                10
2.4 Transistors                                                      11-12 2.5 Relays                                                   13-14
CHAPTER THREE
3.0 Basic construction and operation of the automatic
Voltage Regulator AVRÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 15
3.1 Components                                             15
3.2 Transformers                                             15-18
Circuit diagram of the AVRÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 19
3.3 The working principle                                        19-21
3.4 The main function of the AVRÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 23-25
3.5 The need for voltage regulation/stabilization 25-26
CHAPTER FOUR
4.0 Conclusion and recommendation                  27
4.1 Conclusion                                                  2728
4.2 The importance of voltage Regulation                28-30
4.3 Recommendation                                            30
Reference                                                          31
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CHAPTER ONE
- INTRODUCTION TO AUTOMATIC VOLTAGE REGULATORS.
Automatic voltage regulators (AVR) in power supply unit is a device which is used to regulate or stabilize electrical power supply for electrical or electronic appliances. This device helps automatically to keep the voltage level from the public power supply system constant. In other words, the minimum  and maximum   ranges  of voltage are maintained in order to achieve a constant output    of 220V.
These devices also   serve as    a protective device for appliances connected directly to it, while the AVR is connected directly to the public supply. The protective system in AVR either regulate or stabilize it to 220V output for the safety of our appliances or the fuse in the AVR will rupture by excess current of the surge and thereby cut-off the incoming  power supply.
The stabilization and regulation is achieved through the control circuit which include relays and other components of various voltages from the secondary winding of the auto-transformer used in this project work.
This control circuitry does the work of cut and boost in the case of higher and lower voltage respectively. If the supply voltage drops below 220V down to 180V,the primary control does the work of the boost which brings the output to normal , while when the voltage increases beyond 220V up to  260V ( which is not ideal),  it does the work of cut. The coils of the relay are triggered by the 11.5V D.C from the last stage of the operational Amplification. By this arrangement, an improved automatic voltage regulation is achieved and, is hereby presented in this project.
Different techniques have been employed in the design of AVR circuits in recent times but, in the design and construction of this particular type, high rise voltage, excess current due to dangerous condition externally like lightening effect which may appear on the power supply lines were effectively isolated. The system chips and fragile devices were protected likewise low voltage fluctuations make-brake power supply from public power supply were taken good care of in this AVR construction.
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1.2 OBJECTIVE OF THIS PROJECT
The automatic voltage regulator of rating 2KVA is a natural choice for remote control device for the consistent voltage level fluctuation of our   power supply system. Therefore, we bear the following in mind as our objective while carrying out this project;
1). To fully understand the automatic means of controlling and regulating the system, Its practices, design, construction, operation and application in public electric power system engineering
2). to test the electric power behavior of systems or appliances connected to AVR. Also to perform both  practices network computers, televisions, amplifier sets and other sensitive devices intended to be protected from direct connection to public electric power supply.
3). to practically engage in and fully understand the AVR operational modes and technology or configuration in electrical design and construction
4). To enhance power regulation and stabilization technology  via automatic voltage regulation for our electrical and electronics appliances due to voltage variation and, incessant power –fluctuations.
