Design And Construction Of A 220V/12V Power Supply System

ABSTRACT

This work is on 220vac to 12vac power supply using transformer, which served as a step down transformer whose secondary voltage is less than its primary voltage. It is designed to reduce the voltage (220v) from the primary winding to 12v in the secondary winding.

As a step-down unit, the transformer converts high-voltage, low-current power into low-voltage, high-current power. The larger-gauge wire used in the secondary winding is necessary due to the increase in current. The primary winding, which doesn’t have to conduct as much current, may be made of smaller-gauge wire.

The aim of this work is to design and construct a step-down transformer power supply system with a primary voltage of 220V and a secondary voltage of 12V.

 TABLE OF CONTENTS

 TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

TABLE OF CONTENT

CHAPTER ONE

• INTRODUCTION
• AIM/OBJECTIVE OF THE PROJECT
• SCOPE OF THE PROJECT
• SIGNIFICANCE OF THE PROJECT
• APPLICATION OF THE PROJECT
• LIMITATION OF THE PROJECT
• PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

2.0      LITERATURE REVIEW
2.1      HISTORICAL BACKGROUND OF TRANSFORMER
2.2     CLASSIFICATION PARAMETER OF A TRNSFORMER
2.3     REVIEW OF DIFFERENT TYPES OF TRANSFORMER
2.4     OTHER TYPES OF TRANSFORMERS

CHAPTER THREE

3.0      METHODOLOGY

3.1     CIRCUIT DIAGRAM OF A STEP DOWN TRANSFORMER

3.2    BASIC WORKING PRINCIPLE OF A TRANSFORMER

3.3      TRANSFORMER CONSTRUCTION

3.4     CIRCUIT DISCRIPTION OF A STEP-DOWN TRANSFORMER

3.5   DESIGN FO THE TRANSFORMER PROPER

3.6      TURNS CALCULATION

CHAPTER FOUR

RESULT ANALYSIS

4.1  TESTING OF TRANSFORMER OPERATION

4.2 SHORT-CIRCUIT TEST

4.3 FAULT WITHSTAND

4.4 TRANSFORMER COOLING METHODS
4.5 DESIGN PHOTOGRAPH

4.6 TROUBLESHOOTING METHOD OF A STEP DOWN TRANSFORMER

CHAPTER FIVE

• CONCLUSIONS
• RECOMMENDATION

5.3     REFERENCES

 CHAPTER ONE

1.1                                                        INTRODUCTION

Power supply supplies electric energy to an electrical load. The primary function of a power supply is to convert one form of electrical energy to another and, as a result, power supplies are sometimes referred to as electric power converters. Some power supplies are discrete, stand-alone devices, whereas others are built into larger devices along with their loads. Examples of the latter include power supplies found in desktop computers and consumer electronics devices.

Every power supply must obtain the energy it supplies to its load, as well as any energy it consumes while performing that task, from an energy source. Depending on its design, a power supply may obtain energy from various types of energy sources, including electrical energy transmission systems, energy storage devices such as a batteries and fuel cells, electromechanical systems such as generators and alternators, solar power converters, or another power supply.

All power supplies have a power input, which receives energy from the energy source, and a power output that delivers energy to the load. In most power supplies the power input and output consist of electrical connectors or hardwired circuit connections, though some power supplies employ wireless energy transfer in lieu of galvanic connections for the power input or output.

However, in this work, a power supply was design using a transformer which serves as a step-down transformer. A step down transformer: is one whose secondary voltage is less than its primary voltage. It is designed to reduce the voltage from the primary winding to the secondary winding. This kind of transformer “steps down” the voltage applied to it.

As a step-down unit, the transformer converts high-voltage, low-current power into low-voltage, high-current power. The larger-gauge wire used in the secondary winding is necessary due to the increase in current. The primary winding, which doesn’t have to conduct as much current, may be made of smaller-gauge wire.

For the course of this work, a step down transformer which is used to convert 220V to 12v which is main objective of the project.

1.2                                        AIM/OBJECTIVE OF THE PROJECT

Step down transformer is designed to reduce the voltage from the primary winding to the secondary winding. This kind of transformer “steps down” the voltage applied to it. The aim of this work is to construct a transformer with a primary voltage of 220V and a secondary voltage of 12V. At the end of this work:

• a transformer with primary voltage of 220V and a secondary voltage of 12V would be constructed.
• Principle of operation of a transformer would be learned
• Different types of transformer will be discussed
• Different types of Cooling systems of a transformer will be discussed

1.3                                         SIGNIFICANCE OF THE PROJECT

A step down transformer is needed to decrease the incoming 220 Volt electricity found in most parts of the world to 12 Volts power. It can be safely used powering 12v rated appliances.

1.4                                          APPLICATION OF THE PROJECT

Step down Transformers are also used extensively in electronic products to decrease (or step-down) the supply voltage to a level suitable for the low voltage circuits they contain. The transformer also electrically isolates the end user from contact with the supply voltage.

1.5                                                 SCOPE OF THE PROJECT

This work was carried out using step-down transformer, as evidenced by the high turn count of the primary winding and the low turn count of the secondary. As a step-down unit, this transformer converts high-voltage, low-current power into low-voltage, high-current power. The larger-gauge wire used in the secondary winding is necessary due to the increase in current. The primary winding, which doesn’t have to conduct as much current, may be made of smaller-gauge wire.

The Transformers used is often constructed in such a way that it is not obvious which wires lead to the primary winding and which lead to the secondary. One convention used in the electric power industry to help alleviate confusion is the use of “H” designations for the higher-voltage winding (the primary winding in a step-down unit; the secondary winding in a step-up) and “X” designations for the lower-voltage winding.

1.6                                           LIMITATION OF THE PROJECT

In this work, it is possible to operate either of these transformer types backwards (powering the secondary winding with an AC source and letting the primary winding power a load) to perform the opposite function: a step-up can function as a step-down and visa-versa. However, as we saw in this work, efficient operation of a transformer requires that the individual winding inductances be engineered for specific operating ranges of voltage and current, so if a transformer is to be used “backwards” like this it must be employed within the original design parameters of voltage and current for each winding, lest it prove to be inefficient (or lest it be damaged by excessive voltage or current).

1.7                                        PROJECT WORK ORGANIZATION

The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:

Chapter one of this work is on the introduction to a 220v to 12v power supply system. In this chapter, the background, significance, objective limitation and problem of a 220v to 12v power supply system were discussed.

Chapter two is on literature review of a 220v to 12v power supply system. In this chapter, all the literature pertaining to this work was reviewed.

Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.

Chapter four is on testing analysis. All testing that result accurate functionality was analyzed. Chapter five is on conclusion, recommendation and references.