Design And Construction Of A Mains AC Short Circuit Breaker

The circuit breaker is an absolutely essential device in the modern world, and one of the most important safety mechanisms in homes. Whenever electrical wiring in a building has too much current flowing through it, circuit breaker cut the power until somebody can fix the problem. Without circuit breakers, household electricity would be impractical because of the potential for fires and other mayhem resulting from wiring problems and equipment failures. This work was carried out to build a mains AC short circuit breaker.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

CHAPTER ONE

• INTRODUCTION
• BACKGROUND OF THE PROJECT
• PROBLEM STATEMENT
• AIM OF THE PROJECT
• PURPOSE OF THE PROJECT
• APPLICATION OF THE PROJECT
• LIMITATION OF THE PROJECT
• RESEARCH QUESTION
• DEFINITION OF TERMS
• METHODOLOGY
• PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

• OVERVIEW OF THE STUDY
• TYPES OF ELECTRICAL SHORT CIRCUIT
• MAIN CAUSES OF ELECTRICAL SHORT CIRCUIT
• PREVENTING MEASURES OF A ELECTRICAL SHORT CIRCUIT
• REVIEW OF DEVICES THAT PREVENT SHORT CIRCUIT
• REVIEW OF OTHER TYPES OF CIRCUIT BREAKER
• ORIGINS OF CIRCUIT BREAKER
• STANDARD CURRENT RATINGS

CHAPTER THREE

METHODOLOGY

• SYSTEM BLOCK DIAGRAM
• SYSTEM CIRCUIT DIAGRAM
• PARTS LIST
• CIRCUIT DESCRIPTION

CHAPTER FOUR

4.0      TEST AND RESULT ANALYSIS

• CONSTRUCTION PROCEDURE AND TESTING ANALYSIS
• CASING AND PACKAGING
• ASSEMBLING OF SECTIONS
• TESTING OF SYSTEM OPERATION

CHAPTER FIVE

• CONCLUSION
• RECOMMENDATION
• REFERENCES

CHAPTER ONE

1.0                                                        INTRODUCTION

1.1                                           BACKGROUND OF THE STUDY

Domestic mains electric power, available in every house, carries high voltages and currents and thus is potentially very dangerous. Since this power is intended to be used with quite heavy loads like water heaters, geysers, refrigerators etc., the electricity generated at the power stations is specifically and intentionally raised to powerful levels (Mega Watts) so that it can satisfy the required heavy consumptions at each and every house. The various loads (electrical equipment) in our houses are uniformly distributed, therefore current through the conductors (wires) inside the equipment and out are uniformly and safely distributed. Also, because the relevant wires are properly sized to carry the correct amount of current and the connected loads offer appropriate resistances, everything runs normally and peacefully.

During a short circuit, the conductors (wires) offer no resistance, the flowing current finds a free path to travel and hundreds of amperes of current are instantly dumped into the wires. Since domestic wiring is designed to carry a much lower magnitude of current normally, it becomes red hot and can start burning in such a situation. A short circuit may occur because of human error while repairing or amending the existing wiring of a house, animal interference like rats, or the internal malfunctions of an appliance.

The main aim of this work is to build an electronic circuit breaker for a short circuit faults which will automatically operated electrical switch designed to protect an electrical circuit from damage caused by excess current from short circuit.

1.2                                                  PROBLEM STATEMENT

A short circuit in a house wiring may appear to be something which happens very infrequently and electricity users are not too interested to get any relevant precautionary measure installed in their houses and take the hazard very casually.

However once in a while due to some accidental fault, a short circuit in the mains wiring becomes inevitable and it the happening causes a disaster and huge lose.

At times the consequence leads to fire hazards and even lose of life and property. In other to protect our lives and properties from this risk a short circuit breaker was designed.

1.3                                                     AIM OF THE STUDY

The main aim of this work is to understand the making of a simple 220 V, 120 V AC mains short circuit breaker using an SCR and a triac combination.

1.4                                                PURPOSE OF THIS STUDY

The main purpose of this work is a have a safe supply of electricity, that is, to protect our electricity supply from short circuit.

1.5                                          APPLICATION OF THE PROJECT

Main circuit breaker MCB units can be use in our homes, offices or workshops.

1.6                                           LIMITATION OF THE PROJECT

A relay was not use for the cut-off, because relay contacts will simply fuse with each other due to heavy current arcing across the contacts during a short circuit condition, and therefore it is highly unreliable.

1.7                                                   RESEARCH QUESTION

At the end of this work, this study shall be able to answer these questions:

1. How do you fix a short circuit breaker?
2. What is AC circuit breaker?

• What part of a circuit breaker causes the breaker to trip on a short circuit?

1. What are the causes of short circuit?

1.8                                                        METHODOLOGY

To achieve the aim and objectives of this work, the following are the steps involved:

1. Study of the previous work on the project so as to improve it efficiency.
2. Draw a block diagram.

• Test for continuity of components and devices,

1. Design of the device was carried out.
2. Studying of various component used in circuit.
3. Construction of the circuit was carried out. The construction of this project includes the placing of components on Vero boards, soldering and connection of components,

• Finally, the whole device was cased and final test was carried out.

1.9                                                         DEFINITION OF TERMS

1. AC CIRCUIT: The circuit that is excited using alternating source is called an AC Circuit. The alternating current (AC) is used for domestic and industrial purposes. In an AC circuit, the value of the magnitude and the direction of current and voltages is not constant, it changes at a regular interval of time.
2. CIRCUIT-BREAKER: an automatic device for stopping the flow of current in an electric circuit as a safety measure.

• SHORT CIRCUIT: an electrical circuit in a device of lower resistance than that of a normal circuit, especially one resulting from the unintended contact of components and consequent accidental diversion of the current.

1.10                                                      PROJECT ORGANISATION

The work is organized as follows: chapter one discuses the introductory part of the work, chapter two presents the literature review of the study, chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.