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Design And Construction Of A Mains AC Short Circuit Breaker

Electrical Electronics Engineering | Industrial Physics | Physics

The design and construction of a mains AC short circuit breaker involve intricate engineering processes to ensure efficient protection against electrical faults. This breaker, a crucial component in electrical systems, interrupts excessive currents to prevent damage to equipment and ensure safety. Typically, it consists of a set of contacts, a mechanism for tripping, and an arc extinguishing system. The contacts, often made of copper or other conductive materials, form the path for current flow. Upon detecting a short circuit, the tripping mechanism swiftly separates these contacts, halting current flow. Additionally, an arc extinguishing system quenches the resultant electrical arc, preventing re-ignition and damage to the breaker. Modern designs often incorporate advanced materials and technologies to enhance performance and durability, ensuring reliable operation in diverse electrical environments.

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:

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

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

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:

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

Test for continuity of components and devices,

Design of the device was carried out.
Studying of various component used in circuit.
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

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.
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.