Design And Contruction Of An Automatic Changeover With Alarm System

ABSTRACT

This paper reviewed the methods of implementing change over system and proposed a better and cost effective approach to realizing the same. Some of the approaches which have been employed to implement change over system include manual change over switch box, automatic change over system with electromechanical relays and change over system with automatic transfer switch. Each of the methods has some drawbacks that make it undesirable. Among these drawbacks are time wastage, possibility of fire outbreak, generation of noise, frequent failures, product damage, high component count to mention but a few. These contribute to the high cost of these methods. The approach proposed in this paper makes use of solid state relay(SSR) which eliminates totally the noise, arching, wear and tear associated with electromechanical relays. Digital integrated circuits and microcontroller were used to reduce the component count as well as improve the speed of the system. The system also has some desirable features like liquid crystal display (LCD) which makes the system user friendly, an alarm system for indicating generator failure, automatic phase selector for selecting most appropriate phase, over-voltage and under-voltage level monitoring.

TABLE OF CONTENTS

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

TABLE OF CONTENT

CHAPTER ONE

• INTRODUCTION
• BACKGROUND OF THE PROJECT
• PPROBLEM STATEMENT
• AIM/OBJECTIVE OF THE PROJECT
• SIGNIFICANCE OF THE PROJECT
• PURPOSE OF THE PROJECT
• LIMITATION OF THE PROJECT
• APPLICATION OF THE PROJECT
• DEFINITION OF TERMS
• PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

2.0     LITERATURE REVIEW

2.1     REVIEW OF ELECTRICAL PHASES

2.2     REVIEW OF THREE-PHASE ELECTRIC POWER

2.3     REVIEW OF CAUSES OF POWER FAILURES

2.4       POWER SUPPLY RELIABILITY

2.5       REVIEW OF EXISTING WORK

2.6       DESCRIPTION OF THE NEW SYSTEM

CHAPTER THREE

3.0      CONSTRUCTION METHODOLOGY

3.1      BLOCK DIAGRAM OF THE SYSTEM

3.2     IMPLEMENTATION OF MICROCONTROLLER BASE AUTOMATIC CHANGEOVER WITH ALARM

3.3     FLOWCHART AND SCHEMATIC DIAGRAM OF THE SYSTEM

3.4     SYSTEM CIRCUIT DIAGRAM

CHAPTER FOUR

4.0       TESTING AND RESULT

4.1     DISCUSSION

4.2     AREAS OF APPLICATION

CHAPTER FIVE

• CONCLUSIONS
• RECOMMENDATION

5.3     REFERENCES

CHAPTER ONE

1.0                                         INTRODUCTION

1.1                            BACKGROUND OF THE STUDY

Power instability in developing countries has necessitated the need for automation between public power supply and alternative generators to backup the utility power supply, and as the rate of power instability becomes predominantly high the need for automation also becomes high. And since most industrial and commercial processes require uninterrupted power supply, if the process of power supply changeover is manual, it will not only waste time by slowing the process, but could also cause device, process or product damage. There could also be error during the manual changeover as a result of human factor, and this in some cases can lead to massive loss of revenue. Therefore the major aim of this work is to exploit the ubiquitous microcontroller facilities in bringing about automation of changeover process. One of the most critical needs of an embedded system such as this is to decrease power consumption and space [7] and this is achieved in this work. It has been observed over the years that power instability has caused companies to lose millions of dollar each time there is power failure, as a result of the time lag between power failures and when power is restored. This can be seen clearly in companies like telecommunications, breweries, cold rooms to mention but a few.

This system was designed to proffer solution to the shortcomings of the already existing manual changeover by performing power swap from public power to generator automatically and vice-versa. It has the ability to eliminate the stress of manually switching on the generator when there is public power failure. It has an alarm system for indicating generator failure.

1.2                                   PROBLEM STATEMENT

Power failure or outage in a country, state or city is highly detrimental to development in public and private industries. The insecurity associated with constant or frequent power failure or outage brings about limitation to power  consistent investments, thus hampering the development of industries and multinational ventures. Processes like carrying out surgical operations in hospitals, laboratories which require constant power supply for research, money transactions  between banks and more require constant use of uninterrupted power. In other to solve this problem, an automatic changeover switch was invented. This research covers the design and construction of an automatic power changeover. It has the capacity to automatically switch power from  national grid to generator and vice versa.

1.3                                   AIMS AND OBJECTIVES

The main aim of any electric power supply in the world is to provide uninterrupted power supply at all times to all its consumers, a device which switches on the head from power Holding Company (PHC) to a generator when power fails and vice-versa, using relay as the switching device and it has an alarm system for indicating generator failure.

1.4                          SIGNIFICANCE OF THE PROJECT

The automatic change over switch, the switch aimed at achieving the following automatic actions;

• To change power over to generator
• To change back to PHC
• To change the generator.

The automatic change over unit can be operated in single or three phase system. The automatic change over switch has the following advantages;

• It minimizes damages to lives/equipment since it has its own monitoring system and its switching requires no human contact with the switch, thus eliminating human error.
• It reduces its change over timing to the minimum due to its fast response to power outage.
• It maintains high quality of service through its fast and prompt response.
• Moreover, the size and captivity of the unit will depend upon the load for which it will be used. The unit is also portable, easy, convenient and safe to install.
• Genset is put off automatically when main power resumes.
• Minimized physical activity is to start the generator.
• It can operate in low voltage.
• Fuel is saved due to auto stop facility.

1.5                           PROBLEMS OF THE PROJECT

In every home, office or industries, automatic power changeover plays a vital role, that is, It provides a means of switching from utility AC mains to generator in the case of power failure; This project has been improved on the existing types of electromechanical device that has being in use over the years.

In the course of designing this project, different kinds of problem was notice such as:

• Difficulty in troubleshooting with circuit without the circuit diagram
• Difficulty in connecting the output without short-circuiting, until a multiplexing circuit was gotten.
• Difficult in wiring because of the strong wiring the project required.

1.6                SCOPE AND LIMITATION OF THE STUDY

This work covers only a one phase automatic changeover which can only be used for providing a means of switching from one phase of AC mains to another in the case of failure in public utility. This type of changeover system is better than the manual changeover with switch box because it is automatic and faster, but has its limitations which are listed below:

• Noise associated with switching of
• Wear and
• Arching which can cause fire
• High Component count making the system more prone to

1.7                                    APPLICATIONS OF THE PROJECT

1. This circuit can be used as a home lighting system with few modifications.
2. It can be used to drive other DC loads like a DC motor of any electronic appliance or other toy applications.

1.8                                            DEFINITION OF TERMS

CHANGEOVER: Generally, a changeover switch is a system which could be operated manually or automatically , that changes one source of power supply to another source in case of power failure from either of the two sources.

RELAY: relay is one of the major components used in this work which is an electrical device, typically incorporating an electromagnet, which is activated by a current or signal in one circuit to open or close another circuit.

POWER FLUCTUATIONS: is a periodic dip or spikes in the electrical current of any given circuit.

POWER FAILURE: is a short- or long-term loss of the electric power to an area.    

1.9                          PROJECT WORK ORGANISATION

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 works is on the introduction to changeover switch. In this chapter, the background, significance, objective limitation and problem of changeover switch were discussed.

Chapter two is on literature review of changeover switch. 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.