Design And Construction Of A Programmable Automatic Changeover Switch

ABSTRACT

Power failure is a key issue in many developing countries of the world. To sustain development, the need for alternative power supply becomes necessary. Changing between the main supply line and the alternative supply poses yet another problem. Many attempts have been made to develop automatic power changeover but without due consideration of the fact that there could be times when we need to regulate the behavior of the automatic change over. This paper therefore presents the design and construction of microcontroller based programmable automatic power change over. The paper discusses the design, construction and operation of a program controlled power change over system that allows users to select the mode they would prefer to have their change over operate. Three modes were achieved, including auto mode, timed mode and manual mode, which were selected from push buttons. LCD interface was used for the output display. PIC16F873A microcontroller was used to implement the control program while modular methodology was adopted.

TABLE OF CONTENTS

 TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRCT

TABLE OF CONTENT

CHAPTER ONE

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

CHAPTER TWO

LITERATURE REVIEW

2.1      REVIEW OF THE RELATED STUDY

2.2      HISTORICAL BACKGROUND OF AN AUTOMATIC CHANGEOVER

2.3    REVIEW OF ELECTRICAL PHASES

2.4      REVIEW OF THREE-PHASE ELECTRIC POWER

CHAPTER THREE

3.0      CONSTRUCTION METHODOLOGY

3.1      BLOCK DIAGRAM OF THE SYSTEM

3.2      CIRCUIT DIAGRAM

3.3      HARDWARE DESCRIPTION

3.4      SYSTEM OPERATION

3.5      IMPLEMENTATION

3.6      POWER REQUIREMENT

3.7      PROGRAMMING OF THE MICROCONTROLLER

3.8      DESCRIPTION OF MAJOR COMPONENTS USED

CHAPTER FOUR

4.0      RESULT ANALYSIS

4.1      CONSTRUCTION PROCEDURE AND TESTING

4.2      CASING AND PACKAGING

4.3      ASSEMBLING OF SECTIONS

4.4      TESTING OF SYSTEM OPERATIONOBSERVATIONS

4.6     DIFFICULTIES ENCOUNTERED ON THE SYSTEM

4.7      PICTURE OF THE SYSTEM AFTER CONSTRUCTION

4.7      COST OF PRODUCTION

CHAPTER FIVE

• CONCLUSION
• RECOMMENDATION

5.3     REFERENCES

CHAPTER ONE

• INTRODUCTION

In Nigeria today the problems of power outage across phases is so rampant thus leading to some sensitive equipment and appliances being redundant, this could sometimes be the cause of one phase going out with respect to the other.

It may surprise one to note that in an attempt to solve this problems, so many unskilled electricity consumers has  in recent past resorted to some crude means of swapping between phases to obtain power. So many souls have been lost in this act. This is an undesirable condition to consumers and the need now arises to design a device that can automatically select among the phases and make power supply available at the consumer’s terminal.

However, this can only be possible if one have a three phase met or and there is supply from any of the service line or the entire line, this project known as a three phase automatic phase selector has been constructed with a view of solving the problems stated above. The design and construction was based on the principle of Electro magneto-Dynamism and alignment as demonstrated in the contactor arrangement.

Among other components are the timers miniature-circuit breakers the contactors and indicator bulbs, the ease with which the device is operated is well elaborated to ensure simplicity effort were made to present a stop by step operation of the project. As much as there is no project without limitation and applications, we have as well dedicated a section of this paper to look into it.

In order to ease the effort of technicians in restoring the devices should there be any malfunction associated.

Faults and how they are cleared is presented, however, there are no user serviceable parts in the device therefore all maintenance should be referred to a qualified electrical personnel.

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 from generator to PHC when power comes back, using contactor as the switching device.

• AIM/OBJECTIVE 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.

1.3                        SIGNIFICANCE OF THE PROJECT

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.

1.4                           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.

1.5                               SCOPE OF THE PROJECT

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.

1.6                                         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.

1.7                                            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.    

1.8                            LIMITATION OF THE PROJECT

• It requires maintenance because they involve less complex components, particularly in terms of testing maintenance and replacement part.
• The cost of designing the device is higher the parts are higher than that of the manual changeover.
• Changeover switches have been known to respond to false signals when the switching device becomes faulty, this scenario that could waste generator power, albeit in small amounts.
• Operating voltages: 220V-240
• Phase – one phase
• Capacity – single Phase
• Input Volt – 220v

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.