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Design And Construction Of Automatic Changeover For Three Phase

Electrical Electronics Engineering | Engineering | Industrial Engineering

The design and construction of an automatic changeover for three-phase power systems involve the integration of electronic components and control mechanisms to ensure seamless transitions between power sources in case of a failure or change in supply. This system typically includes relays, contactors, voltage sensors, and a controller programmed to monitor the incoming power sources and activate the appropriate switches accordingly. The design must prioritize reliability, efficiency, and safety, incorporating features such as phase synchronization, voltage regulation, and overload protection. By employing robust engineering principles and utilizing advanced technologies, the automatic changeover system can guarantee uninterrupted power supply to critical loads, making it essential for industrial, commercial, and residential applications where continuity of operation is paramount.

ABSTRACT

The main aim of any electric power supply in the world is to provide uninterrupted power supply at all times to all its consumers. Although in developing countries, the electric power generated to meet the demands of the growing consumers of electricity is insufficient hence instability and outage.

Power instability or outage in general does not promote development in the public and private sector. The inventors do not feel secure to come into a country with constant or frequent power failure.

These limit the development of industries. In addition, there are processes that cannot be interrupted because of their importance. For instance, surgery operation in hospitals, transfer of money between bank and lots more. Power instability and outage in developing countries (Nigeria) creates a need for alternative source of power to backup the main supply.

Automatic changeover switches find a wide application scope wherever the reliability of electric supply from the utilities is low and it is used in lighting motor circuits wherever continuity of supply is necessary. For switching to an alternative source from main supply and vice versa.

This project is a design of an automatic changeover switch this means that when there is any mains failure, the automatic changeover switch will change to an alternative power supply (GENERATOR) and back to the main supply when it is restored.

The purpose of this project is to maintain constant supply to the main circuit that is being supplied by making up for the time delay that usually accompanies the manual switching from one source to another.

The design comprises of the power connection circuit and control connection circuit. The main components to be used include contactor, relay, timers, rectifiere.t.c.

TABLE OF CONTENTS

Title Page i

Certification ii

Acknowledgements iii

Abstract iv

Table of Contents v

CHAPTER ONE

1.1 Introduction 1

1.2 Aim and Objective of the Project 3

1.3 Scope of the Project 3

CHAPTER TWO

2.1 Literature Review 5

2.2 Manual Change-over Switch 5

2.3 Automatic Change-over Switch 6

2.4 Related Work 10

2.5 Reasons for Automatic Change-over Switch 16

2.6 Problems of Automatic Change-over Switch 17

CHAPTER THREE

3.1 Methodology (Material and Methods) 18

3.2 Circuit Conductor 18

3.3 Circuit Breaker 19

3.4 Reset Timer 20

3.5 Contactor 21

3.6 Operation of Timer Delay 24

3.7 Principle of Operation 25

CHAPTER FOUR

4.0 Construction 29

4.1 List of Component Used 29

4.2 Vero Board 29

4.3 Bread Board 30

4.4 Soldering Iron 33

4.5.1 Testing, Maintenance and Discussion 36

4.5.2 Polarity Test 36

4.5.3 Insulation Resistance Test between the Live and Neutral Conductors 37

4.5.4 Earthling Test 37

4.6 Maintenance of Contactor and Installation 37

CHAPTER FIVE

5.1 Conclusion 39

5.2 Recommendation 39

References 40

Bill of Engineering Measurement and Evaluation (BEME) 41

CHAPTER ONE

1.1 INTRODUCTION

Power instability in developing countries creates a need for automation of electrical power generation or alternative sources of power to back-up the utility supply. This automation is requiring as the rate of power outages become predominantly high. Research in the field of electrical electronics engineering has led to the tremendous discovers and inventions especially in the area of automation and power control. These invention have been useful in solving the over-in.

Creating problem posed by power generation, distribution and control, which has been a cause of concern especially in the third world countries (developing countries) like Nigeria. Most industrial and commercial process is dependents on electric power and if process of a change-over is manual, serious time is not only wasted but it creates room for human error (in the area of change over connections) which could result in great economic loss.

This project is all about the construction of an automatic generator change-over panel with timer which aids in the switching over to alternation power supply authority i.e.Power Holding Company of Nigeria (PHCN) popularly known as NEPA which is the main power regulating body in Nigeria. This project consist of circuit breakers, electromagnetic contactor which carry heavy load current relay which work with the principle of electromagnetic induction because it will receive electrical signal to trigger and neumatic timer all incorporated and interconnected to achieve the desire goal.

Also this project is constructed in such a way that provision is made for manually operation (it can be operated manually) when necessary for required for example, in the situation whereby voltage supplied by the authority (PHCN) is fluctuating and one may decided not to use it, so the constructed automatic change-over panel can be permanently switch to generator set temporarily pending the time that utility supply is stable moreover in the hospital where where surgery operations is needed to be carry out and power outage for even five second cause damages, one may decide to neglect the supply from authority (PHCN) and permanently switch the panel to manual operation pending the time or period by which surgery operation is completed. During the pending period this change-over will be working continuously in manual operation. Fill someone or the operation has to switch over to automatic operation. As said earlier, provision is made for these types of generation in this project and there is separate switch that performed the function.

1.2 AIM AND OBJECTIVE OF THE PROJECT

The aim of the project is to design and construction automatic change-over switch load from the mains power supply (PHCN) to a backup power supply (Generator) with simplicity.

The advantages of this project cannot be over emphasized, since outage is a major problem is the advent developing nations like Nigeria, for example, power failure of minute in an airport terminal can create losses that could run into millions of dollars due to loss in air traffic system control the ability for back-up to start and change-over automatically becomes imperative under such circumstances.

Also, this project could play a large role in the security in banks and companies i.e. an outage of up to ten minute in an organized setup is enough to do all the damage required with such an automatic change-over device in place the generator backup would no longer have to depend on security men and of course reduced fear of system breakdown in the companies there by ensuring smooth running of economics activities.

1.3 SCOPE OF THE PROJECT

Basically, this project is a three phase automatic change-over device with the power capacity of 50KVA. Generator as deducted from my calculations it shows that generator of power rating ranging from 0.5KVA to 50KVA is required to be use for this project though the contacts of electromagnetic contactor relays and circuit breakers. Also the maximum load current should be between the ratings of 10A to 90A load current. Therefore the use of 10Amperes in this project is because of future extension.

1.4 REVIEW OF THE STUDY

The purpose of this project is to design and construct this unique equipment that provider a solution to the power supply problem we are facing in Nigeria today. The automatic change-over switch can be describe as a unique power supply to another as well maintaining constancy in the supply to a particular network load this equipment to be designed and constructed in this project will interface between two different electrical power source (e.g. the main supply and the generator).

The main source of supply to the unit is obtained directly from the public supply (PHCN) the relaying and triggering system serve as an interface between the supply and the load hence the load is not directly couple to the public supply. The triggering units sense the failure in supply and immediately the ignition switch of the generator.

Power change-over switch are two different mode of operation namely.

CHAPTER FIVE

5.1 CONCLUSION

The automatic change-over switch has immense advantage in every area where power is required it is a fact that there is hardly any aspect of human life were electrical power is not required, at home, offices, hospital, etc.

It find a wide application scope, wherever the re-ability of electrical supply is necessary, for switching to an alternative source from main.

5.2 RECOMMENDATION

The automatic change-over switch is needed in every home and offices because of the fact that it’s reliable, it’s durable, and it’s affordable and is ability to provide immediate automatic switching from the public power source to other sources.

It is recommended that further work be done on this change-over switch on large scale, for instant an automatic change-over switch that can be use in an industry.