Design And Construction Of A Three Phase Automatic Selector With Generating Plant Changeover

ABSTRACT

This project work is on the design and construction of automatic power changeover for 3-phase power supply. It provides a means of switching from one phase of AC mains to another in the case of failure in the existing phase or under-voltage, and also automatic power changeover from public utility supply to generator and vice versa was aimed at providing a useful system for use in our homes or offices. The system was achieved with a 66A 3-Ф contactor, 100mA transformers and relays. The system turns on a generator when the public utility (PHCN) is off by cranking the starter and a provision was made to stop cranking when the generator is fully started.  This project has been improved on the existing types of electromechanical device that has being in use over the years.  Hence this has been achieved by the use of operational amplifier, timing circuit and high current relay switches and it is powered by 12V dc power supply.

The aim of this work is to design and construct an Auto Phase Selector introduces an automatic solution to overcome power fluctuation/phase, 0r interruption by selecting next most healthy available phase to feed the equipment without any notice of power outage.

TABLE OF CONTENTS

 TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

TABLE OF CONTENT

CHAPTER ONE

• INTRODUCTION
• AIM/OBJECTIVE OF THE PROJECT
• SIGNIFICANCE OF THE PROJECT
• STATEMENT OF THE PROBLEMS
• LIMITATION OF THE PROJECT
• PURPOSE OF THE PROJECT
• APPLICATION OF THE PROJECT
• PROJECT ORGANIZATION

CHAPTER TWO

2.0      LITERATURE REVIEW
2.1      REVIEW OF ELECTRICAL PHASES
2.2     REVIEW OF THREE-PHASE ELECTRIC POWER
2.3     REVIEW OF THREE PHASE GENERATION AND DISTRIBUTION
2.4    REVIEW OF THREE-PHASE LOADS

CHAPTER THREE

3.0      METHODOLOGY

3.1      BLOCK DIAGRAM OF THE SYSTEM

3.2      DESCRIPTION OF SOLAR INVERTER UNITS

3.3      SYSTEM CIRCUIT DIAGRAM

3.4     CIRCUIT OPERATION

3.5     THREE PHASE INPUT TO SINGLE PHASE OUTPUT

3.6      DESCRIPTION OF COMPONENTS USED

CHAPTER FOUR

RESULT ANALYSIS

4.0     CONSTRUCTION PROCEDURE AND TESTING

4.1     CASING AND PACKAGING

4.2     ASSEMBLING OF SECTIONS

4.3     TESTING OF SYSTEM OPERATION

4.4      COST ANALYSIS

CHAPTER FIVE

5.0     CONCLUSION

5.1     RECOMMENDATION

5.2     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 consumers 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 contractors 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.

• OBJECTIVE OF THE PROJECT

The objective of this work is to design a device that will overcome power fluctuation in the phase or interruption by selecting next most healthy available phase to feed the Equipment, to change power over to generator, to change back to PHC to change the generator.

1.3                                      SIGNIFICANCE OF THE PROJECT

Industries require three phases power to run their machinery. Some of them require continuous \ uninterrupted power to maintain their data. Auto phase selector unit for those equipments whose supply is single phase. The single phase supply is selected automatically from three phases supply.

Auto three phase power changeover introduces an automatic solution to overcome power fluctuation \ phase interruption by selecting next most healthy available phase to feed the equipment.

This automatic change over unit operates in 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.

1.4                       STATEMENT OF THE PROBLEMS

In every home, office or industries, automatic changer plays a vital role, that is, It provides a means of switching from one phase of AC mains to another in the case of failure in the existing phase; 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 the three phases short-circuiting, until a multiplexing circuit was gotten.
• Difficult in wiring because of the strong wiring the project required..

1.5                         LIMITATION OF THE PROJECT

This work covers only a three phase automatic changeover which can only be used for providing a means of switching from one phase of AC mains to another or from generator to utility supply in the case of failure in the existing phase.

1.6                             PURPOSE OF THE PROJECT

The purpose of the project is to provide the supply for the single phase load from the one of the active phase of the 3-phase supply but if there is power failure in the three phases the device will switch over to generator set.

Another purpose of this work is to provide a constant power supply to consumers.

1.7                       APPLICATIONS OF THE PROJECT

This device provides constant power supply in our:

• Homes
• Workshops
• Worship centre (such as churches or mosque)
• Offices
• And any other places that electrical energy is been used

1.7                              PROJECT ORGANIZATION

 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 work is on the introduction to this study. In this chapter, the background, significance, objective limitation and problem of this study were discussed.

Chapter two is on literature review of this study. 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.