DESIGN AND CONSTRUCTION OF AUTOMATIC PHASE SELECTOR

ABSTRACT

Auto Phase Selector (ASP) system is used to ensure continuous supply to load in case mains supply is not healthy. This unit is very useful at the site at which main supply is irregular. It may be sometimes very high or sometimes very low voltage. The frequent failure/fluctuations of power affect life of power plant and battery. The objective of the APS is to ensure that there is continued commercial power supplied to the site at all times so as to ensure that the Base Transceiver Station BTS) runs on commercial power until all available phases are either out of electrical tolerance or completely off. This is a microcontroller based unit three and it is used with three phase electrical supply.

Whenever the supply of one or two phases of a three phase electrical line goes off, the ASP system automatically distribute the electrical supply from the active phase to the failed phases. These ensure continues power supply through all the three phases even if only one phase is active.

TABLE OF CONTENT

TITLE PAGE

LETTER OF SUBMISSION

CERTIFICATION

ACKNOWLEDGMENT

DEDICATION

TABLE OF CONTENT

ABSTRACT

CHAPTER ONE

1.0     Introduction

11      Brief Description

1.2     Objectives of the Project

1.3     Significant of the Project

1.4     Project Hypothesis

CHAPTER TWO

2.0     Literature review

2.1     Functions of automatic switch

2.2     Different type of transfer switch

2.3     Conditioning Element

2.3.1 Resistors

2.3.2 Capacitors

2.3.2.1 Capacitors Makings

2.4     Diodes

2.4.1 Types of Diodes

2.5     Bi-Polar Junction Transistors

2.6     Discrete Components

2.6.1 The Electromagnetic Relay

2.6.    Primary Function of a Relay

2.6.2 The Contactor

2.6.3 Indicator Lamp

2.6.4 Selector Switch

2.6.5 Choice of Cable

2.6.5b Determination of Cable size Used

CHAPTER THREE

3.0     The MCU

3.1     Phase Detector

3.1     Phase Detector Circuit Diagram

3.2     Voltage Scalier

3.2     Voltage Scalier Circuit Diagram

3.3     Micro Controller Unit

3.4     Output Stage

3.5     Building an AC to AC Converter

3.6     The Relay

3.6.lb           Problems with Relays

3.6.2 The Crystal

3.6.2b Function of a Crystal 25

3.6.3 The Microcontroller Regulator IC (KLM 7805)

3.6.4 The Liquid Crystal Display (LCD)

3.6.5 The Microcontroller (PICs)

3.6.5 The Microcontroller (P Diagrams

3.6.5b Advantages of the PlC Microcontroller

3.7     Programming of a PlC

3.8     Word size of the PlC

3.9     Description of the Microcontroller (P

3.9b   Features of the PIC16FS76A

3.Sc   Design Specification of the P1C15F876A

CHAPTER FOUR

4.0     Constructional Stage

4.1     Writing of the Source Code

4.2     Assembling of the Code

4.3     Burning of the Code in the MCU Chip

4.4     First test

4.4     Testing of the Circuit on a Breadboard

4.5     Soldering of the Final Project on a veroboard

4.6     Casing of the Circuit

4.7     Advantage of a DPS

4.8     Components Used

4.9     Other Components Used

CHAPTER FIVE

5.0     Result and Conclusion

Testing

Recommendation

References

CHAPTER ONE

1.0    INTRODUCTION

Generation and availability of constant electricity of the right power has lead to the establishment and smooth running of industries, most especially in the advanced countries. At our various homes, electricity has made possible the use of devices like cookers, microwave-ovum, refrigerators, computers and so on. Unfortunately, most developing countries are suffering from high rate of power failure in one or two of the three phases, low voltage or high voltage supply.

In the early period of development of technology transfer switches were operated only manually by an operator.

This project is to improve availability of power supply since interrupted supply is highly required to operate electrical or electronics devices such as in the hospital equipments, to save the lives of patients under surgical operations. Industries also, as mentioned earlier, require continuous power supply in order to keep production operations in continuous form and to save millions of naira that could be lost as a result of power failure. These requirements have hastened the demand for the designing, construction and introduction of Digital Phase Selector which is an electrical/electronic device that switch to the loads, one phase out of the three phases automatically. It can detect and compare the three phases and then select the best (base on voltage measurement) so that power can always be available (provided that at least one of the phases is having power supply). Hence, this project is concerned with the design and construction of Digital Phase Selector, DPS for short.

A DSP can be defined as an electrical/electronic device used to switch electrical power supply into loads automatically and to compare and select the best phase out of the three phases. It is used to supply constant power to loads even if there is power failure on any one or two of the phases.

Moreover, the motive behind this report is to provide a comprehensive and concise coverage of the components used, and fundamentally gives a technical recount of the design and construction process involved. The project is an event-driven system, whose success revolves around a class of device: micro controller unit (Mcli). Detection is effected when sine wave mains voltage on each of the phases is converted into direct current, scaled down into the MCU which does the comparison and selection. It consist of eight stages which are power pack, phase detection, voltage scaller, ADC, comparator/selector, lcd and beeper drivers and output stages. Thus, some of the stages are taken care of by software codes {using basic language} which were burnt into a PlC microcontroller unit. The software approach considerably reduces the number of components, cost of production, project size. But on the other hand, it consumes time i.e. time for code writing and code debugging.

1.1    BRIEF DESCRIPTION

Back-up power could be defined as a system which takes care of the downtime for changing from one phase line or power supply to another. These require a Microcontroller (PIC16FS76A) which acts as the brain of the circuit) the microcontroller IC KLM 7805 etc. Some are manually started and stopped while others start and stop automatically. Based on this project the back-up electrical system is taken care of by the automatic transfer switch which is designed to switch automatically to the best preferred phase whenever there is voltage drop or power failure from PHCN or other sources.

This project is designed for both the three phases and single phase auto-start generator; it also designed for reliability with low maintenance.

1.2    AIMS AND OBJECTIVES

•        The main objective of this project which is part of an advancement in technology is to make life convenient and conducive.

•        To apply the knowledge acquired in the study of computer engineering in the designing of DPS.

•        To appraise a good proportion of the overall knowledge gained through a period of two academic sessions in a signed project work.

•        To enhance the understanding and functions of various electronic components and the combination of their characteristic to solve specific problems.

•        To enhance the scope of the knowledge of the designer in the area of both analogue and digital electronics.

•        To afford the learning of electronic software packages like express PCB for drawing circuit layout, proteus for circuit design and simulation and lastly, Micro basic pro compiler for writing codes, debugging

1.3    SIGNIFICANCE OF THE PROJECT

•        The importance of the project can be viewed from the benefits enjoyed practically and academically.

•        It tends to find answer to psychological reaction of electrical power consumer about electrical power failure.

•        The project will help n specifying the areas of education for engineering students and engineers.

•        The project will have great industries positively by increasing and improving productivity.

•        Academically, the project will provide more insight into phase selector system and engineers and engineering students will broaden their knowledge.

1.4    PROJECT HYPOTHESIS

This project is Instant automatic phase change over when any phase fails and it can get electric supply in all the 3-phase lines (provided any one phase is available) because it need not monitor for switching back and will surely yield the productivities in industries. It will also save time during production if the design and the testing is successful.