DESIGN AND CONSTRUCTION OF AN AUTOMATIC CHANGEOVER SWITCH FOR THREE POWER SOURCES WITH LOAD MANAGEMENT

Abstract
Instability of power supply is a major challenge in developing countries including Nigeria. The need for alternative power supply makes the switching of load between two or more power sources imperative. The Automatic Changeover eliminates the need for manual or human intervention by sensing mains supply and switching to an available source. Automation eliminates the delay and the cost of inefficiency associated with manual operation. The device automatically switches between three power sources. This is implemented using a microcontroller. The automatic changeover consists of power supply circuit consisting of step-down transformer, rectifier (full wave), filter capacitor, voltage regulator, logic circuit that detects when mains supply is restored, a relay driver, a liquid crystal display, a shift register, and an auto-generator start/off circuit. After the design, construction and testing of this system, it was found to have performed satisfactorily in switching from mains supply to renewable energy source and to generator based on the set preference.

CHAPTER ONE
INTRODUCTION
1.1 Background of the Study
For a very long time, power outages, power interrupts and also unexpected routine power line maintenance is one of the major problems faced in industries, hospitals, offices, and homes over the whole world. For that case, this project provides an automatic operation of electrical power distribution systems; rapid and reliable transfer of the system from one power source to another during specific events such as power outages, power interrupts, routine power line maintenance, to achieve the reliability of such systems [1]-[2].
Electrical power supply is one of the primary essential needs of human life today, that is to say, without electrical power supply, most human activities become stand still, postponed and even cancelled since they are dependent on the electrical power supply.
Furthermore, the need for power supply by the masses of both developed and developing countries is very important for the development of the economy of that particular country. In other words, the power sector plays an essential role in the socio-economic development of any nation.
Therefore, this project offers a practical solution by providing an automated switching between three power sources to the load during power cuts or in cases where power outages cannot be avoided.
1.2 Statement of the Problem
Power outage is one of the major challenges faced by homes, schools, offices, hospitals and industries, which is not proper for efficient operation of these organizations.
This project is designed to automatically supply continuous power from three alternative power sources which are; Mains, renewable source and a generator using microcontroller.
1.3 Aim
To design and construct an Automatic Changeover Switch for three power sources with load management.
1.4 Objectives
To design an Automatic Changeover System for three power sources with load management that is affordable by the general public.
Implement an automated system for switching between three power sources.
Implement the system to automatically start the generator when the supply switches to generator mode.
1.5 Expected Benefits of the Project
Safe electrical power source switching as it does not require human intervention.
Increased availability of power supply due to rapid transfer of power between the various sources.
Improved stability of the power supply.
Reduces the downtime associated with power outages and interrupts.
1.6 Scope of the Work
This project work employs microcontroller to achieve rapid and reliable transfer of load between three power sources, setting the order of switching and load separation.
1.7 Limitations of the Project
This project is limited to only the three power sources.
The generator auto-start function is only compatible on a key start or button type of generator.
The GSM module will only alert the user when there is network signal.
1.8 Structure of the Report
This report is organized in five chapters. Chapter one covers the introduction to the research work, stating the problems that led to the research, the objective of the research, the scope, limitation and its significance to life. Chapter two gives an overview and analysis of related works, also it discusses in detail the components used in the design and implementation of the Automatic Changeover Switch. Furthermore, chapter three describes the working principle and the design processes used in the development and implementation of the system. Chapter four states the various test conducted on the developed system to ensure its functionality and the results gotten from the test conducted were collated and analysed with the findings expressed in tables. Finally, chapter five summarizes the entire research work, giving concluding remarks and recommendations for further study.