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DESIGN AND CONSTRUCTION OF SINGLE PHASE AUTOMATIC CHANGE OVER SWITCH FROM GENERATOR TO POWER HOLDING COMPANY OF NIGERIA (P.H.C.N)

CHAPTER ONE

INTRODUCTION

1.1    BACKGROUND OF STUDY

The project is designed for power supply applications. It involves automatic changeover between the main power supply and an auxiliary power supply, such as a generator. The circuit of the project consists of logical control unit and relay switches. The basic operation of the project is to switch ON an auxiliary power supply (like a generator). This operation connects the power supply from the generator to the load after a predetermined time interval. Switching is possible through the use of the relays. The system was designed to automatically change power supply back to the main supply moments after the A.C. mains are restored and to switch OFF the generator. The device removes the stress of manually switching ON the generator when power failure occurs. The operation allows electric current to flow through the motor/starter. It is noted that one of the motors terminals is already connected to 12V+ terminals. The switching of the relay allows the other terminal to be grounded thereby completing the circuit of the electric motor.(Hammed and Mohammed, 2006).

Power supply 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 becomes necessary as the rate of power outage becomes predominantly high. Most industries and commercial processes are partly dependent on generators and public power supply which is epileptic especially in tropical Africould countries where Nigeria forms a part.
However, if the starting of the generator is automatically done by a relay which switches the battery voltage to ignition coil of the generator while the main power relay switches the load to either public supply or generator, the down time would greatly be reduce thereby maintaining the tempo of production in such industries. The approach used in this work is the modular approach where the overall design is first broken into functional blocks. Each of these blocks carries out a specific function in the entire system by the interconnections between the block (Kolo, 2007).

Electricity (energy), which plays a major role in economic development of a nation, forms the basis of this study, with interests in human, infrastructural and economic development. In most developing and underdeveloped parts of the world, the supply of electricity for industrial, commercial and domestic use is highly unstable. This gives rise to the frequent use of alternative sources of power supply to meet up with the energy demands. The introduction of these alternative sources of supply brings forth the challenge of switching smoothly and timely between the mains supply and the alternative sources whenever there is a failure on the mains source. There is also the need to reduce drudgery from switching between the two sources on the human side. Solving these challenges forms the focus of this work. The Automatic Change-over switch, automatically switches over to the alternative source of power supply (generator) when there is a power outage. It equally switches over to the mains supply when power is restored and turns off the generator automatically. Therefore automatic power change-over switch is a