CHAPTER ONE
INTRODUCTION
1.0 BACKGROUND OF THE STUDY
              It is a well known fact today that electrical power supply is not reliable. All over the world, there is a significant electrical power supply interruption. Because of these electrical power supply interruption, many electrical equipments have either developed problems or even stopped working entirely. Hence this has crippled much business thereby affecting even the economy of many countries as Nigeria. Also there is increase in occurrence of power supply disturbance, which can be viewed as a form of power pollution. High voltage spikes and momentary voltage drops are therefore common. These power disturbance may affect the performance of sensitive equipment in private and corporate organization causing loss of data ad even damage to equipment.
             In Nigeria today, it is not an over-statement to talk about the epileptic supply of electrical power. This has become the order of the day such that many Nigeria now view these power outages as “Normal” and part of their daily life. A wide range of factors have been identified for this problem. They include natural disasters, vandalism, maintainability and sustainability and lack of local content. The problem of poor quality power supply cannot be properly addressed without a review of other factors such as lack of political will to invest adequately in power sector, absence of replacement policy resulting in obsolete equipment, unsustainable human capacity building and inadequate reward and remuneration system to motivate human resources team to perform well.
               According to the recommendation made by the Institute of Electrical Electronics Engineering (IEEE), the supplies that should be available for use should be continuous, uninterrupted with constant frequency and within the load determine in terms of voltage and current. These requirements have become even more relevant in view of the high sensitivity and sophistication of modern technological equipment in use today.
               The progress made in developing alternate source of energy over the last decades has shown that independent power systems are not only possible but also very practical. In fact a wide variety of generating equipment is now available to allow individuals take advantage of just any renewable source of energy, for number of reasons, however, most of these system produce only direct current (DC) and often do so only at low voltages. Nonetheless, it is generally agreed that the greatest and most useful form of current is the Alternating current (AC), since these exist in the vast majority of homes.
Therefore, there arises the need to able to convert Direct Current (DC) to Alternating Current (AC) that will be of a constant frequency and also be used to power electrical circuits either in homes or in industries. Such electrical device is called an INVERTER.
             An inverter is a power electronics device or apparatus which converts direct current to alternating current, allowing the direct current power from these generators to be used with ordinary a.c appliances and or mixed with the existing electrical grid.
An inverter is an electrical device that converts direct current (DC) to alternating current (A.C); the converted A.C can at any required voltage and frequencies, with the use of appropriate transformer, switching and control circuit. Inverters are commonly used to supply A.C power from D.C sources such as panels or batteries.
This inverter is designed to provide uninterrupted 220volts a.c supply to the loads connected at its outputs socket. It provide a constant a.c supply to the output socket even when the a.c mains supply is no longer available. When the a.c main supply is available, it goes to the a.c mains sensor, relay and battery charging section of the inverter. This a.c mains sensor informs the relay about the availability of a.c mains supply. When this relay receives a.c mains signals from the main supply, it directly passes the a.c main signals to the inverter output socket.
             The electrical inverter e.g. 5000watts or 5KVA, 220-240v, 50Hz, is high power electronic oscillator. It is also named because early mechanical AC to D.C converters were made to work made to work in reverse and thus were “inverted” to convert D.C to A.C. the inverter performs the opposite function of a rectifier.
If one want to select an inverter, like 5000watts,
Total load to be connected = 5000watts
Power factor = 0.8(all inverters have a power factor between 0.6 and 0.8)
Inverter VA = 5000/0.8 = 6250 VA
So select a 7000VA inverter to run 5000watts loads