CHAPTER ONE INTRODUCTION 1.1     Background to the Study

Electric power interruptions are quite common in every place, especially after a heavy down pour or a severe storm. To counter this power outage, a search has been to find a reliable and economical alternative source of electricity. Although this kind of project has been dealt with for quite a number of time but the fact still remains that an improvement needs to be done. This in essence makes the project topic “Investigation of the performance index of 3.5KVA/48V inverter” purposeful and resourceful.

        An inverter is a device or an electronic that converts or inverts a direct current into a conventional alternating current. A power inverter is a great tool used to run household / office appliances, where there is no electricity. The input voltage and frequency of the inverter may be fixed or it may vary depending on its application. Inverters finds several applications of which are the valuable speed, alternating current motors, uninterrupted power supply etc. They can be used as the front stage of dc to dc converter. Standby inverters are mostly used to provide emergency supply to the main frequency (50Hz). In the event of main failure, the inverter immediately operates with no loss of waveform. This unique ability makes it related to an automatic change over switch but it differs in a way in that it has a battery, which stores energy when the mains is on and gives out energy when the mains is off while the automatic change over switch operates on contactor (open and close).

         There are many types of inverter as described in chapter 2, but they all have the same principle of operations and it all depends on the component used, whether with a thyristor or a bipolar junction transistor for switching the current ON/OFF. The need for man to prevent his activities from being interrupted in order not to render it incomplete which may subsequently become an unfinished job (loss of files in the computer when there is a sudden power outage) has motivated engineers across the globe to design a device which will be more economical, durable and efficient.

It is pertinent to note that in a well organized company in a developing country like Nigeria, where a lot of transactions are made, if there is an epileptic power supply, the flow of transaction will greatly be hindered and there will be no open ground for the infant companies to spring up and wax great. Power should not be an obstruction between companies and their maximum profits, this in essence makes the use of a power inverter relevant and recommended to all and sundry. Hence, the need for the investigation of the performance index of various inverters comes to play. And this helps to determine which inverter is more efficient, portable, durable, and cost effective.

1.2     Statement of the Problem

The primary aim of engineers in the society is to solve the problems militating against technological growth, provide solutions to challenges facing humanities and bringing about efficient flow of ideals and innovators in the world of technology throughout the society and all nation of the earth. Inverter is that device which is being employed by the engineers to tackle and support the power supplies. This support comes to play when there is power outage. Immediately, the power inverter begins to act in place of the main power. Inverter are used in the conversion of direct current to a conventional alternating current, but the need for a reliable and more efficient, stable power supplies make the inverter indispensable especially in developing country like Nigeria where there is an epileptic power supply. Hence the need for investigation of the performance index of 3.5kVA/48V inverter in relation to other inverters becomes vital.

           Although, the electric power in an alternating current form is very difficult to store due to power loss which are associated with the alternating current and when converted, it can be in stored in the battery of which can be recharged.

1.3     Aim of the Study

The aim of the study is to evaluate the performance index of 3.5KVA/48V inverters for domestic electric power supply.

1.4     Objectives of the Study

                The objectives of the study are stated as follow.

1.     To determine the output wave form of the inverter

2.     To determine the battery discharging current/voltage on load and the effect of load on the inverter

3.     The determine the  power efficiency (real-time output power ratings)

1.5     Methodology

`        The methods adopted to achieve the set objectives are as follows.

1.     The Cathode ray oscilloscope was used to measure output wave form.

2.     The resistive and inductive load tests were applied to determine the battery discharging current/voltage on load and the effect of loads on the selected inverter

3.     Clamp meter, amp meter and volt meter were utilized.

1.6     Scope of the Study

In this study, the capacity of power inverters considered is 3.5KVA/48V with an output of 220-230V, frequency of 50Hz. And four different inverters vendors selected are Mercury, Safer power, Sinergy and Su-kam.  The choice of selection is based on the availability, portability, customer patronage and assesses to parts or repair.