1.1 Introduction
Standby power is an extreme necessity these days owing to bad quality of power supply. The present AC power lines are based in spike surges, transients, sags and noise. This result in failure of electronic equipment and without adequate protection; all electronic equipment is at a great risk. The fundamental purpose of a UPs is to provide an uninterruptible source of power for the equipment it protects. For instance, an electric device plugged into the wall has only one source of power, thus if there is a blackout, the electricity is cut and the device obviously goes off immediately. An Uninterruptible Power Supply (UPS) changes all this equation by providing its equipment two sources of power. UPs are designed so that there is one source and another source that kicks in if the primary is disrupted, called the secondary power sources, and the battery contained within the UPs in the other.
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitations of the Study and Definition of technical terms.
1.2 Background of Study
Over the years, there had been epileptic power supply due to uncontrollable factors such as vandalization of electric cables, drop in volume of water flows in dams, heavy rainfall overloading of transformers, bridging of power cables. While there are many less expensive methods one can employ to provide some degree of protection for ones PC (for example) from power problems, none of them c an insulate your system from trouble as well as good UPs with a voltage analyzer. The idea behind a UPs is pretty obvious from the name. In addition to filtering, enhancing or modifying the utility power, special circuiting and batteries are used to prevent the PC (for example) from losing power during a disruption (black out) or voltage sap.
In this design, transistors, comparators and regulators have been used as the basic building blocks in order to facilitate a robust design to give the desired multi-output required. Hence, reducing the number of components used in circuit design and also increases the functionality of the power supply unit. Modified sine wave inverters produce similar square wave output except that the output goes to zero volts for a time before switching positive or negative. They are simple low cost and suitable for many electronic devices except for sensitive or specialized equipment such as computers, laser printers, microwave, ovens, and fluorescent lighting audio equipment. A pure sine wave inverter produces nearly perfect sine wave output (typically below 3% total harmonic distortion) that is essentially the same as utility supply grid power thus it is compatible with AC electronic devices.
Electrical power interruptions are quite common in every place especially after a power outage, heavy down pour or a severe storm. In response to this power outage, a more economical, noiseless and emission free, alternative source of electricity -surpassing the use of the generators, solar and more recently the inverters is both the self-charging inverter. Both the generators and inverters come with their adverse problems such as cost of fuelling, the noise, emissions and the need to recharge the inverter’s batteries after use. However, these different types of inverter require charging of the batteries after depletion (use) and this call for a self-charging inverter that constantly recharges its battery when in use.
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to design and construct a 500 Watts Uninterruptible Power Supply with Voltage Low Indicator (Inverter).
1.3 Statement of Problems
Investigation revealed that the existing system lacks necessary switching transistors, rectifier diodes, and filter capacitors caused certain performance problems that were costly to minimize. As a result, these supplies were used only in airborne, space, or other applications where cost was a secondary consideration to weight and size.
1.4 Aim and Objectives of Study
The aim of the study is to design and construct a 500 Watts Uninterruptible Power Supply with Voltage Low Indicator (Inverter). In achieving this aim, the following specific objectives were laid out as follows to design and construct a system that will:
- Help reduce our reliance on the burning of fossil fuels.
- Produce a constant, stable and efficient electricity supply using inverter.
1.5 Significance of Study
This study will be of immense benefit to Electrical Engineers, PHCN Company and other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.6 Scope of Study
The study of this research is focused on the Design and Construction of 500 Watts Uninterruptible Power Supply with Voltage Low Indicator (Inverter). The project work is limited to the design of a standby Uninterruptible Power Supply (UPS) with a voltage LED indicator.
The designed Uninterruptible Power Supply (UPS) specification is as follows:
Output Capacity
Simple phase = 500Watts
DC Input
Voltage = 12V (battery)
Inverter Output
Voltage = 240V = 5%
Frequency = 50+-1Hz
Output wave form = Square wave
1.7 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).
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