Design And Construction Of An Automatic Phase Selector For 3-Phase Power Supply

1.0 INTRODUCTION
1.1 BACKGROUND OF THE STUDY

In Nigeria today the problems of power outage across phases is so rampant thus leading to some sensitive equipment and appliances being redundant, this could sometimes be the cause of one phase going out with respect to the other.

It may surprise one to note that in an attempt to solve this problems, so many unskilled electricity consumers has  in recent past resorted to some crude means of swapping between phases to obtain power. So many souls have been lost in this act. This is an undesirable condition to consumers and the need now arises to design a device that can automatically select among the phases and make power supply available at the consumers terminal.

However, this can only be possible if one have a three phase met or and there is supply from any of the service line or the entire line, this project known as a three phase automatic phase selector has been constructed with a view of solving the problems stated above. The design and construction was based on the principle of Electro magneto-Dynamism and alignment as demonstrated in the contactor arrangement.

Among other components are the timers miniature-circuit breakers the contactors and indicator bulbs, the ease with which the device is operated is well elaborated to ensure simplicity effort were made to present a stop by step operation of the project. As much as there is no project without limitation and applications, we have as well dedicated a section of this paper to look into it.

In order to ease the effort of technicians in restoring the devices should there be any malfunction associated.

Faults and how they are cleared is presented, however, there are no user serviceable parts in the device therefore all maintenance should be referred to a qualified electrical personnel.

In this system, If any one or two phases in a 3-phase supply interrupted/goes low and you want equipment to work on normal voltages then this circuit will give solution. This system is designed to monitor the presence of supply to the three phases and to display condition of each phase on an LCD.

1.2 AIM AND OBJECTIVES OF THE PROJECT

The main aim of this work is to build a device that will provide uninterruptable power supply for single phase loads even in the failure of one or two phases in a three phase system. The objectives include:-

1. To build the system prototype
2. To develop a simple low cost device aimed at easing the prevalent burden faced by delicate offices, parastatals and institutions who need very low but constant power supply. Since supply is always on along the distribution lines that supply such sites, what pesters on the progress of work thereof is always the unwarranted trip of phases due to power usage from neighboring consumers. The automatic phase selector therefore, erases this setback form the face of progress of work in such offices.
3. To stimulate the interest of upcoming students to take up research not only in their field of study “Electrical/Electronic Engineering” but also to extend their arms to other disciplines, thus enhancing the versatility of Electrical/Electronic Engineering.
4. To create awareness that will stimulate the interest of fellow students who intend to take up research topic on automatic switch of any type.

1.3 SIGNIFICANCE OF THE PROJECT

Industries require three phases power to run their machinery. Some of them require continuous \ uninterrupted power to maintain their data. Auto phase selector unit for those equipment whose supply is single phase. The single phase supply is selected automatically from three phases supply.

Auto Phase Selector introduces an automatic solution to overcome power fluctuation \ phase interruption by selecting next most healthy available phase to feed the equipment.

1.4 STATEMENT OF THE PROBLEMS

In every home, office or industries, automatic phase selector plays a vital role, that is, It provides a means of switching from one phase of AC mains to another in the case of failure in the existing phase; This project has been improved on the existing types of electromechanical device that has being in use over the years.

In the course of designing this project, different kinds of problem was notice such as:

• Difficulty in troubleshooting with circuit without the circuit diagram
• Difficulty in connecting the output without the three phases short-circuiting, until a multiplexing circuit was gotten.
• Difficult in wiring because of the strong wiring the project required..

1.5 SCOPE AND LIMITATION OF THE STUDY

This work covers only a three phase automatic phase selector which can only be used for providing a means of switching from one phase of AC mains to another in the case of failure in the existing phase.

1.6 APPLICATION OF THE PROJECT

Applications of this project are as below:

• Small and Medium Scale Industries
• Residential Apartments.