Automatic Phase Selector With Changeover Switch For 3-Phase Power Supply

ABSTRACT

This project work is on the design and construction of automatic phase selector with changeover switch for 3-phase power supply. It provides a means of switching from one phase of AC mains to another in the case of failure in the existing phase; it also changeover to generator if there is failure in all the three phases of the AC mains. The circuit also senses the restoration of any or all the three phases of the mains and changeover without any notice of power outage. This project has been improved on the existing types of electromechanical device that has being in use over the years.

Hence this has been achieved by the use of operational amplifier, timing circuit and high current relay switches and it is powered by 12V dc power supply. The aim of this work is to design and construct an Auto Phase Selector introduces an automatic solution to overcome power fluctuation/phase interruption by selecting next most healthy available phase to feed the equipment without any notice of power outage.

 CHAPTER ONE

• INTRODUCTION

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.

1.2                                          OBJECTIVE OF THE PROJECT

The objective of this work is to design a device that will overcome power fluctuation phase interruption by selecting next most healthy available phase to feed the equipment.

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 PROJECT

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                                           PURPOSE OF THE PROJECT

The purpose of the project is to provide the supply for the single phase load from the one of the active phase of the 3-phase supply.