Design And Construction Of A 60a Three Phase Automatic Changeover Switch Using Comparactor

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 consumer’s 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. This device is capable of handling load up to 60A and the switching device (relays) are rated 60A.

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 changeover 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 changeover 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 changeover 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 DEFINITION OF TERMS

CHANGEOVER: Generally, a changeover switch is a system which could be operated manually or automatically , that changes one source of power supply to another source in case of power failure from either of the two sources.

RELAY: relay is one of the major components used in this work which is an electrical device, typically incorporating an electromagnet, which is activated by a current or signal in one circuit to open or close another circuit.

POWER FLUCTUATIONS: is a periodic dip or spikes in the electrical current of any given circuit.

POWER FAILURE: is a short- or long-term loss of the electric power to an area.

1.7 LIMITATION OF THE PROJECT

• It requires maintenance because they involve less complex components, particularly in terms of testing maintenance and replacement part. 

• The cost of designing the device is higher the parts are higher than that of the manual changeover.

• Changeover switches have been known to respond to false signals when the switching device becomes faulty, this scenario that could waste generator power, albeit in small amounts.

• Operating voltages: 220V-240

• 60A is the maximium load it can handle.

1.8 PROJECT WORK ORGANISATION

The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:

Chapter one of this works is on the introduction to changeover switch. In this chapter, the background, significance, objective limitation and problem of changeover switch were discussed.

Chapter two is on literature review of changeover switch. In this chapter, all the literature pertaining to this work was reviewed.

Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.

Chapter four is on testing analysis. All testing that result accurate functionality was analyzed.

Chapter five is on conclusion, recommendation and references.