DESIGN AND CONSTRUCTION OF AN AUTOMATIC THREE PHASE SELECTOR

DESIGN AND CONSTRUCTION OF AN AUTOMATIC THREE PHASE SELECTOR

ABSTRACT

Power instability and phase failure has posed serious threat to economic development in Nigeria. Most companies; industrial, commercial and even domestic are dependent on public power supply which have erratic supply such as phase failure, phase imbalances or total power failure due to one or more technical problem in power generation, transmission or distribution. Much time would be wasted in the process of manual change over. This means that time and the process needed for the phase change may cause serious damages to machines even the products and may pose a threat to the life of the person while moving from one phase to a more suitable one. Hence, there is need for automation of phase change during phase failure or total power failure in order to safe guard consumer appliances from epileptic power supply. The following objective were achieved; to develop a simple low cost device aimed at easing the prevalent burden faced by delicate industries and institutions electrical equipment’s, to reduce the damages caused to our household equipment’s, eliminating the loss of human life due to electric shock from the manual selection of the three phases during supply of high voltage. The automatic three phase power system selector was designed and constructed. The device automatically switches over to the alternative phase that has voltage when there is power outage or extremely low voltage in the phase which the load is connected without the power going off. The selector links the load and the other phases and relay switches allowing the usage of the remaining phases where there is outage on the mains source without disturbing or interrupting the load. It maintains constant power supply to the load by automatically activating the phases when the need arises. the specification of Output power, Frequency, Input voltage, and output voltage of the designed Automatic Three phase selector are, Output power=500W, Frequency=50Hz,Input voltage =12Vdcand Output voltage=18Vac.The device reduced the possibility of power being off completely in case of power failure in any particular phase if users connect their electronics gadget to it and reduced the response time needed to switch from one phase to another. It is recommended that a software model of the design should be developed and simulated to enable further research and improve the performance of the system.

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

Power supply in Nigeria and most developing countries of the world is anything but stable. This has adverse effects on the consumers of the electricity and the equipment that are operated from the mains sources of electricity supply in these parts of the world. Power instability and phase failure has posed serious threat to their economic development (khairul, et al., 2011). This means where there is an erratic power supply, there is no development. However, most companies; Industrial, commercial and even domestic are dependent on public power supply which have erratic supply such as phase failure, phase imbalances or total power failure due to one or more technical problem in power generation, transmission or distribution (Adedokun,and osunpidan., 2010). Hence, there is need for automation of phase change during phase failure or total power failure in order to safe guard consumer appliances from epileptic power supply.

In most cases, many manufacturing companies, be it domestic or industrial, which employ single phase equipment for its operation, sometimes experience challenges during unbalance voltages, overloads and under-voltages, in power supply, much time would be required in the process of manual change over. This means that time and the process needed for the phase change may cause serious damages to machines and even the products, hence, there is need for automatic phase switching system. Considering also a case where a single phase public utility prepaid meter is operated with a single phase power supply unit and there is phase failure from the public utility power supply, the prepaid meter will stop reading. At this point, if the phase is not manually changed, the single phase prepaid meter will stop reading. That is to say someone needs to be present always to make the changes at any point in time. But to overcome these protocols, automatic systems need to be used. The automatic phase selector is a system that is capable of comparing three phases and switching automatically to any of the three phases. The system consists of three main parts namely; the transformer, comparators (which is the brain of the system) and electromechanical switching devices (relay/contactors). A step down type transformer (it steps down 220 Vac to 18 Vac) was used and fed in with different phase voltages, rectified, smoothened and regulated. The regulator outputs were connected to comparators. The comparators are connected in a way that each of them will give out an output. The relay in the system is where the output voltage is connected.

The importance and advancement of control system in engineering have created different ways in which automatic switching systems can solve domestic and industrial problems especially in the developing countries.

This project involves the use of transistor driven relays and contactors to effect an automatic change of phase whenever the voltage condition becomes intolerable in the previous phase connected. The design of this circuit involves the use of electromechanical switches but the details of design varies depending on the type of load involved.

1.2 Aim and Objectives

The aim of this work is to design a device that will overcome the challenge of switching over manually during phase interruption or power fluctuation by automatically selecting the next healthiest available phase to feed the equipment. In the implementation of this, the following objective were achieved:-

i. To develop a simple low cost device aimed at easing the prevalent burden faced by delicate industries and institutions electrical equipment’s. 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 neighbouring consumers.

The automatic phase selector therefore, erases this setback from the face of progress of work in such offices.

ii. To enhance a greater sharing load balance and a better three phase power distribution and monitoring for industrial and domestic consumers.

iii. To provide lasting solutions to the heavy losses incurred by commercial institution, industries, hospitals, airport etc. Caused by poor manual selector means and inefficient switching facilities.

iv. To reduce the damages caused to our household equipment’s example electronics like television, radio, video-player etc. And electrical appliances like refrigerator, air condition fans which is usually a result of poor selector of phase manually.

v. It is also aimed at eliminating the loss of human life due to electric shock from the manual selection of the three phases, during supply of high voltage.

TOPIC: DESIGN AND CONSTRUCTION OF AN AUTOMATIC THREE PHASE SELECTOR

Chapters: 1 - 5
Delivery: Email

Number of Pages: 50

Price: 3000 NGN

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