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Design And Construction Of Automatic Change-over For Three Phases
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It has the following draw back
ï¶ Poor sensing ability to fluctuation due the fact that relays do not function optimally at low voltages.
ï¶ Switching time in the event of mains power supply outage is low because switching is done in the basis of energizing and de-energizing of the relay coil
ï¶ Relays generate a lot of heat during switching action which could caused short circuits which are very hazardous
ï¶ Relays draw a lot of power from the power supply thereby increasing the overall power consumed by the load
It time like this, there is really no new invention rather what we have now are just improvement and innovation on fundamental principle of obtaining the desired result. Hence, the automatic change-over switch that is designed and constructed is an improvement on what other have done over the years.
A past project was designed such that is being supplied from just three power sources. The present design is such that it would take two different sources to simultaneously and also give preference to this power sources with the unique ability to ensure that there is always power supply to the load at all times.
2.4 RELATED WORK
The present invention that related to an automatic change over device has been designed for a power sources to automatically switch over system for supplying electric power to an electric load in such a manner that electric power output from an engine generator in supplied to the electric load upon occurrence of the power failure of a regular power sources system as it is been used by used patent on 21st may, 2002.
There is an automatic switch-over known, for example from Japanese patent application laid-open No 5-64382 and the likes which is designed so that a switch in change-over to supply electric power output from an engine generator to an electric load upon occurrence of power failure of a regular power source system.
In such an automatic switch over device for the power source it is necessary not only to provide an emergency automatic switch-over mechanism, but also to provide a measure for enabling switch by an operator’s manuals operation in case of failure or the like of a control unit.
This automatic switch-over devices for a power source comprise switching unit which has first and second individual contacts which is individually leading to a regular power source system and an engine generator and common contact leading to an electric load where the common contact can be alternatively electrically controlled unit for controlling the switching unit in such a manner that the common contact is electrically connected to the second individual contact in response to the regular power source system being electrically failed and the common contact is electrically connected to the first individual contact in response to the restoration of said regular power source system, where in the switching unit is made of a relay which consist of :-
ï¶ A see-sew-type turn member carried on a support frame for turning movement between first turned positions in which the turn member permits the common contact to be electrically connected to the first individual contest and a second turned position in which the turn member permit the common contact to be electrically connected to the second individual contact.
ï¶ A spring member for exiting a spring force for retaining the turn member in one of the first and second turned position in response to the turning movement of the turn member passing through a central point between first and second turned position.
ï¶ A first solenoid capable of exerting an electromagnetic force for driving the turn member toward the turned position against the spring force of the spring member.
ï¶ A second solenoid capable of exerting an electromagnetic for driving the turn member toward the second turned position against the spring force of the spring member.
With such arrangement of the feature the supplying of electric power from the engine generator to the regular power source system and the supplying of the electric power from the regular power source system can be automatically switching manner by the control unit.
According to a second aspect and feature of the present design in addition to the arrangement of the first feature a neumatic timer is incorporate to achieve the aim of letting the switching system switch OFF the generator set when not required for use in a case where power is not restored by the PHCN (supply).
The present design has been achieve with the above circumstances in view and it is an object of the present invention to provide and automatic change-over for a power source where in the switching can be achieved by the operator’s manual operation without provision of a special mechanism.
The above and other objectives features and advantages of the design will become appeared from the following description of the preferred embodiment taken in conjunction with the accompanying diagram (us patents issued 21st May, 2002
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ABSRACT - [ Total Page(s): 1 ]ABSTRACT The main aim of any electric power supply in the world is to provide uninterrupted power supply at all times to all its consumers. Although in developing countries, the electric power generated to meet the demands of the growing consumers of electricity is insufficient hence instability and outage. Power instability or outage in general does not promote development in the public and private sector. The inventors do not feel secure to come into a country with constant or freq ... Continue reading---
APPENDIX A - [ Total Page(s): 1 ]BILL OF ENGENEERING MEARSUREMENT AND EVALUTION (BEME)The table below shows the cost estimate in naira and kobo of constructed automatic change-over panel.Bill of Engineering Measurement and Evaluation ... Continue reading---
TABLE OF CONTENTS - [ Total Page(s): 1 ]TABLE OF CONTENTS Title Page Certification Acknowledgements Abstract Table of Contents CHAPTER ONE1.1 Introduction 1.2 Aim and Objective of the Project 1.3 Scope of the Project CHAPTER TWO2.1 Literature Review 2.2 Manual Change-over Switch 2.3 Automatic Change-over Switch 2.4 Related Work 2.5 Reasons for Automatic Change-over Switch 2.6 Problems of Automatic Change-over Switch CHAPTER THREE3.1 Methodolog ... Continue reading---
CHAPTER ONE - [ Total Page(s): 1 ]CHAPTER ONE1.1 INTRODUCTION Power instability in developing countries creates a need for automation of electrical power generation or alternative sources of power to back-up the utility supply. This automation is requiring as the rate of power outages become predominantly high. Research in the field of electrical electronics engineering has led to the tremendous discovers and inventions especially in the area of automation and power control. These invention have been useful in solvi ... Continue reading---
CHAPTER THREE - [ Total Page(s): 4 ]START AND STOP BUTTONS These two push buttons are used to close and open the circuit respectively. The start push button is a normally open type (NO) while the stop push button is a normally close (NO) type to breaker the circuit when need arise3.5 CONTACTOR Is a device designed for repeatedly making and breaking an electronic power circuit. It is usually operated magnetically. It can be operated in line or be remotely governed by pilot devices or relay. And when there is a s ... Continue reading---
CHAPTER FOUR - [ Total Page(s): 4 ]CHAPTER FOURCONSTRUCTION4.1 LIST OF COMPONENT USEDThe following electronic components used in the project are list below(1) Voltmeter (2) Casing (3) Vero-Board(4) Transformers DC 12V(5) Diodes (6) Capacitors 100(7) Resistors 4k(8) Contactors (9) 16mm2 Cables(10) 1ooAmp connector (11) Bolt and Nuts(12) Indictor light (13) Relay three phase (14) 555IC timer 4.2 VERO BOARD: is a brand of strip-board, a p ... Continue reading---
CHAPTER FIVE - [ Total Page(s): 1 ]CHAPTER FIVE5.1 CONCLUSION The automatic change-over switch has immense advantage in every area where power is required it is a fact that there is hardly any aspect of human life were electrical power is not required, at home, offices, hospital, etc. It find a wide application scope, wherever the re-ability of electrical supply is necessary, for switching to an alternative source from main.5.2 RECOMMENDATIONThe automatic change-over switch is needed in every home and of ... Continue reading---
REFRENCES - [ Total Page(s): 1 ]REFERENCEB.L. and A.K. Theraja (1997): Electrical Technology, S. chand company LTDEngr. A.O Aduloju (2003): Electrical Power System, Evidence Nigeria VentureEngr. M.B Jenyo (2007): Electrical Power System III & IV lecture Notes, UnpublishedEngr. T.A. Mustapha (2006): Electrical Power System I & II inn lecture Notes, unpublishedInternet Research: http://www.electricalsolution.comM.S. Ahmed, A.S. Mohammed & C.B. Augusibo (2006): Development of a single Automatic change-over switch Federal Universi ... Continue reading---
