Design and Construction of Automatic Change-Over Switch With Indicator
Chapter One
AIMS AND OBJECTIVES OF THE PROJECT
The aims and objectives of this project is to:
Design and construct an automatic change-over switch with indicator that will switch load from the mains power supply (PHCN) power supply (Generator) with simplicity.
To introduce a circuitry that will sense power outage and at the same time sense fluctuationin the power supplied to the load at any point time.
CHAPTER TWO
LITERATURE REVIEW
HISTORICAL DEVELOPMENT OF THE PROJECT
Before the development of semiconductor power electronics, changeover switches were manually operated. So many drawback were associated with the manually methods. The evolutionary trend in industrial electronics has brought about a tremendous advancement and innovations. This is borne mostly in automation and control. In 1959, the advent of micro electronics gave birth to the study of integrated circuits, like voltage regulators, op-amps and other solid state pawed devices.
This millennium industrial electronics has brought a lot of modifications and innovations in power electronics automation and control. (Forrest, 1982) Having taken cognizance of this in-depth chronology in automation, I deemed it necessary to embark on a project research on the design and construction of automatic change-over switch with indicator. My first encounter with power change-over was at Metropolitan Electronics Development, Research & Training Institute, where, on a workbench, an RF remote was used to switch ON/OFF of a Gen set from a distance. I decided to modify it by removing the RF part and integrating a delay circuit and a change over circuit to achieve an automatic power change over, with Gen switching.
During my project research, I visited three reputable technological research institutes like SEDI – Enugu, PRODA – Enugu and EDI – Awka where I was furnished with information relevant to my project design by senior colleagues.
APPLICATIONS OF THE PROJECT
This project work has a vast application in almost anywhere power exists. It is very useful in the sense that it eliminates the stress involved in manual change-over and the associated dangers of electrocution and fire out break. It can be used in households and offices that have ignition Gen sets. It can be modified to handle high capacity power Generating Set from 3.5. KVA to any level.
This project work has a vast application in almost anywhere power exists. It is very useful in the sense that it eliminates the stress involved in manual change-over and the associated dangers of electrocution and fire out break. It can be used in households and offices that have ignition Gen sets. It can be modified to handle high capacity power Generating Set from 3.5. KVA to any level.
CHAPTER THREE
DESIGN METHODOLOGY
DESIGN METHODOLOGY
Before any project is achieved, the development methodology should be taken into account. This includes the different distinct phases of achieving the aim. There are three design methodology is used in software/Engineering project development. The choice of the approach is determined by certain factors ranging from cost, time, and reliability and so on.
TOP – DOWN APPROACH
This is a sequential project development approach, in which development is seen as flowing steadily downward like water fall through several phases. Top down methodology is also called Waterfall model. It is a model in which the project is achieved from top to bottom. It also depicts that the project is realized from the known to the unknown. It has some merits associated with it. It is a traditional Engineering model. It is not flexible.
CHAPTER FOUR
SYSTEM DESIGN
DESCRIPTION OF THE SYSTEM BUILDING BLOCKS
The project design and construction of automatic change-over switch is designed using block diagrams to appropriately illustrate the steps involved in its construction. The first block is the power supply unit synthesized from each of the 3 phases. And it is realized in four primary steps. The second block is the voltage regulation realized using shunt regulation. The third block, their outputs are fed into a Decimal – to – BCD priority encoder that selects the highly prioritized phase at any given time. The fourth block is the BCD – to – Decimal decoder configured to select the appropriate phase.
CHAPTER FIVE
IMPLEMENTATION, TESTING AND RESULT
IMPLEMENTATION
The components were all tested one after the other to ensure that they are in good working conditions. After testing the components, they were mounted on project board as specified on the circuit diagram. The different modules were tested on the project board using digital multimeter and were malfunctioning as a result of wrong placement of transistor and zener diodes. (Matha, 2009) After the corrections of these encountered problems, the components were transferred to the Vero-board for permanent soldering. The integrated circuits (ICs) were mounted on IC socket for easy accessibility and protection against thermal runaway during soldering.
CHAPTER SIX
SUMMARY AND CONCLUSION
PROBLEMS ENCOUNTERED AND SOLUTION
During the project research and Implementation period, I encountered some problems that stand as impediments to rapid accomplishment of the project work. These inherent problems include:
Data acquisition on the hardware components procurement especially the priority encoder. This problem was later solved with a helping hand from a reputable institution of electronic system development in Enugu where I was furnished with Boolean algebra equivalent of the priority encoder, and some information on how to realize some of the system configurations and specifications by the procurement of most of these components used for this project.
Transistor identification and partial contacts: I was able to identify the transistors polarity using modern digital meter with Hfe test socket which gave a directions on how to identify the base, Emitter and collector. Also problems of partial contacts came as result of setting with dry joint which was solved by re-soldering with a very sharp bit and soldering lead with reasonable percentage of flux.
One of the most different problems the confronted me during this project was the design calculations which was solved with the aid of some pertinent design analysis in some lecture notes.
RECOMMENDATION
The following recommendations were made after the project research;
I recommend the use of microcontroller or programmable logic device as the control logic in the subsequent researcher in automatic 3 – phase change over with Gen set switching facility.
I also recommend the use of LCD/SSD to display the phase and to make it presentable.
I recommend that entrepreneurs invest in this device owing to it usefulness and reliability.
CONCLUSION
This project, design and construction of an automatic change- over switch with indicator were a dream come through. It was realized using the available electronic components in the local market. It is a prototype of the Real- life system because of the ratings of the contactors used in the design. The design is rated for 2.2.KVA Gen. Set and appliances and should not be used for a higher rated device.
REFERNCES
- Eke, J. (2003) Physical Electronics; El’dmark Pub. Enugu
- Ekemezie, P.N. (2001) Elements of Ind. Electronics
- Forest, M. mins (1982) Electronics Sensor and Circuit
- Guputa, G.R (2002) Power System Control PWB New Delhi
- Jung, W.G. (1983): IC Timer Cookbook (second edition), Sams Technical Publishing.
- Kleitz, W. (2005). Digital Electronics – A practical Approach (Seveth Edition), Pearson Education inc. Upper Saddle River New Jersey.
- Manaha, L. (2008) Modern Power Control Circuit. Norton Mumbai.
- Matha V.K (2009) principle of electronics 8TH ED. S.C. Chanad, N-I
- Mehila, V.K and Robit, M. (2009). Principles of Electronics (Eleventh Edition). Rajendra Printers Ltd.
