ABSTRACT
Auto Phase Selector (ASP) system is used to
ensure continuous supply to load in case mains supply is not healthy. This unit
is very useful at the site at which main supply is irregular. It may be
sometimes very high or sometimes very low voltage. The frequent
failure/fluctuations of power affect life of power plant and battery. The
objective of the APS is to ensure that there is continued commercial power
supplied to the site at all times so as to ensure that the Base Transceiver
Station BTS) runs on commercial power until all available phases are either out
of electrical tolerance or completely off. This is a microcontroller based unit
three and it is used with three phase electrical supply.
Whenever the supply of one or two phases of a
three phase electrical line goes off, the ASP system automatically distribute
the electrical supply from the active phase to the failed phases. These ensure
continues power supply through all the three phases even if only one phase is
active.
TABLE OF CONTENTS
CHAPTER ONE
INTRODUCTION
1.1 Background
1.2 Aims/Objectives of the Project
1.3 Relevance of the Project
1.4 Scope of the Project
1.5 Limitations
1.6 Target Beneficiaries
1.7 Significance of Study
1.8 Achievement of the Construction of the Project
CHAPTER TWO
LITERATURE REWIEW
2.1
Introduction
2.2 Effect of Power Failure
2.3 Equipment Voltage Susceptibility
2.4 System Interactions and Solutions
2.5 Background of the Automatic Three Phase
Selector
CHAPTER THREE
METHODOLOGY
3.1 Information Gathering
3.2
Ways of Effecting the Design and Construction
of an Automatic three Phase Selector
3.2.1 Phase Selection by Manual Control
3.2.2 Phase Selection by Sequential Logic Control
3.2.3 Phase Selection by Microprocessor Control
3.2.4 Phase Selection by Comparator Control
CHAPTER 4
SYSTEM DESIGN ANALYSIS
4.1
Components Used in the Design and
Construction of the Automatic Three-Phase Selector
4.2 The Design Topology
4.2.1 The Power Supply Block
4.2.4 The Relays Switches
4.3 Design of the Circuit
4.4 Work of LM 741 Comparator
4.5 Comparator Using Operational Amplifier
4.6
Principle of Operation/Circuit Working of
the Automatic Three-Phase Selector
CHAPTER FIVE
SYSTEM TESTING,
RECOMMENDATION AND CONCLUSION
5.1 System Testing
5.1.1 Testing
Procedures and Results
5.2 Problems
Encountered
5.3 Result
5.4 Conclusion
5.5 Recommendations
References
LIST
OF FIGURES
Fig 1: Block diagram showing the
various stages of the automatic phase selector.
Fig
2: Block
diagram of power supply
Fig 3: Transformer only
Fig 4:
Transformer + Rectifier
Fig 5: Transformer + Rectifier + Smoothing
Fig 6:
Transformer + Rectifier + Smoothing + Regulator
Fig
7: Transformer windings
Fig
8: The transformer schematic
Fig
9: Transformer circuit
Fig
10: Circuit symbol for bridge rectifier
Fig
11: Output: full-wave varying DC
Fig12
(a): Positive swing of rectification
Fig
12 (b): Negative swing of rectification
Fig
13: The full wave bridge rectifier .
Fig
14: The output of the rectifier circuit.
Fig
15: The filtered output of the
smoothening capacitor
Fig
16: output signal wave form.
Fig
17: Relay
Fig
18: Circuit diagram on automatic phase
selector
LIST
OF TABLES
TABLE
4.1: Fair Child Table
TABLE 4.2: Phase
Selection Table
CHAPTER ONE
INTRODUCTION
As the growing
population of human race widens the gulf between energy supply and energy
demand, the imbalance in energy availability sent researchers into excavating
for a way of settling this age long squabble. A lasting solution is vested on
alternative use of the renewable energy source, a project that is yet to be
widely applied. Hence, the continuation of the unsettled yearns for sufficient
power. Consequently, the power lines are frequently over loaded resulting to a
trip of power by the action of switch gears or by the load shading process
undertaken by the distribution authorities.
Since it is
crystal clear that some institutions such as health related institutions and
some other delicate systems should not be allowed to suffer equally with their
counterparts, Automatic Phase Selector is used to sustain energy consumption in
the time of phase trip. The design of this circuit involves the use of
automatic switches but the details of design varies from place to place, time
to time and also depends on the type of load involved.
This project
involves the use of transistor driven relays to affect the change of phase
whenever the voltage condition becomes intolerable in the previous phase
connected.
1.1 BACKGROUND
The intelligent
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 electrical switching device (relay).
The transformer
used here is the step down type of transformer (it step down 240v to 12v) and
these transformer is feed in with different phase voltage, rectified and
smooth. Then fed in to a voltage regulator that has positive output. The
regulator outputs were connected to comparators. Here the comparators are three
in number. We call the comparators the brain of the system because these
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. In this
project we even went as far as using pictures for illustration of some
components.
1.2 AIMS/OBJECTIVES OF THE PROJECT
The analysis of
this project cannot go without enumerating the goals meant to be achieved in
the pursuit of the work. These objectives include:-
i. To
develop a simple low cost device aimed at easing the prevalent burden faced by
delicate offices, parastatals and institutions who need very low but constant
power supply. 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 form the face of
progress of work in such offices.
ii. To
stimulate the interest of upcoming students to take up research not only in
their field of study “Electrical/Electronic Engineering” but also to extend
their arms to other disciplines, thus enhancing the versatility of
Electrical/Electronic Engineering.
iii. To
create awareness that will stimulate the interest of fellow students who intend
to take up research topic on automatic switch of any type.
1.3 RELEVANCE
OF THE PROJECT
The issue of
selecting or switching over manually is now a thing of the past. Nowadays we
know that homes and offices enjoy steady power supply once the three phases are
available (i.e. red yellow and blue
phases). Is just a question of making a quick and automatic three phase
selector?
1.4 SCOPE
OF THE PROJECT
The scope of the
project covers aspects like the features of automatic three phase selector, its
applications, and its operations. Its advantages and its components.
Finally, it covers
the importance on the need of automatic three phase selector and contributions
toward a greater sharing load balance and a better three phase power
distribution and monitoring for domestics consumers.
1.5 LIMITATIONS
Owning to the
nature of this project, the research centers and the resources were not easy to
come by within the immediate environment. Some of the limitation encountered on
the course of this project include financial and time constrains which did not
really take much room for additional capacity beyond what is at hand.
1.6 TARGET
BENEFICIARIES
This project will
provide lasting solutions to the heavy losses incurred by commercial
institution, industries, hospitals, airport etc caused by poor manual selector
means and efficient switching facilities. It will also be of use in our
household because poor selector of phase manually causes damage to our
household equipment example electronics like television, radio, video player,
etc and electrical appliances like refrigerator, air condition, fans just to
mention but a few. Finally, another target is to eliminate the loss of human
life due to manual selection of the three phases.
1.7 SIGNIFICANCE
OF STUDY
The significance
of this project work cannot be overemphasized. This is because the number of
lives that has being lost to the hand of interruption of power in health
institutions and the like is not negligible. Delicate appliances have become
the main victim of this artificial circumstance. The applicability of the
outcome of this research work in several facets of human endeavour makes this
work of real importance to humanity.
The use of the
device produced from this research work would help to reduce human labour and
hazard, going by the fact that many have been handicapped by electric shock
because of the attempt they made to select another phase, and that the
handicapped are helpless and cannot change phase.
1.8
ACHIEVEMENT OF THE
CONSTRUCTION OF THE PROJECT
As long as
electrical generation and construction is must in everyday activities,
electrical power consumption is expected to be reliable and constant supply.
Therefore, what we
tend to achieve from this project is;
1. To
have constant power supply.
2. To
have quick operation i.e. phase selection
3. Reliable
power supply
4. Easy
operation
5. Avoidance
of risk in doing manual changeover or switch
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