ABSTRACT
This project work-up deals on the
design and construction of a single phase step down nations fermor, with raking
IKVA, 240V/11OV, 80V 12U, 6V. It is a multi-circuit transformer that has one
input as the primary and tappins to produce the output (secondary). It is
considered as a single coil in series with the supply and a common coil to the
head. It is experimentally done using flat metal shocks of cast steel to form
the “E” and “I” shaped laminations and coils of various turns.
Not much progress has been made by
those who were in the field in the production of a much circuit
auto-transformer. While working this project, we got information from some
textbooks on auto-transformer and some expert in the field.
However, the write up goes beyond the
perspectives of an ordinary layman’s belief that the theory behind the
construction of an auto-transformer cannot be achieved practically by Nigerian
Engineers in this country. Every aspect of the auto-transformer.
TABLE OF CONTENTS
Cover Page
Dedication
Acknowledgements
Abstract
Table of
Contents
CHAPTER ONE
1.0
Introduction
1.1 Background
1.2
Aims of Study
1.3
The Scope of Study
1.4
The Auto-Transformer
1.5
Definition of Terms
CHAPTER TWO
2.0
Literature Review
2.1 Definition and Operation of
Auto-Transformer
2.2
Formulae of Auto-Transformer
2.3
Components of Flux in an Auto-Transformer
2.4
Fauits in Auto-Transformer
2.5
Losses in Auto-Transformer
CHAPTER THREE
3.0
Construction
3.1 Construction of the Former
3.2
Methods of Counting Members of Turns
3.3
Standard wire Guages and Lamination
3.4
Construction of the Enclosure and Complete Unit
3.5
Testings
3.6
Precautions
3.7
Bill of Quantities
CHAPTER FOUR
4.0
Conclusion
4.1 Recommendation
References
CHAPTER ONE
1.0
INTRODUCTION
Electrical
energy has been considered as one of the numerous form of energy and it
distinguished itself vividly by the widest application in the recent years.
Electrical
energy is particularly useful by reasons of the case with which it can be
distributed and converted to other desired forms lighting effects, heating
effect magnetic effect of electrical energy can be used to ran our inclustrus,
boil our water, provide light for our homes as well as servicing and easing
other human endeavours.
The wide
use of electricity has necessitated the development of systems of transmission
and distribution. Transmission systems are required (a) to enable sources of
natural energy (eg water fails – dams, or storage loaves, reservoirs for
hydropower station, fuel fields, coal gas, diesel – for thermal generating
station), for distant from the centre of energy demand (e.g large works,
industrial areas of cities), to be economically utilized, (b) to enable
generating plant to be concentrated in a few large. Favourably situated
stations; and (c) to per met of the in for connection of network or
distributing areas to ensure reliability economy and stability or continuity of
supply.
There are
three main facts in the production and utilization of electricity namely:
generations transmission, and distribution generation of electrical energy
employs electrical power stations. These power stations generate electrical
energy making use of fuel (e.g coal, gas, diesel) as mom raw material; hence
thus type is called steam or thermal power station. Other power stations make
use of water falls or storage haves – hence called hydro electric power
station: etc.
No mater
the type of the power station employed, the voltage generated is usually in a
low level e.g 11KV or 25KV. Owing to the distance between the centre of energy
dim and (consumption areas) to the power stations, transmission system of
energy times into play. A high voltage is desirable for transmitting large
power in order to decrease the 12R losses and reduce the amount of
conductor material. Therefore, a transformer is employed to step up the
generated voltage to 3300KV/ the highest National Grid voltage although effort
are being made to increase it to 765KV for transmission. This 330KV is
transmuted to the distribution ends. A very much however voltage, on the other
hand, is required for distribution, for various reasons connected with safely
and convenience. The transformer also mavies this easily and economically
possible as the 330KV is stepped down to 132KV, 66KV, 33KV, 11KV, 415KV and to
a minimum level of 240V for distribution to various load centre (consumption
area).
1.1 BACKGROUND
The device
to increase (step up) or decrease (step down) the generated voltage is called
the transformer. It is a static (stationary) alternating consent machine.
Basically, transformers are classified
according to purpose namely:- power transformer, distribution transformer,
Auto-transformer and instrument transformer, power transformer are large transformers
generally used at generating stations to step up the voltage, and at the
substations to step d0wn the voltage for supplying distribution systems. They
may also be used for tionving together two power stations. The power
transformer has a high utilization factor, e.g it is arranged that they run
with an almost constant load which is equal to their rating. The maximum
efficiency is designed to be at fall load. This means that the fall-load
winding losses must be equal to the here losses.
According to common usage, a
transformer rated over 500KVA is termed a power transformer.
The distribution transformer has a
intermittent and variable head which is usually considerable less than
fall-head rating. They are therefore, designed to have their maximum efficiency
at between half and three – quarter of fall head.
The instrument transformers are of two
types depending on the mode of operation voltage or current transformers. The
current (series) and voltage (shunt) transformers are used for extending the range
of a.c. instruments in preference to shunts and series resistors.
1.2
THE AIM OF
STUDY
The aim of our study is to design
and construct an auto-transformer which can step-down 240V from the local
supply down to 110V, 80V, 12V, 6V, to sent the various voltage requirements of
numerous electrical and electronic appliances, often appliances imported from
say America where the domestic voltage level is 110Volts.
This auto-transformer can
conveniently do at a relatively cheap cost or rate. The output of this transformer
is made by making numerous tapping on the primary winding depending on the
required output.
1.3
SCOPE OF
STUDY
The scope of our study is
committed to 1KVA auto-transformer (stepdown) that has these tappings as
follows 110V, 80V 12V, 6V. In view of this any other thin out side this topic
would not be considered.
Because of
the various voltage levels on the secondary, it can be used to supply voltage
to American equipment at 110V, for welding machines and electronic equipment at
12V, 6V and 80V, and for barberry charging at 6V or 12V.
1.4
DEFINITION
OF TERMS
Transformer: A transformer is alternating
current machine which is usual to increase (step-up) or decrease (step down)
voltage (a.c).
Auto- Transformer: This is a transformer with
single winding. The single winding is common to both the priming and the
secondary of the transformer.
Winding: The winding of a transformer is
the band of copper conductor which is wound into many farms on the transformer
core.
Core: The core of a transformer is a
pile of haminated sheets of science steel.
Turns: This is the number of times or
rounds the copper conductor is wound on the core.
Lamina: This is a single sheet of the soft
iron which is insulated or lamination.
Primary Winding: The primary winding of a
transformer is the winding that is directly connected to the over is the
winding that is directly connected to the supply.
Secondary Winding: This is the winding that is
directly connected to the head.
Tappings: Tappings refers to the connections
which are usually made successively in the winding of a transformer especially
in auto transformer.
Step up: When the primary voltage is lower
than the secondary voltage, the transformer is caved a step up transformer.
Step down: When the primary voltage is higher
than the secondary voltage, the transformer is called a step down transformer.
Window: This is the space in the
transformer core bounded by the 10Kes and the timbs of the transformer.
Varnish: This is an insulating Tigard which
used to increase the insulation of the transformer core and winding as well as
making it inechanically strong. It so laxities when air acts and it.
Copper Conductors: These are bare copper worse
which are used in transformer windings.
Wire Sleeve: This can be fibre or plastic
coating which is used to insulate and isolate the transformer winding
terminals.
Slot Popper: This is a thick insulating paper
which is used to wrap the transformer winding and separate each layer of the
winding. It serves as mechanical protection.
Center Block: This is a wirden block
approximately the size of the central limb of the transformer core. It is on
the centre block that the former is made.