CHAPTER ONE
1.0 INTRODUCTION
As the zeal for change over on public power supply and
stand-by generator increases, Engineers have researched deep into the different
ways and methods of achieving power change-over both manual and automatic
types.
It may not be considered a serious issue in some places where
supply is up-to 90% constant or where intermittent outage causes no great
damage. However, places like the business centers, industrial areas, and even
cold rooms need almost 100% power supply. So in this case there is need to
provide a stand-by power supply in the event of power outage. The important
thing is to make sure an effective stand-by power supply which is constant and
reliable is provided to eliminate the problem of long time outage.
Before, this time, changeovers are operated manually, there
by making it difficult for power continuity without a time wastage. This is
because an operator must always be available at any point in time. This
manually operated change-over switch has two switchable positions-(main and
generator) an arm is also provided from where the operator can have access to
the switching. Here, the effectiveness, i.e. the fastness of the switching
anytime power needs to be changed is slow, and largely depends on the operator,
which means that the system will be in-effective whenever the operator is not
available.
The
second generation of change over switch were made semi-automatic in which the
main power supply directly powers the contactors. This arrangement is made in
such a way that if the main power supply fails, the contactors will all drop,
leaving the supply to the generator position. The effectiveness of the system
will now depend on the operator to start the generator on time.
The main problem suffered by the manual and semi-automatic
systems is that the operator must have to be continuously be on duty for it to
be very effective. This depends on fully closed loop system to operate.
With more research by the scientists and engineers to improve
on the earlier ones, the present day technology has made it possible for the
change over switch to be more effective and fast with less labour more
improvements has be made in terms of number of designs, using the closed loop
system at feed back control. Some also use comparators, logic circuits and
electronics timers to achieve the task.
The design of this project is in such
a way that control or switching is done without any noticeable sign. It uses a
combination of comparators digital switches (relays) and electromagnetic
switches to achieve a very fast and effective change-over in the case of power
failure. This type of switch does not depend on any operator to function well.
1.1 BACK GROUND
The background
to this project work is traced to the in tense demand of the populace and
industries, residential homes, and many more demand for change of power supply
switch for effective and continuity of power supply without a notice
interruption or delay in such process to any alternative supply if the main
supply goes off.
Earlier to
this time, such process is manually operated or not in used at all. The manual
type which is always strenuous and time delayed was a little bit useful but not
to a satisfactorily level. More level and expenses are always required to meet
up with the time factor and effectiveness required of this process of change
over. These expenses and labour could not be afforded by some individuals and
industries that needed to practice this change over.
Regard to this
solutions were suggested to improve the process, so the idea of change or
transforming the manual operated to automatic was discovered and engineers went
into work immediately and came up with this automatic change over switch. But
the demand for this equipment was much that something must be done to meet up
with increasing demand. But this increase in demand topples the decrease in
supply due to the cost of securing this equipment. The students went into this
project to find out how mass production could reduce the increase in demand or
meet up with the demand. They now decide to go further single handedly produce
this work and see how far it can be done without the help of industrial
machine.
After the approval, we went into market survey and evaluation
of the components, after a good study of the circuit diagram. The rating of the
equipment was also considered. A lot of considerations were made based on the
fluctuating nature and inconsistency of our main supply source. The cost of
procuring the system was put together and found out that it is less cost, and
easy in operation. The users can experience change over supply without an input
or extra labour.
With all these
considerations and studies we decided to put together this project.
1.2 AIMS /
OBJECTIVES
The primary
aim and objective of this project work among other things are:
a) To see how the problems of power
change over can be solved with less capital and less labour.
b) To make sure that an average person
can reach to the equipment by the evaluation of the cost of production of this
project.
c) To check the effectiveness of this
work and how fast it can work without risk or extra labour or shock to
personnels.
It is also aimed at improving the availability of power
supply at any point in time with this equipment, due to its automatic nature.
This is because the automatic nature of this project makes it un noticeable at
the out put or at the load.
This
equipment when used will solve the problem of power outage suffered or delayed
in change over suffered by many industries and business centres where power
failure are greatly felt, and can cause a lot of regrets, because information
are lost severally because of power failure, especially in business centres.
This work therefore remedies these problems but can be regrettable.
1.3 SCOPE OR LIMITATION
The scope or range of
this project work is as wide as 2.5KVA
as the rating. This means that it is capable of with standing any input of the
range from any source especially generator sets and can give an output of
220-230Volts.
With this rating of 2.5KVA and a voltage of 230Volts, this work can stand
any load.
The limitation is
within prescribed output /input range. In other words any increase in the input
could cause some damage to the components.
Again, a circuit
breaker was provided to protect the circuit from damage due to voltage surge or
output fault or load fault.
The current rating is
of 10.9Amps which is enough to withstand any load within the range.
1.4 DEFINITION OF TERMS
Generally, a change over switch is a system which could be
manually or automatically operated, that changes one source of power supply to
another source in the case of failure from either of the two sources.
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