Electronic circuir breaker project
CHAPTER ONE
INTRODUCTION
1.1.General Introduction
According to
(Mohankumar, 2013), “Electrical circuit breaker is a device that senses an
overload and short circuit condition, then breaking the circuit to protect the
system or circuit from damages or breakdown”.
Circuit
Breaker was invented over hundred years ago, it was first described by Thomas
Edison (1900) as fuse used by his commercial power distribution. The initial
reasons for developing the circuit breaker was to protect the lighting circuit
wiring from impulse short-circuit and overload (Isreal, 1986). Advancement in
the circuit breaker technology was done with the advance in general technology.
It advancement include the modern miniature circuit breakers similar to those
used currently and it was patented by Brown and Boveri over 90 years ago,
(1924). As time pass, requirement for various other types were created due to
advancements, for instance, the thermal magnetic breaker which is still in use
till date was created by (Stotz, 2006), who advanced on the low voltage circuit
breakers with the introduction of the thermal and thermal magnetic circuit
breakers.
The concept
of electronic circuit breaker came into focus realizing that conventional
circuit breakers such as Miniature Circuit Breakers (MCBs) take longer time to
trip. Therefore, for sensitive loads it is very important to activate the
tripping mechanism at the shortest possible time, preferably instantaneously.
This project is demonstrating fast tripping mechanism as against the slow one
like MCB. Electronic circuit breaker is based on the voltage drop across a
series element proportional to the load current, typically a low value
resistor. This voltage is sensed and rectified to DC which is and then compared
with a preset voltage by a level comparator to generate an output that drives a
relay through a MOSFET to trip the load. The unit is extremely fast and
overcomes the drawback of the thermal type. It uses a microcontroller from 8051
family. Conventional circuit breaker like MCB based is on thermal bimetal lever
trip mechanism. It is very slow and the trip time is dependent upon the
percentage of overload.
Basically, an
electronic circuit breaker works on the principle of current sensing mechanism.
It provides both over load and short circuit protection as in any case the
current through the line is monitored and the switch gets tripped in case of
over current being flowing.
1.2.Problem Statement
Existing miniature circuit breaker has drawbacks
which lead it to have insufficiency performance causes by its bimetallic strip
tends to be deformed easily due to heat which causing a reduction in the
breaker’s current capacity. Also because of mechanical components being used,
they are more prone to wear and tear. Tripping time is slower and non-auto
reclosing on temporary faults. To overcome all these problems, the most
convenient solution is using a high efficiency electronic circuit breaker. It
does not involve any electromagnetic coil or any thermal strip or any mechanical
component and also able to reclose in temporary faults.
1.3.Project Objective
The objective
of this project is divided into two sections which are main objective and specific
objectives.
1.3.1.
Main Objective
The main
object of this project is to design a high efficiency electronic circuit
breaker which will eliminate miniature circuit breaker drawbacks.
1.3.2.
Specific Objectives
i.
To study an
existing system of a circuit breaker working mechanism.
ii.
To design an electronic
circuit breaker which will shut down instantly in occurrence of permanent short
circuit and overloaded and auto reclosing it in temporary short circuit and
overloaded.
iii.
To perform
simulation.
iv.
To build and
test the prototype.
1.4.Significances
i.
Electronic
circuit breakers designed to trip at small overloads and to eliminate inrush
currents.
ii.
To provide
solution to the high rate of damage to our appliances due to have a fast
tripping action.
1.5.Scope
of a project
This project is going to deal with
type B miniature circuit breakers (generally for domestic applications), in
type C and D (higher loads) can be applicable by modifying a current sensing
element by use of current transformer CT.
1.6.Methodology
Methodology describes the various
techniques that show how the project is going to be done in order to fulfill
the objectives, such procedures are as follows: -
- Literature reviews
- Data
collection
- Data
analysis
- System
design
- Circuit simulation
vi.
Circuit implementation and testing
Circuit will be implemented in the
board and tested to see whether the output is the same as the one obtained in
the simulation. In case of any problem, some corrections will be done and
thereafter implementing the circuit on the printed circuit board.
1.6.1.
Literature reviews
This section shows how the existing
system is and its drawbacks that has made to the need of the proposed system.
1.6.2. Data collections
On way towards accomplishment of this project
important data about currently existing system and the proposed system will be
gathered and collected from different relevant sources.
1.6.3.
Data analysis
The data collected will be
analyzed and be implemented in the designing of the project. It comprises the
mathematical analysis together with circuits design and appropriate circuit
components values for the entire system.
1.6.4. Designing the system
The circuit design will base on
information collected and analyzed in order to meet the objective of the
project. Systems design could be seen as the application
of systems theory to product development.
1.6.5. Simulation
Different parts of this system
will be simulated after designing in order to observe results of each part
before implementing the complete circuit.
1.6.6. Circuit implementation
and testing
Circuit will be implemented in the
board and tested to see whether the output is the same as the one obtained in
the simulation. In case of any problem, some corrections will be done and
thereafter implementing the circuit on the printed circuit board.
1.7.Time
Frame
TABLE
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PROJECT ACTIVITIES SCHEDULE
DURATION
MONTHS 2016/2017
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ACTIVITIES
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NOV
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DEC
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JAN
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FEB
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MAR
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APR
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MAY
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JUN
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JUL
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Selection of project title
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Title defending
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Consultation with supervisor
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Literature review
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Data collection
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Data analysis
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Project report writing
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Building
Prototype
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Figure 01. Time frame
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