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: -

1. Literature reviews
2. Data collection
3. Data analysis
4. System design
5. 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	PROJECT ACTIVITIES SCHEDULE DURATION MONTHS 2016/2017
ACTIVITIES	NOV	DEC	JAN	FEB	MAR	APR	MAY	JUN	JUL
Selection of project title
Title defending
Consultation with supervisor
Literature review
Data collection
Data analysis
Project report writing
Building Prototype

Figure 01. Time frame