View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by UTHM Institutional Repository i AUTOMATIC EARTH LEAKAGE CIRCUIT BREAKER WITH BACKUP SUPPLY MOHD ANUAR BIN MOHAMED AYUB A project report submitted in partial fulfillment of the Requirement for the award of the Master of Electrical engineering Faculty of Electrical and Electronic Engineering Universiti Tun Hussein Onn Malaysia DECEMBER 2013 v ABSTRACT Power system protection is the most important requirement in the industrial or domestic electrical to prevent equipment from damage cause by leakage current. The ELCB is an important equipment to install at each of house, hospital, factory, or every place that need the power supply. The device monitors input current from power line by using the sensor Zero phase Current Transformer (ZCT), and then send the signals to the mechanical switch to tripped the circuit breaker. Industrial operation requires protection of their equipment from the lightning short circuit and also over-current, thus the ELCB will serve the purpose as the protection of their system .This research will attempt to improve the exciting ELCB design using PIC microcontroller to automatically switch it back to normal when the ELCB tripped in home during instantaneous over current or short circuit. This system provides a convenient way for house’s owner especially during absences in home. In this research PIC 16F877A microcontroller is used to control overall flow operation and operate the Power Relay /Protection relay, thus replacing the current mechanical switch. The outcome of this research after several testing process shown that the average sensitivity value for ELCB against leakage current is 76mA better 24% than 100mA set by manufacture. vi ABSTRAK Perlindungan sistem kuasa adalah keperluan yang paling penting di dalam indusrtri ataupun sambungan domestic elektrikal bagi mengelakan kerosakan peralatan disebabkan oleh arus bocor . ELCB adalah salah satu peralatan penting yang di pasang di setiap rumah , hospital, kilang ataupun tempat yang memerlukan bekalan kuasa. Peralatan ini bertindak sebagai pemerhati arus masukan dari talian kuasa oleh pengesan Pengubah Tanpa Arus Fasa (ZCT), kemudianya ia menghantar isyarat tersebut ke suis mekanikal untuk terpelantikkan pemutus litar.Operasi industri memerlukan perlindungan mesin mereka daripada kilat, litar pintas dan juga lebihan arus, maka ELCB ini akan di gunakan bagi perlindungan kepada sistem mereka. Projek ini adalah bertujuan untuk menambahbaikan rekabentuk ELCB yang sedia ada menggunakan PIC pengawal mikro untuk menyambung kembali litar ELCB yang telah terpelantik kepada keadaan asal apabila berlakunya litar pintas dan lebihan arus. Sistem ini memberikan manfaat kepada pemilik rumah apabila tiada di rumah. Didalam projek ini PIC16F877A pengawal di gunakan untuk mengawal keseluruhan sistem pengoperasian dan Geganti Kuasa/Geganti Perlindungan yang mana telah di tukarkan kepada suis mekanikal asal. Hasil di akhir projek ini, setelah beberapa kali di uji didapati kepekaan ELCB terhadap arus bocor adalah 76mA di mana 24% lebih baik daripada 100mA telah ditetapkan oleh pembuat. vii TABLE OF CONTENTS TITLE i DECLARATION ii DEDICATION iii ACKNOWLEDGEMENT iv ABCTRACT v ABSTRAK vi TABLE OF CONTENT vii LIST OF TABLE xi LIST OF FIGURE xii LIST OF ABBREVIATION xv LIST OF APPENDIXES xvi CHAPTER 1 INTRODUCTION 1 1.1 Project Background 1 1.2 Objectives 2 1.3 Scopes of Project 3 1.4 Problem Statement 3 CHAPTER 2 LITERATURE REVIEW 4 2.1 Introduction 4 2.2 Earth Leakage Circuit Breaker (ELCB) 5 2.2.1 Voltage Earth Leakage Circuit Breaker (vELCB) 7 viii 2.2.2 Current Earth Leakage Circuit Breaker (iELCB) 8 2.3 Operation of ELCB Trip Situation 8 2.3.1 Permanent Failure or Permanent Damage 8 2.3.2 Temporary Failure or Temporary Damage 9 2.4 Electrical Faults 9 2.4.1 Over-current Fault 9 2.4.2 Short Circuit Fault 10 2.4.3 Lightning Fault 10 2.5 ELCB Features 11 2.6 ELCB Design 12 2.7 Basic Concept of ELCB 14 2.8 Operation of ELCB 15 2.9 Conclusion for previous report 16 CHAPTER 3 METHODOLOGY 18 3.1 Introduction 18 3.2 Planning 19 3.2.1 Phase 1 : Preliminary Investigation 20 3.2.2 Phase 2 : Analysis and Specification 20 3.2.3 Phase 3 : Design 20 3.2.4 Phase 4 : Development and Integration 20 3.2.5 Phase 5 : Testing 21 3.2.6 Phase 6 : Maintenance 21 3.3 Hardware Development (Research Requirement) 21 3.3.1 ELCB Hardware Design 21 3.3.2 ELCB with an Automatic Unit Hardware Design 22 ix 3.3.3 UPS Configuration 23 3.3.3.1 Standby or off-line system 24 3.3.3.2 Double conversion on-line system 24 3.3.3.3 Line interactive system 25 3.4 Hardware Operation Process 26 3.5 Circuit Stage 28 3.5.1 Voltage Regulator Circuit 28 3.5.2 PIC Microcontroller and LCD circuit 29 3.5.3 Relay Driver Circuit 30 3.5.4 Final Stage Circuit 31 3.6 ELCB Hardware Part 32 3.7 Overall System 33 3.8 Hardware and Software Development 34 3.8.1 PIC16F877A 34 3.8.2 Relay 240 Volt 35 3.8.3 Relay Driver 36 3.8.4 Current Sensor 37 3.8.5 MPLAB 38 3.8.6 PROTEUS 39 CHAPTER 4 RESULT AND ANALYSIS 40 4.1 Hardware Result 40 4.1.1 Power Supply Circuit 40 4.1.2 LCD Display 42 4.1.3 Protective Relay 47 4.1.4 Wiring Diagram Of ELCB And Protective Relay 51 4.2 Analysis 53 x 4.2.1 Normal Condition 53 4.2.2 Second Condition: Main Trip 54 4.2.3 Third Condition: Backup Trip 56 4.2.4 Calculation Percentage Between Theories with 62 The Actual voltage 4.2.5 ELCB Test Using Relay Test Unit 62 4.2.6 Calculation Percentage Current 65 Between Manufacturer Rating With Current Measured By Relay Test Unit 4.2.7 Current During Normal And Backup ELCB Trip 66 4.2.8 Calculation Percentage Current Between 70 Ammeter and LCD display 4.2.9 Overall Discussion 70 CHAPTER 5 CONCLUSION AND RECOMMENDATION 72 5.1 Conclusion 70 5.2 Future Recommendation 73 REFFERENCES 74 APPENDICES 76 xi LIST OF TABLES 4.1 Input Voltage For Prototype 41 4.2 Input And Output For ELCB And LCD Display 42 4.3 Current During Normal And Main Trip 44 4.4 Condition Of Relay 48 4.5 Normal Condition (No Trip) 58 4.6 Second Condition (Main Trip) 58 4.7 Third Condition (Backup Trip) 58 4.8 Result For ELCB Test 64 4.9 Current During Normal And Backup ELCB Trip 68 xii LIST OF FIGURES 2.1 TT Network 6 2.2 Home ELCB/RCCB With Housing 11 2.3 The System Inside ELCB 11 2.4 Earth Leakage Circuit Breaker Design 12 2.5 Earth Leakage Circuit Breaker Design Schematic 13 2.6 Operation of ZCT 14 2.7 Earth Leakage Circuit Breaker Operation Flow 15 2.9 Conclusion For Previous Report 16 3.1 Flowchart of Planning 19 3.2 Component and Structure of ELCB 22 3.3 Component and Structure of ELCB with an Automatic Unit 23 3.4 Off-line System Diagram 24 3.5 Double Conversion On-line System Diagram 25 3.6 Line Interactive System Diagram 25 3.7 Hardware Operation Process of Automatic ELCB 28 xiii 3.8 Voltage Regulator Circuit 28 3.9 PIC Microcontroller and LCD Circuit 29 3.10 Relay Driver 30 3.11 Final Stage Circuit For ELCB Control 31 3.12 Final Stage Main Circuit Current Sensor 32 3.13 ELCB Hardware Part 33 3.14 Flowchart of Overall System 34 3.15 The PIC Microcontroller Board 35 3.16 Relay 240 Volt 36 3.17 Relay Driver 37 4.1 Voltage Regulator Circuit With Input 12V And Output 5V 41 4.2 Display on LCD at Normal Condition 43 4.3 Display on LCD at Main Fault Condition 43 4.4 Display on LCD at Backup Tripped 44 4.5 Display On LCD At Current L1 45 4.6 Ammeter Display Current At L1 45 4.7 Display On LCD At Current L2 46 4.8 Ammeter Display Current At L2 46 4.9 Protective Relay for Switching 47 4.10 Relay Driver Circuit Diagram 48 xiv 4.11 Normal Condition 49 4.12 Main Fault Condition 49 4.13 Backup Fault Condition 49 4.14 Wiring Diagram Of ELCB And Protective Relay 52 4.15 Normal Condition 54 4.16 Second Condition of Main Trip 56 4.17 Third Condition of Backup Trip 57 4.18 Normal Condition (No Trip) 59 4.19 Second Condition ( Main Trip) 60 4.20 Third Condition (Backup ELCB Trip) 61 4.21 ELCB Test Using Relay Test Unit 63 4.22 Test ELCB At Current 40mA (No Trip) 63 4.23 Test ELCB At Current 77mA (ELCB Trip) 63 4.24 Result For ELCB Test 64 4.25 Display Current At Load 1 67 4.26 Display Current At Load 2 67 4.27 Result The Current L1 and L2 At Normal Condition 68 4.28 Result The Current L1 And L2 At Backup ELCB Trip 69 xv LIST OF ABBREVIATION PIC Programmable Integrated Circuit ELCB Earth Leakage Circuit Breaker AELCB Automatic Earth Leakage Circuit Breaker RCD Residential Current Device GFCI Ground fault Circuit Interrupted vELCB Voltage Earth Leakage Circuit Breaker iELCB Current Earth Leakage Circuit Breaker ZCT Zero Current Transformer NO Normally Open NC Normally Close LED Light Emitting Diode xvi LIST OF APPENDICES A Gantt Chart 76 B Programming Source Code 80 C Data Sheet 88 CHAPTER 1 INTRODUCTION 1.1 Project background This project is focused on the design and building a unit of Automatic Earth Leakage Circuit Breaker (AELCB) with the backup supply that can auto switching and always on with temporary power supply.