Analysis Of Earthing System In Power Distribution Network

ABSTRACT

Power system equipment are very expensive, and so a very large capital investment. To maximize the return on this outlay, the system must be utilised as much as possible within the applicable constraints of security and reliability of supply. It is expected that power system should operate in a safe manner at all times. No matter how well designed, faults will always occur on a power system, and these faults may represent a risk to personal and/or property. Many power system experts recognize that it is not feasible to design the power system to completely prevent the occurrence. However, it is possible to minimize the damages, using good design practices and proper relay settings, applying new protection system technologies, and improving eartihng system.

The main aim of this paper is to provide a comprehensive study of earthing system to enhance protection system performance in distribution networks.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

CHAPTER ONE

• INTRODUCTION
• BACKGROUND OF THE PROJECT
• PROBLEM STATEMENT
• AIM AND OBJECTIVE OF THE PROJECT
• PURPOSE OF THE PROJECT
• BENEFIT OF EARTHING SYSTEM
• RESEARCH QUESTION
• METHODOLOGY
• DEFINITION OF TERMS
• PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

• INTRODUCTION
• REVIEW OF THE STUDY
• EARTHING METHODS
• COMPONENTS USED IN ELECTRICAL EARTHING SYSTEM
• TYPES OF ELECTRICAL EARTHING SYSTEMS
• OVEVIEW OF REINFORCED CONCRETE POLE
• REVIEW OF ELECTRIC POLE
• HISTORICAL BACKGROUND OF REINFORCED CONCRETE
• USES OF REINFORCED CONCRETE
• ADVANTAGES OF REINFORCED CONCRETE CEMENT

CHAPTER THREE

METHODOLOGY

• BASICS OF EARTHING
• EARTHING RULES
• COMPONENTS OF ELECTRICAL EARTHING SYSTEM
• GENERAL REQUIREMENTS
• STATUTORY REQUIREMENTS
• ELECTRODE DESIGN FOR 11kV

CHAPTER FOUR

4.1      EARTHING SYSTEM TEST ANALYSIS

CHAPTER FIVE

• CONCLUSION
• REFERENCES

CHAPTER ONE

          1.0                                                    INTRODUCTION

          1.1                                       BACKGROUND OF THE STUDY

Electrical earthing for protecting the buildings, equipment from some breakdowns or damages, but the safety of an operator is the most essential element. Power distribution network line troubles can be protected by a proper earthing. It is also the main element for avoiding RF intrusion in communication. Furthermore, the quality of power can be drastically corrupted due to faulty earthing. Executing an electrical earthing is not a simple job. It requires skilled operators with proper planning and quality devices. However, the right electrical earthing is an asset that will provide compensation for the facility of life.

Earthing is the method of transmitting the instant electricity discharge directly to the ground through low resistance wires or electrical cables. This is one of the significant features of electrical networks. Because it builds the most eagerly accessible and hazardous power source much secure to utilize.

The process of earthing in case of short circuit condition, the electrical wire carefully removes the overflow of current and allows it to flow through the earth.

An earthing system connects specific parts of an electric power system with the ground, typically the Earth’s conductive surface, for safety and functional purposes (Manav Energy, 2020). The choice of earthing system can affect the safety and electromagnetic compatibility of the installation. Regulations for earthing systems vary considerably among countries, though most follow the recommendations of the International Electrotechnical Commission. Regulations may identify special cases for earthing in mines, in patient care areas, or in hazardous areas of industrial plants.

In addition to electric power systems, other systems may require grounding for safety or function. Tall structures may have lightning rods as part of a system to protect them from lightning strikes. Telegraph lines may use the Earth as one conductor of a circuit, saving the cost of installation of a return wire over a long circuit. Radio antennas may require particular grounding for operation, as well as to control static electricity and provide lightning protection. However, this study is on earthing system for 11kv distribution network.

1.2                                   PROBLEM STATEMENT

The method use in earthing appliances and low voltage network is different from the method use in earthing distribution network, and this gives rise to carry out the study on the earthing system for a distribution network used on RCC poles.

1.3                          AIM/OBJECTIVES OF THE STUDY

The main aim of this paper is to provide a comprehensive analysis of earthing system to enhance protection system performance in distribution networks. The objectives are:

1. To study the earthing system on RCC poles for 11kv distribution network.
2. To study installation procedure and requirement for 11kv distribution network shall be known.

• To study different types of electric poles shall be studied

1. The general description for earthing system shall also be known.

1.4                                              PURPOSE OF THE STUDY

An earthing system is installed as an integral part of an electricity distribution network, to control the magnitude and distribution of short circuit currents in case of a fault.

1.5                                       BENEFIT OF EARTHING SYSTEM

The main intention of electrical earthing is to keep away from the danger of electric shock due to the outflow of current from ground through the not preferred path as well as to make sure that the potential of a conductor does not increase with respect to the ground than its planned insulation.

When the metallic element of electrical machines approaches in contact by an existing wire, due to a breakdown of fixing the cable, the metal turn into charged and static charge collect on it. If someone contacts such an electric metal, then the outcome is a severe electric shock.

The main benefits of earthing system include protection from overvoltage, stabilization of voltage, and prevention form injury, damage, and death.

1.6                                                 RESEARCH QUESTION

At the end of this work, this research shall bring answer to the following question:

1. What is the purpose of substation earthing system?
2. Which earthing is used in 11kv distribution network?

• What is the importance of earthing in electrical network?

1. What is the purpose of connecting isolated HV supplies to Earth?

1.7                                         METHODOLOGY

In the course of carrying this study, numerous sources were used which most of them are by visiting libraries, consulting journal and news papers and online research which Google was the major source that was used.

1.8                                             DEFINITIONS OF TERMS

COLD SITE:  Any site containing HV equipment that is not a hot site.

EARTH ELECTRODE: A conductor or group of conductors in intimate contact with, and providing an electrical connection to, earth.

EARTH IMPEDANCE: The impedance between the earthing system and remote reference earth.

EARTH POTENTIAL: The difference in potential which may exist between a point on the ground and remote reference earth.

EARTH RESISTANCE: The resistance of the earth between the earth electrode and remote reference earth.

EARTHING CONDUCTOR:  A conductor that connects plant and equipment to an earth electrode.

EARTHING SYSTEM: The complete interconnected assembly of earthing conductors and earth electrodes (including cables with un- insulated sheaths).

HOT SITE: A site containing HV equipment where the rise of earth potential under earth fault conditions can exceed the limits of 430V or 650V, as applicable. The 650V limit only applies where the power system has an operating voltage of 33kV or greater and main protection is designed to clear earth faults within 200ms.

HOT ZONE: The area over which the rise of earth potential may exceed the appropriate 650V or 430V limit.

STEP VOLTAGE: The potential difference between two points on the surface of the soil which are 1m apart.

TOUCH VOLTAGE: Voltage appearing during an insulation fault, between simultaneously accessible parts; hand-to-foot or hand-to- hand.

1.9                                                         PROJECT ORGANISATION

The work is organized as follows: chapter one discuses the introductory part of the work,   chapter two presents the literature review of the study,  chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.