An Introduction to Safety Grounding
- Length: 182 pages
- Edition: 1
- Language: English
- Publisher: CRC Press
- Publication Date: 2021-07-07
- ISBN-10: 0367758717
- ISBN-13: 9780367758714
- Sales Rank: #0 (See Top 100 Books)
Safety or protective grounding is of vital importance for the protection of individuals from electric shock and structures and industrial concerns from potentially damaging lightning and electrostatic discharges. To many electrical engineers the notion of grounding is nebulous and safety grounding is quite often confused with neutral grounding of the power supply. The main objective of this book is to give the reader a better understanding of safety grounding, why it is needed, where it is needed, and what are the requirements which must be met in order to have an effective grounding system. The text as a whole serves to provide the reader with the necessary background for a better appreciation of the various National and International Standards concerned with safety grounding.
This book gives the reader a good understanding of the fundamentals of safety grounding. It is a practical guide that provides a comprehensive coverage of all types of grounding requirements and is intended for students and practicing electrical engineers alike.
- Summarizes the physiological effects of current on the human body and the effect of current duration
- Gives the various methods of measuring soil resistivity and measuring the resistance to ground of an electrode or grounding system
- Reviews different types of ground electrodes and the effect of their geometry and numbers on the resistance to ground
- Presents the components of a ground system, methods of improving soil resistivity, the types of welds and joints, the criteria for determining conductor cross-sections, galvanic corrosion, and a survey of the different grounding practices used at substations and the different types of grounding systems used for the protection of consumers
- Deals with electrostatic and lightning hazards that can cause serious damage and the measures used to protect against such damage
- Throughout the text frequent reference is made to various National and International Standards and their requirements as compliance with these standards is highly advised
Asser A. Zaky, Ph.D., FIET, F.Inst.P., FIEEE, is Emeritus Professor of Electrical Engineering at University of Alexandria, Egypt.
Cover Half Title Title Page Copyright Page Table of Contents Preface Chapter 1 Effect of Current on the Human Body 1.1 Introduction 1.2 Effect of Electric Shock on Human Beings 1.3 Effect of Current Duration 1.4 The Electric Resistance of the Human Body Chapter 2 Resistance to Ground 2.1 Resistance to Ground of a Hemisphere 2.2 Measurement of Electrode Resistance to Ground 2.3 Soil Resistivity 2.4 Measurement of Soil Resistivity 2.4.1 Simple Box Method 2.4.2 Wenner Method 2.4.3 Electromagnetic Induction Method 2.5 Computer Programs Chapter 3 Earthing Electrodes 3.1 Single Driven Rod 3.2 Grounding Using Multiple Rods 3.3 Grounding Using Horizontally Buried Wires 3.4 Grounding Using Buried Plates 3.5 Water Pipes or Steel Reinforcement as Grounding Electrodes 3.6 The Resistance Area Chapter 4 Step, Touch, and Transfer Voltages 4.1 Step Voltage 4.2 Touch Voltage 4.3 Transfer Touch Voltage 4.4 Grounding of Power Towers 4.4.1 Effect of Overhead Ground Wire on Tower Footing Resistance Chapter 5 Grounding Systems 5.1 Magnitude of Resistance to Ground 5.2 Elements of the Grounding System 5.2.1 The Area of Land 5.2.1.1 Use of Chemical Salts 5.2.1.2 Increasing the Soil’s Ability to Retain Water 5.2.2 Ground Electrodes 5.2.2.1 Driven Rods 5.2.2.2 Concrete-Encased Electrodes 5.2.2.3 Water and Gas Pipes 5.2.2.4 Structural and Reinforcing Steel 5.2.2.5 Equipotential Bonding 5.2.3 Connections in Grounding Systems 5.2.4 Grounding Conductors 5.2.4.1 Size of Grounding Conductors 5.2.4.2 Protective Sleeve 5.2.5 Ground Connection Provisions 5.2.6 Equipment Grounding Conductors 5.2.6.1 Conductor Size according to the Adiabatic Equation 5.2.6.2 Conductor Size According to USA Specifications (NFPA-70) 5.2.6.3 Metal Cable Trays as Grounding Conductors 5.2.6.4 Flexible Metal Conduits 5.2.6.5 Cable Sheath and Armor 5.2.6.6 Jumpers 5.3 Metallic Corrosion 5.4 General Rules for the Grounding of Branch Substations 5.5 Protective Grounding of Consumer Installations: Types of Grounding Systems 5.5.1 The TN-C System 5.5.2 The TT System 5.5.3 The TN-S System 5.5.4 Protective Multiple Earthing 5.5.5 The IT System 5.6 Protection by Isolation 5.7 Grounding of Computers and Data Processing Equipment Chapter 6 Substation Grounding Systems 6.1 Introduction 6.2 Design Steps 6.2.1 Ground Mat Resistance 6.2.2 Calculation of Maximum GPR 6.2.3 Determination of Maximum Touch and Step Voltages 6.2.4 Safety Requirements 6.3 Design of Ground Mat using Computer Program Chapter 7 Static Electrification 7.1 Introduction 7.2 Conditions Necessary for Ignition 7.2.1 Explosion Limits 7.2.2 Oxygen 7.2.3 Ignition Sources 7.2.4 Minimum Ignition Energy 7.3 Generation of Electrostatic Charges 7.3.1 Contact Electrification between Solid Surfaces 7.3.2 Static Electrification in Liquids and Gases 7.4 Ways for Reducing the Formation of Surface Charges 7.5 Electrostatic Induction 7.6 Types of Electric Discharges 7.6.1 The Spark or Arc Discharge 7.6.2 Brush Discharges and Propagating Brush Discharges 7.6.3 Corona Discharges 7.7 Methods of Controlling Electrostatic Charges 7.7.1 Grounding and Bonding 7.7.2 Floors and Clothing for Static Control 7.7.2.1 Static Conductive Floors 7.7.2.2 Static Dissipative Floors 7.7.3 Control of Humidity 7.7.4 Ionization Chapter 8 Protection against Lightning 8.1 Nature of Lightning 8.2 Why Protect against Lightning 8.3 Lightning Protection System 8.3.1 The Air Terminals 8.3.2 Mesh Air Termination Networks 8.3.3 Down Conductors 8.3.4 Types of Conductors 8.3.5 Grounding 8.4 Inductance, Side Flashing, and Separation Distance 8.5 Zones of Protection 8.6 Tanks and Stacks 8.7 Protection of Transmission Lines by Aerial Ground Wires 8.7.1 Secondary Field of Ground Conductor 8.7.2 Height of Ground Conductor 8.8 Protection against Surges Appendix A: Wire Sizes Bibliography Index
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