GROUNDS FOR GROUNDING The first book to cover grounding from the circuit to system and across the entire spectrum of applications Grounds for Grounding provides a complete and thorough approach to the subject of designing electrical and electronic circuits and systems, blending theory and practice to demonstrate how a few basic rules can be applied across a broad range of applications. The authors begin with the basic concepts of Electromagnetic Compatibility (EMC) that are essential for understanding grounding theory and its applications, such as “ground loop,” which is one of the most misunderstood concepts in EMC. Next, they provide an introduction to grounding, including safety grounding, grounding for control of electromagnetic interference, and grounding-related case studies. Subsequent chapter coverage includes: Fundamentals of grounding design Bonding principles Grounding for power distribution and lightning protection systems Grounding in wiring circuits and cable shields Grounding of EMI terminal protection devices Grounding on printed circuit boards Integrated facility and platform grounding system Practical case studies are integrated throughout the book to aid in readers’ comprehension and each chapter concludes with a useful bibliography. Grounds for Grounding is an indispensable resource for electrical and electronic engineers who work with the design of circuits, systems, and facilities.

Table of Contents:
Foreword xvii Preface xix 1. Overview 1 Bibliography 6 2. Fundamental Concepts 7 2.1. Maxwell’s Equations Demystified 7 2.1.1. Fundamental Terms 9 2.1.2. Maxwell’s Equations 12 2.2. Boundary Conditions 24 2.3. Intrinsic Inductance of Conductors and Interconnects 26 2.3.1. Concept of Inductance 27 2.3.2. Self-Inductance 27 2.3.3. Mutual Inductance 29 2.3.4. Partial Inductance 30 2.3.5. External and Internal Inductance 37 2.3.6. Skin Effect and Skin Depth 38 2.3.7. Proximity Effect 43 2.4. Nonideal Properties of Passive Circuit Components and Interconnects 45 2.4.1. Resistors 46 2.4.2. Capacitors 47 2.4.3. Inductors 49 2.4.4. Interconnects (Wires and PCB Traces) 49 2.5. Return Current Path Impedance 51 2.5.1. What Path Should Return Currents Follow? 51 2.5.2. Equivalent Circuit Analysis 53 2.5.3. Implication of the Principle 64 2.6. Transmission Line Fundamentals 64 2.6.1. Transmission Line Definition 65 2.6.2. Transmission Line Equations and Intrinsic Parameters 66 2.6.3. Transmission Line Termination and Loading Conditions 69 2.7. Characteristics of Signals and Circuits 74 2.7.1. Spectral Content of Signals 75 2.7.2. Differential-Mode and Common-Mode Signals 81 2.7.3. Common-Mode (CM) to Differential-Mode (DM) Conversion 91 2.7.4. Differential Signaling and Balanced Circuits 95 2.8. Interaction between Sources to Radiated Fields 104 2.8.1. Radiation from Current-Carrying Conductors 104 2.8.2. Flux Cancellation, the Electromagnetics of Balancing 108 Bibliography 110 3. The Grounds for Grounding 113 3.1. Grounding, an Introduction 113 3.1.1. “Grounding,” One Term, Many Imports 113 3.1.2. Grounding—A Historical Perspective and the Evolution of the Term 118 3.1.3. Grounding-Related Myths, Misconceptions, and Misapprehensions 120 3.2. Objectives of Grounding 123 3.2.1. Safety Grounding 126 3.2.2. Grounding for Control of Electromagnetic Interference (EMI) 138 3.2.3. Signal Grounding 141 3.3. Grounding-Related Case Studies 148 3.3.1. Case #1: The Grounds for Electrostatic Discharge (ESD) 148 3.3.2. Case #2: The Grounds for Lightning Protection 149 Bibliography 153 4. Fundamentals of Grounding Design 155 4.1. Ground-Coupled Interference and its Preclusion 155 4.1.1. Grounding May Not be the Solution; Rather it Could be Part of the Problem 155 4.1.2. Controlling Common-Impedance Interference Coupling 161 4.2. Fundamental Grounding Topologies 173 4.2.1. The Need for Different Topologies 173 4.2.2. Grounding Topologies 176 4.3. Grounding Trees 209 4.3.1. Objectives and Basic Design Considerations 209 4.3.2. Ground Tree Design Methodology 210 4.4. Role of Switch-Mode Power Supplies in Grounding System Design 224 4.4.1. Principle of Switch-Mode Power Supply Operation 225 4.4.2. The Need for Isolation 226 4.4.3. Isolation and Grounding in Switch-Mode Power Supplies 229 4.5. Ground Loops 233 4.5.1. Definition of a “Ground Loop” 234 4.5.2. Ground Loop Consequences (“Who’s Afraid of the Big Bad Loop?”) 239 4.5.3. Ground-Loop Interference Coupling 241 4.5.4. Ground-Loop Interactions: Frequency Considerations in between Enclosures 257 4.5.5. Resolving Ground-Loop Problems 264 4.6. Zoned Grounding 291 4.6.1. The Zoning Concept as Applied to Grounding 291 4.6.2. Zoning Compromises and Violations 292 4.6.3. Impact of Zoning on Subsystem Grounding Architecture 293 4.7. Equipment Enclosure and Signal Grounding 296 4.7.1. External Signal and Safety Grounding Interconnects between Enclosures 297 4.7.2. Equipment DC Power, Signal, and Safety Grounding 298 4.7.3. Power Distribution Grounding Schemes in Integrated Clustered Systems 301 4.7.4. Grounding of Equipment Enclosure Shield 305 4.8. Rack and Cabinet Subsystem Grounding Architecture 308 4.8.1. Grounding Ground Rules in Racks and Cabinets 308 4.8.2. Ground Loops and their Mitigation in Racks and Cabinets 310 4.9. Grounding Strategy Applied by System Size and Layout 314 4.9.1. “One Size Fits None” 314 4.9.2. Isolated System 315 4.9.3. Clustered System 315 4.9.4. Distributed System 318 4.9.5. Nested-Distributed System 319 4.9.6. Central System with Extensions 320 Bibliography 321 5. Bonding Principles 323 5.1. Objectives of Bonding 323 5.2. Bond Impedance Requirements 327 5.3. Types of Bonds 329 5.3.1. Direct Bonds 330 5.3.2. Indirect Bonds 335 5.3.3. Bonding Impedance and Effectiveness 337 5.4. Surface Treatment 348 5.5. Dissimilar Metals Consideration: Corrosion Control 351 5.5.1. Electrochemical Basis of Bond Galvanic Corrosion 352 5.5.2. Electrochemical Series 353 5.5.3. Galvanic Series 354 5.5.4. Galvanic Couples 355 5.5.5. Corrosion Protection 360 Bibliography 369 6. Grounding for Power Distribution and Lightning Protection Systems 371 6.1. Introduction 371 6.2. Power System Earthing 372 6.2.1. Objectives of Power System Earthing 372 6.2.2. Faults in Power Supply Systems 373 6.2.3. General Configuration of a Power Distribution System 375 6.2.4. Electric Shock Hazards 377 6.2.5. Methods of Power System Earthing 383 6.2.6. The Ungrounded System 385 6.3. Earthing for Low-Voltage Distribution System 387 6.3.1. TN System 388 6.3.2. TT System 394 6.3.3. IT System 396 6.3.4. Temporary Overvoltage in Low-Voltage Installations Due to Faults between High-Voltage Systems and Earth 397 6.3.5. Earthing Systems and EMC 402 6.3.6. Requirements for the Installation of Equipment with High Protective Earth Conductor Current 404 6.3.7. Application of Residual-Current Devices for Shock Protection 405 6.4. Lightning Protection 408 6.4.1. An Overview of the Lightning Phenomenon 408 6.4.2. Lightning Attachment Point and Zones of Protection 409 6.4.3. Components of the Lightning Protection System 411 6.4.4. Influence of LV Earthing Schemes on Lightning Overvoltages 416 6.5. The Earth Connection 418 6.5.1. Resistance to Earth 419 6.5.2. Soil Resistivity 420 6.6. Types of Earth Electrodes 420 6.6.1. The Earth Rods 422 6.6.2. Earth Plates 426 6.6.3. Horizontal Strip or Round Conductor Electrode 427 6.6.4. The Mesh or Grid Earth Electrode 432 6.6.5. The Ring Earth Electrode 434 6.6.6. Foundation Earth Electrode 437 6.7. Design of Earth Electrodes and their Layout 440 6.7.1. Selection of Material 440 6.7.2. Grounding Requirements of Power Distribution Systems 441 6.7.3. Measures to Reduce Transient Impedance of Earth Electrodes 443 6.7.4. Earthing Requirements for Lightning Protection 445 6.7.5. Earth Potential Rise and Surface Potential Gradients 447 6.8. Measurement of Soil Resistivity, Earth Electrode Resistance and Earthing System Impedance 455 6.8.1. Measurement of Soil Resistivity 455 6.8.2. Measurement of Earth Resistance 457 6.9. Reducing Earth Resistance 462 6.10. Bonding to Building Structures 463 Bibliography 466 7. Grounding in Wiring Circuits and Cable Shields 469 7.1. Introduction: System Interface Problems 469 7.2. To Ground or Not To Ground (Cable Shields) 470 7.3. Fundamentals of Cable Shielding 472 7.3.1. Why Shield Cables? 472 7.3.2. Fundamental Shielding Mechanisms 473 7.3.3. Configuration of Shielded Cables 475 7.3.4. Termination (Grounding) of Cable Shields—A Qualitative Discussion 484 7.3.5. Termination (Grounding) of Cable Shields—A Quantitative Discussion 490 7.3.6. Frequency Considerations in Cable Shield Termination 498 7.4. Shield Surface Transfer Impedance 510 7.4.1. Methods for Cable Shielding 512 7.4.2. Shield Surface Transfer Impedance in Coaxial Lines 514 7.4.3. Where Should a Shield of a Balanced Line be Terminated? 517 7.4.4. Shield Termination—The Key to Optimal Shielding Performance 523 7.4.5. Twisted Cables and the Effect of Grounding 545 7.4.6. Strategies for Shield Termination in Common Types of Shielded Cables 550 7.5. Grounding Considerations in Signal Interfaces 557 7.5.1. Interfacing of Low-Frequency Unbalanced Signal Circuits 557 7.5.2. Interfacing of High-Frequency Unbalanced Signal Circuits 559 7.5.3. Interfacing of Equipment Containing Both Low- and High-Frequency Signals 559 7.5.4. Interfacing of Broadband (Video) Signal Circuits 561 7.5.5. Interfacing of Balanced Signal Circuits 562 7.5.6. Effect of Interface Scheme on Magnetic Interference Susceptibility 566 7.6. Grounding of Transducers and Measurement Instrumentation Systems 569 7.6.1. Measurement Accuracy Concerns 571 7.6.2. Guard Shields and Instrumentation Wiring Shield Interconnection 574 7.6.3. Grounding of Wiring Shields in Analog-Data Acquisition Systems 557 Bibliography 586 8. Grounding of EMI Terminal Protection Devices 589 8.1. Filtering and Transient-Voltage Suppression—Complementary Techniques to Shielding 589 8.2. Types of Conducted Noise 590 8.3. Overview of Filtering and Transient Voltage Suppression 590 8.3.1. Fundamental EMI Filter Devices and Circuits 590 8.3.2. Special EMI Filter Applications 597 8.3.3. Transient-Voltage Protection Devices and Circuits 601 8.4. Grounding of Filters and Transient-Suppression Devices 607 8.4.1. When is Ground Not Equal to Ground? 607 8.4.2. Practices for Grounding of Terminal Protection Devices (TPDs) 614 8.4.3. Terminal Protection Devices (TPDs) Installation and Mounting Practices 619 Bibliography 623 9. Grounding on Printed Circuit Boards (PCBs) 623 9.1. Interference Sources on PCBs 625 9.2. “Grounding” on PCBs 630 9.3. Signal Propagation on PCBs 631 9.3.1. Circuit Representation of Transmission Lines on PCBs 632 9.3.2. Electromagnetic Field Representation of Transmission Lines on PCBs 633 9.3.3. Equivalence of Power and Ground Planes as Return Paths for High-Speed Signal Propagation 636 9.3.4. Common Transmission Line Configurations on PCBs 639 9.3.5. Return Current Path on Printed Circuit Boards 645 9.3.6. Return Current Distribution 652 9.3.7. Crosstalk Mechanisms on PCBs 654 9.3.8. Common Impedance Coupling on PCBs 659 9.3.9. Consequences of Transmission Line Topology on EMI and Crosstalk Control 660 9.4. Return Path Discontinuities: “Mind the Gap” 662 9.4.1. Undesired Effects of Traces Crossing Gaps in the Reference Network (PDN) 666 9.4.2. Reference Plane Discontinuities and Mitigation Strategies 677 9.4.3. Differential Lines Crossing Gaps in Reference Planes 731 9.5. Delta-I (I) and Simultaneous Switching Noise (SSN) in PCBs 743 9.5.1. I Noise Generation in Signal I/O Circuits 745 9.5.2. I Noise Generation Mechanism in the Power Distribution Network (PDN) 752 9.5.3. Effective Management of I Noise Effects in Signal Circuits 754 9.5.4. Control of Delta-I (I) Noise in the Power Distribution Network762 9.5.5. Parallel-Plate Waveguide (PPW) Noise Mitigation Using Electromagnetic Band Gap (EBG) High-Impedance Structures (HIS) 781 9.5.6. Parallel-Plate Waveguide (PPW) Noise Mitigation Using Virtual Islands and Shorting Via Arrays 808 9.6. Return Planes and PCB Layer Stack-up 820 9.6.1. Image Planes 821 9.6.2. Frequently Used PCB Layer Stack-up Configurations 824 9.6.3. Local Ground Structures 827 9.6.4. Shield Traces 833 9.7. Cuts and Splits in Return Planes 840 9.7.1. Circuit Partitioning, Floating, and Moating 842 9.7.2. Circuit Isolation 843 9.7.3. Bridging the Gap 845 9.8. Grounding in Mixed-Signal Systems 849 9.8.1. Origins of Noise in Mixed Digital–Analog Circuits 850 9.8.2. Grounding Analog Circuits 850 9.8.3. Grounding Digital Circuits 851 9.8.4. Grounding in Mixed-Signal PCBs: “To Split or Not to Split (the Ground Plane)?” 851 9.8.5. The Mystery of A/D and D/A Converters Solved 856 9.8.6. Grounding Scheme for a Single ADC/DAC on a Single PCB 860 9.8.7. Grounding Scheme for Multiple ADCs/DACs on a Single PCB 862 9.8.8. Grounding Scheme for ADCs/DACs on Multiple PCBs 868 9.9. Chassis Connections (“Chassis Stitching”) 873 9.9.1. Purpose of Stitching PCB Return Planes to Chassis 974 9.9.2. Direct Stitching of Return Planes to Chassis 880 9.9.3. Hybrid Techniques for Stitching of Return Planes to Chassis 881 9.9.4. Capacitive Stitching of Return Planes to Chassis 886 9.9.5. Controlling Parallel-Plate Waveguide (PPW) Noise in the PCB-Chassis Cavity888 9.9.6. Benefits of Reduced Spacing between a PCB and the Chassis 894 9.9.7. Daughter and Mezzanine Boards Ground Stitching 895 9.9.8. PCB Heat Sinks Grounding Considerations 897 Bibliography 905 10. Integrated Facility and Platform Grounding System 911 10.1. Facility Grounding Subsystems 912 10.1.1. Earth Electrode Subsystem 913 10.1.2. Fault Protection Subsystem 913 10.1.3. Lightning Protection Subsystem 914 10.1.4. Signal Reference Subsystem 914 10.2. Grounding Requirements in Buildings or Facilities 917 10.2.1. Grounding of Power Distribution Systems in Buildings 918 10.2.2. Grounding in Industrial Facilities 921 10.2.3. Grounding for Information Technology Equipment 923 10.2.4. Grounding in Telecommunication and C3I (Command, Control, Communications, and Intelligence) Facilities 926 10.2.5. Grounding in HEMP-Protected and Secure C3I Facilities 934 10.2.6. Grounding of Instrumentation and Control Equipment Collocated with High-Voltage Power Apparatus 941 10.3. Grounding for Preclusion of Electrostatic Discharge (ESD) Effects in Facilities 944 10.3.1. Nature and Sources of Static Electricity 944 10.3.2. Susceptibility to ESD 946 10.3.3. ESD Protected Areas (EPAs) in Facilities 949 10.3.4. ESD Protective Tools, Materials, and Equipment 950 10.3.5. Essentials of Grounding for ESD Control 954 10.3.6 Safety Considerations in ESD Grounding 956 10.4. Grounding Principles in Mobile Platforms and Vehicles 958 10.4.1. Grounding in Transportable Tactical Shelters 958 10.4.2. Grounding in Aircraft 969 10.4.3. Grounding in Spacecraft 975 10.4.4. Grounding in Ships 981 Bibliography 982 APPENDIX A. Glossary of Grounding-Related Terms and Definitions 0997 APPENDIX B. Acronyms 1015 APPENDIX C. Symbols and Constants 1019 APPENDIX D. Grounding Related Standards, Specifications, and Handbooks 1021 D.1. ANSI Standards 1021 D.2. ATIS Standards 1022 D.3. British Standards 1022 D.4. CENELEC and ETSI Publications 1022 D.5. IEC Standards 1023 D.6. IEEE Standards 1026 D.7. International Space Station (ISS) Program Standards 1028 D.8. ITU-T Recommendations 1029 D.9. Military Standards and Handbooks 1030 D.10. NASA Standards and Handbooks 1036 D.11. NFPA Codes and Standards 1037 D.12. SAE Recommended Practices 1037 D.13. TIA/EIA Standards 1037 D.14. UL Standards 1038 D.15. Other (Miscellaneous) Standards 1038 APPENDIX E. On the Correspondence between Ohm’s Law and Fermat’s Least Time Principle 1039 E.1. Origin of the LT/MP Principle 1040 E.2. Statement of the LT/MP Principle 1040 E.3. Derivation of the Equivalence between Ohm’s Law and Fermat’s Least Time Principle 1041 E.4. Equivalence of Ohm’s Law and the LT/MP Theory 1043 Bibliography 1044 APPENDIX F. Overview of S Parameters 1045 F.1. Background 1045 F.2. Ports and Interaction Matrices 1046 F.3. The Scattering Matrix and S Parameters 1047 F.3.1. The Scattering (S) Matrix 1048 F.3.2. S21, or “Forward Transmission Gain/Loss” 1050 F.3.3 S11, or “Input Return Loss” 1051 F.3.4. S22, or “Output Return Loss” 1051 F.3.5. S12, or “Reverse Gain and Reverse Isolation” 1052 F.4. Characteristic Values of S Parameters 1053 F.5. S Parameters in Loss-Free and Lossy Networks 1053 F.5.1. The Loss-Free Network 1053 F.5.2. Lossy Networks 1054 F.5.3. Insertion Loss 1054 F.5.4. Radiation Loss 1054 Bibliography 1055 Index 1057