Design of Shipboard Power System Grounding / Earthing

This book delves into the diverse prerequisites for grounding and earthing in contemporary ship power systems, addressing the evolving landscape of ship design influenced by power electronics The introduction of transformative technologies such as variable frequency drives and electric propulsion systems has heightened the complexity of shipboard grounding systems. This complexity necessitates accommodation for robust electronic systems, extending the focus beyond traditional grounding aspects to include common mode grounding and its profound design implications. Engineers now require a comprehensive guide to navigate the intricacies of shipboard electric power systems. To meet this imperative, Design of Shipboard Power System Grounding/Earthing provides an in-depth exploration of the subject. It offers a step-by-step initiation into the grounding process, supported by numerous case studies for enhanced comprehension. Aligned with both US and international standards, this book serves as an essential resource for engineers engaged in the design and implementation of shipboard power systems. Key highlights for readers encompass meticulous comparisons between terrestrial power system grounding and shipboard power grounding, as well as comprehensive discussions on high resistance grounding, shipboard AC system grounding requirements, DC system grounding, and more, including common mode grounding and earthing. The inclusion of abundant engineering drawings supports significant case studies, enhancing the practical application of the material. Designed to cater to a broad audience, Design of Shipboard Power System Grounding/Earthing is invaluable for readers involved with shipboard electrical systems, including shipbuilders, ship designers, ship operators, and those in regulatory bodies such as the Navy, USCG, ABS, among others. This resource is also well-suited for academicians, particularly final-year undergraduate and graduate students in marine electrical engineering programs.

About the Authors xiii Preface xv 1 Introduction 1 1.1 General 1 1.2 Grounding and Earthing Definitions 2 1.3 Common Mode Terminology 4 1.4 Types of Power Distribution Systems 5 1.5 Types of Power System Grounding Systems 7 1.6 Modeling and Simulation 8 1.7 Book Overview 9 1.8 Legal Notice 13 References 13 2 System Grounding: Shipboard Ungrounded AC Systems (No Greater than 1 kV) 15 2.1 Characteristics 15 2.2 Modeling Shipboard Ungrounded AC Low-Voltage Distribution Systems 19 2.2.1 Low-Voltage AC Cable Model 20 2.2.2 Bus Duct 25 2.2.3 EMI Filters 25 2.2.4 Generators and Motors 25 2.2.5 Transformers 26 2.2.6 System Simulation 26 2.3 Ground Fault Detection 29 2.4 Ground Fault Localization 37 2.5 Electrical Insulation Impacts 41 2.6 One-Line Diagram Symbology 41 2.7 Case Studies 42 2.7.1 Modeling a Low-Voltage AC Cable 42 2.7.2 Modeling a Cable Line-to-Line Capacitance for GFCI Calculations 44 2.8 Reference Cable Data 49 References 53 3 System Grounding: Shipboard HRG AC Low-Voltage Distribution Systems (No Greater than 1 kV) 55 3.1 Characteristics 55 3.2 Grounding Circuit 64 3.2.1 Grounding Resistor Characteristics 64 3.2.2 Neutral Ground 66 3.2.3 Zigzag Transformer 66 3.2.4 Wye-Delta Transformer 67 3.2.5 Wye-Broken Delta Transformer 68 3.2.6 One-Line Diagram Symbology 69 3.2.7 Grounding Transformer Characteristics 70 3.2.8 Grounding Transformer Saturation 70 3.3 Location of Grounding Circuit 74 3.4 Ground Fault Detection 78 3.5 Ground Fault Localization 79 3.5.1 Pulsing System 79 3.5.2 Low-Resistance Ground Fault Clearing 80 3.5.3 Common Mode Current Phase Measurements 82 3.6 Electrical Insulation Impacts 83 3.7 Limiting Ground Fault Current 83 References 84 4 System Grounding: Shipboard Solidly Grounded AC Systems (No Greater than 400 V) 85 4.1 Characteristics 85 4.2 Design Considerations 89 4.2.1 General 89 4.2.2 Transformers 89 4.2.3 Sub-power Panels 94 4.2.4 Ground Fault Protection 94 4.3 Cable Insulation Colors 97 5 System Grounding: Shipboard HRG AC Primary Distribution Systems (Greater than 1 kV) 99 5.1 Characteristics 99 5.2 Grounding Circuit 100 5.2.1 Grounding Resistor Transformer 100 5.2.2 Wye-Broken Delta Transformer 101 5.2.3 Grounding Resistor Design 102 5.3 Modeling Shipboard HRG AC Primary Distribution Systems 102 5.3.1 Three-Conductor Shielded Cable Models 102 5.3.2 Single-Conductor Cable and Insulated Bus Pipe Models 107 5.3.3 EMI and Harmonic Filters 109 5.3.4 Generators and Motors 109 5.3.5 Transformers 112 5.3.6 System Simulation 114 5.4 Location of Grounding Circuit 117 5.5 Ground Fault Detection 118 5.6 Ground Fault Localization 118 5.7 Electrical Insulation Impact 119 5.7.1 Insulation Voltage Rating 119 5.7.2 Partial Discharge 119 5.8 Limiting Ground Fault Current 120 5.9 Cable Terminations 120 References 122 6 System Grounding: Shipboard Ungrounded DC Systems (No Greater than 1 kV) 125 6.1 Characteristics 125 6.2 Modeling 128 6.2.1 Two-Conductor Unshielded Cable 128 6.2.2 Four-Conductor Unshielded Cable 131 6.2.3 Passive Rectifiers 133 6.2.4 Active Rectifiers 133 6.3 Ground Fault Detection 133 6.4 Ground Fault Localization 136 6.5 Auctioneering Diodes 140 6.6 Electrical Insulation Impacts 143 6.7 Cable Insulation Colors 143 References 143 7 System Grounding: Shipboard HRG DC Systems 145 7.1 Characteristics 145 7.2 Grounding Methods 146 7.2.1 Line-to-Ground Resistors 146 7.2.2 Split Power Supply 149 7.2.3 Grounding Bus 150 7.2.4 Current Sensors 150 7.3 Modeling 151 7.3.1 Four-Conductor Shielded Cable 151 7.4 Ground Fault Detection 154 7.5 Ground Fault Localization 154 7.6 Electrical Insulation Impacts 158 7.6.1 Insulation Voltage Rating 158 7.6.2 Partial Discharge 158 7.6.3 Space Charge 159 References 159 8 System Grounding: Shipboard Solidly Grounded DC Systems (No Greater than 1 kV) 161 8.1 Characteristics 161 8.2 Corrosion 163 8.3 Modeling Shipboard Solidly Grounded DC Systems 163 8.4 Ground Fault Detection and Localization 164 8.5 Electrical Insulation Impacts 166 8.6 Cable Insulation Colors 166 9 Designing Shipboard Power System Grounding/Earthing Systems 167 9.1 Introduction 167 9.2 AC Primary Distribution Systems 168 9.3 AC Low-Voltage Distribution Systems 170 9.4 AC Low-Voltage Secondary Distribution Systems 171 9.5 AC Low-Voltage Special Circuits 172 9.6 dc Primary Distribution Systems 172 9.7 dc Low-Voltage Distribution Systems 173 9.8 dc Low-Voltage Secondary Distribution Systems 173 9.9 dc Low-Voltage Special Circuits 174 9.10 Examples 174 9.10.1 AC Low-Voltage Distribution System for Commercial Mechanical Drive Ship 174 9.10.2 AC Primary Distribution System for Commercial Integrated Power System Ship 180 9.10.3 Low-Voltage AC Zonal Distribution 185 9.10.4 Zonal AC Primary Distribution 185 9.10.5 Commercial Ship DC Distribution 190 9.10.6 Zonal DC Primary Distribution 192 References 193 10 Power Conversion Equipment Grounding 195 10.1 Introduction 195 10.2 Transformers 195 10.3 Isolated Power Conversion Equipment 198 10.4 Non-Isolated Power Conversion Equipment 199 10.5 cm Voltage and Current Control 201 10.6 VFD Cable 202 10.6.1 VFD Cable Description and Use 202 10.6.2 VFD Cable Modeling (Without Conductor Shields) 205 10.6.3 VFD Cable Modeling (with Conductor Shields) 208 10.7 Examples 209 10.7.1 Directly Connected VFD and Motor – No More than 1 kV 209 10.7.2 Transformer-Supplied VFD and Motor – No Greater than 1 kV 212 10.7.3 Propulsion Motor Drives – Greater than 1 kV 214 10.8 Maintenance Considerations 217 References 219 11 Shore Power (Cold Ironing) Connection Grounding 221 11.1 Introduction 221 11.2 Low-Voltage Shore Connections 223 11.3 High-Voltage Shore Connections 227 References 237 12 Vehicle Connections Grounding 239 12.1 Introduction 239 12.2 Design Considerations 239 12.2.1 Aircraft Static Electricity 239 12.2.2 Vehicle Electrical Systems 241 References 242 13 Common Mode Grounding: Impact of Common Mode Currents and Voltages on Grounding Systems 243 13.1 Common Mode Fundamentals 243 13.2 Relationship of CM to EMI and EMC 256 13.3 Control of CM Currents and Voltages 257 13.3.1 Equipment Design 258 13.3.2 Cable Shields, Drain Wires, and Ground Conductors 258 13.3.3 Inductors and CM Chokes 261 13.3.4 Capacitors and CM Shunts 264 13.3.5 cm Control Philosophies 267 13.3.5.1 Cable Only Solution 267 13.3.5.2 Cable and CM Choke Solution 268 13.3.5.3 Controlling CM at the Interfaces 268 13.3.5.4 Controlling CM at the HRG 270 13.3.5.5 Controlling CM Within Motors and Generators 270 13.3.6 cm AC Limits 271 13.3.7 cm dc Limits 273 13.4 Advanced CM Modeling 275 13.5 Design Considerations 276 References 276 14 Protective Earthing: Bonding 279 14.1 Introduction 279 14.2 Design Considerations 280 14.3 Testing 286 References 286 15 Current-Related Corrosion 289 15.1 Introduction 289 15.2 Galvanic Corrosion Theory 289 15.3 Impact of Current on Galvanic Corrosion 296 15.3.1 dc Current 296 15.3.2 AC Current 297 15.4 Shipboard Corrosion 297 15.4.1 Hull and Structure Corrosion 297 15.4.2 Propulsion Shaft Corrosion 298 15.4.3 Electrical Connection Corrosion 299 15.4.4 Bearing Corrosion 299 15.5 Cathodic Protection Systems 300 15.5.1 Sacrificial Anodes 300 15.5.2 Impressed Current Cathodic Protection 302 References 303 16 Lightning Protection Systems 305 16.1 Introduction 305 16.2 Design Considerations 308 16.2.1 Zone of Protection 308 16.2.2 Air Terminals 310 16.2.3 Down Conductors 311 16.2.4 Low-Impedance Ground Connection 312 16.2.5 Surge Protection 312 References 314 17 Grounding Systems for Nonmetallic Hull Ships 317 17.1 Design Considerations 317 Reference 319 Appendix A Glossary 321 Appendix B Acronyms and Abbreviations 337 Appendix C Impact of Electric Current on Humans 339 Index 345