Offshore Electrical Engineering

Offshore Electrical Engineering is written based on the author's 20 years electrical engineering experience of electrical North Sea oil endeavor. The book has 14 chapters and five important appendices. The book starts with designing for electrical power offshore application, especially with aspects that are different from land based structures, such as space and weight limitations, safety hazards at sea, and corrosive marine environment. The criteria for selecting prime movers and generators, for example, gas turbines and reciprocating engines, depending on the type of applications, are examined. The machinery drives are then discussed whereby the different offshore electric motor ratings are considered. As in any electrical system, the use of ergonomically designed controls is important. Distribution switchgear, transformers, and cables are described. The book also explains the environmental considerations, power system disturbances, and protection. In an offshore structure, lighting requirements and subsea power supplies, diving life support system, and equipment protection are emphasized. A reliability analysis is also included to ensure continuance of service from the equipment. A general checklist to be used when preparing commissioning workscopes is included, and due to space and weight limitations on offshore installation, the rationale of maintenance and logistics options are explained. The appendices can be used as guides to descriptions offshore installations, typical commissioning test sheets, computerized calculations program, and a comparison of world hazardous area equipment. The text is a suitable reading for offshore personnel, oil-rig administrators, and for readers from all walks of life interested in some technical aspects of offshore structures.

Preface Acknowledgments 1 Introduction: Offshore Power Requirements 1.1 Hazards Offshore 1.2 Electrical System Design Criteria 1.3 Main Prime Movers 1.4 Key Services or Submain Generators 1.5 Medium-Voltage Distribution 1.6 Low-Voltage Distribution 1.7 Emergency or Basic Services Switchboard 1.8 Fire Pumps 1.9 Secure AC and DC Power Supplies 1.10 Drilling Supplies 2 Electrical System General Requirements 2.1 Safety 2.2 Isolated Situation 2.3 Environment 2.4 Water Hazards 2.5 Hydrocarbon Hazards 2.6 Distribution Configuration 2.7 Modular Construction 2.8 Subsea Cable Versus Onboard Generation 3 Prime Mover and Generator Selection 3.1 Gas Turbines 3.2 Gas Turbine Application 3.3 Reciprocating Engines 3.4 Load Profiles 3.5 Choice of Fuel 3.6 Main Generation 3.7 Cooling Systems 3.8 Lube Oil Systems 3.9 Governors 3.10 Alternators and Excitation Systems 3.11 Neutral Earthing 3.12 Starting Requirements 3.13 Emergency Generation 3.14 Key Services Generation 4 Process Drives and Starting Requirements 4.1 Voltage Levels 4.2 Starting 4.3 Speed 4.4 Pole Configuration 4.5 Cooling and Ingress Protection 4.6 Special Applications 5 Control and Monitoring Systems 5.1 Generator Controls 5.2 Load Sharing Systems 5.3 Load Shedding Systems 5.4 Power Management Systems 5.5 Fire and Gas Considerations 5.6 Process Shutdown Considerations 5.7 Effects of ESD System On Electrical Systems 5.8 Uninterruptible and Secure Power Supplies 5.9 DC Supplies 5.10 AC Supplies 5.11 Selection of Voltage Tolerances 5.12 Batteries 6 Generation and Distribution Switchgear and Transformers 6.1 General Requirements 6.2 The Mechanism of Short-Circuit Current Interruption 6.3 Types of Interrupter 6.4 Switchboard Construction 6.5 Drilling Supplies 6.6 Living Quarters Supplies 6.7 Process Area Distribution 6.8 Transformers 7 Cabling Systems and Equipment Installation 7.1 Technical Organization of the Design Programme 7.2 Material and Equipment Handling and Storage 7.3 Erection Procedure 7.4 Switchgear and Motor Control Centers 7.5 Distribution Transformers 7.6 Motors and Generators 7.7 Lighting and Small Power 7.8 Secure Power Supply Systems 7.9 Communications 7.10 Cable Support Systems 7.11 Cables 7.12 Bus Ducting 7.13 Control Stations, Junction Boxes and Distribution Boards 7.14 Earthing 7.15 Installation In Hazardous Areas 8 Environmental Topics 8.1 Weather and Sea Protection 8.2 Enclosure Ingress Protection 8.3 Hazardous Area Applications 8.4 Ventilation 8.5 Logic of Area Classification 8.6 Selection of Motors 8.7 Selection of Other Equipment 8.8 Structural Considerations 8.9 Noise Control 9 Power System Disturbances: Prediction and Protection 9.1 Alternator Faults and Protection Devices 9.2 Transformer Faults and Protection Devices 9.3 Motor Faults and Protection 9.4 Busbar Protection 9.5 Feeder Protection 9.6 Sizing of Conductors 9.7 Worked Example: Fault Calculation 9.8 Worked Example: Relay Setting of Typical MV Platform Scheme 9.9 Worked Example: Setting Voltage Controlled Overcurrent Relays 10 Offshore Lighting 10.1 Lighting Calculations 10.2 Calculation Procedure 10.3 Floodlighting 10.4 Accommodation Lighting 10.5 Process Area Lighting 10.6 Drilling Areas 10.7 Laydown Areas 10.8 Helidecks 10.9 Jacket and Leg Lighting 10.10 Navigational Lighting 10.11 Walkways, Catwalks and Stairways 10.12 Emergency Access Lighting 10.13 Routine Maintenance 11 Subsea Supplies 11.1 Subsea Power Supplies 11.2 Diver's Life Support Equipment 11.3 Diving Chambers 11.4 Inductive Couplers 11.5 Subsea Umbilicals and Power Cables 11.6 Cathodic Protection 11.7 Types of System 11.8 Cathodic Protection Calculations 12 Reliability 12.1 Duplication and Redundancy 12.2 Failure Mode, Effects and Criticality Analysis (FMECA) 12.3 Fault Trees 12.4 Reliability Block Diagrams 12.5 Confidence Limits 13 Commissioning 13.1 Generators 13.2 Switchgear 13.3 Protection Schemes: General Procedures 13.4 Voltage Transformers 13.5 Current Transformers 13.6 Protection Relays 13.7 Motor Commissioning Tests 14 Maintenance and Logistics 14.1 Rationalization of Spares 14.2 Accessibility and Communications 14.3 Maintenance Intervals and Equipment Specification 14.4 Scaffolding 14.5 Transport, Accommodation and POB Problems Appendix A Guide To Offshore Installations Appendix B Typical Commissioning Test Sheets Appendix C Simple Three-Phase Fault Calculation Program Appendix D Commercial Programs for Load Flow, Fault and Transient Stability Appendix E Comparison of World Hazardous Area Equipment Bibliography Index