Insulators for Icing and Polluted Environments
November 2009, Wiley-IEEE Press
Written by prominent experts in the field, this book takes an in-depth look at the issues of electrical insulators for icing and polluted environments. It shows:
Engineers and environmental specialists how to carry out appropriate insulator contamination measurements, understand how these readings change with time and weather, and work out how the readings compare with the upper limits set by insulator dimensions in their existing stations
Design engineers how to assess the likely maximum pollution and icing limits at a substation or along an overhead line, and then select insulators that have appropriate withstand margins
Regulators why modest ice accretion at a moderate 0oC temperature on one occasion can qualify as a major reliability event day, while many similar days pass each winter without power system problems
Educators why the ice surface flashover is well behaved compared to the conventional pollution flashover, making it much more suitable for demonstrations, modeling, and analysis
The book is complemented with case studies and design equations to help readers identify the most appropriate insulators, bushings, and maintenance plans for their local conditions. Additionally, readers may download supplemental materials supporting evaluation of local climate and contamination.
Insulators for Icing and Polluted Environments is indispensable reading for any professional who needs reliable electrical supply from networks exposed to sources of wetting and pollution. It also serves as an excellent introduction to the subjects of high-voltage surface flashover, environmental electrochemistry, and insulation coordination for researchers, professors, and students.
1.1. Scope and Objectives.
1.2. Power System Reliability.
1.3. The Insulation Coordination Process: What Is Involved?
1.4. Organization of the Book.
2. INSULATORS FOR ELECTRIC POWER SYSTEMS.
2.1. Terminology for Insulators.
2.2. Classification of Insulators.
2.3. Insulator Construction.
2.4. Electrical Stresses on Insulators.
2.5. Environmental Stresses on Insulators.
2.6. Mechanical Stresses.
3. ENVIRONMENTAL EXPOSURE OF INSULATORS.
3.1. Pollution: What It Is.
3.2. Pollution Deposits on Power System Insulators.
3.3. Nonsoluble Electrically Inert Deposits.
3.4. Soluble Electrically Conductive Pollution.
3.5. Effects of Temperature on Electrical Conductivity.
3.6. Conversion to Equivalent Salt Deposit Density.
3.7. Self-Wetting of Contaminated Surfaces.
3.8. Surface Wetting by Fog Accretion.
3.9. Surface Wetting by Natural Precipitation.
3.10. Surface Wetting by Artificial Precipitation.
4. INSULATOR ELECTRICAL PERFORMANCE IN POLLUTION CONDITIONS.
4.1. Terminology for Electrical Performance in Pollution Conditions.
4.2. Air Gap Breakdown.
4.3. Breakdown of Polluted Insulators.
4.4. Outdoor Exposure Test Methods.
4.5. Indoor Test Methods for Pollution Flashovers.
4.6. Salt-Fog Test.
4.7. Clean-Fog Test Method.
4.8. Other Test Procedures.
4.9. Salt-Fog Test Results.
4.10. Clean-Fog Test Results.
4.11. Effects of Insulator Parameters.
4.12. Effects of Nonsoluble Deposit Density.
4.13. Pressure Effects on Contamination Tests.
4.14. Temperature Effects on Pollution Flashover.
5. CONTAMINATION FLASHOVER MODELS.
5.1. General Classifi cation of Partial Discharges.
5.2. Dry-Band Arcing on Contaminated Surfaces.
5.3. Electrical Arcing on Wet, Contaminated Surfaces.
5.4. Residual Resistance of Polluted Layer.
5.5. dc Pollution Flashover Modeling.
5.6. ac Pollution Flashover Modeling.
5.7. Theoretical Modeling for Cold-Fog Flashover.
5.8. Future Directions for Pollution Flashover Modeling.
6. MITIGATION OPTIONS FOR IMPROVED PERFORMANCE IN POLLUTION CONDITIONS.
6.1. Monitoring for Maintenance.
6.2. Cleaning of Insulators.
6.3. Coating of Insulators.
6.4. Adding Accessories.
6.5. Adding More Insulators.
6.6. Changing to Improved Designs.
6.7. Changing to Semiconducting Glaze.
6.8. Changing to Polymer Insulators.
7. ICING FLASHOVERS.
7.1. Terminology for Ice.
7.2. Ice Morphology.
7.3. Electrical Characteristics of Ice.
7.4. Ice Flashover Experience.
7.5. Ice Flashover Processes.
7.6. Icing Test Methods.
7.7. Ice Flashover Test Results.
7.8. Empirical Models for Icing Flashovers.
7.9. Mathematical Modeling of Flashover Process on Ice-Covered Insulators.
7.10. Environmental Corrections for Ice Surfaces.
7.11. Future Directions for Icing Flashover Modeling.
8. SNOW FLASHOVERS.
8.1. Terminology for Snow.
8.2. Snow Morphology.
8.3. Snow Electrical Characteristics.
8.4. Snow Flashover Experience.
8.5. Snow Flashover Process and Test Methods.
8.6. Snow Flashover Test Results.
8.7 Empirical Model for Snow Flashover.
8.8. Mathematical Modeling of Flashover Process on Snow-Covered Insulators.
8.9. Environmental Corrections for Snow Flashover.
8.10. Case Studies of Snow Flashover.
9. MITIGATION OPTIONS FOR IMPROVED PERFORMANCE IN ICE AND SNOW CONDITIONS.
9.1. Options for Mitigating Very Light and Light Icing.
9.2. Options for Mitigating Moderate Icing.
9.3. Options for Mitigating Heavy Icing.
9.4. Options for Mitigating Snow and Rime.
9.5. Alternatives for Mitigating Any Icing.
10. INSULATION COORDINATION FOR ICING AND POLLUTED ENVIRONMENTS.
10.1. The Insulation Coordination Process.
10.2. Deterministic and Probabilistic Methods.
10.3. IEEE 1313.2 Design Approach for Contamination.
10.4. IEC 60815 Design Approach for Contamination.
10.5. CIGRE Design Approach for Contamination.
10.6. Characteristics of Winter Pollution.
10.7. Winter Fog Events.
10.8. Freezing Rain and Freezing Drizzle Events.
10.9. Snow Climatology.
10.10. Deterministic Coordination for Leakage Distance.
10.11. Probabilistic Coordination for Leakage Distance.
10.12. Deterministic Coordination for Dry Arc Distance.
10.13. Probabilistic Coordination for Dry Arc Distance.
10.14. Case Studies.
APPENDIX A: MEASUREMENT OF INSULATOR CONTAMINATION LEVEL.
APPENDIX B: STANDARD CORRECTIONS FOR HUMIDITY, TEMPERATURE, AND PRESSURE.
APPENDIX C: TERMS RELATED TO ELECTRICAL IMPULSES.
William A. Chisholm, PhD, is an IEEE Fellow and an internationally acknowledged expert in lightning protection, electrical insulation, and thermal rating of power systems. Dr. Chisholm is an Associate at Kinectrics in Toronto, Canada, and an Adjunct Professor at the University of Québec at Chicoutimi. He is Secretary of the PES Transmission and Distribution Committee.
"Readers who finish this well-written book will be prepared to understand and face a sizeable fraction of the current problems involved in learning to correct icing and pollution problems in electrical line insulation. The book provides clear insight on how they can best position themselves for coping with situations that arise in icing ad polluted environments." (Current Engineering Practice, 1 November 2010)