Electrical Contacts Principles and Applications edited by Paul G» Slade

Transcription

1 Electrical Contacts Principles and Applications edited by Paul G» Slade Cutler-Hammer Horseheads, New Taylor &. Francis Taylor & Francis Group Boca Raton London New York CRC is an imprint of the Taylor & Francis Croup, an informa business

2 Preface Contributors Introduction Hi xiii xv Part One CONTACT INTERFACE CONDUCTION 1 Electrical Contact Resistance: Fundamental Principles 1 Roland S. Timsit 1.1 Introduction Electrical Constriction Resistance The Effect of Surface Films on Constriction and Contact Resistance Temperature of an Electrically Heated a-spot Mechanics of a-spot Formation Breakdown of Classical Electrical Contact Theory Summary 75 Appendix l.a 76 Appendix l.b 79 Appendix l.c 80 83

3 vi Introduction to Contact Tarnishing and Corrosion 89 Paul G. Slade 2.1 Introduction Corrosion Rates Corrosive Gases Types of Corrosion Gas Concentrations in the Atmosphere Measurements Mixed Flow Gas Laboratory Testing Electronic Connectors Power Connectors Other Considerations Contact Corrosion 113 William H. Abbott 3.1 Introduction The Field Environments for Electrical Contacts Laboratory Accelerated Testing Corrosion Inhibition Lubrication Part Two NONARCING CONTACTS 4 Power Connections 155 Milenko Braunovic 4.1 Introduction Types of Power Connectors Properties of Conductor and Connector Materials Parameters Affecting Performance of Power Connector Palliative Measures Accelerated Current-Cycling Tests (Standards) Shape-Memory Alloys (SMA) Low Power Commercial Wiring, Automotive, and Appliance Connections 279 Anthony Lee 5.1 Introduction Connectors Contact Terminals Connector Contact Degradation Summary

4 vii Tribology of Electronic Connectors: Contact Sliding Wear, Fretting, and Lubrication 309 Morton Antler Introduction Sliding Wear Fretting Lubrication Materials, Coatings, and Platings 403 Morton Antler Introduction Metallic Finishes Properties Related to Porosity Metallurgical and Structural Properties Physical and Mechanical Properties Part Three THE ELECTRIC ARC AND SWITCHING DEVICE TECHNOLOGY 8 The Arc and Interruption 433 Paul G. Slade 8.1 Introduction The Fourth State of Matter Establishing an Arc Formation of the Electric Arc The Arc in Air at Atmospheric Pressure The Arc in Vacuum Arc Interruption The Consequences of Arcing 487 Paul G. Slade 9.1 Introduction Arcing Time Arc Erosion of Electric Contacts Blow-Off Force Contact Welding Changes in the Contact Surface as a Result of Arcing Reed Switches 535 Kunio Hinohara 10.1 Principles and Design of the Reed Switch 535

5 WW 10.2 Recommended Contact Plating Contact Surface Degradation and Countermeasures Applications of Reed Switches Low Current Switching 573 John W. McBride 11.1 Introduction and Device Classification Device Types Design Parameters for Static Switching Contacts Mechanical Design Parameters Electrical Characteristics of Low Current Switching Devices at Opening Electrical Characteristics of Low Current Switching Devices at Closure Summary Afterword Medium to High Current Switching 627 Manfred Lindmayer 12.1 General Aspects of Switching in Air Contacts for Switching in Air Low-Voltage Contactors Low-Voltage Circuit-Breakers and Miniature Circuit-Breakers Vacuum Interrupters Part Four ARCING CONTACT MATERIALS 13 Arcing Contact Materials 681 Gerald J. Witter 13.1 Introduction Silver Metal Oxides Silver Refractory Metals Vacuum Interrupter Materials Other Special Applications for Refractory Metals Non-Noble Silver Alloys Silver-Nickel Contact Materials Silver Alloys and Noble Metals Silver Graphite Contact Materials Conclusion

6 14 Contact Design and Attachment Gerald J. Witter and Guenther Horn 14.1 Introduction 14.2 Staked Contact Assembly Designs 14.3 Welded Contact Assembly Designs 14.4 Brazed Contact Assembly Designs 14.5 Clad Metals, Inlay, and Edge Lay 14.6 Non-Arcing Separable Contact Alloys 15 Material Performance Evaluation and Test Methods Werner Rieder 15.1 Purpose 15.2 The Problem of Contact Evaluation 15.3 Test Methods 15.4 Test Realization 16 Arc Interactions with Contaminants Werner Rieder and Gerald J. Witter 16.1 Introduction 16.2 Organic Contamination and Activation 16.3 Mineral Particulate Contamination of Arcing Contacts 16.4 Silicone Contamination of Arcing Contacts 16.5 Lubricants with Refractory Fillers 16.6 Oxidation of Contact Materials 16.7 Resistance Effects from Long Arcs Part Five SLIDING ELECTRICAL CONTACTS 17 Sliding Electrical Contacts (Graphitic Type Lubrication) Erie I. Shobert II 17.1 Introduction 17.2 Mechanical Aspects 17.3 Chemical Aspects 17.4 Electrical Effects 17.5 Thermal Effects 17.6 Brush Wear 17.7 Brush Materials and Abrasion 17.8 Summary

7 Illustrative Modern Brush Applications 873 Wilferd E. Yohe and William A. Nystrom 18.2 Introduction Brush Materials Brush Applications 876 Sliding Contacts for Instrumentation and Control 885 E. W. Glossbrenner 19.1 Definitions: Sliding Versus Static and Wiping Contacts Macro Sliding Contacts Micro Sliding Contact: Mechanical Aspects Micro Sliding Contact: Electrical Aspects Environment and Film Formation Lubrication Contact Parameters and Sliding-Contact Assemblies Friction and Wear Performance Inferences from Test and Examination of Performing Slip Ring and Brush Contacts Summary Metal Fiber Brushes 943 Doris Kuhlmann- Wilsdorf 20.1 Introduction Elastic Versus Plastic Contact Spots Solving the Brush Wear Problem via Elastic Contact Spots Basic Equations Governing Electrical Brush Resistance Surface Films, Friction, and Materials Properties Factors Affecting Performance of Fiber Brushes Fallacious Apparent Speed of Fiber Brushes Based on the "Softening Voltage" Speed-Current-Density Limits Based on Flash Temperatures and Wear Fiber-Brush Cooling and Cooling by Means of Fiber Brushes Optimizing Brush Performance Advancing Towards Widespread Technological Fiber-Brush Application Potential Application of Fiber Brushes and Outlook for the Future 1009 Appendix 1010 Symbols

8 XI Part Six CONTACT DATA 21 Useful Electric Contact Information 1019 Paul G. Slade 21.1 Introduction Notes to the Tables Author Index 1041 Subject Index 1055