electrical contacts - gbv
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Electrical Contacts Principles and Applications
edited by Paul G» Slade
Cutler-Hammer Horseheads, New York
@ Taylor &. Francis Taylor & Francis Group Boca Raton London New York
CRC is an imprint of the Taylor & Francis Croup, an informa business
Contents
Preface Hi Contributors xiii Introduction xv
Part One CONTACT INTERFACE CONDUCTION
1 Electrical Contact Resistance: Fundamental Principles 1 Roland S. Timsit
1.1 Introduction 1 1.2 Electrical Constriction Resistance 2 1.3 The Effect of Surface Films on Constriction and Contact Resistance 15 1.4 Temperature of an Electrically Heated a-Spot 45 1.5 Mechanics of a-Spot Formation 58 1.6 Breakdown of Classical Electrical Contact Theory 72 1.7 Summary 75
Appendix l.A 76 Appendix l.B 79 Appendix l.C 80 References 83
vi
Introduction to Contact Tarnishing and Corrosion 89 Paul G. Slade
2.1 Introduction 89 2.2 Corrosion Rates 90 2.3 Corrosive Gases 92 2.4 Types of Corrosion 93 2.5 Gas Concentrations in the Atmosphere 100 2.6 Measurements 101 2.7 Mixed Flow Gas Laboratory Testing 105 2.8 Electronic Connectors 106 2.9 Power Connectors 108 2.10 Other Considerations 108
References 110
Contact Corrosion 113 William H. Abbott
3.1 Introduction 113 3.2 The Field Environments for Electrical Contacts 117 3.3 Laboratory Accelerated Testing 132 3.4 Corrosion Inhibition—Lubrication 150
References 153
Part Two NONARCING CONTACTS
4 Power Connections 155 Milenko Braunovic
4.1 Introduction 155 4.2 Types of Power Connectors 157 4.3 Properties of Conductor and Connector Materials 158 4.4 Parameters Affecting Performance of Power Connector 169 4.5 Palliative Measures 219 4.6 Accelerated Current-Cycling Tests (Standards) 252 4.7 Shape-Memory Alloys (SMA) 256
References 270
5 Low Power Commercial Wiring, Automotive, and Appliance Connections 279 Anthony Lee
5.1 Introduction 279 5.2 Connectors 281 5.3 Contact Terminals 288 5.4 Connector Contact Degradation 297 5.5 Summary 305
References 306
Contents vii
6.1 6.2 6.3 6.4
Introduction Sliding Wear Fretting Lubrication References
Tribology of Electronic Connectors: Contact Sliding Wear, Fretting, and Lubrication 309 Morton Antler
309 309 332 364 394
Materials, Coatings, and Platings 403 Morton Antler
7.1 Introduction 403 7.2 Metallic Finishes 404 7.3 Properties Related to Porosity 409 7.4 Metallurgical and Structural Properties 414 7.5 Physical and Mechanical Properties 423
References 430
Part Three THE ELECTRIC ARC AND SWITCHING DEVICE TECHNOLOGY
8 The Arc and Interruption 433 Paul G. Slade
8.1 Introduction 433 8.2 The Fourth State of Matter 433 8.3 Establishing an Arc 438 8.4 Formation of the Electric Arc 451 8.5 The Arc in Air at Atmospheric Pressure 454 8.6 The Arc in Vacuum 469 8.7 Arc Interruption 473
References 483
9 The Consequences of Arcing 487 Paul G. Slade
9.1 Introduction 487 9.2 Arcing Time 487 9.3 Arc Erosion of Electric Contacts 496 9.4 Blow-Off Force 508 9.5 Contact Welding 513 9.6 Changes in the Contact Surface as a Result of Arcing 520
References 530
10 Reed Switches 535 Kunio Hinohara
10.1 Principles and Design of the Reed Switch 535
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10.2 Recommended Contact Plating 549 10.3 Contact Surface Degradation and Countermeasures 552 10.4 Applications of Reed Switches 564
References 571
11 Low Current Switching 573 John W. McBride
11.1 Introduction and Device Classification 573 11.2 Device Types 574 11.3 Design Parameters for Static Switching Contacts 584 11.4 Mechanical Design Parameters 586 11.5 Electrical Characteristics of Low Current Switching Devices at
Opening 603 11.6 Electrical Characteristics of Low Current Switching Devices at
Closure 614 11.7 Summary 621 11.8 Afterword 623
References 624
12 Medium to High Current Switching 627 Manfred Lindmayer
12.1 General Aspects of Switching in Air 627 12.2 Contacts for Switching in Air 631 12.3 Low-Voltage Contactors 632 12.4 Low-Voltage Circuit-Breakers and Miniature Circuit-Breakers 648 12.5 Vacuum Interrupters 663
References 675
Part Four ARCING CONTACT MATERIALS
13 Arcing Contact Materials 681 Gerald J. Witter
13.1 Introduction 681 13.2 Silver Metal Oxides 684 13.3 Silver Refractory Metals 703 13.4 Vacuum Interrupter Materials 732 13.5 Other Special Applications for Refractory Metals 732 13.6 Non-Noble Silver Alloys 733 13.7 Silver-Nickel Contact Materials 735 13.8 Silver Alloys and Noble Metals 737 13.9 Silver Graphite Contact Materials 741 13.10 Conclusion 742
References 744
Contents
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
References
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
References
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
References
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
References
Contents
Illustrative Modern Brush Applications 873 Wilferd E. Yohe and William A. Nystrom
18.2 Introduction 873 18.2 Brush Materials 874 18.3 Brush Applications 876
Sliding Contacts for Instrumentation and Control 885 E. W. Glossbrenner
19.1 Definitions: Sliding Versus Static and Wiping Contacts 885 19.2 Macro Sliding Contacts 887 19.3 Micro Sliding Contact: Mechanical Aspects 901 19.4 Micro Sliding Contact: Electrical Aspects 911 19.5 Environment and Film Formation 915 19.6 Lubrication 922 19.7 Contact Parameters and Sliding-Contact Assemblies 927 19.8 Friction and Wear Performance 931 19.9 Inferences from Test and Examination of Performing Slip Ring
and Brush Contacts 936 19.10 Summary 938
References 939
Metal Fiber Brushes 943 Doris Kuhlmann- Wilsdorf
20.1 Introduction 943 20.2 Elastic Versus Plastic Contact Spots 945 20.3 Solving the Brush Wear Problem via Elastic Contact Spots 947 20.4 Basic Equations Governing Electrical Brush Resistance 951 20.5 Surface Films, Friction, and Materials Properties 953 20.6 Factors Affecting Performance of Fiber Brushes 957 20.7 Fallacious Apparent Speed of Fiber Brushes Based on the
"Softening Voltage" 967 20.8 Speed-Current-Density Limits Based on Flash Temperatures
and Wear 971 20.9 Fiber-Brush Cooling and Cooling by Means of Fiber Brushes 982 20.10 Optimizing Brush Performance 992 20.11 Advancing Towards Widespread Technological Fiber-Brush
Application 998 20.12 Potential Application of Fiber Brushes and Outlook for the Future 1009
Appendix 1010 Symbols 1012 References 1015
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