- Cover
- Half Title
- Title Page
- Copyright Page
- Table of Contents
- Preface to the Second Edition
- Preface to the First Edition
- Introduction
- Editor
- Contributors
- Part I Contact Interface Conduction
- 1. Electrical Contact Resistance: Fundamental Principles
- 1.1 Introduction
- 1.2 Electrical Constriction Resistance
- 1.3 Effect of Surface Films on Constriction and Contact Resistance
- 1.3.1 Electrically Conductive Layers on an Insulated Substrate
- 1.3.2 Electrically Conducting Layers on a Conducting Substrate
- 1.3.3 Growth of Intermetallic Layers
- 1.3.4 Possible Effect of Electromigration on Intermetallic Growth Rates
- 1.3.5 Electrically Insulating or Weakly Conducting Films
- 1.3.6 Fritting of Electrically Insulating Surface Films
- 1.4 Temperature of an Electrically Heated a-Spot
- 1.4.1 Voltage–Temperature Relation
- 1.4.2 Voltage–Temperature Relation with Temperature-Dependent Electrical Resistivity and Thermal Conductivity
- 1.4.3 The Wiedemann–Franz Law
- 1.4.4 Temperature Distribution in the Vicinity of an a-Spot
- 1.4.5 Deviation of the Voltage–Temperature Relation in an Assymetric Contact
- 1.4.6 Special Considerations on the “Melting” Voltage in Electrical Contacts
- 1.5 Mechanics of a-Spot Formation
- 1.6 Breakdown of Classical Electrical Contact Theory in Small Contact Spots
- 1.6.1 Electrical Conduction in Small a-Spots
- 1.6.2 Observations of Breakdown of Classical Electrical Contact Theory in Aluminum Contacts
- 1.6.3 Observations of Breakdown of Classical Electrical Contact Theory in Gold Contacts
- 1.6.4 Observations of Breakdown of Classical Electrical Contact Theory in Tin Contacts
- 1.7 Constriction Resistance at High Frequencies
- 1.8 Summary
- Acknowledgments
- References
- 2. Introduction to Contact Tarnishing and Corrosion
- 3. Gas Corrosion
- 3.1 Introduction
- 3.2 The Field Environments for Electrical Contacts
- 3.3 Laboratory Accelerated Testing
- 3.4 Lubrication and Inhibition of Corrosion
- Acknowledgment
- References
- 4. Effect of Dust Contamination on Electrical Contacts
- 4.1 Introduction
- 4.2 Dusty Environment and Dust Composition
- 4.3 The Characteristics of Dust Particles
- 4.4 Application Conditions in Dusty Environment
- 4.4.1 Explanation of the Special Features
- 4.4.1.1 Covered by Accumulated Small Particles
- 4.4.1.2 Accumulative Particles Caused by Micro Motion
- 4.4.1.3 High and Erratic Contact Resistance
- 4.4.1.4 The Element of Si Causes High Contact Resistance
- 4.4.1.5 Organics Act as Adhesives
- 4.4.1.6 Corrosion Products Trap the Dust Particles
- 4.4.1.7 Difference Between Short Life and Longer Life Contacts
- 4.4.1.8 Large Pieces of “Stepping Stones”
- 4.4.1.9 The Performance of Failed Mobile Phones
- 4.4.2 Other Examples
- 4.4.1 Explanation of the Special Features
- 4.5 Theoretical Analysis of Connector Contact Failure due to the Dust
- 4.6 Future Work
- References
- 1. Electrical Contact Resistance: Fundamental Principles
- Part II Nonarcing Contacts
- 5. Power Connectors
- 5.1 Introduction
- 5.2 Types of Power Connectors
- 5.3 Properties of Conductor and Connector Materials
- 5.4 Parameters Affecting Performance of Power Connections
- 5.4.1 Factors Affecting Reliability of Power Connections
- 5.4.2 Contact Area
- 5.4.3 Plastic Deformation
- 5.4.4 Elastic Deformation
- 5.4.5 Plated Contacts
- 5.4.6 Oxidation
- 5.4.7 Corrosion
- 5.4.8 Dust Corrosion
- 5.4.9 Galvanic Corrosion
- 5.4.10 Thermal Expansion
- 5.4.11 Fretting
- 5.4.11.1 Factors Affecting Fretting
- 5.4.11.2 Mechanisms of Fretting
- 5.4.11.3 Examples of Fretting Damage in Power Connections
- 5.4.11.4 Compression Connectors
- 5.4.11.5 Bus-Stab Contacts
- 5.4.11.6 Plug-In Connectors
- 5.4.11.7 Bolted Connections
- 5.4.11.8 Fretting in Aluminum Connections
- 5.4.11.9 Effect of Electrical Current
- 5.4.11.10 Fretting in Coatings (Platings)
- 5.4.11.11 Fretting in Circuit Breaker Contact Materials
- 5.4.12 Intermetallic Compounds
- 5.4.13 Intermetallics in Copper–Tin Systems
- 5.4.14 Stress Relaxation and Creep
- 5.4.15 Nature of the Effect of Electric Current
- 5.4.16 Effect of Electric Current on Stress Relaxation
- 5.4.17 Creep
- 5.5 Palliative Measures
- 5.5.1 Contact Area
- 5.5.2 Contact Pressure
- 5.5.3 Mechanical Contact Device
- 5.5.4 Disc-Spring (Belleville) Washers
- 5.5.5 Wedge Connectors
- 5.5.6 Automatic Splices
- 5.5.7 Dead-end Connectors
- 5.5.8 Shape-Memory Alloy Connector Devices
- 5.5.9 Coating (Plating)
- 5.5.10 Lubrication—Contact Aid Compounds
- 5.5.11 Bimetallic Inserts
- 5.5.12 Transition Washers
- 5.5.13 Multilam Contact Elements
- 5.5.14 Welded Connections
- 5.5.15 Connector Design
- 5.6 Connector Degradation
- 5.7 Prognostic Models
- 5.8 Shape-Memory Alloys (SMA)
- 5.9 Metal Foam Materials
- 5.10 Installation of Power Connections
- 5.11 Accelerated Current-Cycling Tests (Standards)
- References
- 6. Low-Power Commercial, Automotive, and Appliance Connections
- 7. Tribology of Electronic Connectors: Contact Sliding Wear, Fretting, and Lubrication
- 7.1 Introduction
- 7.2 Sliding Wear
- 7.3 Fretting
- 7.3.1 Background
- 7.3.2 Fretting Regimes
- 7.3.3 Static versus Dynamic Contact Resistance
- 7.3.4 Field and Laboratory Testing Methodologies
- 7.3.5 Materials Studies
- 7.3.6 Wear-Out Phenomena
- 7.3.7 Parametric Studies
- 7.3.8 Environmental Effects
- 7.3.9 Thermal
- 7.3.10 Effect of Current
- 7.3.11 Surface Finish and Contact Geometry
- 7.3.12 Material Transfer, Wear, Film Formation, and Contact Resistance
- 7.4 Lubrication
- References
- 8. Materials, Coatings, and Platings
- 8.1 Introduction
- 8.2 Metallic Finishes
- 8.3 Properties Related to Porosity
- 8.3.1 Origins of Porosity
- 8.3.2 Tests of Porosity
- 8.3.3 Relationships between Porosity, Thickness of Finish, and Substrate Roughness
- 8.3.4 Effect of Underplatings, Flash Coatings, and Strikes on the Porosity of Electrodeposits
- 8.3.5 Reduction in the Chemical Reactivity of Finishes by the Use of Underplates
- 8.4 Metallurgical and Structural Properties
- 8.5 Physical and Mechanical Properties
- Acknowledgement
- References
- 5. Power Connectors
- Part III The Electric Arc and Switching Device Technology
- 9. The Arc and Interruption
- 9.1 Introduction
- 9.2 The Fourth State of Matter
- 9.3 Establishing an Arc
- 9.4 The Formation of the Electric Arc
- 9.5 The Arc in Air at Atmospheric Pressure
- 9.6 The Arc in Vacuum
- 9.7 Arc Interruption
- 9.7.1 Arc Interruption in Alternating Current Circuits
- 9.7.2 Arc Interruption in Direct Current Circuits
- 9.7.3 Vacuum Arc Interruption in Alternating Circuits
- 9.7.4 Arc interruption of Alternating Circuits: Current Limiting
- 9.7.5 Interruption of Low Frequency and High Frequency Power Circuits
- 9.7.6 Interruption of Megahertz and Gigahertz Electronic Circuits
- Acknowledgments
- References
- 10. The Consequences of Arcing
- 11. Reed Switches
- 12. Low Current and High Frequency Miniature Switches: Microelectromechanical Systems (MEMS), Metal Contact Switches
- 13. Low Current Switching
- 13.1 Introduction and Device Classification
- 13.2 Device Types
- 13.3 Design Parameters for Static Switching Contacts
- 13.4 Mechanical Design Parameters
- 13.5 The Measurement of Contact Wear and Contact Dynamics
- 13.6 Electrical Characteristics of Low-Current Switching Devices at Opening
- 13.7 Electrical Characteristics of Low Current Switching Devices at Closure
- 13.8 Summary
- Acknowledgments
- References
- 14. Medium to High Current Switching: Low Voltage Contactors and Circuit Breakers, and Vacuum Interrupters
- 14.1 General Aspects of Switching in Air
- 14.2 Contacts for Switching in Air
- 14.3 Low-Voltage Contactors
- 14.4 Low-Voltage Circuit-Breakers and Miniature Circuit-Breakers
- 14.4.1 Principle/Requirements
- 14.4.2 General Arrangement
- 14.4.3 Quenching Principle and Design of Arc Chute and Contact System
- 14.4.4 Trip System
- 14.4.5 Examples of Miniature Circuit-Breakers
- 14.4.6 Contact Materials
- 14.4.7 Special Requirements for DC Switching
- 14.4.8 Current Limitation by Principles Other than Deion Arc Chutes
- 14.5 Simulations of Low-Voltage Switching Devices
- 14.6 Vacuum Interrupters
- References
- 15. Arc Faults and Electrical Safety
- 9. The Arc and Interruption
- Part IV Arcing Contact Materials
- 16. Arcing Contact Materials
- 16.1 Introduction
- 16.2 Silver Metal Oxides
- 16.2.1 Types
- 16.2.2 Manufacturing Technology
- 16.2.2.1 Internal Oxidation
- 16.2.2.2 Post-Oxidized Internally Oxidized Parts (Process B 1.0)
- 16.2.2.3 One-Sided Internally Oxidized Parts (Process B 2.01)
- 16.2.2.4 Preoxidized Internally Oxidized Parts (Process B.2.02)
- 16.2.2.5 Powder Metallurgical (PM) Silver Metal Oxides (Processes C and D)
- 16.2.3 Electrical Performance Factors
- 16.2.3.1 AC versus DC Testing
- 16.2.3.2 High Current Inrush DC Automotive and AC Loads
- 16.2.3.3 Inductive Loads
- 16.2.3.4 Silver–Tin Oxide Type Materials and Additives
- 16.2.3.5 Material Factor
- 16.2.3.6 Interpreting Material Research, Example from Old Silver Cadmium Oxide Research
- 16.2.4 Material Considerations Based on Electrical Switching Characteristics
- 16.2.4.1 Erosion/Materials Transfer/Welding
- 16.2.5 Transfer/Welding
- 16.2.6 Erosion/Mechanisms/Cracking
- 16.2.7 Erosion/Arc Mobility
- 16.2.8 Interruption Characteristics
- 16.2.9 Contact Resistance
- 16.2.9.1 Summary Metal Oxides
- 16.3 Silver Refractory Metals
- 16.3.1 Manufacturing Technology
- 16.3.1.1 Manufacturing Technology/Press Sinter Repress (Process D 1.0)
- 16.3.2 Material Technology/Extruded Material
- 16.3.2.1 Material Technology/Liquid Phase Sintering (Process D 2.0)
- 16.3.2.2 Material Technology/Press Sinter Infiltration (Process D 3.0)
- 16.3.3 Metallurgical/Metallographic Methods
- 16.3.3.1 Metallurgical/Metallographic Methods/Preparation
- 16.3.3.2 Metallurgical/Metallography/Quantitative Analysis
- 16.3.4 Metallurgical/Structure/Strength and Toughness
- 16.3.5 Electrical Properties (EP)
- 16.3.5.1 EP/Arc Erosion/Microstructure and Properties
- 16.3.5.2 EP/Arc Erosion/Silver Refractory
- 16.3.5.3 EP/Graphite Additions to Silver Tungsten and Silver Tungsten Carbide
- 16.3.5.4 EP/Copper Refractory Metals
- 16.3.5.5 EP/Erosion/Summary
- 16.3.5.6 EP/Composite Refractory Materials/Contact Resistance
- 16.4 Vacuum Interrupter Materials
- 16.5 Tungsten Contacts
- 16.6 Non-Noble Silver Alloys
- 16.6.1 Fine Silver
- 16.6.2 Hard Silver and Silver–Copper Alloys
- 16.7 Silver–Nickel Contact Materials
- 16.8 Silver Alloys and Noble Metals
- 16.8.1 Palladium and Silver–Palladium Alloys
- 16.8.2 Platinum
- 16.9 Silver–Graphite Contact Materials
- 16.10 Conclusion
- Acknowledgements
- References
- 17. Contact Design and Attachment
- 17.1 Introduction
- 17.1.1 Arc-Induced Contact Stresses and Interface Bond Quality
- 17.2 Staked Contact Assembly Designs
- 17.2.1 Contact Rivets
- 17.2.1.1 Solid Rivets
- 17.2.1.2 Machine-Made Composite Rivets
- 17.2.1.3 Brazed Composite Rivets
- 17.2.1.4 Rivet Staking
- 17.3 Welded Contact Assembly Designs
- 17.3.1 Resistance Welding
- 17.3.1.1 Button Welding
- 17.3.1.2 Wire-Welding
- 17.3.1.3 Contact Tape Welding
- 17.3.2 Special Welding Methods
- 17.3.2.1 Percussion Welding
- 17.3.2.2 Ultrasonic Welding of Contacts
- 17.3.2.3 Friction Welding of Contacts
- 17.4 Brazed Contact Assembly Designs
- 17.4.1 Methods for Brazing Individual Parts
- 17.4.1.1 Torch Brazing
- 17.4.1.2 Induction Brazing
- 17.4.1.3 Direct and Indirect Resistance Brazing
- 17.4.1.4 Furnace Brazing
- 17.4.1.5 Continuous Laminated Strip Brazing, “Toplay”
- 17.4.1.6 Brazed Assembly Quality Control Methods
- 17.5 Clad Metals, Inlay, and Edge Lay
- 17.6 Contact Alloys for Non-Arcing Separable Contacts
- 17.6.1 Gold and Gold Alloys
- 17.6.2 Manufacturing Technology
- 17.6.3 Physical and Chemical Properties
- 17.6.4 Metallurgical Properties
- 17.6.5 Contact Applications and Performance
- Acknowledgments
- References
- 18. Electrical Contact Material Testing Design and Measurement
- 18.1 Objectives
- 18.2 Device Testing and Model Switch Testing
- 18.2.1 Device Testing
- 18.2.2 Model Switch Testing
- 18.3 Electrical Contact Testing Variables
- 18.3.1 AC versus DC Testing
- 18.3.2 Switching Load Type
- 18.3.3 Opening and Closing Velocity Effects
- 18.3.4 Contact Bounce
- 18.3.5 Contact Carrier Mass and Conductivity
- 18.3.6 Contact Closing Force and Over Travel
- 18.3.7 Enclosed and Open Contact Devices
- 18.3.8 Testing at Different Ambient Temperatures
- 18.3.9 Erosion Measurement
- 18.3.10 Summary Electrical Contact Testing Variables
- 18.4 Electrical Testing Result Types and Measurement Methods
- 18.4.1 Contact Resistance
- 18.4.1.1 Model Testing
- 18.4.1.2 Evaluation and Presentation of Results
- 18.4.2 Contact Bounce Measurement
- 18.4.2.1 Model Testing
- 18.4.2.2 Evaluation
- 18.4.3 Contact Welding Measurement
- 18.4.3.1 Weld Strength Measured
- 18.4.4 Contact Erosion Measurements
- 18.4.4.1 Accelerated and Model Testing
- 18.4.4.2 Extrapolation at Rated Stress
- 18.4.4.3 Increase of the Switching Frequency
- 18.4.4.4 Testing at Increased Electrical Load
- 18.4.4.5 Fixed-Gap Models
- 18.4.4.6 Moving Contact Models
- 18.4.4.7 Evaluation and Presentation of Results
- 18.4.5 AC Arc Reignition Measurement
- 18.4.6 Arc Motion Measurements
- 18.4.6.1 Measurement
- 18.4.6.2 Electronic Optical
- 18.4.6.3 Model Switch Arc Motion Control
- 18.4.6.4 Evaluation and Presentation of Results
- 18.4.7 Arc-Wall Interaction Measurements
- References
- 19. Arc Interactions with Contaminants
- 19.1 Introduction
- 19.2 Organic Contamination and Activation
- 19.2.1 The Phenomena
- 19.2.2 Sources of Organic Vapors
- 19.2.3 Processes of Contact Activation
- 19.2.4 Activation Effects
- 19.2.5 Activation and Contact Resistance Problems
- 19.2.6 Methods for Detecting Carbon Contamination
- 19.3 Mineral Particulate Contamination of Arcing Contacts
- 19.4 Silicone Contamination of Arcing Contacts
- 19.4.1 Contamination from Silicone Vapors
- 19.4.2 Contamination from Silicone Migration
- 19.4.3 Summary of Silicone Contamination Mechanisms
- 19.5 Lubricants with Refractory Fillers
- 19.6 Oxidation of Contact Materials
- 19.7 Resistance Effects from Long Arcs
- Acknowledgments
- References
- 16. Arcing Contact Materials
- Part V Sliding Electrical Contacts
- 20. Sliding Electrical Contacts (Graphitic Type Lubrication)
- 20.1 Introduction
- 20.2 Mechanical Aspects
- 20.2.1 Hardness
- 20.2.2 Friction and Wear
- 20.2.3 Tunnel Resistance and Vibration
- 20.3 Chemical Aspects
- 20.3.1 Oxidation
- 20.3.2 Moisture Film
- 20.4 Electrical Effects
- 20.4.1 Constriction Resistance
- 20.4.2 Film Resistance
- 20.4.3 Fundamental Aspects of Commutation
- 20.4.4 Equivalent Commutation Circuit and DC Motor Driving Automotive Fuel Pump
- 20.4.5 Arc Duration and Residual Current
- 20.5 Thermal Effects
- 20.5.1 Steady State
- 20.5.2 Actual Temperature
- 20.5.3 Thermal Mound
- 20.6 Brush Wear
- 20.6.1 Holm’s Wear Equation
- 20.6.2 Flashes and Smutting
- 20.6.3 Polarities and Other Aspects
- 20.7 Brush Materials and Abrasion
- 20.7.1 Electro- and Natural Graphite Brushes
- 20.7.2 Metal Graphite Brush and Others
- 20.8 Summary
- References
- 21. Illustrative Modern Brush Applications
- 21.1 Introduction
- 21.2 Brush Materials
- 21.2.1 Electrographite
- 21.2.2 Carbon-Graphite
- 21.2.3 Graphite
- 21.2.4 Resin-Bonded
- 21.2.5 Metal-Graphite
- 21.2.6 Altitude-Treated Brushes
- 21.3 Brush Applications
- 21.3.1 Minature Motors
- 21.3.2 Fractional Horsepower Motors
- 21.3.2.1 Wound Field/Permanent Magnet-Motor Characteristics
- 21.3.3 Automotive Brush Applications
- 21.3.3.1 Auxiliary Motors
- 21.3.3.2 Alternators
- 21.3.3.3 Starter Motors
- 21.3.4 Industrial Brushes
- 21.3.5 Diesel Electric Locomotive Brushes
- 21.3.6 Aircraft and Space Brushes
- 21.3.7 Brush Design
- 22. Sliding Contacts for Instrumentation and Control
- 22.1 Introduction
- 22.2 Sliding Contact—The Micro Perspective
- 22.2.1 Mechanical Aspects
- 22.2.2 Motion Initiation (Pre-Sliding)
- 22.2.3 Friction Forces
- 22.2.4 Motion Continuation
- 22.2.5 Adhesion
- 22.2.6 Adhesive Transfer
- 22.2.7 Plowing, or “Two-Body,” Abrasion
- 22.2.8 Hard Particle, or “Three-Body,” Abrasion
- 22.2.9 Motion Over Time
- 22.3 Electrical Performance
- 22.3.1 Contact Resistance Variation (Noise)
- 22.3.2 Non-Ohmic Noise
- 22.3.3 Non-Linear Noise (Frequency Dependent)
- 22.3.4 Contact Impedance
- 22.3.5 Data Integrity
- 22.4 Micro-Environment of Contact Region
- 22.4.1 Film Forming on the a-Spots
- 22.4.2 Unintentional Contamination
- 22.4.2.1 Particulates
- 22.4.2.2 Contamination or “Air Pollution”
- 22.4.2.3 Organic Off-Gasses
- 22.4.2.4 Friction Polymers
- 22.4.3 Lubrication (Intentional Contamination)
- 22.4.4 Lubrication Modes (Anaerobic and Aerobic)
- 22.4.4.1 Anaerobically Lubricated Contacts
- 22.4.4.2 Aerobically Lubricated Contacts
- 22.4.4.3 Temperature Extremes
- 22.4.4.4 Submerged in Flammable Fuels
- 22.4.4.5 Low-Pressure/Vacuum Operation
- 22.4.4.6 Vapor and Gas Lubrication
- 22.5 Macro Sliding Contact
- 22.5.1 Counterface Configuration
- 22.5.1.1 Flat Surfaces
- 22.5.1.2 Cylindrical Surfaces
- 22.5.1.3 Counterface Contact Shapes
- 22.5.2 Real versus Apparent Area of Contact
- 22.5.3 Brush Configurations
- 22.5.3.1 Cartridge Brush
- 22.5.3.2 Cantilever Composite Brush
- 22.5.3.3 Cantilever Metallic Finger
- 22.5.3.4 Cantilever Wire Brush
- 22.5.3.5 Multifilament or Fiber Brush
- 22.5.3.6 Benefits of Multiple Brushes
- 22.5.4 Forces on the Brush
- 22.6 Materials for Sliding Contacts
- 22.6.1 Materials for Counterfaces
- 22.6.2 Solid Lubricated Composite Materials for Brushes
- 22.6.3 Wire Brush Materials Criteria
- 22.7 Friction and Wear Characteristics
- 22.7.1 Friction
- 22.7.2 Wear
- 22.8 Contact Parameters and Sliding-Contact Assemblies
- 22.8.1 Contact Noise
- 22.8.2 Slip Rings as Transmission Lines
- 22.8.3 Results of Normal Operation
- 22.9 Future
- 22.10 Summary
- Acknowledgments
- References
- 23. Metal Fiber Brushes
- 23.1 Introduction
- 23.1.1 Fiber Brushes for Power
- 23.1.2 Diversification of Applications
- 23.1.3 Outline of Chapter
- 23.2 Sliding Wear of Multi-Fiber Brushes
- 23.2.1 Adhesive Wear
- 23.2.2 Holm-Archard Wear Equation
- 23.2.3 Low Wear Equilibrium
- 23.2.4 High Wear Regime
- 23.2.5 Plastic and Elastic Contact
- 23.2.6 Critical or Transition Brush Pressure
- 23.2.7 Wear of Fiber Brushes
- 23.2.8 Effects of Sliding Speed
- 23.2.9 Effect of Arcing and Bridge Transfer
- 23.3 Surface Films, Friction, and Materials Properties
- 23.3.1 Thin Film Behavior
- 23.3.2 Water Molecules
- 23.3.3 Film Disruption
- 23.3.3 Lubrication
- 23.4 Electrical Contact
- 23.4.1 Dependence of Electrical Resistance on Fiber Brush Construction
- 23.5 Brush Dynamics
- 23.5.1 Speed Effect
- 23.6 Future
- 23.7 Summary
- Acknowledgments
- References
- 20. Sliding Electrical Contacts (Graphitic Type Lubrication)
- Part VI Contact Data
- Author Index
- Subject Index
SECOND EDITION
ELECTRICAL CONTACTS
PRINCIPLES AND APPLICATIONS
Edited by
Paul G. Slade
-
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