Electrical Contacts, 2nd Edition
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Book description
Covering the theory, application, and testing of contact materials, Electrical Contacts: Principles and Applications, Second Edition introduces a thorough discussion on making electric contact and contact interface conduction; presents a general outline of, and measurement techniques for, important corrosion mechanisms; considers the results of contact wear when plug-in connections are made and broken; investigates the effect of thin noble metal plating on electronic connections; and relates crucial considerations for making high- and low-power contact joints. It examines contact use in switching devices, including the interruption of AC and DC circuits with currents in the range 10mA to 100kA and circuits up to 1000V, and describes arc formation between open contacts and between opening contacts. Arcing effects on contacts such as erosion, welding, and contamination are also addressed.
Containing nearly 3,000 references, tables, equations, figures, drawings, and photographs, the book provides practical examples encompassing everything from electronic circuits to high power circuits, or microamperes to mega amperes. The new edition:
With contributions from recognized experts in the field, Electrical Contacts: Principles and Applications, Second Edition assists practicing scientists and engineers in the prevention of costly system failures, as well as offers a comprehensive introduction to the subject for technology graduate students, by expanding their knowledge of electrical contact phenomena.
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Table of contents
- 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
- 1.2.1 Circular a-spots
- 1.2.2 Non-Circular and Ring a-Spots
- 1.2.3 Multiple Contact Spots
- 1.2.4 Effect of the Shape of Contact Asperity on Constriction Resistance
- 1.3.1 Electrically Conductive Layers on an Insulated Substrate
- 1.3.1.1 Calculation of Spreading Resistance in a Thin Film
- 1.3.2.1 Electrically Conducting Layers and Thin Contaminant Films
- 1.3.5.1 Growth Rate and Electrical Resistivity of Oxides of Selected Contact Materials
- 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
- 1.4.5.1 Case I: Two Metals in Contact
- 1.4.5.2 Case II: A Metal in Contact with a Non-metal
- 1.5.1 Smooth Interfaces
- 1.5.2 Rough Interfaces
- 1.6.1 Electrical Conduction in Small a-Spots
- 1.6.1.1 Contact Resistance
- 1.6.1.2 Joule Heat Flow through a-Spots
- 1.6.2.1 Experimental Data on Aluminum
- 1.7.1 Skin Depth and Constriction Resistance
- 1.7.2 Evaluation of Constriction Resistance at High Frequencies
- 1.7.3 Constriction versus Connection Resistance at High Frequencies
- 2.1 Introduction
- 2.2 Corrosion Rates
- 2.3 Corrosive Gases
- 2.4 Types of Corrosion
- 2.4.1 Dry Corrosion
- 2.4.2 Galvanic Corrosion
- 2.4.3 Pore Corrosion
- 2.4.4 Creep Corrosion
- 2.4.5 Metallic Electromigration
- 2.4.6 Stress Corrosion Cracking
- 2.4.7 Contacts under Mineral Oil
- 2.6.1 Weight Gain Measurement
- 2.6.2 Visual Inspection
- 2.6.3 Cathodic Reduction
- 2.6.4 Scanning Electron Microscopy with Energy-Dispersive X-Ray Spectroscopy (SEM/EDAX)
- 2.6.5 X-Ray Photoelectron Spectroscopy (XPS)
- 2.6.6 Other Techniques
- 2.6.7 Contact Resistance Measurements
- 2.8.1 Background
- 2.8.2 MFG Test Results
- 3.1 Introduction
- 3.1.1 Scope
- 3.1.2 Background
- 3.2.1 Environmental Variables
- 3.2.2 Corrosion Rates
- 3.2.2.1 Copper and Silver
- 3.2.2.2 Other Metals
- 3.2.2.3 Film Effects
- 3.2.2.4 Shielding Effects
- 3.2.3.1 Severity versus Performance
- 3.2.3.2 Environmental Classes
- 3.2.3.3 Specifications
- 3.2.4.1 Silver
- 3.2.4.2 Copper
- 3.2.4.3 Nickel
- 3.2.4.4 Tin
- 3.2.4.5 Porous Gold Coatings
- 3.2.4.6 Pore Corrosion
- 3.2.4.7 Corrosion Product Creep
- 3.3.1 Objectives
- 3.3.2 Definition of Acceleration Factor
- 3.3.3 Historical Background
- 3.3.4 Single-Gas Corrosion Effects
- 3.3.4.1 Hydrogen Sulfide
- 3.3.4.2 Sulfur Dioxide (SO2)
- 3.3.4.3 Nitrogen Dioxide (NO2)
- 3.3.4.4 Chlorine
- 3.3.4.5 Mixed-Gas Sulfur Environments
- 3.3.4.6 Humidity
- 3.3.4.7 Temperature
- 3.3.4.8 Gas Flow Effects
- 3.3.5.1 Test Systems
- 3.3.5.2 Monitoring Reactivity
- 3.3.6.1 Electronic Connectors
- 3.3.6.2 Mated versus Unmated Exposures
- 3.3.6.3 Other Considerations
- 4.1 Introduction
- 4.1.1 Background
- 4.1.2 The Importance of the Dust Problem
- 4.1.3 The Complexity of the Problem
- 4.1.4 The Purpose of the Studies
- 4.2.1 The Source of Dust
- 4.2.2 The Collection of the Dust Particles for Testing
- 4.2.3 The Shape of the Dust Particles
- 4.2.4 The Identification of the Inorganic Materials
- 4.2.5 The Organic Materials in Dust
- 4.2.6 The Water Soluble Salts in Dust
- 4.3.1 The Electrical Behavior
- 4.3.1.1 Measurement of the Electric Charge
- 4.3.1.2 The Electrostatic Attracting Force on the Particle
- 4.3.2.1 Load Effect
- 4.3.2.2 For Stationary Contacts
- 4.3.2.3 For Sliding Contacts
- 4.3.2.4 The Effect of Lubricants Coated on Contact Surface
- 4.3.2.5 Sliding Contacts on Lubricated and Dusty Contacts
- 4.3.2.6 Fretting (Micro Motion) on Lubricated and Dusty Contacts
- 4.3.3.1 Dust Particles Create Pores
- 4.3.3.2 Corrosion Appears as a Result of Dusty Water Solutions
- 4.3.3.3 Indoor Exposure Results
- 4.3.3.4 Construction of the Corrosion Stain
- 4.3.3.5 Fretting Experiments on Dust Corroded Coupon Surfaces…209
- 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
- 4.5.1 Two Micro Worlds in Contact
- 4.5.1.1 Particles Get into the Contact Interface
- 4.5.2.1 Adhesive Effect
- 4.5.2.2 Trapping Effect of Corrosion Products
- 4.5.3.1 Single Particle and Ideal Model
- 4.5.3.2 Complicated Model – Number of Particles and Morphology of Contact Pairs
- 4.5.4.1 Contact Failure
- 4.6.1 Dust Test for Connectors
- 4.6.2 Suggestion of the Dust Test
- 4.6.3 Minimizing the Dust Problem
- 4.6.3.1 Cleaning the Samples
- 5. Power Connectors
- 5.1 Introduction
- 5.2 Types of Power Connectors
- 5.2.1 Plug-and-Socket Connectors
- 5.2.2 Wire Connectors
- 5.2.3 Bolted Connectors
- 5.2.4 Insulation Piercing Connectors
- 5.3.1 Definition of Conductor and Connector Systems
- 5.3.2 Factors Affecting Conductivity
- 5.3.2.1 Effect of Temperature
- 5.3.2.2 Effect of Lattice Imperfections
- 5.3.2.3 Magnetoresistance
- 5.3.2.4 Skin Effect
- 5.3.3.1 Copper and Copper Alloys
- 5.3.3.2 Aluminum and Its Alloys
- 5.3.4.1 Pure Metals and Alloys
- 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
- 5.4.7.1 Atmospheric Corrosion
- 5.4.7.2 Localized Corrosion
- 5.4.7.3 Crevice Corrosion
- 5.4.7.4 Pitting Corrosion
- 5.4.7.5 Pore Corrosion
- 5.4.7.6 Creep Corrosion
- 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
- 5.4.13.1 Example of Intermetallics Formation in Power Connections
- 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
- 5.5.14.1 Thermite (Exothermic) Welding
- 5.5.14.2 Friction Welding
- 5.5.14.3 Explosion Welding
- 5.5.14.4 Resistance Welding
- 5.5.14.5 Resistance Brazing
- 5.5.15.1 Fired Wedge-Connectors
- 5.5.15.2 Stepped Deep Indentation Connectors
- 5.6.1 Economical Consequences of Contact Deterioration
- 5.6.2 Power Quality
- 5.7.1 Prognostic Model 1 for Contact Remaining Life
- 5.7.2 Prognostic Model 2 for Contact Remaining Life
- 5.7.3 Physical Model
- 5.8.1 Origin of Shape-Memory Effect
- 5.8.1.1 One-Way Memory Effect
- 5.8.1.2 Two-Way Memory Effect
- 5.9.1 Aluminum Foam Materials
- 5.9.1.1 Electrical and Thermal Properties of Foam Materials
- 5.9.1.2 Power Connection Applications
- 5.9.2.1 Applications of Copper Foam Materials
- 5.10.1 Examples of Improper Installations
- 5.11.1 Present Current-Cycling Tests
- 6.1 Introduction
- 6.2 Connectors
- 6.2.1 Functional Requirements
- 6.2.2 Types of Connectors
- 6.2.3 Mechanical Considerations
- 6.3.1 Contact Physics
- 6.3.2 Terminal Types
- 6.3.3 Other Electrical Contact Parameters
- 6.4.1 Surface Films
- 6.4.2 Fretting Corrosion of Tin–Plated Contacts
- 6.4.3 Examples of Contact Failures
- 6.4.3.1 Automotive Position Sensor Connector
- 6.4.3.2 Fuel Injector Connector
- 6.4.3.3 Glowing Contacts
- 6.4.3.4 Electrolytic Corrosion
- 6.4.3.5 Incompatible Plating and Low Contact Force
- 6.5.1 Vehicle Conditions
- 6.5.2 High Power Connectors for Electric and Hybrid Vehicles
- 6.5.3 Aluminum Wiring Connections
- 6.5.4 Connections for High-Vibration Environment
- 7.1 Introduction
- 7.2 Sliding Wear
- 7.2.1 Early Studies
- 7.2.2 Adhesion
- 7.2.2.1 “Wiping” Contaminant from Contact Surfaces
- 7.2.2.2 Mild and Severe
- 7.2.2.3 Prow Formation
- 7.2.2.4 Rider Wear
- 7.2.2.5 Gold Platings: Intrinsic Polymers and Junction Growth
- 7.2.2.6 Electroless Gold Plating
- 7.2.6.1 Hardness
- 7.2.6.2 Roughness
- 7.2.7.1 Hardener Metal Content
- 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
- 7.3.4.1 Generation of Fretting Displacement
- 7.3.4.2 Determination of Contact Resistance
- 7.3.5.1 Apparatus
- 7.3.5.2 Metals Having Little or No Film-Forming Tendency
- 7.3.5.3 Non-Noble Metals/Fretting Corrosion
- 7.3.5.4 Frictional Polymer-Forming Metals
- 7.3.5.5 Dissimilar Metals on Mating Contacts
- 7.3.6.1 Gold-Based Systems
- 7.3.6.2 Palladium-Based Systems
- 7.3.6.3 Tin and Tin–Lead Alloy Systems
- 7.3.6.4 Role of Underplate and Substrate
- 7.3.7.1 Cycle Rate
- 7.3.7.2 Wipe Distance
- 7.3.7.3 Force
- 7.3.12.1 Summary of Physical Processes
- 7.4.1 Introduction
- 7.4.2 Metallic Films
- 7.4.2.1 Principles of Metallic Film Lubrication
- 7.4.2.2 Sliding and Wiping Contacts
- 7.4.2.3 Fretting Contacts
- 7.4.3.1 Background
- 7.4.3.2 Some Fundamental Properties of Lubricants
- 7.4.3.3 Requirements
- 7.4.3.4 Types of Fluid Lubricants: A Sliding Contact Investigation
- 7.4.3.5 Control of Fretting Degradation
- 7.4.5.1 Greases
- 7.4.5.2 Solids
- 8.1 Introduction
- 8.1.1 Scope
- 8.1.2 Requirements of Contact Finishes and Coatings
- 8.1.3 Terminology
- 8.2.1 Wrought Metals
- 8.2.2 Electrodeposits and Electroless Deposits
- 8.2.2.1 Thickness of Platings
- 8.2.2.2 Plating Hardness
- 8.2.2.3 Classification of Platings
- 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
- 8.4.1 Thermal Diffusion
- 8.4.2 Intermetallics
- 8.4.3 Tin Whiskers
- 8.4.4 Silver Whiskers
- 8.5.1 Characteristics of Layered Systems
- 8.5.1.1 Hardness
- 8.5.1.2 Contact Resistance
- 9. The Arc and Interruption
- 9.1 Introduction
- 9.2 The Fourth State of Matter
- 9.3 Establishing an Arc
- 9.3.1 Long-Gap Gas Breakdown
- 9.3.2 Vacuum Breakdown and Short-Gap Breakdown
- 9.3.3 The Volt–Current Characteristics of Separated Contacts
- 9.4.1 The Formation of the Electric Arc during Contact Closing
- 9.4.2 The Formation of the Electric Arc during Contact Opening
- 9.5.1 The Arc Column
- 9.5.2 The Cathode Region
- 9.5.3 The Anode Region
- 9.5.4 The Minimum Arc Current and the Minimum Arc Voltage
- 9.5.5 Arc Volt–Ampere Characteristics
- 9.6.1 The Diffuse Vacuum Arc
- 9.6.2 The Columnar Vacuum Arc
- 9.6.3 The Vacuum Arc in the Presence of a Transverse Magnetic Field
- 9.6.4 The Vacuum Arc in the Presence of an Axial Magnetic Field
- 9.7.1 Arc Interruption in Alternating Current Circuits
- 9.7.1.1 Stage 1 - Instantaneous Dielectric Recovery
- 9.7.1.2 Stage 2 - Decay of the Arc Plasma and Dielectric Reignition
- 9.7.1.3 Thermal Reignition
- 10.1 Introduction
- 10.2 Arcing Time
- 10.2.1 Arcing Time in an AC Circuit
- 10.2.2 Arcing Time in a DC Circuit
- 10.2.3 Activation of the Contact
- 10.2.4 Arcing Time in Very Low-Current DC Circuits: Showering Arcs
- 10.3.1 Erosion on Make and Erosion on Break
- 10.3.2 The Effect of Arc Current
- 10.3.3 The Effect of Contact Size
- 10.3.4 Determination of Contact Size in AC Operation
- 10.3.5 Erosion of Contacts in Low-Current DC Circuits
- 10.3.6 Erosion of Contacts in Low-Current AC Circuits
- 10.4.1 Butt Contacts
- 10.5.1 Welding of Closed Contacts
- 10.5.2 Welding during Contact Closure
- 10.5.3 Welding as Contacts Open
- 10.6.1 Silver–Based Contacts
- 10.6.2 Silver–Refractory Metal Contacts
- 10.6.3 Other Ambient Effects on the Arcing Contact Surface: Formation of Silica and Carbon and Contact Activation
- 11.1 Principles and Design of the Reed Switch
- 11.1.1 Pull-In Characteristics of a Reed Switch
- 11.1.2 Drop-Out Characteristics of a Reed Switch
- 11.1.3 Magnet Drive Characteristics of a Reed Switch
- 11.1.3.1 X–Y Characteristic H (Horizontal)
- 11.1.3.2 X–Z Characteristic H (Horizontal)
- 11.1.3.3 X–Y Characteristic V (Vertical)
- 11.2.1 Materials for Contact Plating
- 11.2.2 Ground Plating
- 11.2.3 Rhodium Plating
- 11.2.4 Ruthenium Plating
- 11.2.5 Other Platings
- 11.2.5.1 Copper Plating
- 11.2.5.2 Tungsten Plating
- 11.2.5.3 Rhenium Plating
- 11.2.5.4 Iridium Plating
- 11.2.5.5 Nitriding the Permalloy (Ni-Fe [48 wt%]) Blade Material
- 11.3.1 Surface Deactivation Treatment
- 11.3.1.1 Life Test of Samples Left for 24 Hours after Sealing
- 11.3.1.2 Life Test of Samples Left for One Week after Sealing
- 11.3.1.3 Life Test of Samples Left for One Month after Sealing
- 11.3.1.4 Life Test of Samples Left for Three Months, Six Months, and One Year after Sealing
- 11.4.1 Reed Relays
- 11.4.2 Applications of Magnetic-Driven Reed Switches
- 12.1 Introduction
- 12.1.1 Common MEMS Actuation Methods
- 13.1 Introduction and Device Classification
- 13.2 Device Types
- 13.2.1 Hand-Operated Switches
- 13.2.1.1 The Rocker Switch Mechanism
- 13.2.1.2 Lever Switches
- 13.2.1.3 Slide Switches
- 13.2.1.4 Rotary Switches
- 13.2.1.5 Push-Button Switches
- 13.2.1.6 Switching Devices Used below 0.5 A
- 13.2.2.1 Limit Switches
- 13.2.2.2 Thermostatic Controls
- 13.2.2.3 Electro-Mechanical Relay
- 13.3.1 Small-Amplitude Sliding Motion
- 13.3.2 Contact Force and Contact Materials
- 13.3.2.1 Contacts at Current Levels below 1 A
- 13.3.2.2 Contacts at Current Levels between 1 and 30 A
- 13.3.2.3 Contact Force
- 13.4.1 Case Study (1): Hand-Operated Rocker-Switch Mechanism
- 13.4.1.1 Moving-Contact Dynamics of a Rocker-Switch Mechanism
- 13.4.1.2 Design Optimization of a Rocker-Switch Mechanism
- 13.4.2.1 Moving Contact Dynamics at Opening
- 13.4.3.1 Impact Mechanics
- 13.4.3.2 The Coefficient of Restitution
- 13.4.3.3 Impact Mechanics for a Pivoting Mechanism
- 13.4.3.4 The Velocity of Impact
- 13.4.3.5 Bounce Times
- 13.4.3.6 Total Bounce Times
- 13.4.3.7 Impact Times
- 13.4.3.8 Design Parameters for the Reduction of Contact Bounce
- 13.5.1 The Measurement of Contact Surfaces
- 13.5.2 Three Dimensional (3-D) Surface Measurement Systems
- 13.5.2.1 Contact Systems
- 13.5.2.2 Non-Contact Systems
- 13.6.1 Low-Current DC Arcs
- 13.6.1.1 Arc Voltage Characteristics
- 13.6.1.2 Voltage Steps below 7 A
- 13.6.1.3 Case Study (3): Arc Voltage, Current and Length under Quasi-Static Conditions for Ag/CdO Contacts
- 13.6.1.4 Opening Speed and Arc Length
- 13.6.1.5 Case Study (4): Automotive Systems
- 13.6.2.1 Ag and Ag/MeO Contact Erosion/Deposition
- 13.6.3.1 Typical Waveforms and Arc Energy
- 13.6.4.1 Point-on-Wave (POW) Studies Using Ag/CdO Contact Materials
- 13.7.1 Contact Welding on Make
- 13.7.2 Reducing Contact Bounce
- 13.7.3 Pre-Impact Arcing
- 13.7.4 Influence of Velocity during the First Bounce
- 13.7.4.1 The First Bounce
- 13.8.1 Switch Design
- 13.8.2 Break Operation
- 13.8.2.1 DC Operation
- 13.8.2.2 AC Operation
- 13.8.3.1 Design Parameters
- 13.8.3.2 Reducing Contact Bounce
- 13.8.3.3 Arcing during the Bounce Process
- 14.1 General Aspects of Switching in Air
- 14.1.1 Arc Chutes
- 14.1.2 Magnetic Blast Field
- 14.1.3 Arc Dwell Time on the Contacts
- 14.1.4 Sticking and Back-Commutation of the Arc
- 14.3.1 Principle/Requirements
- 14.3.2 Mechanical Arrangement
- 14.3.3 Quenching Principle and Contact and Arc Chute Design
- 14.3.4 Contact Materials
- 14.3.5 Trends
- 14.3.5.1 Contactors versus Electronics
- 14.3.5.2 Vacuum Contactors
- 14.3.5.3 Hybrid Contactors
- 14.3.5.4 Integration with Electronic Systems
- 14.4.1 Principle/Requirements
- 14.4.2 General Arrangement
- 14.4.3 Quenching Principle and Design of Arc Chute and Contact System
- 14.4.3.1 Quenching Principles
- 14.4.3.2 Arc Chute and Contact Arrangement
- 14.4.8.1 Arcs Squeezed in Narrow Insulating Slots
- 14.4.8.2 Reversible Phase Changes of Liquid or Low-Melting Metal
- 14.4.8.3 Temperature-Dependent Ceramics or Polymers
- 14.4.8.4 Contact Resistance between Powder Grains
- 14.4.8.5 Superconductors
- 14.5.1 Simulation of Low-Voltage Arcs
- 14.5.1.1 General Principle of Simulation
- 14.5.1.2 Arc Roots on Cathode and Anode
- 14.5.1.3 Radiation
- 14.5.1.4 Interaction between Arc and Electrode or Wall Material (Ablation)
- 14.5.1.5 Plasma Properties
- 14.5.1.6 Simplification by Porous Media
- 14.6.1 Principle/Applications
- 14.6.2 Design
- 14.6.3 Recovery and the Influence of the Design
- 14.6.4 Contact Materials for Vacuum Interrupters and Their Influence on Switching
- 14.6.4.1 Requirements
- 14.6.4.2 Arc Interruption
- 14.6.4.3 Interruption of High Frequency Transients
- 14.6.4.4 Current Chopping
- 15.1 Introduction
- 15.2 Arc Fault Circuit Interrupters (AFCIs)
- 15.3 Arcing Faults
- 15.3.1 Short-Circuit Arcing
- 15.3.2 Series Arcing
- 15.5.1 Frequency
- 15.5.2 Electrode Materials
- 15.5.3 Arc Fault Current
- 15.5.4 Cable Impedance and Cable Length Effects
- 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
- 17.1 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
- 18.1 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
- 19.1 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
- 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
- 21.1 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
- 22.1 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
- 23.1 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
- 24. Useful Electric Contact Information
- 24.1 Introduction
- 24.2 Notes to the Tables
- References
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Product information
- Title: Electrical Contacts, 2nd Edition
- Author(s): Paul G. Slade
- Release date: December 2017
- Publisher(s): CRC Press
- ISBN: 9781351832717