The Vacuum Interrupter: Theory, Design, and Application

Vacuum Interrupter Theory and DesignHigh Voltage Vacuum Interrupter DesignIntroductionThe External DesignElectrical Breakdown in GasCreepage DistanceInsulating Ambients and EncapsulationElectrical Breakdown in VacuumIntroductionThe Electric FieldThe Microscopic Enhancement Factor (βm)The Geometric Enhancement Factor (βg)Pre-Breakdown EffectsField Emission CurrentAnode PhenomenaMicroparticlesMicrodischargesVacuum Breakdown and the Transition to the Vacuum ArcThe Transition to a Self-Sustaining Vacuum ArcTime to BreakdownConditioningSpark Conditioning Using a High Voltage ac Power SupplySpark Conditioning Using a High Voltage PulseCurrent ConditioningOther Conditioning ProcessesPunctureDeconditionincINTERNAL VACUUM INTERRUPTER DESIGNThe Control of the Geometric Enhancement Factor, βgBreakdown of Multiple Vacuum Interrupters in Series for Contact Gaps Greater Than 2mmVoltage Wave Shapes and Vacuum Breakdown in a Vacuum InterrupterImpulse Testing of Vacuum InterruptersTesting for High AltitudeX-Ray EmissionArc Initiation When Closing a Vacuum InterrupterReferencesThe Vacuum ArcThe Closed ContactMaking Contact, Contact Area, and Contact ResistanceCalculation of Contact ResistanceThe Real Area of Contact a Small Disk of Radius “a”Contact Resistance and Contact TemperatureThe Calculation of Contact TemperatureBlow-Off ForceButt ContactsContact Interface Melting During Blow-OffThe Formation of the Vacuum Arc during Contact OpeningThe Diffuse Vacuum ArcCathode SpotsThe Plasma between the Cathode Spot and the AnodeCurrent ChopThe Formation of the Low-Current and High-Current Anode SpotThe Columnar Vacuum ArcThe Transition Vacuum ArcThe Interaction of the Vacuum Arc and a Transverse Magnetic FieldThe Diffuse Vacuum Arc and a Transverse Magnetic FieldThe Columnar Vacuum Arc and a Transverse Magnetic FieldThe Vacuum Arc and an Axial Magnetic FieldThe Low-Current Vacuum Arc in an Axial Magnetic FieldThe High-Current Vacuum Arc in an Axial Magnetic FieldOverview and Review of the Three Forms of Anode SpotReferencesThe Materials, Design, and Manufacture of the Vacuum InterrupterIntroductionVacuum Interrupter Contact MaterialsIntroductionCopper and Copper-Based Contact Materials That Have Been Developed Following the Initial Experiments on High Current Vacuum Arcs Using Copper ContactsRefractory Metals Plus a Good ConductorSemi-Refractory Metals Plus a Good ConductorCopper Chromium Materials Plus an AdditiveChopping CurrentSummaryThe Contact Structures for the Vacuum InterrupterIntroductionDisc- or Butt-Shaped ContactsContacts to Force the Motion of the High Current, Columnar Vacuum ArcContacts to Force the High Current, Columnar Arc into the Diffuse ModeSummaryOther Vacuum Interrupter Design FeaturesThe Insulating BodyThe ShieldThe BellowsVacuum Interrupter ManufactureАssemblyTesting and ConditioningSummaryReferencesVacuum Interrupter ApplicationGeneral Aspects of Vacuum Interrupter ApplicationIntroductionThe Interruption of ac CircuitsThe Interruption of the Diffuse Vacuum Arc for ac Currents Less Than 2 kA (rms.) with a Fully Open Contact GapThe Interruption of the Vacuum Arc for AC Currents Greater than 2 kA (rms.)The Interruption of High Current Vacuum ArcsInterruption of ac Circuits When the Contacts Open Just Before Current ZeroLow Current Vacuum ArcsLow Current Interruption of Inductive CircuitsLow Current Interruption of Capacitive CircuitsHigh Current InterruptionContact WeldingIntroductionWelding of Closed ContactsCold Welding and Diffusion WeldingWelding Caused by the Passage of High CurrentA Comparison of the Calculated “iw" with Experimental ValuesSimple Butt Contacts with One Region of Contact and a Short Current PulseSimple Butt Contacts with More Than One Region of Contact and a Short Current PulseAxial Magnetic, Large Area, Vacuum Interrupter ContactsThe Model to Determine the Threshold Welding Current for Closed Contacts with "n" Regions of Contact for Passage of Current of 1 to 4 SecondsClosed Large Area Vacuum Interrupter Contacts Passing Fault Currents from 1 to 4 SecondsWelding of Contacts That SlideWelding when Contacts Close an Electrical CircuitREFERENCESApplication of the Vacuum Interrupter for Switching Load CurrentsIntroductionLoad Current SwitchingSwitches Used at Distribution VoltagesSwitches Used at Transmission VoltagesSwitching Inductive CircuitsVoltage Surges When Closing an Inductive CircuitVoltage Surges When Opening an Inductive CircuitSurge ProtectionSwitching Three-Phase Inductive Circuits: Virtual Current ChoppingTransformer SwitchingTap ChangersSwitching Off Unloaded TransformersSwitching Off an Unloaded Transformer’s In-Rush CurrentSwitching Off Loaded TransformersVacuum ContactorsIntroductionSolenoid OperationSizing the ContactThe ShieldThe Contact MaterialSwitching Capacitor CircuitsInserting a Capacitor BankDisconnecting a Capacitor BankSwitching Three-Phase Capacitor BanksThe Capacitor Switch Recovery Voltage, Late Restrikes, and NSDDsSwitching Cables and Overhead LinesVacuum Interrupters for Circuit Switching, Circuit Isolation, and Circuit GroundingBackgroundVacuum Interrupter Design Concepts for Load Switching and for IsolationVacuum Interrupter Design for Switching and GroundingVacuum Interrupter Design for Fault Protection, Isolation, and GroundingSummaryReferencesCircuit Protection, Vacuum Circuit Breakers, and ReclosersIntroductionLoad CurrentsShort Circuit CurrentsIntroductionThe Short Circuit Current and AsymmetryThe Transient Recovery Voltage (TRV), for a Terminal FaultFirst Pole-to-Clear FactorThe Terminal Fault Interruption Performance of Vacuum InterruptersThe Transient Recovery Voltage for Short Line Faults (SLF)TRV from Transformer Secondary FaultsLate Breakdowns and Non-Sustained Disruptive Discharges (NSDDs)Vacuum Circuit Breaker DesignIntroductionClosed ContactsMechanism DesignThe Vacuum Interrupter Mounting and InsulationThe Vacuum Circuit Breaker’s Electrical LifeVacuum Circuit Breaker Testing and CertificationDevelopmental Testing of the Vacuum InterrupterCertification Testing at an Independent High-Power Testing LaboratoryFault Current Endurance TestingVacuum Circuit Breakers for Capacitor Switching, Cable and Line Switching, and Motor SwitchingIntroductionCapacitor SwitchingCapacitor Switching and NSDDsCable Switching and Line DroppingMotor SwitchingApplication of Vacuum Circuit Breakers for Distribution Circuits (4.76 kV to 40.5 kV)Indoor SwitchgearOutdoor Circuit BreakersVacuum ReclosersThe Ring Main Unit (RMU) for Secondary DistributionPad-Mount Secondary Distribution SystemsThe Generator Vacuum Circuit BreakerHigh Continuous CurrentsTransformer/System Fed FaultsGenerator Fed FaultsOut-of-Phase SwitchingTransportation Circuit BreakersInterrupting Fault Currents at Frequencies Less Than and Greater Than 50/60 HzSwitching Electric Arc Furnaces (EAF)Vacuum Interrupters in SeriesVacuum Interrupters for Subtransmission and Transmission SystemsSwitching dc Circuits Using Vacuum InterruptersDC Interruption Using the Natural Vacuum Arc InstabilityDC Current Interruption Using an External Magnetic Field PulseSwitching High Voltage DC Transmission Circuits Using a Current Counter PulseDevelopment of Vacuum Interrupters for Low Voltage (< 1000V) Circuit BreakersConcluding SummaryReferences
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