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The Vacuum Interrupter: Theory, Design, and Application
14 Nov 2007-
TL;DR: The VACUUM INTERRUPTER as mentioned in this paper is a high-volume high-volatile interrupter for switch-on/switch-off switch-off applications.
Abstract: PREFACE INTRODUCTION VACUUM INTERRUPTER THEORY AND DESIGN HIGH-VOLTAGE VACUUM INTERRUPTER DESIGN Introduction The External Design Electrical Breakdown in Vacuum Internal Vacuum Interrupter Design X-Ray Emission Arc Initiation When Closing a Vacuum Interrupter References THE VACUUM ARC The Closed Contact The Formation of the Vacuum Arc during Contact Opening The Diffuse Vacuum Arc The Columnar Vacuum Arc The Transition Vacuum Arc The Interaction of the Vacuum Arc and a Transverse Magnetic Field The Vacuum Arc and an Axial Magnetic Field Overview References THE MATERIALS, THE DESIGN, AND THE MANUFACTURE OF THE VACUUM INTERRUPTER Introduction Vacuum Interrupter Contact Materials The Contact Structures for the Vacuum Interrupter Other Vacuum Interrupter Design Features Vacuum Interrupter Manufacture References VACUUM INTERRUPTER APPLICATION GENERAL ASPECTS OF VACUUM INTERRUPTER APPLICATION Introduction The Interruption of AC Circuits Interruption of AC Circuits When the Contacts Open Just before Current Zero Contact Welding References APPLICATION OF THE VACUUM INTERRUPTER FOR SWITCHING LOAD CURRENTS Introduction Load Current Switching Switching Inductive Circuits Vacuum Contactors Switching Capacitor Circuits Vacuum Interrupters for Circuit Switching, Circuit Isolation, and Circuit Grounding Summary References CIRCUIT PROTECTION, VACUUM CIRCUIT BREAKERS, AND RECLOSERS Introduction Load Currents Short-Circuit Currents Late Breakdowns and Nonsustained Disruptive Discharges Vacuum Circuit Breaker Design Vacuum Circuit Breaker Testing and Certification Vacuum Circuit Breakers for Capacitor Switching, Cable and Line Switching, and Motor Switching Application of Vacuum Circuit Breakers Concluding Summary References AUTHOR INDEX SUBJECT INDEX
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CERN1
TL;DR: In this paper, the authors analyzed the role of field emission in dc and rf breakdown in a simple setup and found that the breakdown field is constant and depends only on the electrode material.
Abstract: Breakdowns occurring in rf accelerating structures will limit the ultimate performance of future linear colliders such as the Compact Linear Collider (CLIC). Because of the similarity of many aspects of dc and rf breakdown, a dc breakdown study is underway at CERN to better understand the vacuum breakdown mechanism in a simple setup. Measurements of the field enhancement factor $\ensuremath{\beta}$ show that the local breakdown field is constant and depends only on the electrode material. With copper electrodes, the local breakdown field is around $10.8\text{ }\text{ }\mathrm{GV}/\mathrm{m}$, independent of the gap distance. The $\ensuremath{\beta}$ value characterizes the electrode surface state, and the next macroscopic breakdown field can be well predicted. In breakdown rate experiments, where a constant field is applied to the electrodes, clusters of consecutive breakdowns alternate with quiet periods. The occurrence and lengths of these clusters and quiet periods depend on the evolution of $\ensuremath{\beta}$. The application of a high field can even modify the electrode surface in the absence of breakdown. Measurements of time delays to breakdown show two distinct populations, immediate and delayed breakdowns, indicating that two different mechanisms could exist. The ratio of these two populations depends on the conditioning state of the electrodes and on material. Gas release during breakdown is dominated by ${\mathrm{H}}_{2}$ and CO. This degassing is mainly due to electron-stimulated desorption. During the quiet periods without breakdown, gases are also released but the quantities are much smaller. All the measurements presented here emphasize the crucial role of field emission in the breakdown triggering.
93 citations
CERN1
TL;DR: In this article, a dc breakdown study is underway at CERN in order to test candidate materials and surface preparations, and have a better understanding of the breakdown mechanism under ultrahigh vacuum in a simple setup.
Abstract: The rf accelerating structures of the Compact Linear Collider (CLIC) require a material capable of sustaining high electric field with a low breakdown rate and low induced damage Because of the similarity of many aspects of dc and rf breakdown, a dc breakdown study is underway at CERN in order to test candidate materials and surface preparations, and have a better understanding of the breakdown mechanism under ultrahigh vacuum in a simple setup Conditioning speeds and breakdown fields of several metals and alloys have been measured The average breakdown field after conditioning ranges from $100\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ for Al to $850\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ for stainless steel, and is around $170\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ for Cu which is the present base-line material for CLIC structures The results indicate clearly that the breakdown field is limited by the cathode The presence of a thin cuprous oxide film at the surface of copper electrodes significantly increases the breakdown field On the other hand, the conditioning speed of Mo is improved by removing oxides at the surface with a vacuum heat treatment, typically at $875\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ for 2 hours Surface finishing treatments of Cu samples only affect the very first breakdowns More generally, surface treatments have an effect on the conditioning process itself, but not on the average breakdown field reached after the conditioning phase In analogy to rf, the breakdown probability has been measured in dc with Cu and Mo electrodes The dc data show similar behavior as rf as a function of the applied electric field
85 citations
TL;DR: In this paper, the atomic scale processes taking place in metal nanotips under intense field emission conditions are investigated, and it is shown that when a sufficiently high electric field is applied to the tip, the emission-generated heat partially melts it and the field-induced force elongates and sharpens it.
Abstract: When an electron emitting tip is subjected to very high electric fields, plasma forms even under ultra high vacuum conditions. This phenomenon, known as vacuum arc, causes catastrophic surface modifications and constitutes a major limiting factor not only for modern electron sources, but also for many large-scale applications such as particle accelerators, fusion reactors etc. Although vacuum arcs have been studied thoroughly, the physical mechanisms that lead from intense electron emission to plasma ignition are still unclear. In this article, we give insights to the atomic scale processes taking place in metal nanotips under intense field emission conditions. We use multi-scale atomistic simulations that concurrently include field-induced forces, electron emission with finite-size and space-charge effects, Nottingham and Joule heating. We find that when a sufficiently high electric field is applied to the tip, the emission-generated heat partially melts it and the field-induced force elongates and sharpens it. This initiates a positive feedback thermal runaway process, which eventually causes evaporation of large fractions of the tip. The reported mechanism can explain the origin of neutral atoms necessary to initiate plasma, a missing key process required to explain the ignition of a vacuum arc. Our simulations provide a quantitative description of in the conditions leading to runaway, which shall be valuable for both field emission applications and vacuum arc studies.
58 citations
01 Sep 2015
TL;DR: In this paper, a Thomson coil based fast mechanical switch for hybrid AC and DC circuit breakers rated at 30 kV voltage and 630 A current is presented, which can travel 1.3 mm in the first 1 ms and 3.1 mm in 2 ms when driven by a 360 V 2 mF capacitor bank pre-charged to 500 V.
Abstract: The paper presents the design and experimental results of a Thomson coil based fast mechanical switch for hybrid AC and DC circuit breakers rated at 30 kV voltage and 630 A current. The compact design with optimized circuit parameters and geometric dimensions of components targets 2 mm travel within 1 ms when driven by a 2 mF capacitor bank pre-charged to 500 V. The use and design of a disc spring as the damping and holding mechanism is presented. Structural design of a complete switch assembly rather than just the actuator is given. Experimental results show that the switch can travel 1.3 mm in the first 1 ms, and 3.1 mm in the first 2 ms when driven by a 360 V 2 mF capacitor bank. Such fast mechanical switches facilitate hybrid circuit breaker interruptions within 2 or 3 milliseconds for ultra fast and highly efficient protections in 5–35 kV medium voltage DC as well as AC systems.
48 citations
Cites background from "The Vacuum Interrupter: Theory, Des..."
...Magnetic mechanisms often come with vacuum interrupters because they are suitable for short stroke movement with fewer moving parts [20]....
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TL;DR: In this article, a transient magnetohydrodynamic (MHD) model of an anode melting pool (AMP) flow was established and the influence of different heat flux densities to melting pool flow velocities (including azimuthal, radial, and axial velocity), anode temperature, fraction of liquid, melting depth, melting radius, and anode vapor flux was analyzed.
Abstract: In this paper, a transient magnetohydrodynamic (MHD) model of an anode melting pool (AMP) flow (AMPF) is established. Mass equation, momentum equations along axial, radial and azimuthal directions, energy equation, and current continuity equations are considered in the model. In the momentum equations, the influence of electromagnetic force, viscosity force and Marangoni force (anode surface shear stress) are included. Joule heating is also included in the energy equations. According to the MHD model of AMPF, the influence of different heat flux densities to melting pool flow velocities (including azimuthal, radial, and axial velocity), anode temperature, fraction of liquid, melting depth, melting radius, and anode vapor flux will be analyzed. In the AMP, the azimuthal velocity is dominant, whose value approximately approaches velocity magnitude, the radial velocity is much smaller than azimuthal velocity, and the axial velocity is the smallest one compared with radial and azimuthal velocity. According to...
47 citations