Proceedings ArticleDOI
Gassing arc chamber wall material effect on post current-zero recovery voltage breakdown
John J. Shea
- Vol. 27, Iss: 1, pp 42-50
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TLDR
In this article, the breakdown strength of the insulation in the arc chamber was investigated and the results showed that the amount of carbon deposited on the cathode surface provided a good source for thermionic emission.Abstract:
Experimental measurements and theoretical calculations were used to identify and quantify important factors that arc chamber insulation has on post-current zero recovery voltage. Gas analysis, pressure measurements, and post current-zero breakdown voltages were used to rank arc chamber wall material according to breakdown voltage. Generally, breakdown voltage increased with pressure at breakdown. However, nylon 6/6, which had a reduced pressure rise but still had a relatively high breakdown strength, was an exception. Pyrolysis of each material was performed to identify gases produced by arc chamber materials. Gas chromatography was used to determine the types and amounts of gases emitted by the various wall materials. Unlike most other materials, nylon 6/6 sample showed a relatively low percentage of hydrogen but high ethylene percentage, along with no carbon residue. The combination of gases that produced high pressures and low solid carbon had the higher breakdown strength. Theoretical calculations showed breakdown strength to depend on the pressure at breakdown, cathode temperature, and contact material (Ag/W), and carbon (C) deposits on the contacts. Based on theoretical calculations, it was postulated that the wall materials not only determined the pressure at breakdown but also, the amount of carbon deposited on the cathode surface (C, along with the W and oxides, provided a good source for thermionic emission). The greater the amount of carbon deposited on the cathode surface, produced from the insulation, the lower the breakdown strength for a given amount of W. This could explain why nylon performed well, since it produced no carbon residue during pyrolysis. Theoretical calculations of the breakdown voltage, based on dielectric breakdown of the plasma sheath formed in front of the cathode, were also compared to experimental values to obtain estimates of sheath thickness and cathode temperatures. Sheath breakdown values were obtained numerically by solving Townsend's criteria for various sheath thickness and cathode temperatures. Experimental values were plotted on the theoretical curves to obtain estimates of the plasma parameters. In addition to ranking the insulation, peak chamber pressure and arc voltages are given for practical molded case circuit breaker (MCCB) design.read more
Citations
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Low-voltage circuit breaker arcs—simulation and measurements
TL;DR: In this article, the authors present a review of the air arc modeling and measurement in low-voltage dc circuit breakers, focusing on the modelling and measurement of these phases.
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High Current AC Break Arc Contact Erosion
TL;DR: In this article, a review of arc plasma theory pertaining to contact erosion in air at atmospheric pressure including metallic bridge formation, metallic-to-gaseous arc phase transition, plasma sheath formation, anode and cathode erosion, contact area effects, material composition, manufacturing methods, and metal vapor jet formation.
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Optical fiber imaging for high speed plasma motion diagnostics: applied to low voltage circuit breakers.
TL;DR: An integrated portable measurement system is described for the study of high speed and high temperature unsteady plasma flows such as those found in the vicinity of high current switching arcs.
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Study of the Influence of Arc Ignition Position on Arc Motion in Low-Voltage Circuit Breaker
TL;DR: In this article, the influence of the gassing material on arc-motion velocity was also studied experimentally, and the commercial computational fluid dynamics software FLUENT was adapted and modified to develop a 2D magneto-hydrodynamic model of the arc with the same conditions as the experimental model.
Journal ArticleDOI
Imaging and spectrum diagnostics of air arc plasma characteristics
TL;DR: In this paper, an optical high-speed imaging system is integrated with pressure sensing, arc current, and voltage measurement to investigate high speed and high-temperature unsteady arc plasma motion in a molded case circuit breaker (MCCB) model, especially with the influence of polyoxymethylene (POM), polycarbonate (PBT), nylon, and ceramic arc chamber wall materials.
References
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Electrical contacts : principles and applications
TL;DR: In this paper, the authors discuss the effect of dust contamination on the performance of electrical contact devices and propose a method to prevent contact failure due to the presence of dust in the contact surfaces.
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Fundamental Principles of Polymeric Materials
TL;DR: In this paper, the types of Polymers Bonding in polymers Stereoisomerism Characterization of Molecular Weight Polymer Solubility and Solutions Transitions in Polymers POLYMER SYNTHESIS Step-Growth (Condensation) Polymerization Free-Radical Addition (ChainGrowth) polymerization Nonradical Addition Polymerisation Copolymerization POLYmer PROPERTIES Rubber Elasticity Purely Viscous Flow Viscometry and Tube Flow Linear Viscoelasticity
MonographDOI
Power circuit breaker theory and design
TL;DR: This book discusses the development of circuit breakers, design criteria for reliability, maintenance and safety, and the construction of circuit-breaker specification and testing.