Journal: Plasma Physics and Technology

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Publisher

Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Physics

Journal Volumes

ISSN

2336-2634

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2017 - 201932020 - 20253
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Publications 1 - 6 of 6
  • Influence of Ablation on Differential Arc Resistance
    Item type: Journal Article
    Bort, Lorenz; Freiermuth, Vincent; Franck, Christian (2017)
    Plasma Physics and Technology
    The influence of ablation on the du/di behavior of an arc in a model gas circuit breaker was examined. Specifically the transition from a state without ablation in the nozzle towards states with ablation was of interest, since prior work indicated that for high currents the voltage becomes constant or du/di gets even positive if ablation is present. Measurements with different blow pressures and rectangular DC currents of varying amplitude were compared, using PMMA-nozzles and dry air as blowing gas. Ablation was measured by weighing the nozzle, scanning the cross section, and using a coordinate measuring machine. The results agreed well, and confirmed that higher pressure shifts the du/di curve towards more favorable values.
  • Post-Arc Current Measurement in Mechanical Circuit Breakers for HVDC Applications
    Item type: Journal Article
    Schultz, Tim (2017)
    Plasma Physics and Technology
  • Statistical Methods for Identifying Small Differences in the Thermal Interruption Performance of SF6 Alternatives
    Item type: Journal Article
    Engelbrecht, Joseph T.; Pietrzak, Paweł; Christen, D.; et al. (2023)
    Plasma Physics and Technology
    A paradigm shift is underway in high-voltage power transmission, with long-standing SF6-insulated designs being phased out in favor of alternatives with lower global warming potential. A number of proposed solutions for SF6-free gas circuit-breakers use CO2-based mixtures. In such mixtures the thermal switching behavior is mainly set by the CO2 base gas, making the influence of additives challenging to detect experimentally. To investigate the switching processes in these mixtures, a test device based on the puffer circuit-breaker principle has been developed, enabling the study of pure gas properties under highly controlled conditions [2]. This contribution will present thermal interruption limit measurements performed with this device, and establish a statistical method to assess the reignition probability as a function of the prospective current slope. The method will be used to show that the interruption limit in CO2 follows a blow pressure scaling of 3.1 A/μs√bar . Using this approach, the interruption limit may be determined with an uncertainty much smaller than the scatter of individual test results, thereby allowing small changes in interrupting performance to be detected.
  • Thermal Current Interruption Performance of CO2 and CO2/C4F7N mixture
    Item type: Journal Article
    Pietrzak, Paweł; Engelbrecht, Joseph T.; Simka, Philipp; et al. (2023)
    Plasma Physics and Technology
    This contribution aims to compare the thermal interruption performance of pure CO2 with a mixture of CO2/C4F7N. Measurements primarily show higher interrupting capability for a mixture with C4F7N. Detailed analysis shows a distinct difference in the failure mechanism which for CO2/C4F7N is thermal failure and for CO2 mostly “hot dielectric” failure. The difference in the failure mechanism is relevant for the test duties with the most severe TRV. The influence of ablated nozzle material on the interruption process can be ruled out.
  • Recent Trends in Development of High Voltage Circuit Breakers with SF6 Alternative Gases
    Item type: Conference Paper
    Seeger, Martin; Smeets, Rene; Yan, Josef; et al. (2017)
    Plasma Physics and Technology
    The available knowledge of state-of-the-art of SF6 alternative gases in switching applications was collected and evaluated in an initiative of the Current Zero Club [1] together with CIGRE. The present contribution summarizes the main results of this activity and will also include the latest trends. The main properties and switching performance of new gases are compared to SF6. The most promising new gases are at the moment perfluoroketones and perfluoronitriles. Due to the high boiling point of these gases, in HV applications mixtures with CO2 are used. For MV insulation perfluoroketones are mixed with air, but also other combinations might be possible. The dielectric and switching performance of the mixtures, with mixing ratios that allow sufficiently low operating temperatures, is reported to be only slightly below SF6. Minor design changes or de-rating of switchgear are therefore necessary. Differences between the gas mixtures are mainly in the boiling point and the GWP
  • Free burning arc black-box modeling in CO2/O2
    Item type: Conference Paper
    Gfrörer, Tino; Franck, Christian (2025)
    Plasma Physics and Technology
    Black-box arc parameters were fitted from free-burning arc experiments in a 3 bar abs. CO2/O2 (90%/10%) mixture for the first time. Best fits were achieved with a novel Cassie-based model for low-current arcs. Averaged arc time parameters were τ ≈ 170 µs at low currents (20–50 A) and τ ≈ 33 µs at high currents (1–3 kA), respectively. A decrease of τ could be observed for elongated arcs. Explanations based on thermodynamic arc properties are consistent with measured variations of τ .
Publications 1 - 6 of 6