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Home > Thèses et HDR > Thèses en 2020

23/09/2020 - Antoine PEREZ

by Laurent Krähenbühl - published on , updated on


  • Wednesday 23 September 2020 from 09:30 to 11:30 -

    Thèse Antoine PEREZ

    Résumé :

    Electric arc development mechanisms study on insulating materials surface and in CO2/fluoronitrile gaseous mixtures
    ... détails ...

    Lieu : SuperGrid Institute, 23 rue Cyprian, Villeurbanne.

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Mr Antoine Perez defends his PhD on Sept. 23, 2020 at 9:30 AM.
Place : SuperGrid Institute, 23 rue Cyprian, Villeurbanne.

Titre :
Electric arc development mechanisms study on insulating materials surface and in CO2/fluoronitrile gaseous mixtures

Jury :
Rapporteurs :
Membres :
- A. GIRODET (SuperGrid Institute)
- C. JOUBERT (Ampère)
- A. BEROUAL (Ampère, Directeur de thèse)

Abstract :
Because of its excellent dielectric properties, sulfur hexafluoride (SF6) is currently the most used gas in gas insulated substations (GIS). However, its greenhouse capacities are well known, with a global warming potential of 23900 times that of CO2 over a 100 years period, and an approximately 3200 years lifetime in the atmosphere. Thus, since the Kyoto summit (COP 3), international authorities tend to reduce or banish its use. For the past several years, manufacturers investigated more eco-friendly alternative solutions, showing equivalent or superior physical properties in comparison with SF6. One of the suggested solution is the fluoronitrile (C4F7N), a gas having alone a dielectric withstand 2.7 times higher than SF6. However, its high liquefaction temperature requires to dilute it for use, mixed with CO2. O2 can also be added to address issues regarding the gas mixture decomposition in arc interruption. The resulting gas mixture can be used at relatively low temperature, with dielectric properties close to that of SF6. To correctly use this new mixture in GIS, its characterization must be completed by the study of its dielectric behavior at the interface with solid insulators in the stations. Based upon previous studies found in the literature, a first set of experiments was conducted under radial geometry, in order to measure the discharges extensions without flashover, to be compared to those obtained in SF6. A second comparative study was then conducted in tangential electric field geometry, allowing to measure streamers propagation velocities during flashover. O2 influence on the gas mixture dielectric strength was also examined. Finally, in order to give sizing criteria for GIS conception using fluoronitrile/CO2 mixtures, flashover voltages measurements were made under various experimental conditions, including particle pollution on surface, under lightning impulse and alternative voltage.

Keywords : GIS; fluoronitrile/CO2 mixture; C4F7N; SF6; epoxy-anhydride resin; surface discharges; streamers; surface withstand; particle