Impact of Volume Breakdown on Surface Flashover in High Pressure SF6
A.A. Neuber, J.T. Krile, G. Rogers and H. Krompholz
Texas Tech University, Center for Pulsed Power & Power Electronics, Lubbock, TX, USA
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We investigate the pulsed flashover voltage of dielectric samples at up to 4 bar SF6 in the simultaneous presence of a high current (>10 kA, ∼20 microsecond pulse) volume discharge nearby. The chosen distance, ∼7 cm, between surface and volume breakdown is consistent with conditions found in the Sandia Z machine type rimfire switch. For a flashover gap distance of 24 mm and a simultaneous excitation within ∼ 5 microseconds, we observe an average reduction in the flashover voltage from 164 kV to 142 kV at 3.7 bar when the volume discharge is turned on. The test setup utilizing a magnetic switching scheme operating at 320 kV and 10 kA is briefly discussed along with the breakdown properties and the spectral characterization of the volume/surface flashover discharge plasma. In general, UV light propagates relatively unattenuated for wavelengths >160 nm in the high pressure SF6 from the volume discharge to the dielectric surface, setting up conditions which are conducive to photoelectron emission from the dielectric.
DOI: 10.12693/APhysPolA.115.995
PACS numbers: 51.50.+v, 52.80.Mg, 52.70.Kz