Yoshihisa Sekiya

DC breakdown characteristics in the gap with thin dielectric sheet in air

The dc breakdown characteristics in the gap with the thin dielectric sheet under atmospheric air were investigated experimentally. The breakdown phenomena were divided into three patterns by current and discharge light (photon) waveforms. The first pattern consisted of a single waveform as a primary pulse. The second pattern consisted of multiple secondary pulses as the successors of the primary pulse. The third pattern was a developing process from the second pattern to the breakdown of the sheet as a final stage. The breakdown voltage of the sheet was irregular even under the same experimental conditions, and its value increased with the sheet thickness. On the other hand, the breakdown voltage in the complex gap consisting of the thin sheet and air gap became higher than that of the thin sheet, and its maximum value reached the breakdown voltage in the air gap. These phenomena and the breakdown mechanism for each pattern were analyzed by the electric field distribution between the electrodes. The breakdown models in the gap with the thin sheet and the complex gap were proposed by comparing the experimental results with the breakdown mechanisms.

An investigation of breakdown voltage with small arc current due to poor contact in SF/sub 6/ gas

Using an experimental apparatus modeled for the contact portion of a gas insulated switchgear (GIS), the influence of the distance between the portion and the dead tank of the GIS and arc duration on the breakdown voltage was investigated. The study was conducted both experimentally and theoretically for the case when the arc was ignited in the portion. In the theoretical analysis, profiles of flow velocity and gas density were calculated. Breakdown voltage evaluated through the gas density was in relatively good agreement with that of the experiment. >

Breakdown mechanism of a gap with a small arc current in SF/sub 6/ gas

Using an experimental apparatus modeled for a gas-insulated switchgear (GIS), the influence of the arc duration on the breakdown voltage between the contact and the grounded tank of the GIS was investigated in the case that the arc was kept ignited in the contact area. From the result, characteristics of the breakdown voltage vs. the arc duration were found to be divided into six stages and the characteristics in each stage were estimated. >

Characteristics of the N 2/O 2 mixtures

The characteristics of the prebreakdown phenomena in low-pressure N2/O2 mixtures under quasi-dc uniform field gap were investigated. The appearance characteristics expressed schematically. The light, voltage and current waveforms of prebreakdown phenomena and the onset voltage of glow discharges were measured under conditions of 1/spl les/ pd/spl les/ 6 (Torr.cm) for N2/O2 mixtures. From these results it became clear that the forms of prebreakdown phenomena of the glow discharges observed under lowpressure N2/O2 mixtures were divided into four types, and these appearance characteristics were expressed schematically and discussed.