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44 results on '"Matsuoka, Shigeyasu"'

2. Gaseous electrical discharge characteristics in air and nitrogen at cryogenic temperature

Author

Toyota, Hiroyuki, Zama, Shigeyuki, Akamine, Yotaro, Matsuoka, Shigeyasu, and Hidaka, Kunihiko

Subjects
Dielectric devices -- Research, Materials at low temperatures -- Research, Business, Electronics, Electronics and electrical industries
Abstract

In designing superconducting electrical power apparatus, the knowledge of cryogenic gas and liquid insulation characteristics is essential. The authors have studied the discharge characteristics of relatively long-gap configurations in air and nitrogen at a cryogenic temperature. A sphere-to-sphere electrode with a gap length of 20 to 150 mm is used for measurements in uniform electric field. The breakdown voltage characteristics basically obey Paschen's law at cryogenic temperature for 50 Hz, ac, dc and lightning impulse voltage applications. A rod-to-plane electrode with a gap length of 20 to 330 mm is used for measurements in non-uniform electric field. In air at cryogenic temperature and nitrogen gas at both room and cryogenic temperature, streamer-like corona discharge appears near the tip of the rod electrode before the breakdown, and the breakdown voltage increases linearly with gap length. In air at room temperature thin film-like corona discharge, however, appears near the tip of the rod electrode before breakdown, and the breakdown voltage becomes higher than the other case. In order to examine the variation of corona discharge characteristics, some additional experiments are conducted. As a result, it becomes clear that thin film-like glow corona discharge appears when electronegative gas is contained and sufficient electrons are supplied from the cathode. Index Terms--Cryogenic temperature, electrical discharge, air, nitrogen, uniform field, non-uniform field, ac, dc, lightning impulse.

Published
2002

44. Measurement of sparkover voltage and time lag characteristics in CF3I–N2 and CF3I– air gas mixtures by using steep-front square voltage.

Author

Toyota, Hiroyuki, Matsuoka, Shigeyasu, and Hidaka, Kunihiko

Subjects
*DIELECTRICS, *NITROGEN, *ELECTRIC fields, *SATURATION vapor pressure, *ELECTRIC discharges, *ATMOSPHERIC pressure
Abstract

A square pulse voltage is useful for studying electrical discharge physics or very fast transient overvoltage issues. This paper describes sparkover voltages and time lag (V– t) characteristics of CF3I gas, which has very low environmental effects and high dielectric strength, and its mixtures with nitrogen gas or air in a very short time range below a microsecond. They are measured by using a steep-front square voltage with a rise time of 16 ns and a peak value of 200 kV. Pure CF3I gas has 20% higher dielectric strength than SF6 gas. The V– t characteristics of CF3I–N2 or CF3I– air gas mixtures, which contain 60% CF3I gas, are equivalent to those of pure SF6 gas at the same total pressure. A quantitative evaluation of V– t characteristics by the equal-area criterion is also performed. The equal-area parameter which is obtained by applying a voltage high enough to make the formative time lag dominant should be chosen. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(2): 1–7, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20325 [ABSTRACT FROM AUTHOR]

Published
2006
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