dc pre-breakdown phenomena and breakdown characteristics in the presence of free conducting particles in liquid nitrogen are studied experimentally. The results show that a microdischarge occurs when a charged particle is approaching an oppositely charged electrode. An intense microdischarge can trigger a complete breakdown of the gap. The breakdown voltage of a uniform field gap with a free metallic particle of mm size might be reduced well below that of a point-to-plane gap without a particle in liquid nitrogen. Heavy contamination by a metallic powder produces a large reduction in the breakdown voltage, with a horizontal spacer surface. However carbon powder is less hazardous compared to metallic powder.
|ジャーナル||IEEE Transactions on Dielectrics and Electrical Insulation|
|出版ステータス||出版済み - 2 2002|
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