This paper describes the rectangular pulse discharge characteristics of the composite electrodes in N2 gas. A glass or ZnO contacts with the needle for the needle-plane electrodes configuration. In the case of the glass contacted with the needle, the discharge voltage increased with increasing L (the distance from the tip of a needle to the dielectric). In the case of ZnO contacted with the needle, the discharge voltage increased with increasing L from 0mm to 2mm, but it gradually decreased with increasing L from 2mm to 10mm. It is considered that these differences on the discharge voltage characteristics originate from the corona extension process and discharge path.

SUMMARYDischarge characteristics have been investigated for a needle-plane electrode configuration containing insulating barriers with a narrow gap which has been placed between the needle and the plane. The characteristics of creeping discharge developed in the narrow gap of the barrier filled with SF 6 are especially considered. In the case of a configuration with a backside electrode below the needle, the corona generated from the needle easily extended to the gap. On the other hand, for a configuration without a backside electrode, the corona has hardly extended to the gap, and on increasing the applied voltage the corona developed greatly in the gap. This difference in corona extension should affect the flashover characteristics in the present system.

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SUMMARYThis paper describes local corona behavior and creeping discharge on composite electrode systems in N 2 . The composite electrode consisted of a needle contacted with a borosilicate glass or a ZnO disk on a needle-plane configuration. The discharge voltages increased when the needle was in contact with the glass with increasing creeping distance (L) from the needle tip to the bottom of the disk. The discharge voltages showed a reversed polarity effect beginning at L = 4 mm. In the case of a needle in contact with ZnO, the discharge voltage increased with distance until L = 2 mm, but decreased beyond L = 2 mm. Observation using an ultrahigh-speed camera showed that the discharge behavior was different for the glass and for the ZnO. Corona photographs taken by a camera with an image intensifier showed that the corona was generated at the triple junction in the case of ZnO. The differences in discharge voltage characteristics and the discharge behavior between the glass and ZnO were associated with the corona properties.

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This paper describes the discharge characteristics of a needle/dielectric composite electrode in N 2 gas produced by a rectangular pulse voltage. Glass or ZnO was placed in contact with the needle for the needleplane electrode configuration. In the case of glass in contact with the needle, the discharge voltage increased with increasing L (the distance from the tip of the needle to the dielectric). In the case of ZnO in contact with the needle, the discharge voltage increased with increasing L from 0 mm to 2 mm, but it gradually decreased with increasing L from 2 mm to 10 mm. It is considered that these differences in the discharge voltage characteristics originate from the corona extension process and discharge path. © 2001 Scripta Technica, Electr Eng Jpn, 137(1): 18, 2001