Characteristics of creeping discharge developed in a narrow gap between insulators and effect of a backside electrode

Abstract

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.

Characteristics of N2/SF6 mixture gas in creeping discharge developing in narrow gap with backside electrode

“…The corona is generated from near the tip of the upper needle electrode regardless of the backside needle electrode position and the SF 6 gas content [8,9]. Hence, the effects of photoelectrons emitted from the barrier surface due to ultraviolet light and the initial corona, space charges near the edge of the narrow gap, and the accumulated charge on the barrier surface should be taken into consideration in corona development.…”

“…Local nonuniform fields will be caused by floating metallic contaminations and protrusions on conductors inside power apparatus as a result of lightning surges, leading to malfunctions in the apparatus. It is necessary to elucidate the characteristics of creeping discharges developing in narrow spaces in order to improve the reliability of insulating technology in power apparatus, since they are not as yet clearly understood [8,9].…”