Abstract
When metal particle is attached on spacer surface, it will distort surface electric field and may reduce surface insulation level. Therefore, it is important to research the relationship between metal particle attachment and surface flashover property. In this study, the effect of metal particle materials on surface flashover performance of alumina-filled epoxy resin spacers in SF6/N2 mixtures is investigated. Three kinds of metal particle materials including copper, iron and aluminum are considered. The results reveal that, at low gas pressure or low surface electric field, the material of metal particle has no obvious effect on flashover voltage. At high gas pressure and high surface electric field, the flashover voltage is almost the same when the iron or aluminum particle is attached, which is lower than that with copper particle attached. It is revealed that at high pressure and high electric field, metal powders and vapor of micron size can be generated from the attached metal particle surface by electric field forces and Joule Heating Effect, which may be responsible for the difference in flashover voltage for different metal particle materials.
Highlights
Due to the advantages of good insulation performance, high reliability, compact structure and large transmission capacity etc., Gas insulated metal-enclosed transmission line (GIL) filled with SF6 or SF6/N2 mixtures gets more and more applications in the field of large-capacity power transmission.1–4 metal particles are usually inevitable produced during the production, transportation, installation and operation of GIL
It is believed that surface charge accumulation on an insulators under DC voltages would incur a flashover since the accumulated charges can provide seed electrons for flashover
In order to study the influence of metal particle materials on flashover voltage in different insulating gas, copper, iron and aluminum particles are fixed on the spacer, respectively, the mixing ratio of SF6/N2 is set as 0%, 20%, 40%, 60%, 80% and 100%, and the gas pressure is set as 0.05MPa, 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa and 0.45MPa
Summary
Due to the advantages of good insulation performance, high reliability, compact structure and large transmission capacity etc., Gas insulated metal-enclosed transmission line (GIL) filled with SF6 or SF6/N2 mixtures gets more and more applications in the field of large-capacity power transmission. metal particles are usually inevitable produced during the production, transportation, installation and operation of GIL. It is of great significance to investigate the influence of metal particles on surface flashover characteristics of insulator in GIL. The effect of metal particles on the insulator flashover voltage becomes more significantly under higher SF6 gas pressure.. Xiaoxing Zhang et al studied the influence of Cu, Al and Fe free metal particles on the insulating performance of SF6 in C-GIS, and the Material Studio software was used to calculate the reaction barrier of SF6 with copper, aluminum and iron. The results showed that under the same conditions with copper or aluminum particles, the breakdown voltages of SF6 were similar, and both lower than that with iron particles, which can be explained by the reaction barrier between SF6 and different metals.. Based on the experimental results, the mechanism of the difference in flashover voltage caused by different metal particles is analyzed
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