報告書番号

T64

タイトル（和文）

山頂負荷供給配電線の雷害防止対策

タイトル（英文）

Lightning Protection of Power Distribution Lines Located in Mountainous Areas

概要 （図表や脚注は「報告書全文」に掲載しております）

山頂負荷供給配電線の雷害様相を調査するとともに、実験と解析により各種の雷害対策手法の効果を明らかにした。得られた主な結果は次の通りである。（１）山頂負荷配電線の主要な雷被害の原因は山頂負荷落雷時の逆流雷であり、被害は山頂負荷へ電力を供給する柱上変圧器が施設された高圧柱に集中する。機器別の被害割合では、高圧避雷器と低圧避雷器で５０％をしめる。（２）架空地線の設置により、避雷器の焼損率を３分の１から４分の１に低減できるが、架空地線なしで避雷器容量を２倍にしても避雷器焼損率を３分の２にしか減らせない。架空地線を２条に増やすと、避雷器焼損率を１条の場合のさらに３分の１に減らすことができる。（３）避雷器の焼損率を低減させるために、特性の異なる避雷器を並列に施設しても、並列動作率が低く効果の得られない場合が多い。（４）被害様相の特徴と、ここで明らかにした個々の雷害対策の効果を基に､山頂負荷供給配電線の合理的な雷害対策の策定手法を提案した。

概要 （英文）

We have investigated the characteristics of lightning outages on power distribution lines located in mountainous areas facing the Sea of Japan in the Hokuriku and Tohoku districts. Moreover, experimental and analytical studies have been carried out in order to establish the better protection methods of overhead power distribution lines located in mountainous areas.The major conclusions are summarized as follows:(1) Most of the lightning outages in mountainous areas are caused by backflow lightning currents from a tall structure into power distribution lines. Lightning protection for poles supplying power to a tall structure should be emphasized.(2) Surge arresters on power distribution lines located in mountainous areas constitute the large part of damaged apparatuses. Lightning protection against surge arrester damages caused by winter lightning should have priority over all other measures.(3) Installation of an overhead ground wire can reduce the failure rate of a surge arrester to about 20 ～ 30%. On the other hand an increase in the withstand capability of surge arresters can only reduce it to about 60 ～ 70%. When an overhead ground wire is installed on a distribution line, the increase in the withstand capability of surge arresters, from 15kJ to 30kJ, is effective, and it can reduce the failure rate to less than 50%.(4) In the case of two sets of 2.5kA rated arresters with the same discharge voltage, simultaneous discharge can be obtained easily when the peak value of the injected current is large or the rise time of the injected current is short. In the case of two sets of surge arresters with different current capacity, namely 2.5kA rated arresters and 10kA rated ones, the simultaneous operation rate of surge arresters is very small and 2.5kA rated arresters share most of the energy of lightning.(5) Taking these results into consideration, protection design procedures are proposed against lightning for overhead distribution lines located in mountainous areas.

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