JPH0828142B2 - Lightning arrester - Google Patents

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明は送電線あるいは配電線路に雷サージ電流が流
れた場合にそれを速やかに大地へ放電するとともに、そ
の後生じる商用周波の続流電流を抑制遮断することがで
きる避雷碍子に関するものである。DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention rapidly discharges a lightning surge current to a ground when a power transmission line or a distribution line flows, and further suppresses a commercial frequency follow-up current generated thereafter. The present invention relates to a lightning protection insulator capable of suppressing and blocking.

（従来の技術及び発明が解決しようとする問題点） 従来の避電碍子として第７図に示すように、耐張絶縁
棒31に円環状の限流素子32を嵌装し、該耐張絶縁棒31の
両端にはキャップ金具33,34を配設し、前記限流素子32
をキャップ金具33,34間に弾性体35の弾発下に保持させ
るとともに、限流素子32外周を磁器製の絶縁外套体36に
より被覆して限流素子32を密封包蔵した構造のものがあ
った。(Problems to be Solved by Conventional Techniques and Inventions) As a conventional antistatic insulator, as shown in FIG. 7, a ring-shaped current limiting element 32 is fitted on a tension insulating rod 31, and the tension insulating Cap fittings 33 and 34 are provided at both ends of the rod 31, and the current limiting element 32 is provided.
There is a structure in which the current limiting element 32 is hermetically enclosed while the outer periphery of the current limiting element 32 is covered with an insulating outer body 36 made of porcelain while the elastic body 35 is held elastically between the cap metal fittings 33, 34. It was

ところが、上記避雷碍子は前記外套体36が磁器により
形成されていたので、想定を越える雷撃その他の原因に
よって源流素子32が導通状態となって高温、高圧のアー
クが発生すると、それを放圧するための手段として一定
圧力により破裂する破裂板を前記キャップ金具33に設け
る必要があり、このため、その放圧構造が複雑となり、
製造が煩わしいばかりでなく破裂板を接着あるいは密接
する方式のため気密信頼性にも問題があった。However, in the above-mentioned lightning protection insulator, since the mantle 36 is made of porcelain, if the source element 32 becomes conductive due to unexpected lightning strike or other reasons, a high temperature and high pressure arc occurs, so that it releases the pressure. As a means of this, it is necessary to provide a rupture plate that ruptures with a constant pressure on the cap fitting 33, and therefore the pressure release structure becomes complicated,
Not only is the manufacturing cumbersome, but there is also a problem with airtight reliability due to the method of adhering or closely contacting the rupture plate.

この問題を解決するため、本願出願人は第８図に示す
避雷碍子を提案した。この避雷碍子は筒状をなす耐圧絶
縁筒37の両端開口部に対し、キャップ金具38,39を嵌装
固定し、該耐圧絶縁筒37内には限流素子32を収容して、
前記キャップ金具38,39に電気的に接続するとともに、
該耐圧絶縁筒37には限流素子32両端部に対応するように
少なくとも一以上の放圧孔37aを透設し、前記キャップ
金具38,39にはアーク招弧部材40を該放圧孔37a外側にそ
れぞれ対応するように設け、さらに、前記耐圧絶縁筒37
の外周及び耐圧絶縁筒37と限流素子32との間隙をゴム製
の有機絶縁材41によりモールドしてなる避雷碍子を提供
している。In order to solve this problem, the applicant of the present application has proposed a lightning protection insulator shown in FIG. This lightning insulator has cap metal fittings 38 and 39 fitted and fixed to both end openings of a pressure-resistant insulating cylinder 37 having a tubular shape, and the current limiting element 32 is accommodated in the pressure-resistant insulating cylinder 37.
While electrically connecting to the cap fittings 38, 39,
At least one pressure release hole 37a is provided through the pressure-resistant insulating cylinder 37 so as to correspond to both ends of the current limiting element 32, and the arc fitting member 40 is provided in the cap fittings 38 and 39. It is provided so as to correspond to the outside, respectively.
Provided is a lightning protection insulator in which the outer periphery and the gap between the withstand voltage insulating cylinder 37 and the current limiting element 32 are molded with a rubber organic insulating material 41.

ところが、この避雷碍子は耐圧絶縁筒37と限流素子32
との間隙ｇにゴム製の有機絶縁材41が充填されているの
で、万一、何等かの原因で限流素子32が導通状態となっ
た場合には、耐圧絶縁筒はアークにより生じる圧力に耐
える必要があるため、その分厚肉にすることとなり、避
雷碍子が大型化するという問題があった。However, this lightning protection insulator has a withstand voltage insulation tube 37 and a current limiting element 32.
Since the organic insulating material 41 made of rubber is filled in the gap g between the and, in the unlikely event that the current limiting element 32 becomes conductive due to some reason, the pressure-proof insulating cylinder is set to the pressure generated by the arc. Since it is necessary to endure it, the thickness must be increased, and there is a problem that the lightning protection insulator becomes large.

本発明の目的は、上記従来の技術に存する問題点を解
消して、避雷碍子に万一、想定を越える雷サージ電流が
侵入し、あるいは他の原因で限流素子が導通状態となっ
たような場合に、その高温、高圧のアークを碍管に設け
た放圧栓を迅速、かつ確実に溶融飛散させて放圧を行な
うことができ、さらに、碍管を薄肉化して避雷碍子の小
型化を計り、既設設備への適用性に優れた避雷碍子を提
供することにある。The object of the present invention is to solve the problems existing in the above-mentioned conventional techniques, and in the unlikely event that a lightning surge current intrudes into the lightning protection insulator, which is beyond the assumption, or the current limiting element becomes conductive due to other causes. In this case, the pressure relief plug provided with the high-temperature, high-pressure arc on the insulator tube can be quickly and reliably melted and scattered to release the pressure, and the insulator tube can be made thinner to reduce the size of the lightning protection insulator. , To provide a lightning protection insulator which has excellent applicability to existing equipment.

（問題点を解決するための手段） 本発明は前記問題点を解消するため、絶縁ひだ付きの
碍管の両端部に接地側の電極金具と課電側の電極金具を
気密的に嵌合固定し、該碍管の密閉空間にはその内周面
と所定の間隙をもって電圧−電流特性が非直線性の限流
素子を収容し、前記電極金具と限流素子の上下両端部を
電気的に接続し、前記密閉空間には絶縁性のガスを封入
し、さらに、前記碍管の少なくとも一部に対し、前記絶
縁ひだの間に位置するように放圧孔を貫通して設け、該
放圧孔には実用上非透湿性及び気密性を有する放圧栓を
気密的に嵌入固定し、放圧栓に前記密閉空間に連通する
凹部を形成するという手段を採っている。(Means for Solving the Problems) In order to solve the above problems, the present invention hermetically fits and fixes the ground-side electrode fittings and the power-supply-side electrode fittings on both ends of the insulator-insulated porcelain tube. The sealed space of the porcelain tube accommodates a current limiting element having a non-linear voltage-current characteristic with a predetermined gap from its inner peripheral surface, and electrically connects the upper and lower ends of the electrode fitting and the current limiting element. Insulating gas is sealed in the closed space, and further, at least a part of the porcelain insulator is provided with a pressure relief hole penetrating it so as to be located between the insulating folds. In practice, a pressure-release plug having a non-moisture-permeability and air-tightness is fitted and fixed in an air-tight manner, and a concave portion communicating with the closed space is formed in the pressure-release plug.

（作用） 本発明は碍管を設けた絶縁ひだの間に放圧孔を設け、
そこに放圧栓を嵌入固定しているので、放圧栓の直径や
厚さや、材質等の要素を最適に設定することにより、放
圧圧力を厳密に管理することができるため、その放圧圧
力を必要最小限にすることができ、従って、碍管に加わ
る圧力が低下し、その分解管の肉厚を薄肉化して避雷碍
子の小型化を計ることができる。(Operation) In the present invention, a pressure release hole is provided between the insulating folds provided with the insulator tube,
Since the pressure relief plug is fitted and fixed there, the pressure relief pressure can be strictly controlled by optimally setting factors such as the diameter, thickness and material of the pressure relief plug. The pressure can be minimized, and therefore, the pressure applied to the porcelain insulator is reduced, and the wall thickness of the decomposition pipe can be made thin to miniaturize the lightning arrester.

特に、この発明では放圧栓に対し密閉空間に連通する
凹部を形成したので、密閉空間から高温・高圧のガスが
凹部に進入し、該放圧栓の内頂面にガス圧が作用し易く
なり、この結果前述した放圧栓の諸要素をさらに最適に
設定することができる。放圧栓に凹部が形成されていな
い構造では、密閉空間を長手方向にガスが流動し易く、
ガスの回り込みがないので、放圧栓を溶融破壊するため
の圧力を効率よく作用させることができない。In particular, in the present invention, since the depression is formed in communication with the pressure relief plug in the closed space, high-temperature, high-pressure gas enters the depression from the enclosed space, and gas pressure easily acts on the inner top surface of the pressure relief plug. As a result, the above-mentioned various elements of the pressure relief plug can be set more optimally. In the structure where the pressure relief plug is not formed with the recess, the gas easily flows in the longitudinal direction in the sealed space,
Since there is no gas wraparound, the pressure for melting and breaking the pressure relief plug cannot be applied efficiently.

（実施例） 以下、本発明を具体化した一実施例を第１図〜第５図
に基づいて説明する。(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

外周に多数の絶縁ひだ1aを一体形成した耐候性を有す
る耐強化樹脂（例えばERP）よりなる円筒状の碍管１の
上端部には第２図に示すように内外二層の嵌合筒部1bが
形成されている。この嵌合筒部1bには接着剤２により接
地側の電極金具３の下側円筒部が嵌合固定され、該電極
金具３の外周面には図示しない鉄塔の支持アームに取着
した取付アダプタに取付けられるフランジ部3aが一体に
形成されている。As shown in FIG. 2, at the upper end of the cylindrical porcelain tube 1 made of weatherproof reinforced resin (for example, ERP) integrally formed with a large number of insulating folds 1a on the outer periphery, the inner and outer two-layered fitting tubular portion 1b is formed. Are formed. The lower cylindrical portion of the ground-side electrode fitting 3 is fitted and fixed to the fitting tubular portion 1b with an adhesive 2, and the outer peripheral surface of the electrode fitting 3 is a mounting adapter attached to a support arm of a steel tower (not shown). The flange portion 3a attached to the is integrally formed.

又、前記碍管１の下端部に形成した嵌合筒部1bには接
着剤２により有底円筒状の課電側の電極金具４が気密的
に嵌合固定され、該電極金具４の下面には図示しない
が、送電線側に取着した課電側のアークホーンと所定の
気中放電間隙をもって対向する接地側のアークホーンを
取付けるためのブラケット4aが一体に形成されている。
なお、前記碍管１と電極金具3,4は成形型により同時に
インサート成型してもよい。In addition, a bottomed cylindrical electrode metal fitting 4 having a bottom shape is hermetically fitted and fixed to the fitting cylinder portion 1b formed at the lower end portion of the porcelain bushing 1 by an adhesive 2 and is attached to the lower surface of the electrode fitting 4. Although not shown in the figure, a bracket 4a for attaching the arc horn on the power supply side attached to the power transmission line side and the arc horn on the ground side facing each other with a predetermined air discharge gap is integrally formed.
The porcelain bushing 1 and the electrode fittings 3 and 4 may be insert-molded at the same time by a molding die.

前記課電側の電極金具４の内底面には嵌合筒部4bが形
成され、これには課電側の導体金具５の下端部が嵌合固
定されている。該導体金具５の上面には、電圧−電流特
性が非直線性を有する酸化亜鉛を主材とする限流素子６
が直列に積層載置され、この源流素子６の上端面には有
底円筒状をなすバネ受を兼用する接地側の導体金具７が
支持されている。A fitting cylindrical portion 4b is formed on the inner bottom surface of the electrode-side metal fitting 4 on the power-charging side, and the lower end of the conductor fitting 5 on the power-charging side is fitted and fixed thereto. On the upper surface of the conductor fitting 5, a current limiting element 6 composed mainly of zinc oxide having a non-linear voltage-current characteristic is formed.
Are stacked in series, and a grounded conductor fitting 7 which also serves as a spring receiver and has a bottomed cylindrical shape is supported on the upper end surface of the source element 6.

一方、前記接地側の電極金具３の内周面に形成したネ
ジ部3bには締付リング８が螺合され、該リング８内に嵌
合した中間導体９と前記導体金具７との間には、通電用
のシャント10を有するコイル状のバネ11が介在されてい
る。このバネ11の弾発力により前記限流素子６が課電側
の導体金具５と接地側の導体金具７との間に押圧固定さ
れる。On the other hand, a tightening ring 8 is screwed into the threaded portion 3b formed on the inner peripheral surface of the ground-side electrode fitting 3, and between the intermediate conductor 9 fitted in the ring 8 and the conductor fitting 7. A coil-shaped spring 11 having a shunt 10 for energizing is interposed. Due to the resilience of the spring 11, the current limiting element 6 is pressed and fixed between the conductor fitting 5 on the voltage applying side and the conductor fitting 7 on the ground side.

さらに、前記接地側の電極金具３の開口部には、前記
絶縁リング８及び中間導体９を覆うように絶縁密閉体13
が接着剤２により気密的に嵌合固定されている。Furthermore, an insulating hermetically sealed body 13 is provided in the opening of the ground-side electrode fitting 3 so as to cover the insulating ring 8 and the intermediate conductor 9.
Are hermetically fitted and fixed by the adhesive 2.

前記課電側の電極金具４にはガス封入孔4cが形成さ
れ、この封入孔4cから前記碍管１と限流素子６との間に
形成された密閉空間Ｒに対し、窒素ガスあるいは六フッ
化硫黄（SF6）等の絶縁性に優れたガスが封入され、封
入後は密栓14により封止されている。A gas filling hole 4c is formed in the electrode metal fitting 4 on the side of charging, and nitrogen gas or hexafluoride is introduced into the closed space R formed between the porcelain tube 1 and the current limiting element 6 from the filling hole 4c. A gas having excellent insulating properties such as sulfur (SF6) is enclosed, and after the enclosure, it is sealed with a tight plug 14.

又、前記碍管１の絶縁ひだ1a,1a間には第１図及び第
２図に示すように円形あるいは長孔状の放圧孔1cが複数
箇所に形成され、該放圧孔1cにはアルミニウム、銅等の
金属製の有底円筒状をなす放圧栓15が気密的に嵌入さ
れ、接着剤２により接合されている。そして、前記密閉
空間Ｒ内が所定温度及び所定圧力以上となった場合に、
前記放圧栓15が溶融破裂して放圧し得るようにしてい
る。Further, as shown in FIGS. 1 and 2, circular or elongated pressure release holes 1c are formed between the insulating folds 1a, 1a of the porcelain tube 1 at a plurality of positions, and the pressure release holes 1c are made of aluminum. A pressure release plug 15 made of a metal such as copper and having a bottomed cylindrical shape is hermetically fitted and joined by an adhesive 2. Then, when the inside of the closed space R becomes a predetermined temperature and a predetermined pressure or more,
The pressure release plug 15 melts and bursts so that pressure can be released.

前記放圧栓15には前記密閉空間Ｒに連通するように凹
部16が形成されている。この放圧栓15の肉厚を例えば0.
05〜0.2mm程度あればよい。A recess 16 is formed in the pressure release plug 15 so as to communicate with the closed space R. The wall thickness of this pressure release plug 15 is, for example, 0.
It should be about 05-0.2 mm.

次に、前記のように構成した避雷碍子について、その
作用を説明する。Next, the operation of the lightning protection insulator configured as described above will be described.

さて、避雷碍子を鉄塔に装着した状態において、送電
線に雷サージ電流が流れると、その電流は送電線側のア
ークホーン（図示略）から避雷碍子下端のアークホーン
（図示略）にフラッシオーバされ、課電側に電極金具
４、導電金具５、限流素子６、導体金具７、シャント1
0、中間導体９及び締付リング８を経て、接地側の電極
金具３に流れ、さらに、図示しない取付アダプタを介し
て鉄塔へ流れ、大地に放電される。When a lightning surge current flows through a transmission line with the lightning protection insulator attached to a tower, the current is flashed from an arc horn (not shown) on the transmission line side to an arc horn (not shown) at the lower end of the lightning protection insulator. , Electrode metal fitting 4, conductive metal fitting 5, current limiting element 6, conductor metal fitting 7, shunt 1 on the voltage applying side
After passing through 0, the intermediate conductor 9 and the tightening ring 8, it flows to the grounded side electrode fitting 3 and further to the steel tower through a mounting adapter (not shown) to be discharged to the ground.

又、その後生じる続流は前記両アークホーンと限流素
子６とにより抑制遮断される。Further, the subsequent current generated thereafter is suppressed and cut off by both arc horns and the current limiting element 6.

本発明は碍管１に対し絶縁ひだ1a,1aの間に位置する
ように放圧孔1cを貫設し、そこへ放圧線15を気密的に嵌
入接合したので、放圧栓15の材質あるいは肉厚等の要素
を管理することにより、放圧圧力を最小限として、碍管
１に作用する圧力を軽減し、その分碍管１の肉厚を小さ
くして、避雷碍子の小型、軽量化を計ることができる。According to the present invention, the pressure relief hole 1c is provided so as to be located between the insulating pleats 1a, 1a in the porcelain bushing 1, and the pressure relief wire 15 is hermetically fitted and joined thereto. By controlling factors such as wall thickness, the pressure release pressure is minimized, the pressure acting on the porcelain bushing 1 is reduced, and the wall thickness of the porcelain bushing 1 is reduced to reduce the size and weight of the lightning protection insulator. be able to.

特に、前記実施例では放圧栓15に密閉空間Ｒに連通す
る凹部16を形成したので、密閉空間Ｒから高温高圧のガ
スが凹部16に回り込むようにして進入し、該放圧栓15の
内頂面に高圧のガスが効率良く作用し、この結果前述し
た作用効果をさらに向上することができる。In particular, in the above-described embodiment, since the recess 16 communicating with the closed space R is formed in the pressure release plug 15, the high-temperature and high-pressure gas enters from the closed space R so as to wrap around the recess 16 and enter the pressure release plug 15. The high-pressure gas efficiently acts on the top surface, and as a result, the above-described effects can be further improved.

前記実施例では碍管１と限流素子６との間の密閉空間
Ｒ内に絶縁性ガスを密封したので、万一、想定を越える
大規模の雷サージ電流が限流素子６に印加されて、該限
流素子６が導通状態となり、高温・高圧のアークが発生
したような場合でも、そのアークは、空間Ｒ内の絶縁性
ガスを押し退けて放圧栓15へと速やかに伝播され、この
結果、高圧のアークが迅速に該放圧栓15を破壊あるいは
溶融して外部へ放出されるので、密閉空間Ｒにシリコー
ンゴム等の絶縁充填材を封入した場合と比較して、碍管
１内部の圧力上昇を低減でき、碍管１本体の肉厚を一層
薄肉化することが可能となり、避雷碍子の小型化を計る
ことができる。In the above-described embodiment, since the insulating gas is sealed in the closed space R between the porcelain bushing 1 and the current limiting element 6, a large-scale unexpected lightning surge current is applied to the current limiting element 6 by any chance. Even when the current limiting element 6 becomes conductive and a high-temperature and high-pressure arc is generated, the arc pushes away the insulating gas in the space R and quickly propagates to the pressure relief plug 15. Since a high-pressure arc rapidly breaks or melts the pressure release plug 15 and is released to the outside, the pressure inside the porcelain tube 1 is higher than that when the insulating space R is filled with an insulating filler. The rise can be reduced, the wall thickness of the main body of the porcelain insulator 1 can be further reduced, and the lightning protection insulator can be miniaturized.

又、本発明は次のようにして具体化することも可能で
ある。The present invention can also be embodied as follows.

（１）前記放圧孔1cは最低一個あればよいが、複数個設
ける場合には、碍管１の機械的強度面から千鳥状に配列
するのが望ましい。(1) At least one pressure release hole 1c may be provided, but when a plurality of pressure release holes 1c are provided, it is desirable to arrange them in a zigzag manner from the viewpoint of mechanical strength of the porcelain insulator 1.

（２）前記実施例では樹脂碍管を使用したが、磁器製の
碍管を使用すること。(2) Although the resin porcelain insulator was used in the above embodiment, a porcelain insulator is used.

発明の効果 以上詳述したように、この発明は万一、想定を越える
雷撃、その他の原因によって限流素子が導通状態とな
り、高温・高圧のアークが発生したような場合、放圧栓
を溶融破壊して、放圧を迅速に行い、放圧栓の圧力管理
を容易化して、碍管の圧力上昇を低減しその薄肉化を計
り、避雷碍子を小型化することができる効果がある。Effects of the Invention As described in detail above, the present invention melts the pressure relief plug in the event that a current limiting element becomes conductive due to unexpected lightning strikes or other causes, and a high temperature / high pressure arc occurs. There is an effect that the lightning arrester can be downsized by destroying and quickly releasing the pressure, facilitating the pressure control of the pressure relief plug, reducing the pressure rise of the porcelain tube, making it thinner.

特に、この発明では放圧栓に密閉空間に連通する凹部
を形成したので、密閉空間から高温・高圧のガスが凹部
に回り込むようにして進入し、該放圧栓の内頂面に高温
・高圧のガスが効率良く作用し、この結果前述した効果
を促進することができる。In particular, in this invention, since the depression is formed in the pressure relief plug so as to communicate with the closed space, high-temperature, high-pressure gas enters from the enclosed space so as to circulate into the depression and enters the inner top surface of the pressure relief plug at high temperature and high pressure. The gas described above efficiently acts, and as a result, the above-mentioned effects can be promoted.

【図面の簡単な説明】[Brief description of drawings]

第１図は本発明の避雷碍子の一実施例を示す半縦断面
図、第２図は碍管の部分破断斜視図、第３図は第１図の
Ａ−Ａ線断面図、第４図は第１図のＢ−Ｂ線断面図、第
５図は第１図のＣ−Ｃ線断面図、第６図及び第７図はそ
れぞれ従来例を示す縦断面図である。 １……碍管、1a……絶縁ひだ、1b……嵌合筒部、1c……
放圧孔、３……接地側の電極金具、４……課電側の電極
金具、５……導電金具、６……限流素子、７……導体金
具、８……締付リング、９……中間導体、10……シャン
ト、11……バネ、13……絶縁密閉体、14……密栓、15…
…放圧栓、16……凹部、Ｒ……密閉空間。FIG. 1 is a semi-longitudinal sectional view showing an embodiment of a lightning arrester of the present invention, FIG. 2 is a partially cutaway perspective view of an insulator tube, FIG. 3 is a sectional view taken along the line AA of FIG. 1, and FIG. 1 is a sectional view taken along the line BB in FIG. 1, FIG. 5 is a sectional view taken along the line CC in FIG. 1, and FIGS. 6 and 7 are vertical sectional views showing a conventional example. 1 ... Insulator, 1a ... Insulation pleats, 1b ... Fitting cylinder, 1c ...
Pressure relief hole, 3 ... grounding side electrode fitting, 4 ... voltage applying side electrode fitting, 5 ... conductive fitting, 6 ... current limiting element, 7 ... conductor fitting, 8 ... tightening ring, 9 …… Intermediate conductor, 10 …… Shunt, 11 …… Spring, 13 …… Insulation sealing body, 14 …… Seal plug, 15…
… Press release plug, 16 …… recessed part, R …… closed space.

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】絶縁ひだ付きの碍管の両端部に接地側の電
極金具と課電側の電極金具を気密的に嵌合固定し、該碍
管の密閉空間にはその内周面と所定の間隔をもって電圧
−電流特性が非直線性の限流素子を収容し、前記電極金
具と限流素子の上下両端部を電気的に接続し、前記密閉
空間には絶縁性のガスを封入し、さらに、前記碍管の少
なくとも一部に対し、前記絶縁ひだの間に位置するよう
に放圧孔を貫通して設け、該放圧孔には実用上非透湿性
及び気密性を有する放圧栓を気密的に嵌入固定し、該放
圧栓の内側に前記密閉空間に連通する凹部を形成したこ
とを特徴とする避雷碍子。1. A ground-side electrode fitting and a power-supply-side electrode fitting are airtightly fitted and fixed to both ends of an insulating pleated porcelain tube, and the sealed space of the porcelain tube has a predetermined distance from its inner peripheral surface. With a voltage-current characteristic accommodates a non-linear current limiting element, the electrode fitting and the upper and lower ends of the current limiting element are electrically connected, an insulating gas is sealed in the sealed space, and At least a part of the porcelain tube is provided with a pressure release hole penetrating it so as to be positioned between the insulating folds, and a pressure release plug having practically non-moisture impermeable and airtight properties is airtightly provided in the pressure release hole. A lightning protection insulator, wherein the lightning protection insulator is fitted in and fixed to the pressure relief plug, and a recess communicating with the closed space is formed inside the pressure relief plug. 【請求項２】前記放圧栓はアルミニウム、銅等の非透湿
性のない薄い金属板により形成され、放圧孔の内周面に
接着されている特許請求の範囲第１項に記載の避雷碍
子。2. The lightning arrester according to claim 1, wherein the pressure relief plug is formed of a thin non-moisture-permeable metal plate such as aluminum or copper and adhered to the inner peripheral surface of the pressure relief hole. insulator.