JP4357131B2 - Vacuum circuit breaker - Google Patents

Description

【０００１】
【発明の属する技術分野】
本発明は、遮断特性と再点弧特性の優れた接点を有する真空バルブを備えた真空遮断器に関する。
【０００２】
【従来の技術】
一般に真空遮断器は、真空中でのアークの拡散性を利用して高真空中で電流遮断を行わせる真空バルブの接点は、対向する固定、可動の２つの接点から構成されている。
【０００３】
代表的な真空バルブは図１に示す如く、絶縁容器１０１の両端開口部を蓋体１０２ａ，１０２ｂにより閉塞した真空容器１０３内に、一対の接触子１０４，１０５を対向させて設けると共にこれらを蓋体１０２ａ，１０２ｂを貫通させて真空容器１０３内に挿入された通電軸１０６，１０７の端部にそれぞれ装着し、その一方の通電軸１０７を図示しない操作機構により軸方向に移動可能として、一方の接点（以下、固定接点）１０４に対して、他方の接点（以下、可動接点）１０５を接触または開離できるように構成してある。この場合、蓋体１０２ｂと通電軸１０７との間には、真空容器１０３内を真空気密に保持しかつ通電軸１０７の軸方向への移動を可能とするベローズ１０８が設けられている。また、各接点１０４，１０５及び通電軸１０６，１０７を包囲する如く設けられたシールド１０９を絶縁容器１０１の内壁及び蓋体１０２ａ，１０２ｂの内側に固定されている。
【０００４】
真空遮断器は、通電状態では通常両接点１０４，１０５が接触している。この通電状態から開動作により通電軸１０７が図中矢印Ｍ方向に移動すると、可動接点１０５が固定接点１０４から開離し、両接点間にはアークが発生する。このアークは陰極例えば可動接点１０５側からの金属蒸気の発生により維持され、電流がゼロ点（零点）に達すると金属蒸気の発生が止まってアークが維持できなくなり、遮断が完了する。
【０００５】
ところで、両接点１０４，１０５間に発生するアークは、遮断電流が大きいとアーク自身により生じた磁場と外部回路の作る磁場との相互作用により著しく不安定な状態となる。その結果、アークは接点面上を移動し（接点が電極に取り付けられ一体化している時には、アークは電極面上にも移動している場合もある）、接点の端部あるいは周辺部に片寄り、その部分を局部的に過熱し、多量の金属蒸気を放出させて、真空容器１０３内の真空度を低下させる。その結果、真空遮断器の遮断性能は低下する。これらは金属組織などで代表される接点の状態に依存することが多い。
【０００６】
図２は他の代表的な真空バルブの断面図である。この真空バルブが図１の真空バルブと異なる構成は、一対の接点４１，５１を対向させて設けると共に、接点４１の背面には平板型電極４０、接点５１の背面には平板型電極５０をそれぞれ装着した点である。また、接点４１の背面にはコイル電極、接点５１の背面にはコイル電極をそれぞれ装着した真空バルブも知られている。
一般に真空遮断器では、大電流遮断性能、耐電圧性能、耐溶着性能の基本的３要件の他に、再点弧現象の発生の抑制が重要な要件となっている。
【０００７】
しかしながら、これらの要件の中には相反するものがある関係上、単一の金属種によって総ての要件を満足させることは不可能である。このため、実用されている多くの接点材料においては、不足する性能を相互に補うような２種以上の元素を組み合わせることによって、例えば大電流用、高耐圧用などのように特定の用途に合った接点材料の選択採用が行われ、それなりに優れた特性を持つ真空バルブが開発されているが、それでも一部の機能を犠牲にして対応している製品が多い。さらに強まる要求を十分満足する真空バルブはいまだ得られていないのが実情である。
【０００８】
例えば、大電流遮断性を目的とした接点として、Ｃｒを５０ｗｔ％程度含有させたＣｕ−Ｃｒ合金（特公昭４５-３５１０１号公報）が知られている。この合金は、Ｃｒ自体がＣｕとほぼ同等の蒸気圧特性を保持し、かつ強力なガスのゲッタ作用を示す等の効果で高電圧大電流遮断性を実現し、高耐圧特性と大容量遮断とを両立させ得る接点として多用されている。
【０００９】
この合金は、活性度の高いＣｒを使用していることから、原料粉の選択、不純物の混入、雰囲気の管理などに十分に配慮しながら接点素材を製造（焼結工程など）したり、接点素材から接点片へと加工に配慮しながら接点製品としているが、再点弧の発生が引金となって遮断性能を低下させる場合が見られ、その改善が望まれている。
【００１０】
【発明が解決しようとする課題】
ＣｕＣｒ接点は、両者の高温度での蒸気圧特性が近似していることなどが主因となって、遮断した後でも接点表面は比較的平滑な損傷特性を示し、安定した電気特性を発揮している。
【００１１】
近年では一層の大電流遮断や、より高電圧が印加される可能性のある回路への適応が日常的に行われる結果、接点として加工した新品時の表面状態、電流遮断後の接点表面の損傷状態などによっては、次の定常電流の開閉時の接触抵抗の異常上昇や温度の異常上昇を引き起こす原因となったり、耐電圧不良を示し、再点弧発生の一因となっている。
しかし、接点の表面状態を管理しても完全には再点弧発生を抑制することができず、十分な電流遮断特性が得られていないのが現実である。
【００１２】
さらに、例えばＣｕ−Ｃｒ合金の再点弧特性と遮断特性は、合金中のＣｒ量の変動、Ｃｒ粒子の粒度分布、Ｃｒ粒子の偏析の程度、合金中に存在する空孔の程度などに依存することが判明しているが、これらの最適化を進めているにも拘らず、上述した近年の適応状態では、まだ再点弧特性にはばらつきが見られ、遮断特性との両特性を兼備した真空バルブが必要となってきた。
【００１３】
本発明は上記状況に対処するためになされたもので、その目的は接点合金の再点弧特性を安定化させて電流遮断特性の優れた真空バルブを備えた真空遮断器を提供することにある。
【００１４】
【課題を解決するための手段】
電流を遮断した直後の接点面は、主としてアーク熱によって極めて高温度になり、溶融した接点面からは多量のガスが電極空間に放出される。このガスが電極間に所定時間以上停滞したり、特にまだ十分に電極が開極していない時点では、真空の持つ優れた絶縁性は破壊される。従って電極間の絶縁耐力を維持し、優れた遮断特性と再点弧特性の両立を図るには、放出されたガスを速やかに電極間以外に拡散除去させることが重要であり、また接点面から放出されるガスの絶対量もあらかじめ極少にしておくことが重要である。
【００１５】
本発明者等の研究によれば、真空容器内に貫通される接離可能な一対の通電軸と、一端が通電軸に接合される通電部と、通電部の他端側に配設され通電軸の操作により、接離可能な一対の接点とを有する真空バルブを備えた真空遮断器において、常温から１６００℃までの加熱過程で放出される放出ガスの累積量（Ｖ_L）が大である接点では、遮断の初期過程の真空度が十分に回復しない時点、すなわち絶縁が十分に回復しない段階で、電極間に多量のガス放出がなされる結果、耐電圧性の低下による再点弧特性の低下によって、真空遮断器は遮断不能を呈する。従って、遮断特性と再点弧特性の両立を図るのには、比較的低い温度領域、すなわち常温から１６００℃までの加熱過程で放出される放出ガスの累積量（Ｖ_L）の方が、１６００℃を超え少なくとも２６００℃までの加熱過程で放出される放出ガスの累積量（Ｖ_H）よりも、両特性の低下に対する影響度が大きい傾向にある。常温から少なくとも２６００℃まで加熱する過程で放出される放出ガスの累積量（Ｖ_L＋Ｖ_H）を（Ｖ₀）とした時、前記接点の（Ｖ_L／Ｖ₀）比率を８０容積％以下、好ましくは５０％以下（０％含む）に制御することを要する。（Ｖ₀）中に占める（Ｖ_L）を少なくすることが必要である。
【００１６】
ここで、前記（Ｖ_L）、（Ｖ_H）の測定において、測定の区切りの温度として特に１６００℃の温度に注目する理由は下記による。すなわち、一般に昇温過程でのガス放出は５００℃前後で接点表面に単に吸着している水分の完全な放出が見られることや、接点中のＣｕが溶融温度１０８１℃に達した時点で、多量のガス放出が見られることから、接点表面に吸着している気体分子を確実かつ効率的に排除すると共に、溶融に達した時点での多量に放出されるガスも確実かつ効率的に排除し、測定精度にも配慮した上で、水分が完全に放出する５００℃やＣｕが溶融する１０８１℃よりも十分に高い温度１６００℃を選択した。
【００１７】
（Ｖ_L）値は開極の直後から比較的短時間内のガス放出、（Ｖ_H）値は開極から比較的長時間後のガス放出に相当する。従って（Ｖ_L）値が大である場合は、開極直後の電極間の絶縁回復が遅れ、遮断特性を低下させる。そのことから接点中の特に（Ｖ_L）値は所定量以上の存在は好ましくない。
【００１８】
真空バルブの再点弧特性、遮断特性の安定化には、一般に接点材料の組成、成分量の変動、粒度、粒度分布、偏析の程度、合金中に存在する空孔の程度などに依存するが、特に再点弧特性のよりいっそうの安定化には、上記に加えて接点からのガス放出挙動、すなわち加熱過程での前記接点から放出される放出ガス累積量が関与する。特に、常温から少なくとも２６００℃まで加熱する過程で放出される放出ガス累積量（Ｖ₀）と、常温から１６００℃までの加熱過程で放出される放出ガス累積量（Ｖ_L）との、相互の関係が極めて重要であることが分かった。
【００１９】
上記目的を達成するために、本発明の請求項１は、真空容器内に貫通される接離可能な一対の通電軸と、一端が通電軸に接合され、接離可能な対向する一対の接点と、必要によりアークシールドを有する真空バルブを備えた真空遮断器において、
前記接点は、導電性成分として０．００５〜０．５重量％のＣｒを固溶した１５〜９０重量％未満のＣｕＣｒ固溶体と、残部が耐弧成分として平均粒子直径０．１〜１５０μｍ未満のＣｒからなるＣｕＣｒ合金であって、常温から１６００℃までの加熱過程で前記接点から放出される放出ガス累積量を（Ｖ_L ）、１６００℃を越え少なくとも２６００℃までの加熱過程で放出される放出ガス累積量を（Ｖ_H ）、常温から少なくとも２６００℃まで加熱する過程で放出される放出ガス累積量を（Ｖ_L ＋Ｖ_H ）＝（Ｖ_O ）として前記接点の評価試験をおこなったとき、前記接点の（Ｖ_L ／Ｖ_O）比率が８０％以下、好ましくは５０％以下（０％を含む）であることを特徴とする。
【００２０】
すなわち、接点の（Ｖ_L／Ｖ₀）比率を８０容積％以下、好ましくは５０％以下とすることによって、遮断によって電極空間に放出された放出ガスが所定量以上残存していると、再点弧の発生や遮断性能の低下を招き、好ましくない（所定量とは、放出ガス累積量（Ｖ_H）が８０容積％を超えて残存している状態を指す）。従って好ましい状態は、（Ｖ_L／Ｖ₀）比率を８０容積％以下、好ましくは５０％以下であり、（Ｖ_L／Ｖ₀）比率が８０容積％を超えて多く残存すると絶縁破壊を一層助長するので好ましくない。
【００２９】
【発明の実施の形態】
本発明の実施例と比較例について以下に詳細に説明する。
（１）まず、遮断テスト用実験バルブの組立ての概要を説明する。
端面の平均表面粗さを約１．５μｍに研磨したセラミックス製絶縁容器（主成分：Ａｌ₂Ｏ₃）を用意し、このセラミックス製絶縁容器については、組立て前に１６００℃の前加熱処理を施した。封着金具として、板厚さ２ｍｍの４２％Ｎｉ−Ｆｅ合金を用意した。ロウ材として、厚さ０．１ｍｍの７２％Ａｇ−Ｃｕ合金板を用意した。上記用意した各部財を被接合物間（セラミックス製絶縁容器の端面と封着金具）に気密封着接合が可能なように配置して、５×１０^-4Ｐａの真空雰囲気で封着金具とセラミックス製絶縁容器との気密封着工程に供した。
【００３０】
（２）次に、供試接点の選出とＶ _L ，Ｖ ₀ の測定について説明する。
接点素材中に含有されるガスのうちで、
・常温から１６００℃までの加熱過程で、前記接点から放出される放出ガス累積量を（Ｖ_L）、
・１６００℃を超え少なくとも２６００℃までの加熱過程で放出される放出ガス累積量を（Ｖ_H）、
・常温から少なくとも２６００℃まで加熱する過程で放出される放出ガス累積量を（Ｖ_L＋Ｖ_H）、すなわち（Ｖ₀）とする。
【００３１】
これらの調整は、各接点素材を各種条件（雰囲気など）で加熱処理で製造した中から選出した。すなわち加熱処理は、原料の前処理時点や接点の製造時点での加熱条件（加熱速度、冷却速度、加熱保持温度と時間）と雰囲気（真空の場合は真空度、各種ガスの場合は露点）を調節した。また、各種ガス雰囲気中で加熱処理した後、真空雰囲気中で再加熱するあるいはその逆など、複数の熱処理を組み合わせながら微調整も行った。
【００３２】
一方、このようにして得た接点を十分洗浄しかつ乾燥した後、所定の温度で所定時間加熱保持中に接点から放出されるガス量（Ｖ_L）、（Ｖ_H）、（Ｖ₀）を測定すると共に、その時の各放出温度（放出のピーク温度）を確認した。
【００３３】
（３）再点弧特性；
直径３０ｍｍ、厚さ５ｍｍの円板状接点片を、ディマウンタブル型真空バルブに装着し、２４ｋＶ×５００Ａの回路を２０００回遮断した時の再点弧発生頻度を表示した。
【００３４】
なお、結果は（実施例２）の発生数の平均を１．０とした時の発生倍率が、０．１倍未満の場合を（Ａ）、０．１〜０．８倍を（Ｂ）、０．８〜１．２倍を（Ｃ）、１．２〜１．５倍を（Ｄ）、１．２〜１０倍を（Ｘ）、１０〜１００倍を（Ｙ）、１００倍以上を（Ｚ）として表示し、（Ａ）〜（Ｄ）を合格、（Ｘ）〜（Ｚ）を不良（不合格）の目安とした。
【００３５】
（４）遮断特性；
直径７０ｍｍの接点を装着した遮断テスト用実験バルブを開閉装置に取り付けると共に、ベーキング、電圧エージング等を与えた後、２４ｋＶ，５０Ｈｚの回路に接続し、電流をほぼ１ｋＡずつ増加しながら遮断限界を真空バルブ３本につき比較評価した。なお、数値は（実施例２）の値を１．０とした時の比較値をバラツキ幅をもって示した。
【００３６】
１（実施例１〜４，比較例１〜２）
この例では、接点素材中に含有される所定の温度で所定時間加熱保持中に接点から放出されるガス量に注目している。
そこで、本発明の実施例及び比較例では、評価用代表接点製造は、Ｃｕ粉、Ｃｒ粉の成型体に対して、例えば１０６０℃の加熱処理によって製造（目的とする（Ｖ_L／Ｖ₀）比率とするために、雰囲気を真空、窒素、水素などの製造雰囲気の選択とその質、処理温度、時間、原料粉の調節など）した７５％Ｃｕ−Ｃｒ合金に対して、常温から１６００℃までの加熱過程で放出される放出ガス累積量（Ｖ_L）と常温から少なくとも２６００℃まで加熱する過程で放出される放出ガス累積量（Ｖ₀）とを測定し、これらの素材の中から幅広く（Ｖ_L／Ｖ₀）比率を変動させた接点を選出した。
【００３７】
その素材の中から、（Ｖ_L／Ｖ₀）比率が、９５以上（比較例１）、９０（比較例２）、７８〜８０（実施例１）、４５〜５０（実施例２）、２５〜２７（実施例３）、０〜４（実施例４）の範囲にある素材を選出し試験に供した。
【００３８】
再点弧特性及び遮断特性は、（実施例２）の再点弧特性を標準とした時の各接点の再点弧発生率との相対値を調査すると共に、遮断特性も（実施例２）の遮断電流値を１．０とした時の各接点の相対値を評価し、その条件と結果を表１（条件）、表２（条件）、表３（結果）に示す。以下に評価する実施例３，４及び比較例１，２についてもその条件と結果を表１（条件）、表２（条件）、表３（結果）に示す。
【００３９】
その結果、（Ｖ_L／Ｖ₀）＝７８〜８０％の（実施例１）では、再点弧発生の頻度は０．８〜１．２倍（評価Ｃ）と１．２〜１．５倍（評価Ｄ）を示し、標準とする（実施例２）とほぼ同程度の再点弧特性である。遮断倍率も（０．９〜０．９５）倍を示し標準とする（実施例２）とほぼ同程度の遮断特性であり、いずれも合格である。
【００４０】
（Ｖ_L／Ｖ₀）＝２５〜２７％の（実施例３）では、再点弧発生の頻度は０．１〜０．８倍（評価Ｂ）と０．８〜１．２倍（評価Ｃ）を示し、標準とする（実施例２）と同程度またはそれ以上の再点弧特性である。遮断倍率も（１．１〜１．２）倍を示し、標準とする（実施例２）以上の遮断特性であり、いずれも合格である。
【００４１】
（Ｖ_L／Ｖ₀）＝０〜４％の（実施例４）では、再点弧発生の頻度は０．１倍未満（評価Ａ）を示し、標準とする（実施例２）と比較して極めて良好の再点弧特性である。遮断倍率も（１．３〜１．４）倍を示し標準とする（実施例２）と比較して極めて良好の遮断特性であり、いずれも合格である。
以上から（実施例１〜４）は、明らかに接点素材中に含有される（Ｖ_L／Ｖ₀）比率が低減する場合に再点弧特性は向上する傾向にあることを示唆している。
【００４２】
（Ｖ_L／Ｖ₀）＝９０％の（比較例２）では、遮断直後の絶縁回復が遅く耐電圧性低下で再点弧が多発し、１．５〜１０倍（評価Ｘ）と１０〜１００倍（評価Ｙ）を示し、再点弧特性は低下した。遮断倍率も（０．６〜０．８）倍を示し、標準とする（実施例２）と比較して劣化した遮断特性であり、いずれも不合格である。
【００４３】
（Ｖ_L／Ｖ₀）＝９５〜９９％の（比較例１）では、遮断直後の絶縁回復が著しく遅く耐電圧性低下で再点弧が多発し、１０〜１００（評価Ｙ）と１００以上（評価Ｚ）を示し再点弧特性は低下した。遮断倍率も（０．４〜０．５）倍を示し、標準とする（実施例２）と比較して大幅に低下した遮断特性であり、いずれも不合格である。
以上から（比較例１〜２）は、明らかに接点素材中に含有される（Ｖ_L／Ｖ₀）比率が増加する場合に再点弧特性は低下する傾向にあることを示唆している。
【００４４】
以上の事例により、本発明を適応する接点素材中に含有される（Ｖ_L／Ｖ₀）比率は８０％以下、好ましくは５０％以下（０％含む）の範囲の接点を使用するのが好ましい。
【００４５】
２（実施例５〜７，比較例３〜４）
実施例１〜４及び比較例１〜２では、接点素材中に含有される（Ｖ_L／Ｖ₀）比率の再点弧特性、遮断特性に及ぼす影響を、接点合金中のＣｕ量を７５重量％（以下、接点材料については重量％）とした７５％Ｃｕ−Ｃｒ接点について示したが、本例ではこれに限ることなくその効果を発揮する。
【００４６】
すなわち、接点合金中の（Ｖ_L／Ｖ₀）比率を１５〜２０％とした上で、接点合金中のＣｕ量を５％とした５％Ｃｕ−Ｃｒ（比較例３）、１５％Ｃｕ−Ｃｒ（実施例５）、５０％Ｃｕ−Ｃｒ（実施例６）、８５％Ｃｕ−Ｃｒ（実施例７）、９８％Ｃｕ−Ｃｒ（比較例４）を製造した上で、これらの接点材料の中から接点合金中の（Ｖ_L／Ｖ₀）比率を１５〜２０％の範囲内にある接点材料を選択し、前記１の場合と同様の評価を実施し、その条件と結果を表１（条件）、表２（条件）、表３（結果）に示す。なお、以下の実施例及び比較例についての条件と結果も、表１，２と表３に示す。
【００４７】
８５％Ｃｕ−Ｃｒ（実施例７）では、再点弧発生の頻度は０．８〜１．２倍（評価Ｃ）と１．２〜１．５倍（評価Ｄ）を示し、標準とする（実施例２）とほぼ同程度の再点弧特性である。しゃ断倍率も（１．１〜１．２）倍を示し、標準とする（実施例２）以上の遮断特性であり、いずれも合格である。
【００４８】
５０％Ｃｕ−Ｃｒ（実施例６）では、再点弧発生の頻度は０．８〜１．２倍（評価Ｃ）を示し、標準とする（実施例２）と同等の再点弧特性である。遮断倍率も（１．０〜１．０５）倍を示し、標準とする（実施例２）と同等の遮断特性であり、いずれも合格である。
【００４９】
１５％Ｃｕ−Ｃｒ（実施例５）では、再点弧発生の頻度は０．１〜０．８倍（評価Ｂ）と０．８〜１．２倍（評価Ｃ）を示し、標準とする（実施例２）と同程度またはそれ以上の再点弧特性である。遮断倍率も（０．９〜０．９５）倍を示し、標準とする（実施例２）とほぼ同程度の遮断特性であり、いずれも合格である。
【００５０】
これに対して接点中のＣｕ量が（実施例５）より少ない５％Ｃｕ−Ｃｒ（比較例３）では、再点弧発生の頻度は０．１〜０．８倍（評価Ｂ）を示し、標準とする（実施例２）以上の良好な再点弧特性であるが、遮断倍率が（０．５５〜０．６５）倍を示し、標準とする（実施例２）と比較して大幅に低下した遮断特性を示した。再点弧特性は良好であったが遮断特性が好ましくなく、総合的には不合格である。接点素材自体の低い導電率に原因している（比較例３）。
【００５１】
一方、接点中のＣｕ量が（実施例７）よりさらに大きい９８％Ｃｕ−Ｃｒ（比較例４）では、電流遮断時に一部に溶着現象の発生や接点表面の荒れが大きくなる現象を見せる。接点の耐電圧特性の低下によって遮断直後の接点表面の損傷が大きく耐電圧特性の低下によって、再点弧が多発し、１０〜１００（評価Ｙ）と１００以上（評価Ｚ）を示し、再点弧特性は低下した。遮断倍率も（０．６〜１．２５）倍を示し、標準とする（実施例２）と比較して大幅に低下すると共にバラツキ幅も増大した。接点表面の荒れが起因して遮断特性は大きなバラツキを示した（比較例４）。
【００５２】
以上の事例より、（Ｖ_L／Ｖ₀）比率を前記所定範囲内とした上で、本発明を適応する接点素材中に含有されるＣｕ量は１５〜８５％の範囲の接点を使用するのが好ましい。
【００５３】
３（実施例８〜１０，比較例５〜６）
実施例１〜７及び比較例１〜４では、接点素材中に含有される（Ｖ_L／Ｖ₀）比率の再点弧特性、遮断特性に及ぼす影響を，接点合金中の導電成分（Ｃｕ）中に固溶する耐弧成分の種類をＣｒとし、その量を０．０２％とした接点について示したが、本例ではこれに限ることなく、その効果を発揮する。
【００５４】
すなわち接点合金中の導電成分中に固溶する耐弧成分（Ｃｒ）の量を０．００５％、０．１４％、０．５％とした７５％Ｃｕ−Ｃｒ（実施例８〜１０）を、主として冷却過程での冷却速度を調整しながら製造した上で、前記１の場合と同様の評価を実施した。
【００５５】
導電成分中に固溶する耐弧成分（Ｃｒ）の量が０．００５重量％（実施例８）では、再点弧発生の頻度は、０．１倍未満（評価Ａ）及び０．１〜０．８倍（評価Ｂ）を示し、標準とする（実施例２）よりも再点弧特性は向上する。遮断倍率も（１．０〜１．１）倍を示し、標準とする（実施例２）と同等以上の遮断特性であり、いずれも合格である。
【００５６】
導電成分中に固溶する耐弧成分（Ｃｒ）の量が０．１４重量％（実施例９）、０．５重量％（実施例１０）では、再点弧発生の頻度は、両者とも０．８〜１．２倍（評価Ｃ）を示し、標準とする（実施例２）と同等の再点弧特性である。遮断倍率も（１．０〜１．０５）倍、（０．９〜０．９５）倍を示し、標準とする（実施例２）とほぼ同等の遮断特性であり、いずれも合格である。
【００５７】
しかし、導電成分中に固溶する耐弧成分（Ｃｒ）の量が０．００５重量％未満（比較例５）では、再点弧発生の頻度は前記した（実施例８）と同等の０．１倍未満（評価Ａ）及び０．１〜０．８倍（評価Ｂ）を示し良好であったが、遮断倍率は（０．６〜０．７５）倍を示し、標準とする（実施例２）よりも大幅に低下した遮断特性である。導電率の大幅な低下に起因して十分な遮断性能を発揮できず、いずれも不合格である。その上、接点素材中に含有される導電成分中に固溶する耐弧成分（Ｃｒ）の量を、安定して０．００５重量％未満とすることは、製造コストが高く供給性に難があり、製造技術的観点から本発明の好ましい範囲から除外する（比較例５）。
【００５８】
これに対して、導電成分中に固溶する耐弧成分（Ｃｒ）の量が０．５重量％以上（比較例６）では、再点弧発生の頻度は０．８〜１．２倍（評価Ｃ）及び１０〜１００倍（評価Ｙ）を示し、標準とする（実施例２）と比較してバラツキ幅の大きい再点弧特性を示し好ましくない。接点素材中に含有される導電成分中に固溶する耐弧成分（Ｃｒ）の量を、安定して０．５重量％以上とすることは、製造コストが高く供給性に難があり、製造技術的観点から本発明の好ましい範囲から除外する（比較例６）。
【００５９】
以上の事例より、（Ｖ_L／Ｖ₀）比率を前記所定範囲内とした上で、本発明を適応する接点素材中に含有される導電成分中に固溶する耐弧成分（Ｃｒ）の量は、０．００５〜０．５重量％未満の範囲の接点を使用するのが好ましい。
【００６０】
４（実施例１１〜１５）
実施例１〜１０及び比較例１〜６では、接点素材中に含有される耐弧成分の種類としてＣｒを選択した接点について、（Ｖ_L／Ｖ₀）比率の再点弧特性、遮断特性に及ぼす影響を示したが、本発明は接点を構成する耐弧成分の種類はＣｒに限ることなくその効果を発揮する。
【００６１】
すなわち接点を構成する耐弧成分の種類が、Ｗ（残部が７５％Ｃｕ、実施例１１）、Ｍｏ（残部が７５％Ｃｕ、実施例１２）、Ｔｉ（残部が７５％Ｃｕ、実施例１３）、Ｔａ（残部が７５％Ｃｕ、実施例１４）、Ｎｂ（残部が７５％Ｃｕ、実施例１５）と置換しても、再点弧発生の頻度は１．２〜１．５倍（評価Ｄ）から０．１〜０．８倍（評価Ｂ）の間の特性を示し、標準とする（実施例２）とほぼ同等の再点弧特性である。遮断倍率も（０．９〜０．９５）倍から（１．０〜１．０５）の間の特性を示し、標準とする（実施例２）と同等の遮断特性であり、（実施例２）とほぼ同等またはそれ以上の再点弧特性及び遮断倍率（０．９）倍以上の遮断特性を示し、いずれも好ましい結果を得た（実施例１１〜１５）。
【００６２】
以上の事例より、（Ｖ_L／Ｖ₀）比率を前記所定範囲内とした上で、本発明を適応する接点素材中の耐弧成分の種類は、Ｗ，Ｍｏ，Ｔｉ，Ｔａ，Ｎｂから選択した接点を使用するのが好ましい。
【００６３】
５（実施例１６〜２２）
実施例１〜１５及び比較例１〜６では、接点素材中に含有される耐弧成分の種類としてＣｒを選択した接点（実施例１〜１０）、Ｗ，Ｍｏ，Ｔｉ，Ｔａ，Ｎｂを選択した接点（実施例１１〜１５）について、（Ｖ_L／Ｖ₀）比率の再点弧特性、遮断特性に及ぼす影響を示したが、本発明は接点を構成する耐弧成分の種類はこれら単一の成分に限ることなくその効果を発揮する。
【００６４】
すなわち接点を構成する耐弧成分の種類が、ＣｒＷ合金（Ｃｒ：Ｗ＝９５：５、実施例１６）、ＣｒＭｏ合金（Ｃｒ：Ｍｏ＝９５：５、実施例１７）、ＣｒＴｉ合金（Ｃｒ：Ｔｉ＝９５：５、実施例１８）、ＣｒＴａ合金（Ｃｒ：Ｔａ＝８０：２０、実施例１９）、ＣｒＮｂ（Ｃｒ：Ｎｂ＝７０：３０、実施例２０）、ＴａＮｂ（Ｔａ：Ｎｂ＝６０：４０、実施例２１）、ＷＭｏ（Ｗ：Ｍｏ＝５０：５０、実施例２２）と置換しても、再点弧発生の頻度は０．８〜１．２倍（評価Ｃ）から１．２〜１．５倍（評価Ｄ）の間を示し、標準とする（実施例２）とほぼ同等の再点弧特性である。しゃ断倍率も（０．９〜０．９５）倍から（１．０〜１．０５）倍の間を示し、標準とする（実施例２）と同等の遮断特性であり、（実施例２）とほぼ同等またはそれ以上の再点弧特性及び遮断倍率（０．９）倍以上の遮断特性を示し、いずれも好ましい結果を得た（実施例１６〜２２）。
【００６５】
以上の事例より、（Ｖ_L／Ｖ₀）比率を前記所定範囲内とした上で、本発明技術を適応する接点素材中の耐弧成分の種類は、Ｗ，Ｍｏ，Ｔｉ，Ｔａ，Ｎｂを複合化した接点を使用するのが好ましい。
【００６６】
６（実施例２３〜２５，比較例７〜８）
実施例１〜２２及び比較例１〜６では、接点素材中に含有される耐弧成分の平均粒子直径を６２〜１４９μｍを選択した接点について、（Ｖ_L／Ｖ₀）比率が再点弧特性、遮断特性に対して及ぼす影響を示したが、本発明はこれに限ることなくその効果を発揮する。
【００６７】
すなわち接点合金中の耐弧成分の平均粒子直径が０．０５〜１．０μｍ（実施例２３）、１０〜６２μｍ（実施例２４）、４４〜１０５μｍ（実施例２５）では、再点弧発生の頻度は、０．１〜０．８（評価Ｂ）から１．２〜１．５（評価Ｄ）の間の特性を示し、標準とする（実施例２）とほぼ同等の再点弧特性である。遮断倍率も（１．０〜１．１）倍から（１．１５〜１．２）倍の間の特性を示し、標準とする（実施例２）と同等またはそれ以上の遮断特性を示し、いずれも合格である（実施例２３〜２５）。
【００６８】
なお、接点合金中の耐弧成分の平均粒子直径が２５０μｍ以上では、再点弧発生の頻度は１．２〜１．５倍（評価Ｄ）と１０〜１００倍（評価Ｙ）の間の特性を持ち、標準とする（実施例２）と比較して極めて大きなバラツキ幅を持つ再点弧特性を示した。遮断倍率も（０．７５〜１．０）倍を示し、標準とする（実施例２）より大幅に低下した遮断特性である。粗大の混在による組織の不均一さに起因して十分な遮断性能を発揮できない。いずれも不合格である（比較例８）。
【００６９】
一方、接点合金中の耐弧成分の平均粒子直径が０．０５μｍ以下では、再点弧発生の頻度は、０．１〜０．８（評価Ｂ）の特性を示し、標準とする（実施例２）より優れた再点弧特性を示し良好であったが、Ｃｒ粒子直径を０．０５μｍ以下に揃えるためには、製造コストが高く供給性に難があり、製造技術的観点から本発明の好ましい範囲から除外する（比較例７）。
【００７０】
以上の事例より、（Ｖ_L／Ｖ₀）比率を前記所定範囲内とした上で、本発明に適応する接点素材中の耐弧成分の平均粒子直径は、０．０５〜１４９μｍの範囲の接点を使用するのが好ましい。
【００７１】
７（実施例２６〜３１，比較例９〜１０）
実施例１〜２５及び比較例１〜７では、（Ｖ_L／Ｖ₀）比率が再点弧特性、遮断特性に対して及ぼす影響を、接点合金中にＢｉなどの耐溶着性を改善する補助成分のない接点について示したが、本発明はこれに限ることなく、上記した接点合金中にＢｉなどが所定量以内存在してもその効果を維持する。
【００７２】
すなわち、接点合金中にＢｉを０．１％、１．０％添加した７５％Ｃｕ−Ｃｒ（実施例２６〜２７）を製造した上で、これらの（Ｖ_L／Ｖ₀）比率が所定範囲内にある接点材料を選択し、前記評価を実施した。接点合金中のＢｉ量を０．１％とした（実施例２６）及びＢｉ量を１．０％とした（実施例２７）では、再点弧発生の頻度は０．１〜０．８倍（評価Ｂ）、０．８〜１．２倍（評価Ｃ）を示し、標準とする（実施例２）と比較してほぼ同等（実施例２７）かまたはそれ以上（実施例２６）の再点弧特性である。大幅に耐溶着性が改善され、遮断後の接点表面の平滑化が寄与している。遮断倍率も（０．９〜０．９５）倍の特性を示し、標準とする（実施例２）とほぼ同等またはそれ以上の遮断特性を示し、いずれも合格である（実施例２６〜２７）。
【００７３】
しかし、接点合金中のＢｉ量を２％とした（比較例９）では、再点弧発生の頻度は１０〜１００（評価Ｙ）及び１００以上（評価Ｚ）となり、標準とする（実施例２）と比較して再点弧特性の大幅な低下とバラツキ幅の拡大が見られ、好ましくない。遮断時に生ずるＢｉの選択的蒸発によって、接点表面の荒損し耐電圧性の低下を招く結果、遮断倍率は（０．３〜０．４５）倍の特性を示し、標準とする（実施例２）と比較して大幅に低下した（比較例９）。
【００７４】
接点合金中のＢｉ量を０．１％とした（実施例２６）及びＢｉ量を１．０％とした（実施例２７）では、再点弧発生の頻度は０．１〜０．８倍（評価Ｂ）、０．８〜１．２倍（評価Ｃ）を示し、標準とする（実施例２）と比較してほぼ同等（実施例２７）かまたはそれ以上（実施例２６）の再点弧特性である。大幅に耐溶着性が改善され、遮断後の接点表面の平滑化が寄与している。遮断倍率も（０．９〜０．９５）倍の特性を示し、標準とする（実施例２）とほぼ同等またはそれ以上の遮断特性を示し、いずれも合格である（実施例２６〜２７）。
【００７５】
さらに、接点合金中のＰｂ量を０．３重量％とした（実施例２８）、Ｓｂ量を０．１重量％とした（実施例２９）、Ｔｅ量を５．０重量％とした（実施例３０）、Ｓｅ量を１．０重量％とした（実施例３１）などの他の耐溶着性成分を含有する７５％Ｃｕ−Ｃｒ合金においても、再点弧発生の頻度は０．８〜１．２倍（評価Ｃ）及び１．２〜１．５倍（評価Ｄ）を示し、良好な再点弧特性を示すと共に遮断倍率も０．９〜０．９５倍を示し、良好な遮断特性を示す。
【００７６】
これに対して、接点合金中のＴｅ量を８．０重量％とした（比較例１０）では、再点弧発生の頻度は１０〜１００（評価Ｙ）及び１００以上（評価Ｚ）となり、標準とする（実施例２）と比較して再点弧特性の大幅な低下とバラツキ幅の拡大が見られ、好ましくない。遮断時に生ずるＴｅの選択的蒸発によって、接点表面の荒損し耐電圧性の低下を招く結果、遮断倍率は（０．４〜０．５）倍の特性を示し、標準とする（実施例２）と比較して大幅に低下した（比較例１０）。
【００７７】
以上の事例より、（Ｖ_L／Ｖ₀）比率を前記所定範囲内とした上で、本発明を適応する接点素材中の補助成分は、Ｂｉ，Ｐｂ，Ｓｂの場合１重量％以下、Ｔｅ，Ｓｅの場合５重量％以下の範囲の接点を使用するのが好ましい。
上記各実施例及び各比較例の評価条件と評価結果をまとめると、下記表１，表２，表３となる。
【００７８】
【表１】

【００７９】
【表２】

【００８０】
【表３】

【００８１】
８（変形例）
変形例１：接点は、（Ｖ_L／Ｖ₀）比率を前記所定範囲内とした上で、少なくとも２０％ＩＡＣＳの導電率を持つ合金であることが好ましい。導電率が２０％ＩＡＣＳ未満の場合では再点弧特性には変化が見られていないが、遮断倍率が０．６〜０．８倍を示し、遮断特性の低下が認められる。
【００８２】
変形例２：真空遮断器の通電軸は、（Ｖ_L／Ｖ₀）比率を前記所定範囲内とした上で、少なくとも７０％ＩＡＣＳの導電率を持つことが好ましい。導電率が７０％ＩＡＣＳ未満の場合では再点弧特性には変化は見られていないが、遮断倍率が０．７〜０．９５倍を示し、遮断特性の低下が認められる。
【００８３】
変形例３：真空遮断器のコイル電極は、（Ｖ_L／Ｖ₀）比率を前記所定範囲内とした上で、少なくとも７０％ＩＡＣＳの導電率を持つことが好ましい。導電率が７０％ＩＡＣＳ未満の場合では再点弧特性には変化は見られていないが、遮断倍率が０．６〜０．８５倍を示し、遮断特性の低下が認められる。
【００８４】
【発明の効果】
以上説明したように本発明によれば、再点弧特性と遮断特性とを両立させた真空バルブを備えた真空遮断器を提供することができる。
【図面の簡単な説明】
【図１】従来の真空バルブの断面図。
【図２】従来の他の真空バルブの断面図。
【符号の説明】
４０…電極、４１…固定側接点、５０…電極、５１…可動側接点、１０１…絶縁容器、１０２ａ…固定側蓋体、１０２ｂ…可動側蓋体、１０３…真空容器、１０４…固定接点、１０５…可動側接点、１０６…固定通電軸、１０７…可動通電軸、１０８…ベローズ、１０９…アークシールド、Ｍ…通電軸の移動方向。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum circuit breaker including a vacuum valve having a contact having excellent breaking characteristics and re-ignition characteristics.
[0002]
[Prior art]
In general, in a vacuum circuit breaker, a contact of a vacuum valve for interrupting a current in a high vacuum using arc diffusibility in a vacuum is composed of two opposed fixed and movable contacts.
[0003]
As shown in FIG. 1, a typical vacuum valve is provided with a pair of contacts 104 and 105 facing each other in a vacuum vessel 103 in which openings at both ends of an insulating vessel 101 are closed by lids 102a and 102b. The energizing shafts 106 and 107 inserted into the vacuum vessel 103 through the bodies 102a and 102b are respectively attached, and one energizing shaft 107 is movable in the axial direction by an operating mechanism (not shown). A contact (hereinafter referred to as a fixed contact) 104 is configured such that the other contact (hereinafter referred to as a movable contact) 105 can be contacted or separated. In this case, a bellows 108 is provided between the lid 102b and the energizing shaft 107 so as to keep the inside of the vacuum chamber 103 vacuum-tight and allow the energizing shaft 107 to move in the axial direction. Further, a shield 109 provided so as to surround each of the contacts 104 and 105 and the energizing shafts 106 and 107 is fixed to the inner wall of the insulating container 101 and the inside of the lids 102a and 102b.
[0004]
The vacuum circuit breaker is normally in contact with both contacts 104 and 105 when energized. When the energizing shaft 107 is moved in the direction of arrow M in the figure by the opening operation from this energized state, the movable contact 105 is separated from the fixed contact 104, and an arc is generated between the two contacts. This arc is maintained by the generation of metal vapor from the cathode, for example, the movable contact 105 side. When the current reaches the zero point (zero point), the generation of metal vapor stops and the arc cannot be maintained, and the interruption is completed.
[0005]
By the way, the arc generated between the two contacts 104 and 105 becomes extremely unstable due to the interaction between the magnetic field generated by the arc itself and the magnetic field generated by the external circuit when the breaking current is large. As a result, the arc moves on the contact surface (when the contact is attached to and integrated with the electrode, the arc may also move on the electrode surface) and is offset to the end or the periphery of the contact. The portion is locally heated to release a large amount of metal vapor, and the degree of vacuum in the vacuum vessel 103 is lowered. As a result, the breaking performance of the vacuum circuit breaker decreases. These often depend on the state of the contact represented by the metallographic structure.
[0006]
FIG. 2 is a cross-sectional view of another typical vacuum valve. The vacuum valve is different from the vacuum valve shown in FIG. 1 in that a pair of contacts 41 and 51 are provided facing each other, a flat electrode 40 is provided on the back of the contact 41, and a flat electrode 50 is provided on the back of the contact 51. It is the point where it wore. There is also known a vacuum valve in which a coil electrode is mounted on the back surface of the contact 41 and a coil electrode is mounted on the back surface of the contact 51.
In general, in a vacuum circuit breaker, in addition to the three basic requirements of large current interruption performance, withstand voltage performance, and welding resistance, suppression of the occurrence of a re-ignition phenomenon is an important requirement.
[0007]
However, because some of these requirements are contradictory, it is impossible to satisfy all the requirements with a single metal species. For this reason, in many contact materials that are in practical use, a combination of two or more elements that complement each other in deficient performance can be used for a specific application, such as for high currents and high withstand voltages. However, there are many products that are compatible at the expense of some functions. In fact, a vacuum valve that sufficiently satisfies the increasing demand has not yet been obtained.
[0008]
For example, a Cu—Cr alloy (Japanese Patent Publication No. 45-35101) containing about 50 wt% of Cr is known as a contact for the purpose of interrupting a large current. This alloy realizes high voltage and large current interruption due to the effect that Cr itself retains vapor pressure characteristics almost equivalent to Cu and exhibits a powerful gas getter action. It is widely used as a contact that can achieve both.
[0009]
Since this alloy uses highly active Cr, contact materials can be manufactured (sintering process, etc.) while paying sufficient attention to the selection of raw material powder, mixing of impurities, atmosphere control, etc. The contact product is made from the material to the contact piece while considering the processing, but the occurrence of re-ignition triggers the interruption performance, and the improvement is desired.
[0010]
[Problems to be solved by the invention]
CuCr contacts are mainly due to their close vapor pressure characteristics at high temperatures, and the contact surface shows relatively smooth damage characteristics even after interruption, and exhibits stable electrical characteristics. Yes.
[0011]
In recent years, as a result of routine application to circuits where higher current interruption and higher voltage may be applied in recent years, the surface condition of a new product processed as a contact, damage to the contact surface after current interruption Depending on the state and the like, it may cause an abnormal increase in contact resistance and an abnormal increase in temperature at the time of opening and closing of the next steady current, or it shows a withstand voltage failure, which is a cause of reignition.
However, even if the surface state of the contact is controlled, the occurrence of re-ignition cannot be suppressed completely, and the actual current interruption characteristic is not obtained.
[0012]
In addition, for example, the re-ignition characteristics and interruption characteristics of a Cu—Cr alloy depend on fluctuations in the amount of Cr in the alloy, the particle size distribution of the Cr particles, the degree of segregation of the Cr particles, the degree of vacancies present in the alloy, etc. In spite of these optimization efforts, the re-ignition characteristics still vary in the above-mentioned adaptation conditions, and both characteristics of the cut-off characteristics are combined. A vacuum valve has become necessary.
[0013]
The present invention has been made to cope with the above situation, and an object of the present invention is to provide a vacuum circuit breaker having a vacuum valve with excellent current interruption characteristics by stabilizing the re-ignition characteristic of the contact alloy. .
[0014]
[Means for Solving the Problems]
The contact surface immediately after the current is cut off becomes extremely high mainly due to arc heat, and a large amount of gas is released from the molten contact surface into the electrode space. The excellent insulating property of the vacuum is destroyed when the gas stagnates between the electrodes for a predetermined time or more, or particularly when the electrodes are not sufficiently opened. Therefore, in order to maintain the dielectric strength between the electrodes and to achieve both excellent interruption characteristics and re-ignition characteristics, it is important to diffuse and remove the released gas quickly between the electrodes and from the contact surface. It is important to minimize the absolute amount of gas released in advance.
[0015]
According to the present inventors' research, a pair of energized shafts that can be brought into and out of the vacuum vessel, an energized portion whose one end is joined to the energized shaft, and an energized portion disposed on the other end of the energized portion In a vacuum circuit breaker equipped with a vacuum valve having a pair of contacts that can be separated from each other by operating the shaft, the cumulative amount of gas released in the heating process from room temperature to 1600 ° C. (V_L) Is large, a large amount of gas is released between the electrodes when the degree of vacuum in the initial process of breaking is not sufficiently restored, that is, when insulation is not sufficiently restored. Due to the deterioration of the re-ignition characteristic, the vacuum circuit breaker is unable to be interrupted. Therefore, in order to achieve both the cutoff characteristic and the re-ignition characteristic, the cumulative amount (V) of the released gas released in the heating process from a relatively low temperature range, that is, from room temperature to 1600 ° C._L) Is the cumulative amount of emitted gas (V) that is released during the heating process exceeding 1600 ° C. and up to at least 2600 ° C._H) Tends to have a greater influence on the deterioration of both characteristics. Cumulative amount of released gas released in the process of heating from room temperature to at least 2600 ° C (V_L+ V_H) To (V₀) Of the contact point (V_L/ V₀) It is necessary to control the ratio to 80% by volume or less, preferably 50% or less (including 0%). (V₀) (V)_L) Must be reduced.
[0016]
Here, (V_L), (V_HIn the measurement of), the reason for paying particular attention to the temperature of 1600 ° C. as the temperature of the measurement break is as follows. That is, in general, the gas release during the temperature rising process is about 500 ° C., when a complete release of moisture simply adsorbed on the contact surface is observed, or when the Cu in the contact reaches the melting temperature of 1081 ° C. Gas release is seen, so gas molecules adsorbed on the contact surface are surely and efficiently excluded, and a large amount of gas released at the time of melting is reliably and efficiently removed, In consideration of measurement accuracy, a temperature of 1600 ° C., which is sufficiently higher than 500 ° C. at which moisture is completely released and 1081 ° C. at which Cu melts, was selected.
[0017]
(V_L) Value is the gas release within a relatively short time immediately after the opening, (V_HThe value corresponds to the gas release after a relatively long time from the opening. Therefore (V_L) When the value is large, the insulation recovery between the electrodes immediately after the opening is delayed, and the interruption characteristic is deteriorated. That is why (V_L) It is not preferable that the value is larger than a predetermined amount.
[0018]
The stabilization of the re-ignition characteristics and interruption characteristics of a vacuum valve generally depends on the composition of the contact material, fluctuations in the amount of components, particle size, particle size distribution, degree of segregation, and the degree of holes present in the alloy. In particular, further stabilization of the re-ignition characteristic involves in addition to the above, the gas release behavior from the contact, that is, the cumulative amount of gas released from the contact during the heating process. In particular, the cumulative amount of released gas (V) released in the process of heating from room temperature to at least 2600 ° C.₀) And the cumulative amount of gas released (V) during the heating process from room temperature to 1600 ° C._L) And the mutual relationship was found to be extremely important.
[0019]
  In order to achieve the above-mentioned object, claim 1 of the present invention includes a pair of contactable and energized shafts penetrating into the vacuum vessel, and a pair of opposing contacts that are joined at one end to the current-carrying shaft. And a vacuum circuit breaker with a vacuum valve having an arc shield if necessary,
  The contact has a CuCr solid solution of 15 to less than 90% by weight in which 0.005 to 0.5% by weight of Cr is dissolved as a conductive component, and the remainder is an average particle diameter of less than 0.1 to 150 μm as an arc resistant component. A CuCr alloy made of Cr,Heating process from room temperature to 1600 ℃BeforeCumulative amount of gas released from the contactThe(V_L ) Cumulative amount of released gas released in the heating process exceeding 1600 ° C to at least 2600 ° CThe(V_H ), Cumulative amount of released gas released during heating from room temperature to at least 2600 ° CThe(V_L + V_H ) = (V_O)As an evaluation test of the contact,(V_L / V_O) Ratio is 80%Below, preferably 50%The following (including 0%).
[0020]
That is, (V_L/ V₀) By setting the ratio to 80% by volume or less, preferably 50% or less, if a predetermined amount or more of the released gas remains in the electrode space due to interruption, re-ignition occurs and the interruption performance decreases. Unfavorable (predetermined amount is the cumulative amount of released gas (V_H) Indicates a state in which the residual amount exceeds 80% by volume). Therefore, the preferred state is (V_L/ V₀) The ratio is 80% by volume or less, preferably 50% or less, and (V_L/ V₀) If the ratio exceeds 80% by volume, the dielectric breakdown is further promoted, which is not preferable.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the present invention and comparative examples will be described in detail below.
(1) First, an outline of assembly of a test valve for a shut-off test will be described.
Ceramic insulation container with an average end surface roughness of about 1.5 μm (main component: Al₂O_ThreeThe ceramic insulating container was preheated at 1600 ° C. before assembly. A 42% Ni—Fe alloy having a thickness of 2 mm was prepared as a sealing metal fitting. A 72% Ag—Cu alloy plate having a thickness of 0.1 mm was prepared as a brazing material. The above-prepared components are arranged between the objects to be joined (the end face of the ceramic insulating container and the sealing metal fitting) so as to be hermetically sealed and bonded, and 5 × 10^-FourIt was subjected to a hermetic sealing process between the sealing metal fitting and the ceramic insulating container in a vacuum atmosphere of Pa.
[0030]
(2) Next, the selection of test contactsV _L , V ₀ ofMeasurementWill be described.
  Of the gases contained in the contact material,
・ In the heating process from room temperature to 1600 ° C, the cumulative amount of released gas released from the contact (V_L),
-Cumulative amount of released gas released in the heating process exceeding 1600 ° C to at least 2600 ° C (V_H),
-Cumulative amount of released gas released in the process of heating from room temperature to at least 2600 ° C (V_L+ V_H), Ie (V₀).
[0031]
For these adjustments, each contact material was selected from among those manufactured by heat treatment under various conditions (atmosphere, etc.). In other words, the heat treatment involves heating conditions (heating rate, cooling rate, heating holding temperature and time) and atmosphere (degree of vacuum in the case of vacuum, dew point in the case of various gases) at the time of raw material pretreatment and contact production. Adjusted. Further, fine adjustment was performed while combining a plurality of heat treatments, such as heat treatment in various gas atmospheres and then reheating in a vacuum atmosphere or vice versa.
[0032]
On the other hand, after sufficiently washing and drying the contact thus obtained, the amount of gas (V_L), (V_H), (V₀) And the respective release temperatures (peak temperature of the release) at that time were confirmed.
[0033]
(3) Re-ignition characteristics;
A disk-shaped contact piece having a diameter of 30 mm and a thickness of 5 mm was attached to a demountable vacuum valve, and the re-ignition occurrence frequency when the circuit of 24 kV × 500 A was interrupted 2000 times was displayed.
[0034]
In addition, as for a result, when the generation | occurrence | production magnification | multiplying_factor when the average of the generation | occurrence | production number of (Example 2) is 1.0 is less than 0.1 times (A), 0.1-0.8 times (B) 0.8 to 1.2 times (C), 1.2 to 1.5 times (D), 1.2 to 10 times (X), 10 to 100 times (Y), 100 times or more Was displayed as (Z), and (A) to (D) were accepted, and (X) to (Z) were taken as references for failure (failed).
[0035]
(4) interception characteristics;
A break test test valve with a 70 mm diameter contact is attached to the switchgear, and after baking, voltage aging, etc., it is connected to a 24 kV, 50 Hz circuit, and the break limit is reduced while increasing the current by approximately 1 kA. The three valves were evaluated for comparison. In addition, the numerical value showed the comparative value when the value of (Example 2) was 1.0 with the variation width.
[0036]
1 (Examples 1-4, Comparative Examples 1-2)
In this example, attention is paid to the amount of gas released from the contact during heating and holding for a predetermined time at a predetermined temperature contained in the contact material.
Thus, in the examples and comparative examples of the present invention, the representative contact for evaluation is manufactured by subjecting a molded body of Cu powder and Cr powder to, for example, heat treatment at 1060 ° C._L/ V₀) From 75 ° C to 1600 ° C for a 75% Cu-Cr alloy whose production atmosphere such as vacuum, nitrogen, hydrogen, etc. is selected and its quality, processing temperature, time, raw material powder, etc. Cumulative amount of released gas (V_L) And the cumulative amount of released gas released in the process of heating from room temperature to at least 2600 ° C. (V₀) And a wide range of these materials (V_L/ V₀) Selected contacts with varying ratios.
[0037]
From the materials, (V_L/ V₀) The ratio is 95 or more (Comparative Example 1), 90 (Comparative Example 2), 78-80 (Example 1), 45-50 (Example 2), 25-27 (Example 3), 0-4 ( Materials in the range of Example 4) were selected and subjected to a test.
[0038]
As for the re-ignition characteristic and the interruption characteristic, the relative value with the re-ignition occurrence rate of each contact when the re-ignition characteristic of (Example 2) is used as a standard is investigated, and the interruption characteristic is also (Embodiment 2). The relative value of each contact when the breaking current value is 1.0 is evaluated, and the conditions and results are shown in Table 1 (conditions), Table 2 (conditions), and Table 3 (results). The conditions and results of Examples 3 and 4 and Comparative Examples 1 and 2 evaluated below are shown in Table 1 (Condition), Table 2 (Condition), and Table 3 (Result).
[0039]
As a result, (V_L/ V₀) = 78 to 80% (Example 1), the frequency of occurrence of reignition is 0.8 to 1.2 times (Evaluation C) and 1.2 to 1.5 times (Evaluation D). The re-ignition characteristics are almost the same as those of (Example 2). The blocking magnification is (0.9 to 0.95) times, which is almost the same as the standard (Example 2), and both pass.
[0040]
(V_L/ V₀) = 25 to 27% (Example 3), the frequency of occurrence of re-ignition is 0.1 to 0.8 times (Evaluation B) and 0.8 to 1.2 times (Evaluation C). The re-ignition characteristic is equal to or higher than (Example 2). The blocking magnification also indicates (1.1 to 1.2) times, which is a blocking characteristic higher than the standard (Example 2), and both pass.
[0041]
(V_L/ V₀) = 0-4% (Example 4), the frequency of re-ignition is less than 0.1 times (Evaluation A), which is very good compared to the standard (Example 2). Arc characteristics. The blocking magnification is (1.3 to 1.4) times, which is extremely good blocking characteristics as compared with the standard (Example 2), both of which are acceptable.
From the above (Examples 1 to 4) are clearly contained in the contact material (V_L/ V₀This suggests that the re-ignition characteristics tend to improve when the ratio decreases.
[0042]
(V_L/ V₀) = 90% (Comparative Example 2) Insulation recovery immediately after interruption is slow, and withstand voltage decreases, frequent re-ignition occurs, 1.5 to 10 times (Evaluation X) and 10 to 100 times (Evaluation Y) The re-ignition characteristics were reduced. The blocking ratio also shows (0.6 to 0.8) times, which is a blocking characteristic deteriorated compared to the standard (Example 2), and both are unacceptable.
[0043]
(V_L/ V₀) = 95-99% (Comparative Example 1), the insulation recovery immediately after the interruption is remarkably slow and the re-ignition frequently occurs due to a decrease in withstand voltage, indicating 10 to 100 (Evaluation Y) and 100 or more (Evaluation Z). The re-ignition characteristics are degraded. The blocking ratio also shows (0.4 to 0.5) times, which is a blocking characteristic that is significantly lower than that of the standard (Example 2), both of which are unacceptable.
From the above (Comparative Examples 1-2) is clearly contained in the contact material (V_L/ V₀) This suggests that the re-ignition characteristics tend to decrease when the ratio increases.
[0044]
By the above example, it is contained in the contact material to which the present invention is applied (V_L/ V₀) It is preferable to use contacts with a ratio of 80% or less, preferably 50% or less (including 0%).
[0045]
2 (Examples 5-7, Comparative Examples 3-4)
In Examples 1-4 and Comparative Examples 1-2, it is contained in the contact material (V_L/ V₀) The effect of the ratio on the re-ignition characteristics and the breaking characteristics is shown for a 75% Cu—Cr contact with 75% by weight of Cu in the contact alloy (hereinafter referred to as weight% for contact materials). Then, the effect is not limited to this.
[0046]
That is, (V_L/ V₀) 5% Cu—Cr (Comparative Example 3), 15% Cu—Cr (Example 5), 50% Cu—Cr with a ratio of 15 to 20% and a Cu content in the contact alloy of 5%. (Example 6) After producing 85% Cu-Cr (Example 7) and 98% Cu-Cr (Comparative Example 4), among these contact materials, (V_L/ V₀) Select a contact material having a ratio in the range of 15 to 20%, perform the same evaluation as in the case 1, and show the conditions and results in Table 1 (Condition), Table 2 (Condition), Table 3 ( Results). Tables 1, 2 and 3 also show conditions and results for the following examples and comparative examples.
[0047]
In 85% Cu-Cr (Example 7), the frequency of re-ignition generation is 0.8 to 1.2 times (Evaluation C) and 1.2 to 1.5 times (Evaluation D), which are standard. The re-ignition characteristics are almost the same as those in Example 2. The cutoff magnification also shows (1.1 to 1.2) times, which is a cutoff characteristic higher than the standard (Example 2), and both pass.
[0048]
In 50% Cu—Cr (Example 6), the frequency of occurrence of re-ignition is 0.8 to 1.2 times (Evaluation C), and the re-ignition characteristic is the same as that of the standard (Example 2). is there. The blocking magnification also shows (1.0 to 1.05) times, which is a blocking characteristic equivalent to the standard (Example 2), and both pass.
[0049]
In 15% Cu—Cr (Example 5), the frequency of re-ignition generation is 0.1 to 0.8 times (Evaluation B) and 0.8 to 1.2 times (Evaluation C), which are standard. The re-ignition characteristics are the same as or higher than those of (Example 2). The blocking magnification also shows (0.9 to 0.95) times, which is approximately the same blocking characteristics as the standard (Example 2), and both pass.
[0050]
On the other hand, in the case of 5% Cu—Cr (Comparative Example 3) in which the amount of Cu in the contact is less than (Example 5), the frequency of re-ignition generation is 0.1 to 0.8 times (Evaluation B). The re-ignition characteristic is better than the standard (Example 2), but the cutoff magnification is (0.55 to 0.65) times, which is significantly larger than the standard (Example 2). Showed a reduced blocking characteristic. Although the re-ignition characteristic was good, the interruption characteristic was not preferable, and overall, it was rejected. This is due to the low conductivity of the contact material itself (Comparative Example 3).
[0051]
On the other hand, in the case of 98% Cu—Cr (Comparative Example 4) in which the amount of Cu in the contact is larger than that of (Example 7), a phenomenon that the occurrence of welding phenomenon and the roughness of the contact surface become large is partially exhibited during current interruption. Damage to the contact surface immediately after interruption due to a decrease in the withstand voltage characteristics of the contact is large, and re-ignition frequently occurs due to a decrease in the withstand voltage characteristics, indicating 10 to 100 (Evaluation Y) and 100 or more (Evaluation Z). The arc characteristics are degraded. The blocking magnification also showed (0.6 to 1.25) times, which was significantly lower than the standard (Example 2) and increased in variation width. Due to the roughness of the contact surface, the interruption characteristics showed large variations (Comparative Example 4).
[0052]
From the above example, (V_L/ V₀) It is preferable to use a contact having a Cu content of 15 to 85% in the contact material to which the present invention is applied after the ratio is within the predetermined range.
[0053]
3 (Examples 8 to 10, Comparative Examples 5 to 6)
In Examples 1-7 and Comparative Examples 1-4, it is contained in the contact material (V_L/ V₀) The effect of the ratio on the re-ignition characteristics and breaking characteristics is shown for contacts with Cr as the kind of arc-resistant component that dissolves in the conductive component (Cu) in the contact alloy and 0.02% of the amount. However, in this example, the effect is not limited to this.
[0054]
That is, 75% Cu—Cr (Examples 8 to 10) in which the amount of arc resistant component (Cr) dissolved in the conductive component in the contact alloy is 0.005%, 0.14%, and 0.5% is used. The same evaluation as in the above case 1 was performed after manufacturing while adjusting the cooling rate mainly in the cooling process.
[0055]
When the amount of the arc resistant component (Cr) dissolved in the conductive component is 0.005% by weight (Example 8), the frequency of occurrence of reignition is less than 0.1 times (Evaluation A) and 0.1 to 0.1%. 0.8 times (evaluation B) is shown, and the re-ignition characteristic is improved as compared with the standard (Example 2). The blocking magnification also indicates (1.0 to 1.1) times, which is a blocking characteristic equal to or higher than that of the standard (Example 2), and both pass.
[0056]
When the amount of the arc resistant component (Cr) dissolved in the conductive component is 0.14% by weight (Example 9) and 0.5% by weight (Example 10), the frequency of occurrence of re-ignition is 0 for both. .8 to 1.2 times (Evaluation C), which is a re-ignition characteristic equivalent to the standard (Example 2). The blocking magnifications are (1.0 to 1.05) times and (0.9 to 0.95) times, which are blocking characteristics almost equivalent to the standard (Example 2), both of which are acceptable.
[0057]
However, when the amount of the arc resistant component (Cr) dissolved in the conductive component is less than 0.005% by weight (Comparative Example 5), the frequency of occurrence of re-ignition is the same as that described above (Example 8). Less than 1 time (Evaluation A) and 0.1 to 0.8 times (Evaluation B) were good, but the blocking magnification was (0.6 to 0.75) times, which is a standard (Example) It is a cut-off characteristic significantly lower than 2). Due to a significant decrease in electrical conductivity, sufficient shut-off performance cannot be exhibited, and both fail. In addition, the stable amount of the arc resistant component (Cr) dissolved in the conductive component contained in the contact material is less than 0.005% by weight, which is difficult to supply due to high manufacturing costs. Excluded from the preferred range of the present invention from the viewpoint of production technology (Comparative Example 5).
[0058]
On the other hand, when the amount of the arc resistant component (Cr) dissolved in the conductive component is 0.5% by weight or more (Comparative Example 6), the frequency of occurrence of re-ignition is 0.8 to 1.2 times ( Evaluation C) and 10 to 100 times (Evaluation Y) are shown, and the re-ignition characteristic having a large variation width compared with the standard (Example 2) is not preferable. If the amount of arc-resistant component (Cr) dissolved in the conductive component contained in the contact material is set to 0.5% by weight or more stably, the manufacturing cost is high and the supply is difficult. Excluded from the preferred range of the present invention from a technical point of view (Comparative Example 6).
[0059]
From the above example, (V_L/ V₀) The ratio of the arc resistant component (Cr) dissolved in the conductive component contained in the contact material to which the present invention is applied after the ratio is within the predetermined range is 0.005 to 0.5% by weight. It is preferred to use contacts in the range below.
[0060]
4 (Examples 11 to 15)
In Examples 1 to 10 and Comparative Examples 1 to 6, with respect to the contacts in which Cr was selected as the type of arc-resistant component contained in the contact material, (V_L/ V₀) Although the influence of the ratio on the re-ignition characteristic and the interruption characteristic has been shown, the present invention exhibits its effect without being limited to the kind of the arc-resistant component constituting the contact.
[0061]
That is, the types of arc-resistant components constituting the contact are W (remaining 75% Cu, Example 11), Mo (remaining 75% Cu, Example 12), Ti (remaining 75% Cu, Example 13) , Ta (remaining 75% Cu, Example 14) and Nb (remaining 75% Cu, Example 15) are replaced with 1.2 to 1.5 times the frequency of re-ignition (Evaluation D) ) To 0.1 to 0.8 times (Evaluation B), which is a re-ignition characteristic substantially equivalent to the standard (Example 2). The cutoff magnification also shows a characteristic between (0.9 to 0.95) times to (1.0 to 1.05), which is equivalent to the standard (Example 2). The re-ignition characteristics almost equal to or higher than the above and the interruption characteristics greater than the interruption magnification (0.9) times were obtained, and all obtained preferable results (Examples 11 to 15).
[0062]
From the above example, (V_L/ V₀) It is preferable to use a contact selected from W, Mo, Ti, Ta, and Nb as the arc-proof component in the contact material to which the present invention is applied while keeping the ratio within the predetermined range.
[0063]
5 (Examples 16 to 22)
In Examples 1 to 15 and Comparative Examples 1 to 6, contacts (Examples 1 to 10), W, Mo, Ti, Ta, and Nb selected as Cr as the type of arc-resistant component contained in the contact material are selected. Contact points (Examples 11 to 15)_L/ V₀) Although the influence of the ratio on the re-ignition characteristic and the interruption characteristic has been shown, the present invention exhibits its effect without limiting the type of arc-proof component constituting the contact point to these single components.
[0064]
That is, the types of arc-resistant components constituting the contacts are CrW alloy (Cr: W = 95: 5, Example 16), CrMo alloy (Cr: Mo = 95: 5, Example 17), CrTi alloy (Cr: Ti = 95: 5, Example 18), CrTa alloy (Cr: Ta = 80: 20, Example 19), CrNb (Cr: Nb = 70: 30, Example 20), TaNb (Ta: Nb = 60: 40) Example 21), even if replaced with WMo (W: Mo = 50: 50, Example 22), the frequency of re-ignition occurrence is 0.8 to 1.2 times (Evaluation C) to 1.2 to Between 1.5 times (Evaluation D), the re-ignition characteristic is almost the same as the standard (Example 2). The cutoff magnification is also between (0.9 and 0.95) times (1.0 to 1.05) times, and is the same as the standard (Example 2), and (Example 2). The re-ignition characteristic was almost equal to or higher than that, and the interruption characteristic was more than the interruption magnification (0.9) times, and preferable results were obtained (Examples 16 to 22).
[0065]
From the above example, (V_L/ V₀) It is preferable to use a contact in which W, Mo, Ti, Ta, and Nb are combined as the arc-proof component in the contact material to which the present invention is applied while the ratio is within the predetermined range.
[0066]
6 (Examples 23 to 25, Comparative Examples 7 to 8)
In Examples 1 to 22 and Comparative Examples 1 to 6, for the contacts in which the average particle diameter of the arc-resistant component contained in the contact material was selected to be 62 to 149 μm, (V_L/ V₀) Although the influence of the ratio on the re-ignition characteristic and the interruption characteristic is shown, the present invention exhibits its effect without being limited to this.
[0067]
That is, when the average particle diameter of the arc resistant component in the contact alloy is 0.05 to 1.0 μm (Example 23), 10 to 62 μm (Example 24), and 44 to 105 μm (Example 25), re-ignition occurs. The frequency indicates a characteristic between 0.1 and 0.8 (Evaluation B) to 1.2 to 1.5 (Evaluation D), and is a re-ignition characteristic almost equivalent to that of the standard (Example 2). is there. The blocking magnification also shows a characteristic between (1.0-1.1) times and (1.15-1.2) times, and shows a blocking characteristic equal to or higher than the standard (Example 2), All are acceptable (Examples 23 to 25).
[0068]
When the average particle diameter of the arc resistant component in the contact alloy is 250 μm or more, the frequency of occurrence of re-ignition is a characteristic between 1.2 to 1.5 times (Evaluation D) and 10 to 100 times (Evaluation Y). The re-ignition characteristic having a very large variation width as compared with the standard (Example 2). The blocking magnification also shows (0.75 to 1.0) times, which is a blocking characteristic significantly lower than the standard (Example 2). Due to the unevenness of the structure due to the mixture of coarse particles, sufficient blocking performance cannot be exhibited. Both are unacceptable (Comparative Example 8).
[0069]
On the other hand, when the average particle diameter of the arc resistant component in the contact alloy is 0.05 μm or less, the frequency of occurrence of reignition shows a characteristic of 0.1 to 0.8 (Evaluation B), which is a standard (Example) 2) Excellent re-ignition characteristics and good, but in order to make the Cr particle diameter equal to 0.05 μm or less, the production cost is high and the supply ability is difficult. Exclude from the preferred range (Comparative Example 7).
[0070]
From the above example, (V_L/ V₀) It is preferable to use a contact having an average particle diameter of an arc resistant component in the contact material applicable to the present invention in the range of 0.05 to 149 μm while keeping the ratio within the predetermined range.
[0071]
7 (Examples 26 to 31, Comparative Examples 9 to 10)
In Examples 1 to 25 and Comparative Examples 1 to 7, (V_L/ V₀) The effect of the ratio on the re-ignition characteristic and the interruption characteristic is shown for the contact having no auxiliary component for improving the welding resistance such as Bi in the contact alloy, but the present invention is not limited to this. Even if Bi or the like is present within a predetermined amount in the contact alloy, the effect is maintained.
[0072]
That is, 75% Cu—Cr (Examples 26 to 27) in which 0.1% and 1.0% Bi were added to the contact alloy was manufactured, and then these (V_L/ V₀) A contact material having a ratio within a predetermined range was selected and the evaluation was performed. When the Bi content in the contact alloy was 0.1% (Example 26) and the Bi content was 1.0% (Example 27), the frequency of re-ignition was 0.1 to 0.8 times. (Evaluation B), 0.8 to 1.2 times (Evaluation C), which is substantially equivalent (Example 27) or more (Example 26) compared to the standard (Example 2). It is a starting characteristic. The welding resistance has been greatly improved, and the smoothing of the contact surface after interruption has contributed. The blocking factor also shows (0.9-0.95) times the characteristics, and shows a blocking characteristic almost equal to or higher than the standard (Example 2), both of which are acceptable (Examples 26-27). .
[0073]
However, when the Bi content in the contact alloy is 2% (Comparative Example 9), the frequency of re-ignition is 10 to 100 (Evaluation Y) and 100 or more (Evaluation Z), which is the standard (Example 2). ), The re-ignition characteristic is greatly reduced and the variation width is increased, which is not preferable. As a result of the selective evaporation of Bi generated at the time of breaking, the contact surface is damaged and the withstand voltage is lowered. As a result, the breaking magnification shows a characteristic of (0.3 to 0.45) times, which is a standard (Example 2). (Comparative Example 9).
[0074]
When the Bi content in the contact alloy was 0.1% (Example 26) and the Bi content was 1.0% (Example 27), the frequency of re-ignition was 0.1 to 0.8 times. (Evaluation B), 0.8 to 1.2 times (Evaluation C), which is substantially equivalent (Example 27) or more (Example 26) compared to the standard (Example 2). It is a starting characteristic. The welding resistance has been greatly improved, and the smoothing of the contact surface after interruption has contributed. The blocking factor also shows (0.9-0.95) times the characteristics, and shows a blocking characteristic almost equal to or higher than the standard (Example 2), both of which are acceptable (Examples 26-27). .
[0075]
Further, the amount of Pb in the contact alloy was set to 0.3% by weight (Example 28), the amount of Sb was set to 0.1% by weight (Example 29), and the amount of Te was set to 5.0% by weight (implementation). Example 30) Also in 75% Cu—Cr alloy containing other welding resistant components such as Se amount of 1.0% by weight (Example 31), the frequency of occurrence of re-ignition is 0.8 to 1.2 times (Evaluation C) and 1.2 to 1.5 times (Evaluation D), showing good re-ignition characteristics, and breaking rate of 0.9 to 0.95 times. Show the characteristics.
[0076]
On the other hand, when the amount of Te in the contact alloy was 8.0% by weight (Comparative Example 10), the frequency of re-ignition was 10 to 100 (Evaluation Y) and 100 or more (Evaluation Z). Compared with (Example 2), the re-ignition characteristic is significantly lowered and the variation width is increased, which is not preferable. As a result of the selective evaporation of Te generated at the time of interruption, the contact surface is damaged and the withstand voltage is lowered. As a result, the interruption magnification shows a characteristic of (0.4 to 0.5) times, which is a standard (Example 2). (Comparative Example 10).
[0077]
From the above example, (V_L/ V₀) When the ratio is within the predetermined range, the auxiliary component in the contact material to which the present invention is applied is a contact in the range of 1% by weight or less for Bi, Pb, Sb, and 5% by weight or less for Te, Se. Is preferably used.
Table 1, Table 2, and Table 3 below summarize the evaluation conditions and evaluation results of the above Examples and Comparative Examples.
[0078]
[Table 1]

[0079]
[Table 2]

[0080]
[Table 3]

[0081]
8 (Modification)
Modification 1: The contact is (V_L/ V₀) An alloy having a conductivity of at least 20% IACS with the ratio within the predetermined range is preferable. When the electrical conductivity is less than 20% IACS, no change is observed in the re-ignition characteristic, but the interruption ratio is 0.6 to 0.8 times, and a reduction in the interruption characteristic is recognized.
[0082]
Modification 2: The current-carrying shaft of the vacuum circuit breaker is (V_L/ V₀) It is preferable to have a conductivity of at least 70% IACS while keeping the ratio within the predetermined range. When the electrical conductivity is less than 70% IACS, no change is observed in the re-ignition characteristic, but the interruption ratio is 0.7 to 0.95 times, and a reduction in the interruption characteristic is recognized.
[0083]
Modification 3: The coil electrode of the vacuum circuit breaker is (V_L/ V₀) It is preferable to have a conductivity of at least 70% IACS while keeping the ratio within the predetermined range. When the electrical conductivity is less than 70% IACS, no change is observed in the re-ignition characteristic, but the interruption ratio is 0.6 to 0.85 times, and the reduction of the interruption characteristic is recognized.
[0084]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a vacuum circuit breaker including a vacuum valve that achieves both re-ignition characteristics and interruption characteristics.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a conventional vacuum valve.
FIG. 2 is a cross-sectional view of another conventional vacuum valve.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 40 ... Electrode, 41 ... Fixed side contact, 50 ... Electrode, 51 ... Movable side contact, 101 ... Insulation container, 102a ... Fixed side cover, 102b ... Movable side cover, 103 ... Vacuum container, 104 ... Fixed contact, 105 ... movable side contact, 106 ... fixed energizing shaft, 107 ... movable energizing shaft, 108 ... bellows, 109 ... arc shield, M ... direction of movement of the energizing shaft.

Claims (1)

真空容器内に貫通される接離可能な一対の通電軸と、一端が通電軸に接合され、接離可能な対向する一対の接点と、必要によりアークシールドを有する真空バルブを備えた真空遮断器において、
前記接点は、導電性成分として０．００５〜０．５重量％のＣｒを固溶した１５〜９０重量％未満のＣｕＣｒ固溶体と、残部が耐弧成分として平均粒子直径０．１〜１５０μｍ未満のＣｒからなるＣｕＣｒ合金であって、常温から１６００℃までの加熱過程で前記接点から放出される放出ガス累積量を（Ｖ_L ）、１６００℃を越え少なくとも２６００℃までの加熱過程で放出される放出ガス累積量を（Ｖ_H ）、常温から少なくとも２６００℃まで加熱する過程で放出される放出ガス累積量を（Ｖ_L ＋Ｖ_H ）＝（Ｖ_O ）として前記接点の評価試験をおこなったとき、前記接点の（Ｖ_L ／Ｖ_O）比率が８０％以下、好ましくは５０％以下（０％を含む）であることを特徴とする真空遮断器。A vacuum circuit breaker having a pair of energizing shafts that can be contacted / separated penetrating into the vacuum vessel, a pair of opposing contacts that are joined to the energizing shaft and capable of contacting / separating, and a vacuum valve having an arc shield if necessary. In
The contact has a CuCr solid solution of 15 to less than 90% by weight in which 0.005 to 0.5% by weight of Cr is dissolved as a conductive component, and the remainder is an average particle diameter of less than 0.1 to 150 μm as an arc resistant component. a CuCr alloy consisting of cr, the released gas accumulation amount emitted from the front SL contacts during heating from room temperature to 1600 ℃ (V _L), is released by the heating process up to at least 2600 ° C. exceed 1600 ° C. the released gas accumulation amount (V _H), released gas accumulation amount (V _L + V _H) which is released in the process of heating from room temperature to at least 2600 ℃ = (V _O) as when subjected to the evaluation test of the contact, A vacuum circuit breaker characterized in that the (V _L / V _O ) ratio of the contact is 80 % or less, preferably 50 % or less (including 0%).

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