JP4421173B2

JP4421173B2 - Vacuum circuit breaker

Info

Publication number: JP4421173B2
Application number: JP2002165890A
Authority: JP
Inventors: 功奥富; 貴史草野; 敦史山本; 淑子南
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2002-06-06
Filing date: 2002-06-06
Publication date: 2010-02-24
Anticipated expiration: 2022-06-06
Also published as: JP2004014293A

Description

【０００１】
【発明の属する技術分野】
この発明は、優れた遮断特性と再点弧特性とを有する接点を備えた真空バルブを用いた真空遮断器に関する。
【０００２】
【従来の技術】
一般に、真空遮断器に於いて、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】
図７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、一対の接点１０４、１０５を対向させて設けると共に、これらを、前記蓋体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、前記一方の接点である固定接点１０４に対して、他方の接点である可動接点１０５を接触または開離出来るようにしてある。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が設けられる。なお図中１０９は、前記各接点１０４、１０５および通電軸１０６、１０７を包囲する如く設けられたシールドである。
【０００４】
上記真空遮断器は、通常両接点１０４、１０５が接触し通電状態となる。この状態からの動作により通電軸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、上記両接点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）、接点の端部或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８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真空バルブである。また接点４１の背面にはコイル電極４０、接点５１の背面にはコイル電極５０をそれぞれ装着することもできる。
【０００７】
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。
【０００８】
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。この為、実用されている多くの接点材料に於いては、不足する性能を相互に補うような２種以上の元素を組合せることによって、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。
【０００９】
さらに強まる要求を充分満足する真空バルブは未だ得られていないのが実情である。
【００１０】
例えば、大電流遮断性を目的とした接点として、Ｃｒを５０重量％（ｗｔ％）程度含有させたＣｕ−Ｃｒ合金（特公昭４５−３５１０１号）が知られている。この合金は、Ｃｒ自体がＣｕと略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。
【００１１】
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たりしているが、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。
【００１２】
【発明が解決しようとする課題】
一般に、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。
【００１３】
しかし、近年では、一層の大電流遮断や一層の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の状態、電流遮断後の接点表面の損傷の状態などによっては、次の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たりしている。
【００１４】
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出来ていないのが現実であり、十分な電流遮断特性が得られていないのが現実である。
【００１５】
そこで、ＣｕＣｒ合金の再点弧特性と遮断特性の安定化には、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、接点表面および内部のガスの量や存在状態などの最適化が重要となっている。しかし上述した近年の適応状況では、これらの最適化を進めているにも拘らず、まだ再点弧発生頻度が高い場合と低い場合が見られている。再点弧特性と遮断特性を兼備した真空バルブの実現は未達成であり、これらを両立させた真空遮断器の開発が期待されている。
【００１６】
この発明の目的は、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用いた真空遮断器を提供するにある。
【００１７】
【課題を解決するための手段】
本発明に係る真空遮断器は、真空容器と、ベローズと、通電軸と、対向する一対の接点とを備えた真空遮断器に於いて、接点は、Ｃｕから成る導電性成分とＣｒ酸化物を被着させたＣｒ粉を原料としたＣｒから成る耐弧性成分とを含有したＣｕ−Ｃｒ系接点から成り、０．１〜１５０μｍの平均粒子直径を持つＣｒ粒子と、Ｃｕマトリックス中に固溶させたＣｒと、Ｃｕマトリックス中に析出させたＣｒと、Ｃｒ酸化物、Ｃｒ窒化物、Ｃｒ炭化物の少なくとも１つを含む酸に融解しない物質中のＣｒ成分である酸非溶解性Ｃｒ成分とから成るＣｒの総量が、接点中で１５〜９０重量％を占め、酸非溶解性Ｃｒ成分が３０ｐｐｍ〜３５００ｐｐｍであり、Ｃｕマトリックス中に固溶させたＣｒの量が０．００５〜０．５重量％であることを特徴とする。
【００１８】
このような構成により、再点弧特性と遮断特性とを両立させることができる。
【００１９】
すなわち、まず、使用するＣｒ粒子（ａ）については、０．１〜１５０μｍの範囲のＣｒ粒子が、好ましくは少なくとも７５容積％を占める時、安定した再点弧特性を発揮する。接点中のＣｒ総量を１５〜９０重量％の範囲に制御したとしても、粒子径が０．１μｍ未満では、Ｃｕ−Ｃｒ合金中のＣｒ粒子の分布は、十分には分散出来ず凝集部分が存在すると共に、表面吸着ガスの管理が十分に行えず、接点製造後のガス量にバラツキが見られ、いずれも再点弧発生を増長させている。
【００２０】
使用するＣｒ粒子の直径が１５０μｍを越すと、耐溶着性特性や接触抵抗特性にバラツキが見られる。仕上げ加工した接点表面には、Ｃｒ粒子とＣｕ相界面に引っかき状の傷を残し、平滑で均一な状態が得難く再点弧発生に大きなバラツキを示す。その為、本発明の効果を発揮させるのに使用するＣｒの粒子直径は、０．１〜１５０μｍの範囲であることが好ましい。
【００２１】
また、０．１〜１５０μｍの平均粒子直径を持つＣｒ粒子（ａ）と、Ｃｕマトリックス中に固溶させたＣｒ（ｂ）と、Ｃｕマトリックス中に析出させたＣｒ（ｃ）と、酸非溶解性Ｃｒ成分（ｄ）とから成るＣｒの総量（ａ＋ｂ＋ｃ＋ｄ）は、接点中で１５〜９０重量％を占めることが好ましい。
【００２２】
Ｃｒ総量（ａ＋ｂ＋ｃ＋ｄ）が１５重量％未満の接点では、電流遮断時に耐アーク性が劣り、遮断後の接点の表面損傷が著しく、再点弧特性の低下を招き好ましくない。一方、Ｃｒ総量が９０重量％を越えると定格電流の開閉および大電流の遮断によって、接点部もしくは遮断器の温度上昇特性、接触抵抗特性の低下を招き好ましくない。
【００２３】
また、酸非溶解性Ｃｒ成分（ｄ）の量は、３０ｐｐｍ〜３５００ｐｐｍであることが好ましい。
【００２４】
酸非溶解性Ｃｒ成分（ｄ）の量が、３５００ｐｐｍを越えて過大に存在する場合には、再点弧発生頻度が大となる傾向を示すのみならず、遮断器では遮断毎に接点に注入されるエネルギーの大きさが大幅に相違する為、再点弧発生状況は遮断毎に相違し（バラツキとして現れ）好ましくない。
【００２５】
一方酸非溶解性Ｃｒ成分（ｄ）の量が３０ｐｐｍ未満の場合には、低い再点弧発生頻度を発揮すると共に、遮断特性にも好影響を与えている。しかし、酸非溶解性Ｃｒ成分（ｄ）の量を３０ｐｐｍ未満とする為には、原料の必要以上の吟味や、特に加熱処理時の雰囲気の制御を要するなど、繁雑な製造過程と高度な製造技術を要し、接点素材の高コスト化を招き工業的には好ましくない。
【００２６】
そこで本発明で使用する接点中の酸非溶解性Ｃｒ成分（ｄ）は、３０〜３５００ｐｐｍの範囲が得策である。
【００２７】
なお、酸非溶解性Ｃｒ成分（ｄ）を、アルカリ溶液にも非溶解性のものとし、その量を３５００ｐｐｍ以下に制御することによって、一層低い再点弧発生頻度を発揮する。
【００２８】
また、Ｃｕマトリックス中に固溶させたＣｒの量（ｂ）は、０．００５〜０．５重量％とすることが好ましい。
【００２９】
すなわち、たとえ前記Ｃｕ−Ｃｒ合金中のＣｒ総量を前記接点中で１５〜９０重量％とし、合金中の酸非溶解性Ｃｒ成分（ｄ）を、３０ｐｐｍ〜３５００ｐｐｍ以内に制御したとしても、Ｃｕマトリックス中に固溶しているＣｒの量（ｂ）が、０．５重量％を越えると、接点の製造技術上経済性の面で問題であると共に、接点の導電率を著しく低下させ、接点部温度もしくは遮断器端子部温度の上昇を招き、その結果遮断特性の維持に好ましくない。
【００３０】
一方、Ｃｕマトリックス中に固溶しているＣｒの量（ｂ）を０．００５％未満とすると、接点部もしくは遮断器端子部の温度上昇特性は向上するが、工業的にも経済的にも得策でない。
【００３１】
【発明の実施の形態】
以下、本発明の実施形態について詳細に説明する。
【００３２】
研究によれば、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気体状成分や固体状成分が電極空間に放出される。このうち気体状成分が電極間に所定時間以上停滞していると、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するには、接点面から放出される気体状成分の絶対量をあらかじめ極少にしておくことや、放出された気体状成分を速やかに電極間以外に拡散除去することも重要である。
【００３３】
すなわち、接点の表面或いは接点内部に存在する物質（上述の気体状成分や固体状成分）内で、アーク熱によって簡単に分解あるいは除去される様な物質の場合には、遮断前の段階（アークによって接点が昇温して行く前）や昇温過程の極く初期の段階に電極空間に移動し、再点弧発生の直接的原因となる確率は低いことが観察された。
【００３４】
逆に、簡単に分解あるいは除去されない物質の場合には、遮断完了しても分解あるいは除去が進行し電極空間に移動し、再点弧発生の重要な一因となることが観察された。
【００３５】
前記した物質が分解される過程で生成されるガス（気体）の場合では、質量数の大きい成分ほど拡散速度が遅く電極空間に残存し易く、真空度の回復が遅れる傾向にあり、その結果絶縁破壊を誘発する。
【００３６】
ここで、接点の表面或いは接点内部に存在する物質には、アーク熱やジュール熱で簡単に排除可能の物質と、簡単には排除不可能の物質の２種類の存在が考えられる。この内で、特に後者の物質の取扱いが再点弧に対して重要となる。すなわち、電流を遮断する前の段階で（或いは接点が昇温して行く途中の極く初期の段階で）、簡単に分解あるいは電極空間に放出・除去出来ない物質を、低減化することが重要となる。その為には、簡単に分解あるいは除去出来ない物質がどの程度の量存在するかを、実際の電流を遮断することなくどう定量化するかも重要となる。
【００３７】
接点の総てを完全に蒸気状態にまで加熱すれば、その時に放出される表面ガス量や内蔵ガス量を総て捕捉することが出来るが、接点の総てを完全に蒸気状態にまで加熱することは不可能であって、実際には融解中に分解しない物質が存在するので、表面或いは接点内部に存在する物質の総量を捕捉することは出来ないのが実情である。
【００３８】
ＣｕＣｒ合金を塩酸、硝酸などの酸類及び必要により塩化ナトリウム、塩化カリウムなどのアルカリ類によって溶解すると、酸やアルカリに溶解して除去される成分と、これとは別に酸やアルカリに溶解しない非溶解物が残存する。
【００３９】
前者の酸（アルカリ）に溶解し除去可能の成分は、アーク熱を受けた時点で接点表面へ拡散し易く、除去され易い成分に相当する。
【００４０】
これに対して、後者の酸（アルカリ）に非溶解で除去不可能の成分は、Ｃｒ酸化物やＣｒ窒化物やＣｒ炭化物として接点表面部や接点内部に固形体として存在し、これらは簡単には分解あるいは除去され難い物質に相当し、再点弧抑制に対して重要な意味を持つ。
【００４１】
前記固形体のうち接点表面部分に存在する酸（アルカリ）非溶解物は、アークを受けた時、分解して瞬間的に多量のガスを放出したり、分解生成物を放出したりして、これが再点弧発生の一因となる。一方の接点内部に存在する酸（アルカリ）非溶解物も、アークによって分解して同様に多量のガスを放出したり、分解生成物を放出したりして、同様に再点弧発生の一因となる。接点表面への拡散が遅れる為、遮断後或る時間経過後に見られる再点弧の一因となる。
【００４２】
（実験１）：発明者らの実験によれば、極微少の酸非溶解性Ｃｒ（前述の様にアルカリ性溶液にも非溶解性の物質も含まれる）を接点中に存在させる一つの手段として、有機溶媒中に懸濁させたサブミクロン級のＣｒ酸化物を被着させたＣｒ粉を原料として、Ｃｒスケルトンを製造し、このＣｒスケルトンの空隙中にＣｕを溶浸させる溶浸法によって、極く微量で微細Ｃｒ酸化物を内部に持つＣｕＣｒ合金を製造した。有機溶媒中に懸濁させるＣｒ酸化物の量を調整することによって、ＣｕＣｒ合金中の微細Ｃｒ酸化物の量を調製することは容易である。
【００４３】
同じく他の手段として、有機溶媒中に懸濁させたサブミクロン級のＣｒ酸化物を被着させたＣｒ粉とＣｕ粉とを固相焼結してＣｕＣｒ合金を製造した。
【００４４】
いずれの製造法によって得たＣｕＣｒ合金でも、Ｃｒ酸化物の量が多量の場合には再点弧の発生頻度が大となるのに対して、Ｃｒ酸化物の量が少量の場合には再点弧の発生頻度が極めて少ない傾向にある。この酸非溶解物を分析すると、その中には特に酸非溶解性Ｃｒ化合物（ｄ）の存在が確認される。
【００４５】
（実験２）：発明者らの他の観察によれば、接点材料中には、極く微細な析出物が存在する場合と、析出物の無い場合とが見られる。
【００４６】
実際の真空遮断器に於いて、再点弧発生頻度の高い真空バルブに搭載した接点を更に微視的に観察すると、極く微細な析出物、介在物（いずれも酸に非溶解）が確認され、この場合の酸に非溶解の物質中にはＣｒ成分が一定量以上に存在していることを確認した。これに対して、再点弧発生頻度の少ない真空バルブに搭載した接点を更に微視的に観察すると、微細析出物、介在物中（いずれも酸に非溶解）にはＣｒ成分が少ない傾向にあった。
【００４７】
従ってこの実験から、酸非溶解性物質の存在とその中のＣｒ成分（ｄ）の量が再点弧特性と深く関わっていることが示唆される。
【００４８】
真空バルブの再点弧特性、遮断特性の安定化には、一般的には接点材料の組成、成分量の変動、ガス量、組織形態（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、および接点の表面形態に強く依存するが、特に再点弧特性のより一層の安定化には、上記に加えてＣｕＣｒ合金を酸溶液によって溶解した後に、溶解せずに溶液中に残存している酸非溶解性Ｃｒ成分が深く関与する。
【００４９】
以下に、本発明を実施例と比較例とで詳細に説明する。評価条件と評価結果を図１〜６に示す。
【００５０】
（１）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測定した。尚、結果は再点弧頻度を下記の様に表示した。
【００５１】
すなわち、実施例５の発生数を1とした時の倍率が、０．１未満を評価（Ａ）、０．１〜０．８を評価（Ｂ）、０．８〜１．２を評価（Ｃ）、１．２〜１．５を評価（Ｄ）、１．５〜１０を評価（Ｘ）、１０〜１００を評価（Ｙ）、１００以上を評価（Ｚ）とした。
【００５２】
なお、評価（Ａ）〜（Ｄ）を「合格」、評価（Ｘ）〜（Ｚ）を「不良」の目安とした。
【００５３】
（２）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本につき評価した。尚、数値は実施例５の値を１．０とした時の比較値を、バラツキ幅を持って示した。
【００５４】
（３）遮断テスト用実験バルブの組立ての概要
遮断テスト用実験バルブの組立ての概要を示す。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。上記用意した各部材を被接合物間（セラミックス製絶縁容器の瑞面と封着金具）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緑容器との気密封着工程に供した。
【００５５】
（４）接点合金中の酸非溶解性Ｃｒ成分の定量
接点素材中に含有される合金中の酸非溶解性Ｃｒの定量は、例えば下記の方法で実施した。ＣｕＣｒ接点に硝酸を加えた後、ろ液（Ｃｕ相）と沈殿物とに分別する。沈殿物についてアルカリ溶解、酸溶解によって、ろ液（Ｃｒ相）と沈殿物（酸非溶解物質）とに分別し、それぞれをＩＣＰ−ＡＥＳなどの分析装置で定量化した。使用する酸は硝酸、塩酸、弗酸など、アルカリは塩化ナトリウム、塩化カリウムなどが利用可能である。
【００５６】
（実施例１〜３、比較例１）
本発明では、再点弧特性、遮断特性と、接点素材中に含有される酸非溶解性Ｃｒ成分との関係が重要である。
【００５７】
酸非溶解性Ｃｒ成分（ｄ）の量は以下の条件で定量化した。
【００５８】
代表接点としてＣｕ−２５％Ｃｒ合金を選択し、この接点素材から約１０ｇｒ．を採取した。１００℃で３Ｎ（規定）の硝酸中で約１０分間加熱分解の後、これをろ過し、ろ液Ａ（Ｃｕ²⁺）と沈殿物Ａとに分別する。ここでろ液Ａ（Ｃｕ²⁺）はＣｕ相に相当する。このろ液Ａ（Ｃｕ²⁺）中に存在するＣｒ量をＩＣＰ−ＡＥＳなどで定量することによって、前記Ｃｕマトリックス中に固溶させたＣｒ（ｂ）を知る。
【００５９】
次いで、この沈殿物Ａを６Ｎの塩酸によって加熱分解（１００℃で３０分間）することによって、ろ液Ｂ（Ｃｒ³⁺）と沈殿物Ｂとに分別する。ここでろ液Ｂ（Ｃｒ³⁺）は、前記原料として使用している０．１〜１５０μｍのＣｒ粒子（ａ）と、前記Ｃｕマトリックス中に析出させたＣｒ（ｃ）との合計（ａ＋ｃ）に相当する。
【００６０】
次いで、沈殿物Ｂをアルカリ溶液中での溶解、更には酸溶液中での溶解を実施し、両溶液に非溶解の物質を回収し、ＩＣＰ−ＡＥＳなどによる定量分析によって、酸非溶解性Ｃｒ成分（ｄ）の量を知る（正確には酸・アルカリ非溶解性Ｃｒ）。なお、上記した（ｂ）＋（ａ＋ｃ）＋（ｄ）の合計量は、代表接点として選択したＣｕＣｒ合金中のＣｒ量である２５重量％とほぼ一致した。
【００６１】
例えば、処理雰囲気の選択とその質、処理温度、時間、冷却条件、原料粉（Ｃｕ、Ｃｒ）の調節などによって、接点素材中の酸非溶解性Ｃｒ成分（ｄ）の量を、３０〜８５００ｐｐｍの範囲にある素材を製造し試験に供した（実施例１〜３、比較例１）。
【００６２】
すなわち、評価用代表接点としてＣｕ粉、Ｃｒ粉の成型体に対して、１０６０℃の加熱処理を与えたＣｕ−２５％Ｃｒ合金を選定し、これらの接点合金に対して、前記した方法で接点素材中に含有される酸非溶解性Ｃｒ成分（ｄ）の量を、３０〜１５０ｐｐｍ（実施例１）、４００〜２８００ｐｐｍ（実施例２）、２０００〜３５００ｐｐｍ（実施例３）、５５００〜８５００ｐｐｍ（比較例１）を製造した。
【００６３】
遮断特性の評価は、各接点について遮断電流値を測定し、後述する実施例５の遮断電流値を１．０とした時の倍率で示した。
【００６４】
再点弧特性の評価は、各接点について２４ｋｖ×５００Ａの回路を２０００回遮断した時の再点弧発生頻度について、実施例５の発生数を1とした時の倍率が、０．１倍未満を評価（Ａ）、０．１〜０．８倍を評価（Ｂ）、０．８〜１．２倍を評価（Ｃ）、１．２〜１．５倍を評価（Ｄ）として分けこれらを「合格」と判断し、１．５〜１０倍を評価（Ｘ）、１０〜１００倍を評価（Ｙ）、１００倍以上を評価（Ｚ）として分けこれらを「不良」と判断した。
【００６５】
まず、再点弧特性（再点弧発生の頻度）は、接点素材中に含有される酸非溶解性Ｃｒ成分（ｄ）の量が、３０〜１５０ｐｐｍ（実施例１）では、後述する実施例５の発生頻度と比較して０．１倍未満を示し、極めて良好な再点弧特性（評価Ａ）を発揮した。
【００６６】
酸非溶解性Ｃｒ成分（ｄ）の量が、４００〜２８００ｐｐｍ（実施例２）では、後述する実施例５の発生頻度と比較して０．８および１．５倍を示し、良好な再点弧特性（評価Ｃ〜Ｄ）を発揮した。
【００６７】
酸非溶解性Ｃｒ成分（ｄ）の量が、２０００〜３５００ｐｐｍ（実施例３）では、後述する実施例５の発生頻度と比較して１．２〜１．５倍を示し、良好な再点弧特性（評価Ｄ）を発揮した。
【００６８】
これに対して、酸非溶解性Ｃｒ成分（ｄ）の量が、前記実施例１〜３よリ多い５５００〜８５００ｐｐｍ（比較例１）では、後述する実施例５の発生頻度と比較して１００倍以上に増大した再点弧発生頻度（評価Ｚ）を示した。
【００６９】
酸非溶解性Ｃｒ成分（ｄ）の量が、３５００ｐｐｍ以下の場合では、好ましい再点弧特性が見られるのに対して、酸非溶解性Ｃｒ成分（ｄ）の量が実施例３より多い５５００〜８５００ｐｐｍ（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、１００倍以上の再点弧発生頻度（評価Ｚ）を示し、再点弧特性は著しく低下した。
【００７０】
明らかに接点素材中に含有される酸非溶解性Ｃｒ成分（ｄ）の量が所定量以下の時に良好な再点弧特性を発揮する。
【００７１】
次いで、遮断特性の評価結果は、接点素材中に含有される酸非溶解性Ｃｒ成分（ｄ）の量が、３０〜１５０ｐｐｍ（実施例１）の時の遮断倍率は、（１．０〜１．１）倍を示し、酸非溶解性Ｃｒ成分（ｄ）の量が、４００〜２８００ｐｐｍ（実施例２）の時の遮断倍率も、（１．０〜１．１）倍を示し、酸非溶解性Ｃｒ成分（ｄ）の量が、２０００〜３５００ｐｐｍ（実施例３）の時の遮断倍率も、（１．０〜１．１）倍を示し、いずれも標準とする実施例５とほぼ同程度若しくはそれ以上の好ましい遮断特性にある。
【００７２】
これに対して、酸非溶解性Ｃｒ成分（ｄ）の量が、前記実施例１〜３より多い５５００〜８５００ｐｐｍ（比較例１）の時の遮断倍率は、（０．８〜０．９５）倍に低下した。
【００７３】
明らかに接点素材中の酸非溶解性Ｃｒ成分（ｄ）の量が増加する場合に遮断特性は低下する傾向にある。
【００７４】
従って、接点素材中に含有される酸非溶解性Ｃｒ成分（ｄ）の量は、３５００ｐｐｍ以下とすることが好ましく、下限は経済性によって決定され例えば３０ｐｐｍ程度である。
【００７５】
（実施例４〜６、比較例２〜３）
前記実施例１〜３、比較例１では、接点素材中に含有される酸非溶解性Ｃｒ成分（ｄ）の量の再点弧特性、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Ｃｕ−２５％Ｃｒ接点について示したが、本発明技術はこれに限ることなく上記Ｃｕ−２５％Ｃｒ接点以外でもその効果を発揮する。すなわち接点合金中のＣｕ量を５％とした５％Ｃｕ−Ｃｒ（比較例２）、１０％Ｃｕ−Ｃｒ（実施例４）、５０％Ｃｕ−Ｃｒ（実施例５）、８５％Ｃｕ−Ｃｒ（実施例６）、９８％Ｃｕ−Ｃｒ（比較例３）を製造した上で、これらの接点材料の中から酸非溶解性Ｃｒ成分（ｄ）の量が１００〜６５０ｐｐｍの範囲内にある接点材料を選択した上で、前記評価を実施した。
【００７６】
再点弧特性（再点弧発生の頻度）は、接点中のＣｕ量を５％とした５％Ｃｕ−Ｃｒ（比較例２）、１０％Ｃｕ−Ｃｒ（実施例４）の時には、標準とする５０％Ｃｕ−Ｃｒ（実施例５）と同等の０．１〜０．８倍および０．８〜１．２倍（評価Ｂ〜Ｃ）を示し良好な再点弧特性を発揮している。また、８５％Ｃｕ−Ｃｒ（実施例６）においても０．８〜１．２倍および１．２〜１．５倍（評価Ｃ〜Ｄ）を示し合格の範囲内である。
【００７７】
これに対して、接点中のＣｕ量が実施例６の８５％より多い９８％Ｃｕ−Ｃｒ（比較例３）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接点の耐電圧特性の低下によって、１．５〜１０倍および１００倍以上（評価Ｘ〜Ｚ）を示し、再点弧特性は大きなバラツキを示すと共に、著しく低下し好ましくない。
【００７８】
以上により、本発明技術を適応する接点素材中に含有されるＣｕ量は８５％以下が好ましい。
【００７９】
遮断特性は、接点中のＣｕ量が１０％Ｃｕ−Ｃｒ（実施例４）の遮断倍率は（０．９〜０．９５）倍、８５％Ｃｕ−Ｃｒ（実施例６）の遮断倍率は（１．０〜１．１）倍を示し、標準とする実施例５とほぼ同程度の遮断特性にある。
【００８０】
接点中のＣｕ量が実施例４の１０％より少ない５％Ｃｕ−Ｃｒ（比較例２）の遮断倍率は、接点材料自体の低導電率化によって（０．５５〜０．７）倍を示し、大幅な低下を示している。
【００８１】
これに対して、接点中のＣｕ量が（実施例６）の８５％より多い９８％Ｃｕ−Ｃｒ（比較例３）の遮断倍率は（０．７〜１．１５）倍を示し、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した。
【００８２】
以上により、本発明技術を適応する接点素材中に含有されるＣｕ量は、１０〜８５％の範囲、換言すればＣｒ量（ａ＋ｂ＋ｃ＋ｄ）は１５〜９０％の範囲の接点を使用するのが好ましい。
【００８３】
（実施例７〜８）
前記実施例１〜６では、接点素材中の導電性分としてＣｕを選択した場合の例について示したが、本発明技術はこれに限ることなくＣｕ以外でもその効果を発揮する。
【００８４】
すなわち接点素材中の導電性成分をＡｇとした４０％Ａｇ−Ｃｒ（実施例７）であっても、再点弧発生の頻度は１．２〜１．５倍の良好な再点弧特性（評価Ｄ）を示し、導電性成分をＡｇ＝５４％、Ｃｕ＝２１％とした７５％（Ａｇ＋Ｃｕ）−Ｃｒ（実施例８）であっても、再点弧発生の頻度は０．８〜１．２倍および１．２〜１．５倍の良好な再点弧特性（評価Ｃ〜Ｄ）を示し、いずれも合格の範囲である。
【００８５】
遮断特性は、標準とする実施例５の遮断特性を１．０とした場合の、（０．９）倍（実施例７）、（０．９５〜１．０５）倍（実施例８）を示しいずれも合格の範囲である。
【００８６】
以上のように、接点素材中の導電性分、すなわちＣｕマトリックスの一部または総てをＡｇで置換しても、Ｃｕマトリックスの場合と同等の特性を発揮する。
【００８７】
（実施例９〜１１、比較例４〜５）
前記実施例１〜８、比較例１〜３では、再点弧特性、遮断特性に及ぼす接点合金中の酸非溶解性Ｃｒ成分（ｄ）の量の影響を、接点合金中のＣｕマトリックス中に固溶させたＣｒ（ｂ）の量を０．０２％（重量％）とした接点について示したが、本発明技術でのＣｕマトリックス中に固溶させたＣｒ（ｂ）の量は０．０２％に限ることなくその効果を発揮する。
【００８８】
すなわち接点合金中のＣｕマトリックス中に固溶させたＣｒ（ｂ）の量を、０．００５％、０．１％、０．５％とした７５％Ｃｕ−Ｃｒ（実施例９〜１１）、および０．００５％未満とした７５％Ｃｕ−Ｃｒ（比較例４）、０．５％より多い量とした７５％Ｃｕ−Ｃｒ（比較例５）の各合金を、主として接点製造時の冷却過程での冷却速度を調整しながら製造した上で、これらの接点材料中の酸非溶解性のＣｒ成分の量（ｄ）が１００〜６５０ｐｐｍの範囲内にある接点材料を選択し、前記評価を実施した。
【００８９】
再点弧特性（再点弧発生の頻度）は、導電成分中に固溶する耐弧成分の量すなわちＣｕマトリックス中に固溶させたＣｒ（ｂ）の量が実施例５の０．０２％より少ない０．００５％の場合（実施例９）では、実施例５より優れた０．１倍未満および０．１〜０．８倍（評価Ａ〜Ｂ）の再点弧特性を示した。
【００９０】
更にＣｕマトリックス中に固溶させたＣｒの量（ｂ）が０．１％の場合（実施例１０）、０．５％の場合（実施例１１）では、いずれも０．８〜１．２倍（評価Ｃ）を示し、好ましい再点弧特性を示した。
【００９１】
これに対して、Ｃｕマトリックス中に固溶するＣｒ（ｂ）の量が、０．５％より多い場合（比較例５）では、０．８〜１．２倍および１０〜１００倍（評価Ｃ〜Ｙ）を示し、バラツキ幅の大きい再点弧特性を示し好ましくない。
【００９２】
一方、Ｃｕマトリックス中に固溶するＣｒ（ｂ）の量を実施例９の０．００５％より少なくした比較例４では、前記した実施例９と同等の０．１未満および０．１〜０．８（評価Ａ〜Ｂ）を示し良好であったが、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。
【００９３】
遮断特性については、Ｃｕマトリックス中に固溶するＣｒ（ｂ）の量が実施例５の０．０２％より少ない０．００５％（実施例９）の遮断倍率は（１．０〜１．１）倍、０．１％（実施例１０）の遮断倍率は（０．９〜１．０）倍、０．５％（実施例１１）の遮断倍率は（０．９〜０．９５）倍を示し、いずれも良好の範囲である。
【００９４】
これに対して、Ｃｕマトリックス中に固溶するＣｒ（ｂ）の量を実施例１１の０．５％より多くした場合（比較例５）では、（０．６〜０．７５）倍を示し大幅に劣化し好ましくない。
【００９５】
以上から、本発明を実施する上では、接点合金中のＣｕマトリックス中に固溶させたＣｒの量（ｂ）は、０．００５〜０．５％（重量％）の範囲にある接点合金を選択することが好ましい。
【００９６】
（実施例１２〜１７、比較例６）
前記実施例１〜１１、比較例１〜５では、接点中の耐弧成分の種類としてＣｒを選択したＣｕＣｒ接点について再点弧特性、遮断特性に及ぼす効果を示したが、本発明技術はこれに限ることなくＣｕ−Ｃｒ接点以外でもその効果を発揮する。
【００９７】
すなわち、接点合金中のＣｕマトリックス中に固溶させたＣｒ（ｂ）の量を、０．０２％、接点素材中に含有される酸非溶解性Ｃｒ成分（ｄ）の量を、１００〜６５０ｐｐｍ、残部をＣｕとした上で、接点素材中に存在する耐弧性成分（重量比）の種類を、ＣｒＷ（Ｃｒ：Ｗ＝９：１）、ＣｒＷ（Ｃｒ：Ｗ＝５：５）で置換しても、標準としている実施例５と同等若しくはそれ以上の好ましい再点弧特性（評価Ａ〜Ｂ）、（評価Ｂ〜Ｃ）を示した（実施例１２〜１３）。
【００９８】
しかし、ＣｒとＷとの比率がＣｒ：Ｗ＝２：８の場合の様にＣｒ成分が少ない時には、再点弧発生頻度が０．８〜１．２倍（評価Ｃ）の好ましい値から、１．５〜１０倍（評価Ｘ）の好ましくない値まで大きなバラツキを示した（比較例６）。
【００９９】
ＣｒＭｏ（Ｃｒ：Ｍｏ＝９：１）、ＣｒＴｉ（Ｃｒ：Ｔｉ＝９：１）、ＣｒＴａ（Ｃｒ：Ｔａ＝９：１）、ＣｒＮｂ（Ｃｒ：Ｎｂ＝９：１）で置換しても、標準としている実施例５と同等以上の再点弧特性（評価Ａ〜Ｂ）を示した（実施例１４〜１７）。
【０１００】
接点素材中に存在する耐弧性成分（重量比）の種類をＣｒＷ（Ｃｒ：Ｗ＝９：１）、ＣｒＷ（Ｃｒ：Ｗ＝５：５）で置換しても、標準としている（実施例５）と同等以上の好ましい遮断特性（０．９〜１．１）倍を示した（実施例１２〜１３）。
【０１０１】
しかし、ＣｒとＷとの比率が（Ｃｒ：Ｗ＝２：８）の場合の様にＣｒ成分が少ない時には、多量の熱電子放出の影響で遮断電流値は（０．４〜０．５５）倍の好ましくない値と大きなバラツキを示した（比較例６）。
【０１０２】
ＣｒＭｏ（Ｃｒ：Ｍｏ＝９：１）、ＣｒＴｉ（Ｃｒ：Ｔｉ＝９．：１）、ＣｒＴａ（Ｃｒ：Ｔａ＝９：１）、ＣｒＮｂ（Ｃｒ：Ｎｂ＝９：１）で置換しても、標準としている実施例５とほぼ同等の遮断特性（０．９５〜１．１５）倍を示した（実施例１４〜１７）。
【０１０３】
以上から、前記接点に於ける耐弧性成分は、Ｃｒの一部を５０％以下のＷ、Ｍｏ、Ｔｉ、Ｔａ、Ｎｂの１つで置換しても同等の効果を得る。
【０１０４】
すなわち、Ｃｒの一部をＷ、Ｍｏ、Ｔｉ、Ｔａ、Ｎｂの１つで置換することによって、Ｃｕ−Ｃｒ接点素材全体の機械的強度を大とし、Ｃｒ粒子の脱落が引き金となって引き起こされる再点弧発生を軽減化することができる。
【０１０５】
＜実施例１５＞
なお、上記実施例１〜１４では、接点合金中の導電成分（Ｃｕマトリックス）中に固溶させた耐弧成分の種類としてＣｒを選択したが、本発明技術はこれに限ることなく、耐弧成分の種類がＴｉであってもその効果を発揮する。すなわち接点合金中の導電成分中に固溶する耐弧成分をＴｉとし、その量を、０．０２とした７５％Ｃｕ−Ｃｒ（実施例１５）を製造し、前記評価を実施した。
【０１０６】
再点弧発生の頻度は、（実施例５）と同等以上の０．１倍未満および０．１〜０．８倍（評価Ａ〜Ｂ）を示し、良好な再点弧特性を発揮している。
【０１０７】
遮断特性も、遮断倍率（０．９５〜１．１５）倍を示し、実施例５と同等の範囲である。
【０１０８】
（実施例１８〜１９、比較例７〜８）
前記実施例１〜１７、比較例１〜６では、Ｃｕマトリックス中の耐弧成分（Ｃｒ）の粒子直径を４０〜８０μｍとした場合について再点弧特性、遮断特性に及ぼす効果を示したが、本発明技術ではこれに限ることなくその効果を発揮する。
【０１０９】
すなわち、接点合金中のＣｕマトリックス中に固溶させたＣｒ（ｂ）の量を、０．０２％、接点素材中に含有される酸非溶解性Ｃｒ成分（ｄ）の量を、１００〜６５０ｐｐｍ、残部をＣｕとした上で、耐弧成分（Ｃｒ）の粒子直径を０．１〜２５μｍ、７０〜１５０μｍとしても、標準としている実施例５とほぼ同等の好ましい再点弧特性（評価Ｂ〜Ｃ）、（評価Ｃ〜Ｄ）を示した（実施例１８〜１９）。遮断特性も（０．９５〜１．０５）倍および（１．０〜１．１）倍を示し、標準としている実施例５の遮断特性１．０と比較してほぼ同等の好ましい値である（実施例１８〜１９）。
【０１１０】
しかし、Ｃｕマトリックス中の耐弧成分（Ｃｒ）の粒子直径を、０．１μｍ未満とした場合には、標準としている実施例５以上の好ましい再点弧特性（評価Ａ〜Ｂ）を示しているにもかかわらず、Ｃｕマトリックス中の耐弧成分（Ｃｒ）の粒子直径を０．１μｍ未満とする為の生産性の低さなど高い製造コストによって本発明外とする（比較例７）。
【０１１１】
平均粒子直径が１５０μｍを越える接点では、実施例５と比較した再点弧発生の頻度は、１．５〜１０倍および１００倍以上（評価Ｘ〜Ｚ）を示し、大きなバラツキ幅を示す。また、遮断倍率も（０．７５倍〜１．０）倍を示し、やはり大きなバラツキ幅を示し好ましくない（比較例８）。
【０１１２】
以上から、前記接点中の耐弧性成分は、０．１〜１５０μｍの平均粒子直径を持つことが好ましい。
【０１１３】
（実施例２０〜２５、比較例９）
前記実施例１〜１９、比較例１〜８では、接点合金中にＢｉなど溶着を軽減させる為の補助成分を含有していないＣｕＣｒ接点について、耐溶着性を改善する為の補助成分を含まない接点ついて、再点弧特性、遮断特性に及ぼす影響を示したが、本発明技術はこれに限ることなく上記した接点合金中にＢｉなどの補助成分が所定量以内存在してもその効果を維持する。
【０１１４】
すなわち接点合金中にＢｉを０．１％、１．０％添加した７５％Ｃｕ−Ｃｒ合金（実施例２０〜２１）、同じくＢｉを２．０％添加した７５％Ｃｕ−Ｃｒ合金（比較例９）、Ｐｂを０．３％添加した７５％Ｃｕ−Ｃｒ合金（実施例２２）、Ｓｂを０．１％添加した７５％Ｃｕ−Ｃｒ合金（実施例２３）、Ｔeを３．０％添加した７５％Ｃｕ−Ｃｒ合金（実施例２４）、Ｓeを１．０％添加した７５％Ｃｕ−Ｃｒ合金（実施例２５）を製造した上で前記評価を実施した。
【０１１５】
再点弧発生の頻度は、Ｂｉ量を０．１％とした実施例２０およびＢｉ量を１．０％とした実施例２１では、０．１〜０．８倍および０．８〜１．２倍（評価Ｂ〜Ｃ）、０．８〜１．２倍および１．２〜１．５倍（評価Ｃ〜Ｄ）を示し、実施例５とほぼ同等かそれ以上の好ましい再点弧特性を示した。
【０１１６】
しかしＢｉ量を２．０％とした比較例９では、１０〜１００倍および１００倍以上（評価Ｙ〜Ｚ）を示し、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。
【０１１７】
なお、Ｂｉの存在によって実施例５よりも大幅に耐溶着性が改善される。
【０１１８】
遮断特性は、Ｂｉ量を０．１％とした実施例２０およびＢｉ量を１．０％とした実施例２１では、（０．９５）倍および（０．９）倍を示し、いずれも実施例５とほぼ同等の特性を示した。
【０１１９】
これに対してＢｉ量を２．０％とした比較例９では、遮断時に生ずるＢｉの選択的蒸発によって、接点表面が荒損し耐電圧性の低下を招く結果、遮断倍率は（０．３〜０．４５）倍を示し好ましくない（比較例９）。
【０１２０】
Ｐｂ量を０．３％とした実施例２２、Ｓｂ量を０．１％とした実施例２３、Ｔe量を３．０％とした実施例２４、Ｓe量を１．０％とした実施例２５などの他の耐溶着性成分を含有する７５％Ｃｕ−Ｃｒ合金に於いても、０．８〜１．２倍および１．２〜１．５倍（評価Ｃ〜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）倍、あるいは（０．９〜０．９５）倍を示し良好な遮断特性を示す（実施例２２〜２５）。
【０１２１】
以上のように、Ｃｕ相中での１％以下の補助成分Ｂｉ、Ｐｂ、Ｓｂの存在は電流遮断後の接点表面の過度の荒れを抑制し、耐電圧特性を安定化させる結果、再点弧発生頻度を一層低くするのに貢献する。また、Ｃｕ相中での補助成分Ｔe、Ｓeの存在は、５％以下なら電流遮断後の接点表面荒れを安定化させ再点弧発生レベルを低くする。しかし、１％を越す補助成分Ｂｉ、Ｐｂ、Ｓｂの存在または５％を越す補助成分Ｔe、Ｓeの存在は、再点弧発生の頻度を増加させると共に遮断特性の低下を招き好ましくない。
【０１２２】
（実施例２６〜２８、比較例１０〜１１）
前記接点は、少なくとも１０％ＩＡＣＳの導電率を持つ合金であることが好ましい。導電率が１０％ＩＡＣＳ未満の場合、例えば導電率が８％ＩＡＣＳ以下の比較例２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（０．５５〜０．７）倍を示し遮断特性の低下が認められる。
【０１２３】
すなわち、接点合金の導電率が１０％ＩＡＣＳ未満では、遮断特性が大幅に低下する。また、接触抵抗、回路抵抗、温度上昇の増加を招き遮断電流値の低下、定格開閉電流値の低下を来たし好ましくない。
【０１２４】
また、本発明の実施に於ける真空遮断器の通電軸の導電率は、通常１００％ＩＡＣＳのＣｕを用いるが、本発明では９５％ＩＡＣＳの場合（実施例２６）、７０％ＩＡＣＳの場合（実施例２７）であっても、再点弧発生頻度は（評価Ｂ〜Ｃ）であり再点弧特性には変化は見られていないが、通電軸の導電率が５０％ＩＡＣＳの０．３重量％Ｚr−Ｃｕ合金を用いた場合（比較例１０）では、遮断特性に於いて（０．５〜０．６５）倍の遮断倍率を示し、遮断特性は大幅に低下する。
【０１２５】
従って、通電軸の導電率は少なくとも７０％ＩＡＣＳの導電率を持つことが好ましい。
【０１２６】
すなわち、通電軸の導電率が７０％ＩＡＣＳ未満では、回路抵抗、温度上昇の増加を招き遮断電流値の低下、定格開閉電流値の低下を来たし好ましくない。
【０１２７】
また、本発明の実施に於ける真空遮断器のコイル電極は、通常１００％ＩＡＣＳのＣｕを用いるが、本発明では、コイル電極が０．１重量％Ｃｒ−Ｃｕで製造した７０％ＩＡＣＳの場合（実施例２８）であっても、再点弧発生頻度は（評価Ｂ〜Ｃ）であり再点弧特性には変化は見られていないし、遮断倍率も（０．９）倍である。コイル電極の導電率が５０％ＩＡＣＳの０．３重量％Ｚr−Ｃｕ合金を用いた場合（比較例１１）では、遮断特性に於いて（０．４〜０．５５）倍の遮断倍率を示し、遮断特性の大幅な低下が認められる。
【０１２８】
従って、コイル電極の導電率は少なくとも７０％ＩＡＣＳの導電率を持つことが好ましい。
【０１２９】
すなわち、コイル電極の導電率が７０％ＩＡＣＳ未満では、回路抵抗を増加させ温度上昇の増加を招き遮断電流値の低下、定格開閉電流値の低下を来たし好ましくない。
【０１３０】
【発明の効果】
以上したように、本発明の真空遮断器によれば、再点弧特性と遮断特性とを両立させることができる。
【図面の簡単な説明】
【図１】本発明に係る真空遮断器の実施例１〜８および比較例１〜３の評価条件を示す表図。
【図２】本発明に係る真空遮断器の実施例９〜１９および比較例４〜８の評価条件を示す表図。
【図３】本発明に係る真空遮断器の実施例２０〜２８および比較例９〜１１の評価条件を示す表図。
【図４】本発明に係る真空遮断器の実施例１〜８および比較例１〜３の評価結果を示す表図。
【図５】本発明に係る真空遮断器の実施例９〜１９および比較例４〜８の評価結果を示す表図。
【図６】本発明に係る真空遮断器の実施例２０〜２８および比較例９〜１１の評価結果を示す表図。
【図７】代表的な真空バルブの構成例を示す断面図。
【図８】代表的な真空バルブの他の構成例を示す断面図。
【符号の説明】
４０…電極（接点４１の背面）
４１…固定接点
５０…電極（接点５１の背面）
５１…可動接点
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１０７の移動方向[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum circuit breaker using a vacuum valve having a contact having excellent breaking characteristics and re-ignition characteristics.
[0002]
[Prior art]
In general, in a vacuum circuit breaker, the contact of a vacuum valve that cuts off a current in a high vacuum using the diffusibility of an arc in vacuum is composed of two fixed and movable contacts facing each other. .
[0003]
As shown in FIG. 7, a pair of contacts 104 and 105 are provided opposite to each other in a vacuum vessel 103 in which openings at both ends of the insulating vessel 101 are closed by lids 102a and 102b, and these are attached to the lids 102a and 102b. Are attached to the ends of the current-carrying shafts 106 and 107 inserted through the vacuum vessel 103, and one of the current-carrying shafts 107 can be moved in the axial direction by an operating mechanism (not shown). The movable contact 105, which is the other contact, can be brought into contact with or separated from the fixed contact 104. In this case, a bellows 108 is provided between the lid 102b and the energizing shaft 107 so as to hold the inside of the vacuum vessel 103 in a vacuum-tight manner and allow the energizing shaft 107 to move in the axial direction. In the figure, reference numeral 109 denotes a shield provided so as to surround the contact points 104 and 105 and the energizing shafts 106 and 107.
[0004]
The vacuum circuit breaker is normally energized when both the contacts 104 and 105 are in contact with each other. When the energizing shaft 107 is moved in the direction of arrow M in the figure by the operation from this 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 shifted 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. 8 shows a vacuum valve in which a pair of contacts 41 and 51 are provided facing each other, and a flat plate electrode 40 is mounted on the back of the contact 41 and a flat electrode 50 is mounted on the back of the contact 51. Further, the coil electrode 40 can be mounted on the back surface of the contact 41, and the coil electrode 50 can be mounted on the back surface of the contact 51, respectively.
[0007]
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.
[0008]
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 specific purposes such as for high currents and high withstand voltages. Selection of contact materials suitable for the application has been made, and vacuum valves with excellent characteristics have been developed. However, there are still many products that can be used at the expense of some functions.
[0009]
In fact, a vacuum valve that sufficiently satisfies the increasing demand has not yet been obtained.
[0010]
For example, a Cu—Cr alloy (Japanese Patent Publication No. 45-35101) containing about 50 wt% (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 maintains a vapor pressure characteristic substantially equivalent to that of Cu and exhibits a powerful gas getter action. It is widely used as a contact that can achieve both.
[0011]
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. Although it is made into a contact product while considering processing from a material to a contact piece, the occurrence of re-ignition triggers a reduction in the breaking performance, and improvement is desired.
[0012]
[Problems to be solved by the invention]
In general, CuCr contacts have a relatively smooth damage characteristic even after breaking, mainly due to their close vapor pressure characteristics at high temperatures. is doing.
[0013]
However, in recent years, as a result of routine adaptation to circuits where higher current interruption and higher voltage may be applied, the surface condition of a new article processed as a contact, Depending on the condition of the contact surface damage, it may cause an abnormal increase in contact resistance and temperature when the next current is opened or closed, or it may cause a re-ignition due to a withstand voltage failure. ing.
[0014]
However, in reality, even if the surface state of the contact is controlled, the occurrence of re-ignition cannot be completely suppressed, and it is a reality that sufficient current interruption characteristics are not obtained.
[0015]
Therefore, in order to stabilize the re-ignition characteristic and the interruption characteristic of the CuCr alloy, the fluctuation of the Cr amount in the alloy, the particle size distribution of the Cr particles, the degree of segregation of the Cr particles, the degree of vacancy existing in the alloy, the contact point It is important to optimize the amount and presence of gas on the surface and inside. However, in the above-described recent adaptation situation, there are still cases where the frequency of re-ignition is high and low despite these optimizations. The realization of a vacuum valve that combines re-ignition characteristics and interrupting characteristics has not been achieved, and the development of a vacuum circuit breaker that combines these characteristics is expected.
[0016]
An object of the present invention is to provide a vacuum circuit breaker using a vacuum valve that stabilizes the re-ignition characteristic of a contact alloy and has excellent current interruption characteristics.
[0017]
[Means for Solving the Problems]
The vacuum circuit breaker according to the present invention is a vacuum circuit breaker comprising a vacuum vessel, a bellows, a current-carrying shaft, and a pair of opposed contacts, wherein the contact is made of a conductive component made of Cu. The raw material is Cr powder coated with Cr oxide. It consists of a Cu-Cr system contact containing an arc-resistant component made of Cr, Cr particles having an average particle diameter of 0.1 to 150 μm, Cr dissolved in the Cu matrix, and precipitation in the Cu matrix And the total amount of Cr in the contact is 15% in the contact, and the acid-insoluble Cr component, which is a Cr component in a material that does not melt into an acid containing at least one of Cr oxide, Cr nitride, and Cr carbide. It is characterized by occupying ˜90% by weight, the acid non-soluble Cr component is 30 ppm to 3500 ppm, and the amount of Cr dissolved in the Cu matrix is 0.005 to 0.5% by weight.
[0018]
With such a configuration, it is possible to achieve both re-ignition characteristics and interruption characteristics.
[0019]
That is, first, with respect to the Cr particles (a) to be used, when the Cr particles in the range of 0.1 to 150 μm preferably occupy at least 75% by volume, stable re-ignition characteristics are exhibited. Even if the total amount of Cr in the contacts is controlled within the range of 15 to 90% by weight, if the particle diameter is less than 0.1 μm, the distribution of Cr particles in the Cu—Cr alloy cannot be sufficiently dispersed and there is an agglomerated portion. At the same time, the surface adsorbed gas cannot be sufficiently managed, and the amount of gas after the contact is manufactured varies, all of which increase the occurrence of re-ignition.
[0020]
When the diameter of the Cr particles used exceeds 150 μm, the welding resistance characteristics and the contact resistance characteristics vary. The finished contact surface has scratched scratches at the interface between the Cr particles and the Cu phase, and it is difficult to obtain a smooth and uniform state. Therefore, the particle diameter of Cr used for exhibiting the effects of the present invention is preferably in the range of 0.1 to 150 μm.
[0021]
Further, Cr particles (a) having an average particle diameter of 0.1 to 150 μm, Cr (b) dissolved in a Cu matrix, Cr (c) precipitated in the Cu matrix, and acid insoluble It is preferable that the total amount (a + b + c + d) of Cr composed of the crystalline Cr component (d) occupies 15 to 90% by weight in the contact.
[0022]
A contact having a total Cr amount (a + b + c + d) of less than 15% by weight is not preferable because the arc resistance at the time of current interruption is poor, the surface damage of the contact after interruption is remarkable, and the re-ignition characteristic is lowered. On the other hand, if the total amount of Cr exceeds 90% by weight, switching of the rated current and interruption of a large current cause a decrease in temperature rise characteristics and contact resistance characteristics of the contact portion or circuit breaker, which is not preferable.
[0023]
The amount of the acid insoluble Cr component (d) is preferably 30 ppm to 3500 ppm.
[0024]
When the amount of the acid insoluble Cr component (d) is excessively present exceeding 3500 ppm, not only does the re-ignition occurrence frequency tend to increase, but the circuit breaker injects into the contact at each interruption. Since the magnitudes of the generated energy are greatly different, the re-ignition occurrence situation is different for each interruption (appears as variation), which is not preferable.
[0025]
On the other hand, when the amount of the acid-insoluble Cr component (d) is less than 30 ppm, it exhibits a low re-ignition occurrence frequency and also has a favorable effect on the interruption characteristics. However, in order to reduce the amount of the acid insoluble Cr component (d) to less than 30 ppm, it is necessary to examine the raw material more than necessary, and in particular, to control the atmosphere during the heat treatment. This technique is not preferable from an industrial viewpoint because it requires technology and increases the cost of the contact material.
[0026]
Therefore, the acid insoluble Cr component (d) in the contact used in the present invention is preferably in the range of 30 to 3500 ppm.
[0027]
In addition, the acid insoluble Cr component (d) is insoluble in an alkaline solution, and by controlling the amount to 3500 ppm or less, a lower re-ignition occurrence frequency is exhibited.
[0028]
Further, the amount (b) of Cr dissolved in the Cu matrix is preferably 0.005 to 0.5% by weight.
[0029]
That is, even if the total amount of Cr in the Cu—Cr alloy is 15 to 90 wt% in the contact and the acid insoluble Cr component (d) in the alloy is controlled within 30 ppm to 3500 ppm, the Cu matrix If the amount of Cr (b) in the solid solution exceeds 0.5% by weight, there is a problem in terms of economics in terms of contact manufacturing technology, and the contact conductivity is remarkably lowered. The temperature or the circuit breaker terminal temperature rises, and as a result, it is not preferable for maintaining the breaking characteristics.
[0030]
On the other hand, if the amount (b) of Cr dissolved in the Cu matrix is less than 0.005%, the temperature rise characteristic of the contact portion or the circuit breaker terminal portion is improved, but both industrially and economically. It's not a good idea.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0032]
According to research, the contact surface immediately after the current is interrupted becomes extremely high mainly due to arc heat, and a large amount of gaseous components and solid components are released from the molten contact surface into the electrode space. Among these, when the gaseous component stays between the electrodes for a predetermined time or more, the excellent insulating property of the vacuum is destroyed. Therefore, in order to maintain the dielectric strength between the electrodes, the absolute amount of the gaseous component released from the contact surface must be minimized in advance, or the released gaseous component can be quickly diffused and removed between the electrodes. It is also important.
[0033]
That is, in the case of a substance that can be easily decomposed or removed by arc heat in the substance on the contact surface or inside the contact (the above-mentioned gaseous component or solid component), the stage before the interruption (arc It was observed that there was a low probability that it would move directly into the electrode space at a very early stage of the temperature rising process and directly cause reignition.
[0034]
Conversely, in the case of substances that are not easily decomposed or removed, it was observed that decomposition or removal proceeds and moves to the electrode space even after completion of blocking, which is an important cause of reignition.
[0035]
In the case of a gas (gas) generated in the process of decomposing the substance described above, the component having a larger mass number has a slower diffusion rate and tends to remain in the electrode space, and the recovery of the degree of vacuum tends to be delayed, resulting in insulation. Trigger destruction.
[0036]
Here, there are two types of substances existing on the surface of the contact or inside the contact, a substance that can be easily eliminated by arc heat or Joule heat and a substance that cannot be easily eliminated. Of these, the handling of the latter material is particularly important for reignition. In other words, it is important to reduce substances that cannot be easily decomposed or released / removed into the electrode space before the current is interrupted (or at an extremely early stage while the contacts are warming up). It becomes. For that purpose, it is also important how to quantify the amount of substances that cannot be easily decomposed or removed without interrupting the actual current.
[0037]
If all the contacts are fully heated to the vapor state, the amount of surface gas and the amount of internal gas released at that time can be captured, but all the contacts are completely heated to the vapor state. In reality, there is a substance that does not decompose during melting, so the total amount of substance present on the surface or inside the contact cannot be captured.
[0038]
When a CuCr alloy is dissolved with acids such as hydrochloric acid and nitric acid and, if necessary, alkalis such as sodium chloride and potassium chloride, components that are dissolved and removed in acid and alkali, and insoluble that does not dissolve in acid and alkali. Things remain.
[0039]
The former component that can be dissolved and removed in the acid (alkali) is easy to diffuse to the contact surface when it receives arc heat, and corresponds to a component that is easily removed.
[0040]
On the other hand, the latter components that are not dissolved in the acid (alkali) and cannot be removed exist as solid bodies on the contact surface portion or inside the contact as Cr oxide, Cr nitride, or Cr carbide. Corresponds to a substance that is difficult to decompose or remove, and has an important meaning for suppressing re-ignition.
[0041]
The acid (alkali) non-dissolved substance present on the contact surface portion of the solid body decomposes when it is subjected to an arc, and instantaneously releases a large amount of gas, or releases decomposition products, This contributes to reignition. An acid (alkali) non-dissolved substance in one contact is also decomposed by an arc to release a large amount of gas or a decomposition product in the same manner. It becomes. Since the diffusion to the contact surface is delayed, it contributes to the re-ignition seen after a certain period of time after the interruption.
[0042]
(Experiment 1): According to the experiments by the inventors, as a means for causing a very small amount of acid insoluble Cr (including an alkaline solution and an insoluble substance as described above) to exist in the contact point. By using an infiltration method in which Cr powder coated with submicron grade Cr oxide suspended in an organic solvent is used as a raw material, Cr skeleton is produced, and Cu is infiltrated into the voids of the Cr skeleton. A CuCr alloy having a very small amount of fine Cr oxide inside was produced. It is easy to adjust the amount of fine Cr oxide in the CuCr alloy by adjusting the amount of Cr oxide suspended in the organic solvent.
[0043]
Similarly, as another means, a CuCr alloy was manufactured by solid-phase sintering of Cr powder and Cu powder coated with submicron grade Cr oxide suspended in an organic solvent.
[0044]
In any CuCr alloy obtained by any manufacturing method, when the amount of Cr oxide is large, the frequency of re-ignition increases, whereas when the amount of Cr oxide is small, re-ignition occurs. The frequency of arcs tends to be very low. When this acid-insoluble substance is analyzed, the presence of an acid-insoluble Cr compound (d) is particularly confirmed therein.
[0045]
(Experiment 2): According to other observations by the inventors, there are cases where extremely fine precipitates are present and no precipitate is present in the contact material.
[0046]
In an actual vacuum circuit breaker, further microscopic observation of the contacts mounted on a vacuum valve with a high re-ignition frequency confirmed extremely fine precipitates and inclusions (both insoluble in acid). In this case, it was confirmed that the Cr component was present in a certain amount or more in the substance insoluble in the acid. On the other hand, when the contact mounted on the vacuum valve having a low re-ignition frequency is observed microscopically, the Cr component tends to be less in the fine precipitates and inclusions (both insoluble in the acid). there were.
[0047]
Therefore, this experiment suggests that the presence of the acid-insoluble substance and the amount of the Cr component (d) therein are deeply related to the reignition characteristics.
[0048]
In order to stabilize the re-ignition characteristics and interruption characteristics of vacuum valves, the composition of contact materials, fluctuations in the amount of components, the amount of gas, the structure of the structure (particle size, particle size distribution, degree of segregation, present in the alloy) In addition to the above, after dissolving the CuCr alloy with an acid solution, it is strongly dependent on the contact surface morphology, etc. The acid insoluble Cr component remaining in the solution is deeply involved.
[0049]
Hereinafter, the present invention will be described in detail by way of examples and comparative examples. Evaluation conditions and evaluation results are shown in FIGS.
[0050]
(1) 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 a circuit of 24 kv × 500 A was interrupted 2000 times was measured. In addition, the result displayed the re-ignition frequency as follows.
[0051]
That is, when the number of occurrences in Example 5 is 1, the magnification is less than 0.1 (A), 0.1 to 0.8 is evaluated (B), and 0.8 to 1.2 is evaluated ( C), 1.2 to 1.5 were evaluated (D), 1.5 to 10 were evaluated (X), 10 to 100 were evaluated (Y), and 100 or more were evaluated (Z).
[0052]
The evaluations (A) to (D) were evaluated as “pass”, and the evaluations (X) to (Z) were determined as “bad”.
[0053]
(2) Interrupting 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 vacuumed while increasing the current by approximately 1 kA. Three valves were evaluated. In addition, the numerical value showed the comparative value when the value of Example 5 was set to 1.0 with a variation width.
[0054]
(3) Outline of assembly of test valve for shut-off test
An outline of the assembly of the test valve for shut-off test is shown. Ceramic insulation container with an average end surface roughness of about 1.5μm (main component: AL ₂ O _Three The 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. Each of the prepared members is arranged between the objects to be joined (the polished surface of the ceramic insulating container and the sealing metal fitting) so as to be able to be hermetically sealed and joined. ^-Four It was subjected to a hermetic sealing process between the sealing metal fitting and the ceramic green container in a vacuum atmosphere of Pa.
[0055]
(4) Determination of acid-insoluble Cr component in contact alloys
Quantification of acid-insoluble Cr in the alloy contained in the contact material was performed, for example, by the following method. After adding nitric acid to the CuCr contact, it is separated into filtrate (Cu phase) and precipitate. The precipitate was separated into a filtrate (Cr phase) and a precipitate (acid non-dissolved substance) by alkali dissolution and acid dissolution, and each was quantified with an analyzer such as ICP-AES. As the acid to be used, nitric acid, hydrochloric acid, hydrofluoric acid and the like can be used, and as the alkali, sodium chloride, potassium chloride and the like can be used.
[0056]
(Examples 1 to 3, Comparative Example 1)
In the present invention, the relationship between the re-ignition characteristic, the interruption characteristic, and the acid-insoluble Cr component contained in the contact material is important.
[0057]
The amount of the acid insoluble Cr component (d) was quantified under the following conditions.
[0058]
A Cu-25% Cr alloy was selected as the representative contact, and about 10 gr. Were collected. After thermal decomposition for about 10 minutes in 3N (normal) nitric acid at 100 ° C., this is filtered and filtrate A (Cu ²⁺ ) And precipitate A. Here, filtrate A (Cu ²⁺ ) Corresponds to the Cu phase. This filtrate A (Cu ²⁺ ) The amount of Cr present therein is quantified by ICP-AES or the like, whereby Cr (b) dissolved in the Cu matrix is known.
[0059]
The precipitate A is then thermally decomposed with 6N hydrochloric acid (100 ° C. for 30 minutes) to obtain filtrate B (Cr ³⁺ ) And precipitate B. Here filtrate B (Cr ³⁺ ) Corresponds to the total (a + c) of 0.1 to 150 μm Cr particles (a) used as the raw material and Cr (c) precipitated in the Cu matrix.
[0060]
Next, the precipitate B is dissolved in an alkaline solution, and further dissolved in an acid solution. Undissolved substances are collected in both solutions, and acid-insoluble Cr is obtained by quantitative analysis using ICP-AES or the like. Know the amount of component (d) (exactly acid / alkali insoluble Cr). The total amount of (b) + (a + c) + (d) described above substantially coincided with 25 wt%, which is the Cr amount in the CuCr alloy selected as the representative contact.
[0061]
For example, the amount of the acid-insoluble Cr component (d) in the contact material is adjusted to 30 to 8500 ppm by selecting the treatment atmosphere and its quality, treatment temperature, time, cooling conditions, adjusting the raw material powder (Cu, Cr), etc. The raw material in the range was manufactured and used for the test (Examples 1 to 3, Comparative Example 1).
[0062]
That is, as a representative contact for evaluation, a Cu-25% Cr alloy subjected to heat treatment at 1060 ° C. was selected for a molded body of Cu powder and Cr powder, and the contact method was performed on these contact alloys by the method described above. The amount of the acid-insoluble Cr component (d) contained in the material is 30 to 150 ppm (Example 1), 400 to 2800 ppm (Example 2), 2000 to 3500 ppm (Example 3), 5500 to 8500 ppm ( Comparative Example 1) was produced.
[0063]
The breaking characteristics were evaluated by measuring the breaking current value for each contact, and the magnification when the breaking current value of Example 5 described later is 1.0.
[0064]
The evaluation of the re-ignition characteristics is as follows. The re-ignition frequency when the circuit of 24 kv × 500 A is interrupted 2000 times for each contact is less than 0.1 times when the number of occurrences in Example 5 is 1. (A), 0.1 to 0.8 times as evaluation (B), 0.8 to 1.2 times as evaluation (C), and 1.2 to 1.5 times as evaluation (D). Was evaluated as “pass”, 1.5 to 10 times as evaluation (X), 10 to 100 times as evaluation (Y), and 100 times or more as evaluation (Z), and these were determined as “bad”.
[0065]
First, the re-ignition characteristic (frequency of re-ignition occurrence) is such that the amount of the acid insoluble Cr component (d) contained in the contact material is 30 to 150 ppm (Example 1), which will be described later. Compared with the frequency of occurrence of 5, it was less than 0.1 times and exhibited very good re-ignition characteristics (Evaluation A).
[0066]
When the amount of the acid insoluble Cr component (d) is 400 to 2800 ppm (Example 2), it shows 0.8 and 1.5 times the occurrence frequency of Example 5 to be described later. The arc characteristics (evaluations C to D) were exhibited.
[0067]
When the amount of the acid insoluble Cr component (d) is 2000 to 3500 ppm (Example 3), it shows 1.2 to 1.5 times the occurrence frequency of Example 5 to be described later, which is a good score. The arc characteristics (Evaluation D) were demonstrated.
[0068]
On the other hand, the amount of the acid insoluble Cr component (d) is 5500 to 8500 ppm (Comparative Example 1), which is larger than that of Examples 1 to 3, compared with the occurrence frequency of Example 5 described later. The re-ignition frequency (assessment Z) increased more than twice.
[0069]
When the amount of the acid insoluble Cr component (d) is 3500 ppm or less, preferable re-ignition characteristics are observed, whereas the amount of the acid insoluble Cr component (d) is 5500, which is larger than that in Example 3. At ~ 8500ppm (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, and the re-ignition occurrence frequency (evaluation Z) is 100 times or more. Remarkably reduced.
[0070]
Clearly, good re-ignition characteristics are exhibited when the amount of the acid-insoluble Cr component (d) contained in the contact material is not more than a predetermined amount.
[0071]
Next, the evaluation result of the breaking characteristics shows that the breaking magnification when the amount of the acid insoluble Cr component (d) contained in the contact material is 30 to 150 ppm (Example 1) is (1.0 to 1). 0.1) times, and the blocking ratio when the amount of the acid insoluble Cr component (d) is 400-2800 ppm (Example 2) is also (1.0-1.1) times, The blocking magnification when the amount of the soluble Cr component (d) is 2000 to 3500 ppm (Example 3) is also (1.0 to 1.1) times, which is almost the same as that of Example 5 as a standard. It is in the preferred barrier properties at or above.
[0072]
On the other hand, when the amount of the acid-insoluble Cr component (d) is 5500 to 8500 ppm (Comparative Example 1), which is greater than those of Examples 1 to 3, the blocking magnification is (0.8 to 0.95). Doubled.
[0073]
Obviously, when the amount of the acid-insoluble Cr component (d) in the contact material increases, the breaking characteristics tend to decrease.
[0074]
Therefore, the amount of the acid-insoluble Cr component (d) contained in the contact material is preferably 3500 ppm or less, and the lower limit is determined by economic efficiency, for example, about 30 ppm.
[0075]
(Examples 4-6, Comparative Examples 2-3)
In Examples 1 to 3 and Comparative Example 1, the effect of the amount of the acid insoluble Cr component (d) contained in the contact material on the re-ignition characteristics and the interruption characteristics is determined by the amount of Cu in the contact alloy. Although the Cu-25% Cr contact is shown as 75% by weight (hereinafter referred to as weight% for the contact material), the technology of the present invention is not limited to this, and the effect is exhibited even in cases other than the Cu-25% Cr contact. In other words, 5% Cu—Cr (Comparative Example 2), 10% Cu—Cr (Example 4), 50% Cu—Cr (Example 5), 85% Cu—Cr with 5% Cu in the contact alloy. (Example 6) After producing 98% Cu-Cr (Comparative Example 3), the contact amount in which the amount of the acid-insoluble Cr component (d) is within the range of 100 to 650 ppm from these contact materials. The evaluation was performed after selecting materials.
[0076]
The re-ignition characteristics (frequency of re-ignition occurrence) are 5% Cu-Cr (Comparative Example 2) and 10% Cu-Cr (Example 4) with 5% Cu content in the contact point. It exhibits 0.1 to 0.8 times and 0.8 to 1.2 times (evaluation B to C) equivalent to 50% Cu—Cr (Example 5), and exhibits good re-ignition characteristics. . Moreover, also in 85% Cu-Cr (Example 6), it shows 0.8 to 1.2 times and 1.2 to 1.5 times (evaluation CD), and is in the range of a pass.
[0077]
On the other hand, in 98% Cu—Cr (Comparative Example 3) in which the amount of Cu in the contact is greater than 85% of Example 6, the phenomenon that the welding phenomenon is partially generated and the contact surface is greatly roughened when the current is interrupted. The contact voltage characteristics of the contacts are reduced, and 1.5 to 10 times and 100 times or more (evaluation X to Z) are shown. The re-ignition characteristics show a large variation and are remarkably lowered.
[0078]
As described above, the amount of Cu contained in the contact material to which the present invention technique is applied is preferably 85% or less.
[0079]
As for the breaking characteristics, the amount of Cu in the contact is 10% Cu—Cr (Example 4) is (0.9 to 0.95) times larger, and the rate of interruption of 85% Cu—Cr (Example 6) is ( 1.0 to 1.1) times as high as that of the standard example 5.
[0080]
The interruption ratio of 5% Cu—Cr (Comparative Example 2) in which the amount of Cu in the contact is less than 10% of Example 4 shows (0.55 to 0.7) times as the contact material itself has a low conductivity. Shows a significant decline.
[0081]
On the other hand, the interruption rate of 98% Cu—Cr (Comparative Example 3) in which the amount of Cu in the contact is greater than 85% of (Example 6) is (0.7 to 1.15) times, and the contact surface Due to the rough surface, the breaking characteristics varied greatly.
[0082]
As described above, the amount of Cu contained in the contact material to which the present invention technology is applied is preferably in the range of 10 to 85%, in other words, the amount of Cr (a + b + c + d) is in the range of 15 to 90%. .
[0083]
(Examples 7 to 8)
In the first to sixth embodiments, an example in which Cu is selected as the conductive component in the contact material has been shown. However, the present invention is not limited to this, and the effect is exhibited even when other than Cu.
[0084]
That is, even with 40% Ag-Cr (Example 7) in which the conductive component in the contact material is Ag, the re-ignition frequency is 1.2 to 1.5 times as good as the re-ignition characteristic ( Evaluation D), and 75% (Ag + Cu) -Cr (Example 8) in which the conductive component is Ag = 54% and Cu = 21%, the frequency of re-ignition is 0.8-1 .2 times and 1.2 to 1.5 times good re-ignition characteristics (evaluation C to D) are shown, both of which are acceptable.
[0085]
The interruption characteristics are (0.9) times (Example 7) and (0.95 to 1.05) times (Example 8) when the interruption characteristic of Example 5 as a standard is 1.0. Both of these are acceptable ranges.
[0086]
As described above, even if the conductive component in the contact material, that is, a part or all of the Cu matrix is replaced with Ag, the same characteristics as in the case of the Cu matrix are exhibited.
[0087]
(Examples 9-11, Comparative Examples 4-5)
In Examples 1 to 8 and Comparative Examples 1 to 3, the effect of the amount of the acid-insoluble Cr component (d) in the contact alloy on the re-ignition characteristics and the interruption characteristics was measured in the Cu matrix in the contact alloys. A contact having a solid solution amount of Cr (b) of 0.02% (weight%) is shown, but the amount of Cr (b) solid solution in the Cu matrix in the present technology is 0.02%. The effect is demonstrated without being limited to%.
[0088]
That is, 75% Cu—Cr (Examples 9 to 11) in which the amount of Cr (b) dissolved in the Cu matrix in the contact alloy was 0.005%, 0.1%, and 0.5%, And 75% Cu—Cr (Comparative Example 4) of less than 0.005% and 75% Cu—Cr (Comparative Example 5) of more than 0.5%, mainly cooling process during contact manufacturing The contact material with the amount (d) of the acid-insoluble Cr component in these contact materials in the range of 100 to 650 ppm was selected and manufactured by adjusting the cooling rate at did.
[0089]
The re-ignition characteristic (frequency of re-ignition) was such that the amount of arc-resistant component dissolved in the conductive component, that is, the amount of Cr (b) dissolved in the Cu matrix was 0.02% of Example 5. In the case of less 0.005% (Example 9), the re-ignition characteristics of less than 0.1 times and 0.1 to 0.8 times (Evaluations A to B) superior to Example 5 were shown.
[0090]
Further, when the amount (b) of Cr dissolved in the Cu matrix is 0.1% (Example 10) and 0.5% (Example 11), both are 0.8 to 1.2. Double (Evaluation C) was shown, and favorable re-ignition characteristics were shown.
[0091]
On the other hand, when the amount of Cr (b) dissolved in the Cu matrix is more than 0.5% (Comparative Example 5), 0.8 to 1.2 times and 10 to 100 times (Evaluation C) To Y), which shows a re-ignition characteristic with a large variation width, which is not preferable.
[0092]
On the other hand, in Comparative Example 4 in which the amount of Cr (b) dissolved in the Cu matrix was less than 0.005% of Example 9, it was less than 0.1 equivalent to Example 9 described above and 0.1 to 0 .8 (Evaluations A to B) showing good results, but the production cost is high and the supply ability is difficult, and is excluded from the preferred range of the present invention from the viewpoint of production technology.
[0093]
As for the barrier property, the barrier magnification of 0.005% (Example 9) in which the amount of Cr (b) dissolved in the Cu matrix is less than 0.02% of Example 5 is (1.0 to 1.1). ) Times, 0.1% (Example 10) has a blocking ratio of (0.9 to 1.0) times, and 0.5% (Example 11) has a blocking ratio of (0.9 to 0.95) times. These are all in the good range.
[0094]
On the other hand, when the amount of Cr (b) dissolved in the Cu matrix is larger than 0.5% of Example 11 (Comparative Example 5), (0.6 to 0.75) times is shown. It deteriorates significantly and is not preferable.
[0095]
From the above, in carrying out the present invention, the amount (b) of Cr dissolved in the Cu matrix in the contact alloy is a contact alloy in the range of 0.005 to 0.5% (weight%). It is preferable to select.
[0096]
(Examples 12 to 17, Comparative Example 6)
In the above Examples 1 to 11 and Comparative Examples 1 to 5, the effect on the re-ignition characteristic and the interruption characteristic was shown for the CuCr contact point in which Cr was selected as the kind of arc-proof component in the contact point. The effect is demonstrated not only in Cu-Cr contacts but also in other cases.
[0097]
That is, the amount of Cr (b) dissolved in the Cu matrix in the contact alloy is 0.02%, and the amount of the acid insoluble Cr component (d) contained in the contact material is 100 to 650 ppm. The remainder is made of Cu, and the arc resistance component (weight ratio) present in the contact material is replaced with CrW (Cr: W = 9: 1) and CrW (Cr: W = 5: 5). Even so, preferable re-ignition characteristics (evaluations A to B) and (evaluations B to C) equivalent to or higher than the standard example 5 were shown (examples 12 to 13).
[0098]
However, when the Cr component is small as in the case where the ratio of Cr and W is Cr: W = 2: 8, the re-ignition frequency is 0.8 to 1.2 times (evaluation C) from a preferable value. A large variation was exhibited up to an undesirable value of 1.5 to 10 times (Evaluation X) (Comparative Example 6).
[0099]
Even if it is replaced by CrMo (Cr: Mo = 9: 1), CrTi (Cr: Ti = 9: 1), CrTa (Cr: Ta = 9: 1), CrNb (Cr: Nb = 9: 1) The re-ignition characteristics (evaluations A to B) equivalent to or better than those of Example 5 are shown (Examples 14 to 17).
[0100]
Even if the kind of arc-resistant component (weight ratio) present in the contact material is replaced with CrW (Cr: W = 9: 1) or CrW (Cr: W = 5: 5), it is standard (Example) It showed a preferable cutoff characteristic (0.9 to 1.1) times equal to or higher than 5) (Examples 12 to 13).
[0101]
However, when the Cr component is small as in the case where the ratio of Cr and W is (Cr: W = 2: 8), the cutoff current value is (0.4 to 0.55) due to the large amount of thermionic emission. Double unfavorable values and large variations were shown (Comparative Example 6).
[0102]
Even if replacing with CrMo (Cr: Mo = 9: 1), CrTi (Cr: Ti = 9.1: 1), CrTa (Cr: Ta = 9: 1), CrNb (Cr: Nb = 9: 1) The interruption characteristics (0.95 to 1.15) times almost the same as the standard example 5 were shown (examples 14 to 17).
[0103]
From the above, the arc resistance component in the contact can obtain the same effect even if a part of Cr is replaced with one of W, Mo, Ti, Ta, and Nb of 50% or less.
[0104]
That is, by replacing a part of Cr with one of W, Mo, Ti, Ta, and Nb, the mechanical strength of the entire Cu—Cr contact material is increased, and the drop of Cr particles is triggered. Re-ignition generation can be reduced.
[0105]
<Example 15>
In Examples 1 to 14 above, Cr was selected as the type of arc resistant component dissolved in the conductive component (Cu matrix) in the contact alloy. However, the present invention is not limited to this, and the arc resistance is not limited thereto. The effect is exhibited even if the type of component is Ti. That is, 75% Cu—Cr (Example 15) was manufactured by setting Ti as an arc-proof component dissolved in the conductive component in the contact alloy and setting its amount to 0.02, and the evaluation was performed.
[0106]
The frequency of re-ignition occurrence is less than 0.1 times equal to or greater than (Example 5) and 0.1 to 0.8 times (Evaluation A to B), and exhibits good re-ignition characteristics. Yes.
[0107]
The cutoff characteristic also shows the cutoff magnification (0.95 to 1.15) times, and is in the same range as Example 5.
[0108]
(Examples 18-19, Comparative Examples 7-8)
In Examples 1 to 17 and Comparative Examples 1 to 6, the effect on the re-ignition characteristic and the interruption characteristic was shown for the case where the particle diameter of the arc-resistant component (Cr) in the Cu matrix was 40 to 80 μm. The technique of the present invention is not limited to this and exhibits its effect.
[0109]
That is, the amount of Cr (b) dissolved in the Cu matrix in the contact alloy is 0.02%, and the amount of the acid insoluble Cr component (d) contained in the contact material is 100 to 650 ppm. In addition, even when the remainder is Cu, and the particle diameter of the arc resistant component (Cr) is 0.1 to 25 μm and 70 to 150 μm, preferable re-ignition characteristics (evaluation B to C) and (Evaluation C to D) are shown (Examples 18 to 19). The interruption characteristics also show (0.95 to 1.05) times and (1.0 to 1.1) times, which is a preferable value substantially equivalent to the interruption characteristic 1.0 of Example 5 as a standard. (Examples 18 to 19).
[0110]
However, when the particle diameter of the arc-resistant component (Cr) in the Cu matrix is less than 0.1 μm, preferable re-ignition characteristics (evaluations A to B) that are equal to or higher than Example 5 are shown. Nevertheless, it is outside the scope of the present invention due to high production costs such as low productivity to make the particle diameter of the arc resistant component (Cr) in the Cu matrix less than 0.1 μm (Comparative Example 7).
[0111]
In a contact having an average particle diameter exceeding 150 μm, the frequency of re-ignition compared with Example 5 is 1.5 to 10 times and 100 times or more (evaluation X to Z), and shows a large variation width. Further, the blocking magnification is also (0.75 times to 1.0) times, and also shows a large variation width, which is not preferable (Comparative Example 8).
[0112]
From the above, it is preferable that the arc resistant component in the contact has an average particle diameter of 0.1 to 150 μm.
[0113]
(Examples 20 to 25, Comparative Example 9)
In Examples 1 to 19 and Comparative Examples 1 to 8, CuCr contacts that do not contain an auxiliary component for reducing welding such as Bi in the contact alloy do not include an auxiliary component for improving the welding resistance. Although the impact on re-ignition characteristics and interruption characteristics was shown for the contacts, the technology of the present invention is not limited to this, and the effect is maintained even if auxiliary components such as Bi are present within a predetermined amount in the contact alloys described above. To do.
[0114]
That is, 75% Cu—Cr alloy with 0.1% and 1.0% Bi added to the contact alloy (Examples 20 to 21), and 75% Cu—Cr alloy with 2.0% Bi added (Comparative Example) 9) 75% Cu—Cr alloy containing 0.3% Pb (Example 22), 75% Cu—Cr alloy containing 0.1% Sb (Example 23), and adding 3.0% Te The 75% Cu—Cr alloy (Example 24) and 75% Cu—Cr alloy (Example 25) to which Se was added 1.0% were manufactured, and the evaluation was performed.
[0115]
The frequency of re-ignition was 0.1 to 0.8 times and 0.8 to 1 in Example 20 in which the Bi amount was 0.1% and Example 21 in which the Bi amount was 1.0%. Preferred re-ignition characteristics of 2 times (evaluation B to C), 0.8 to 1.2 times and 1.2 to 1.5 times (evaluation C to D), which are substantially equal to or higher than those of Example 5 showed that.
[0116]
However, in Comparative Example 9 in which the Bi amount is 2.0%, 10 to 100 times and 100 times or more (evaluation Y to Z) are shown, and the re-ignition characteristic is greatly lowered and the variation width is increased. .
[0117]
The presence of Bi significantly improves the welding resistance compared to Example 5.
[0118]
In Example 20 in which the Bi amount was 0.1% and Example 21 in which the Bi amount was 1.0%, the blocking characteristics were (0.95) times and (0.9) times, both of which were implemented. The characteristics were almost the same as in Example 5.
[0119]
On the other hand, in Comparative Example 9 in which the Bi amount was 2.0%, the selective evaporation of Bi generated at the time of breaking caused the contact surface to be damaged and the voltage resistance decreased. As a result, the breaking magnification was (0.3 to 0.45) is not preferable (Comparative Example 9).
[0120]
Example 22 with Pb content of 0.3%, Example 23 with Sb content of 0.1%, Example 24 with Te content of 3.0%, Example with Se content of 1.0% Even in a 75% Cu—Cr alloy containing other welding-resistant components such as 25, 0.8 to 1.2 times and 1.2 to 1.5 times (evaluation CD) are shown and good In addition to exhibiting a good re-ignition characteristic, the interruption ratio is (0.9) times or (0.9 to 0.95) times, indicating good interruption characteristics (Examples 22 to 25).
[0121]
As described above, the presence of auxiliary components Bi, Pb, and Sb of 1% or less in the Cu phase suppresses excessive roughening of the contact surface after current interruption and stabilizes the withstand voltage characteristic. Contributes to lowering the frequency of occurrence. Further, if the presence of auxiliary components Te and Se in the Cu phase is 5% or less, the contact surface roughness after current interruption is stabilized and the re-ignition occurrence level is lowered. However, the presence of auxiliary components Bi, Pb, Sb exceeding 1% or the auxiliary components Te, Se exceeding 5% is not preferable because it increases the frequency of re-ignition and decreases the interruption characteristics.
[0122]
(Examples 26 to 28, Comparative Examples 10 to 11)
Preferably, the contact is an alloy having a conductivity of at least 10% IACS. When the conductivity is less than 10% IACS, for example, in Comparative Example 2 where the conductivity is 8% IACS or less, no change is seen in the re-ignition characteristics, but the cutoff magnification is (0.55 to 0.7). A decrease in the blocking characteristics is observed.
[0123]
That is, when the electrical conductivity of the contact alloy is less than 10% IACS, the breaking characteristics are greatly deteriorated. In addition, the contact resistance, circuit resistance, and temperature increase are increased, resulting in a decrease in the cutoff current value and a decrease in the rated switching current value.
[0124]
In the practice of the present invention, the conductivity of the current-carrying shaft of the vacuum circuit breaker is usually 100% IACS Cu, but in the present invention, 95% IACS (Example 26), 70% IACS ( Even in Example 27), the re-ignition occurrence frequency is (Evaluation B to C) and the re-ignition characteristic is not changed, but the conductivity of the conduction shaft is 0.3% of 50% IACS. When the weight% Zr—Cu alloy is used (Comparative Example 10), the interruption characteristic shows (0.5 to 0.65) times the interruption factor, and the interruption characteristic is greatly deteriorated.
[0125]
Therefore, it is preferable that the conductivity of the conducting shaft has a conductivity of at least 70% IACS.
[0126]
That is, if the conductivity of the current-carrying shaft is less than 70% IACS, the circuit resistance and the temperature increase are increased, and the cut-off current value is lowered and the rated switching current value is lowered.
[0127]
In the practice of the present invention, the coil electrode of the vacuum circuit breaker is usually made of 100% IACS Cu. However, in the present invention, the coil electrode is 70% IACS manufactured with 0.1 wt% Cr—Cu. Even in Example 28, the re-ignition occurrence frequency is (Evaluation B to C), no change is observed in the re-ignition characteristics, and the cutoff magnification is (0.9) times. When a 0.3 wt% Zr—Cu alloy having a coil electrode conductivity of 50% IACS is used (Comparative Example 11), the interruption characteristic shows (0.4 to 0.55) times the interruption magnification. A significant decrease in the blocking characteristics is observed.
[0128]
Therefore, the coil electrode preferably has a conductivity of at least 70% IACS.
[0129]
That is, if the electrical conductivity of the coil electrode is less than 70% IACS, the circuit resistance is increased, causing an increase in temperature, resulting in a decrease in the cutoff current value and a decrease in the rated switching current value.
[0130]
【The invention's effect】
As described above, according to the vacuum circuit breaker of the present invention, both the re-ignition characteristic and the interruption characteristic can be achieved.
[Brief description of the drawings]
FIG. 1 is a table showing evaluation conditions of Examples 1 to 8 and Comparative Examples 1 to 3 of a vacuum circuit breaker according to the present invention.
FIG. 2 is a table showing the evaluation conditions of Examples 9 to 19 and Comparative Examples 4 to 8 of the vacuum circuit breaker according to the present invention.
FIG. 3 is a table showing the evaluation conditions of Examples 20 to 28 and Comparative Examples 9 to 11 of the vacuum circuit breaker according to the present invention.
FIG. 4 is a table showing the evaluation results of Examples 1 to 8 and Comparative Examples 1 to 3 of the vacuum circuit breaker according to the present invention.
FIG. 5 is a table showing evaluation results of Examples 9 to 19 and Comparative Examples 4 to 8 of the vacuum circuit breaker according to the present invention.
FIG. 6 is a table showing evaluation results of Examples 20 to 28 and Comparative Examples 9 to 11 of the vacuum circuit breaker according to the present invention.
FIG. 7 is a cross-sectional view showing a configuration example of a typical vacuum valve.
FIG. 8 is a cross-sectional view showing another configuration example of a typical vacuum valve.
[Explanation of symbols]
40 ... Electrode (rear surface of contact 41)
41 ... Fixed contact
50 ... Electrode (rear surface of contact 51)
51. Movable contact
101 ... Insulating container
102a ... Fixed side lid
102b ... movable side lid
103 ... Vacuum container
104: Fixed contact
105 ... movable contact
106: Fixed energizing shaft
107 ... movable energizing shaft
108 ... Bellows
109 ... Arc shield
M: Movement direction of the energizing shaft 107

Claims

In a vacuum circuit breaker comprising a vacuum vessel, a bellows, a current-carrying shaft, and a pair of opposed contacts, the contact is made of a Cr powder coated with a conductive component made of Cu and Cr oxide. Made of a Cr—Cr-based contact containing an arc resistant component made of Cr, Cr particles having an average particle diameter of 0.1 to 150 μm, Cr dissolved in a Cu matrix, and a Cu matrix The total amount of Cr consisting of Cr deposited on and an acid-insoluble Cr component that is a Cr component in a substance that does not melt into an acid, including at least one of Cr oxide, Cr nitride, and Cr carbide, The acid non-soluble Cr component is 30 ppm to 3500 ppm, and the amount of Cr solid-solved in the Cu matrix is 0.005 to 0.5 wt%. Characteristic vacuum Cross-sectional device.

The vacuum circuit breaker according to claim 1, wherein the acid-insoluble Cr component is also insoluble in an alkaline solution.