JP3943652B2 - Superconducting conductor and superconducting / normal conducting transition resistance type fault current limiter - Google Patents
Superconducting conductor and superconducting / normal conducting transition resistance type fault current limiter Download PDFInfo
- Publication number
- JP3943652B2 JP3943652B2 JP13747597A JP13747597A JP3943652B2 JP 3943652 B2 JP3943652 B2 JP 3943652B2 JP 13747597 A JP13747597 A JP 13747597A JP 13747597 A JP13747597 A JP 13747597A JP 3943652 B2 JP3943652 B2 JP 3943652B2
- Authority
- JP
- Japan
- Prior art keywords
- superconducting
- superconductor
- current
- reba
- bulk
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000004020 conductor Substances 0.000 title claims description 27
- 230000007704 transition Effects 0.000 title claims description 19
- 239000002887 superconductor Substances 0.000 claims description 69
- 241000954177 Bangana ariza Species 0.000 claims description 27
- 239000013078 crystal Substances 0.000 claims description 26
- 229910052684 Cerium Inorganic materials 0.000 claims description 5
- 229910052692 Dysprosium Inorganic materials 0.000 claims description 5
- 229910052691 Erbium Inorganic materials 0.000 claims description 5
- 229910052693 Europium Inorganic materials 0.000 claims description 5
- 229910052688 Gadolinium Inorganic materials 0.000 claims description 5
- 229910052689 Holmium Inorganic materials 0.000 claims description 5
- 229910052765 Lutetium Inorganic materials 0.000 claims description 5
- 229910052779 Neodymium Inorganic materials 0.000 claims description 5
- 229910052772 Samarium Inorganic materials 0.000 claims description 5
- 229910052771 Terbium Inorganic materials 0.000 claims description 5
- 229910052775 Thulium Inorganic materials 0.000 claims description 5
- 229910052769 Ytterbium Inorganic materials 0.000 claims description 5
- 229910052746 lanthanum Inorganic materials 0.000 claims description 5
- 229910052727 yttrium Inorganic materials 0.000 claims description 4
- 229910052777 Praseodymium Inorganic materials 0.000 claims description 3
- 230000000977 initiatory effect Effects 0.000 claims 2
- 239000000463 material Substances 0.000 description 12
- 238000000034 method Methods 0.000 description 10
- 238000010586 diagram Methods 0.000 description 6
- 238000010791 quenching Methods 0.000 description 6
- 239000000843 powder Substances 0.000 description 5
- 230000035939 shock Effects 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000012071 phase Substances 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 229910002480 Cu-O Inorganic materials 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 229910003460 diamond Inorganic materials 0.000 description 2
- 239000010432 diamond Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- 238000010583 slow cooling Methods 0.000 description 2
- 229910000679 solder Inorganic materials 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical group [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000013590 bulk material Substances 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 238000010338 mechanical breakdown Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
Landscapes
- Inorganic Compounds Of Heavy Metals (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
- Containers, Films, And Cooling For Superconductive Devices (AREA)
- Emergency Protection Circuit Devices (AREA)
- Superconductors And Manufacturing Methods Therefor (AREA)
Description
【０００１】
【産業上の利用分野】
本発明は、永久電流スイッチ、更には超電導コイルに利用される超電導導体、及び超電導・常電導転移抵抗型限流器に関する。
【０００２】
【従来の技術】
超電導状態と常電導状態では電気抵抗の比が無限大近くになり、これをスイッチとして利用する試みが古くからなされている。超電導・常電導転移抵抗型限流器は、ある過電流が流れた時、電気抵抗ゼロの超電導状態から、ある有限な抵抗を有する常電導転移をすることを利用し、他のバイパス経路に電流のほとんどを分流させることによって、送電系統あるいはその末端の電機機器を保護する装置である。
一方、永久電流スイッチは超電導体にヒーターを付設しておき、主として熱的に超電導状態と常電導状態を制御し、スイッチとして利用するものである。
【０００３】
これらの応用に要求される材料特性は、スイッチとしての特性が優れた常電導状態での高い抵抗率である。本発明で挙げたＹＢａ2Ｃｕ3Ｏx系超電導体もその１つである酸化物超電導体は常電導状態の電気抵抗率は一般的に高い。加えて臨界電流密度が高いほど、電流経路の断面積が小さくて済むため、常電導状態の電気抵抗を相対的に大きく設計することができる。このように臨界電流密度も高い方が好ましい。特にＹＢａ2Ｃｕ3Ｏx系超電導体の臨界電流密度は高く、限流器などの応用には適していると考えられる。Ｙの位置は他のＬａ，Ｃｅ，Ｐｒ，Ｎｄ，Ｐｍ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂ，Ｌｕからなる群から選ばれた１種類以上の元素で置換してもよく、以下ＲＥＢａ2Ｃｕ3Ｏxと表記する。
【０００４】
このＲＥＢａ2Ｃｕ3Ｏxの製法としては、Ｑｕｅｎｃｈ ａｎｄ Ｍｅｌｔ Ｇｒｏｗｔｈ法（特許登録番号０１８６９８８４、および特開平５−１９３９３８号公報）で代表されるような溶融法が挙げられる。本製法を用いることによって、臨界電流密度が高く、比較的大型の超電導材料を得ることができる。
【０００５】
しかしながら、この方法で得られる形状がバルク状であるために、直線的な電流経路を長くとることに限界がある。従って、常電導状態での電気抵抗を大きくするために、ジグザグな電流経路（ミアンダ構造）とし、全体としての電流経路を長くとる方法がとられる。従来、ミアンダ構造をつくる場合、切断加工を施し、製造するため、導体の強度は断面積を狭くするほど低くなる。また通電によって隣り合う導体間に引力が働くため場合によっては破壊してしまう可能性もある。このため、ミアンダ構造などでは強度が弱く、壊れやすい難点があった。特に常電導転移時の熱的衝撃や、大電流を流すことによる電磁力に耐性のある構造が望まれていた。
【０００６】
【発明が解決しようとする課題】
本発明は電流経路が長く、常電導転移時の熱的衝撃や大電流を流すことによる電磁力に耐性のある構造を有するＲＥＢａ2Ｃｕ3Ｏx系バルク材料を提供することにある。
【０００７】
【課題を解決するための手段及び実施の形態】
本発明は上記の問題を解決するために、Ｑｕｅｎｃｈ ａｎｄ Ｍｅｌｔ Ｇｒｏｗｔｈ法によって作製された材料のように、配向したＲＥＢａ2 Ｃｕ3 Ｏx 系バルク超電導体のＲＥの組成を部分的にＰｒに置換させることによってその部分の超電導性を失わせしめ超電導電流の電流経路を形成させ、結果的に電流経路を長くとる手段を講じたものである。
【０００８】
本発明の第１の特徴は、配向したＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体（１）の内部に前記ＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体と一体形成したＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体（２）により、バルク超電導体（１）の超電導状態での電流経路が形成され、前記ＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体のＰｒの割合ｙが０．５≦ｙ≦１．０であることを特徴とする超電導導体である。ここでＲＥはＹ，Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ，Ｐｍ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂ，Ｌｕからなる群から選ばれた１種類以上の元素をさす。またＲＥ’はＹ，Ｌａ，Ｃｅ，Ｎｄ，Ｐｍ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂ，Ｌｕからなる群から選ばれた１種類以上の元素をさす。
【０００９】
本発明での非超電導体（２）とは、該バルク超電導体（１）が超電導状態となる温度（臨界温度）またはそれ以上の温度において、非電導状態の材料をさす。また本発明での非超電導体（２）により、超電導状態の電流経路を形成されていることとは、該非超電導状態である材料（２）で、該バルク超電導体（１）を流れる電流経路を制限し、電流経路を長くすることを意味する。例えばバルク超電導体（１）の電流経路をミアンダ構造にする場合には、該非超電導状態である材料（２）を図１の（１１）の部分へ配置することが挙げられる。また図１のような２次元的なミアンダ構造だけでなく、電流経路を特開平８−１８１１０号公報のように３次元的なミアンダ構造となるように形成されていてもよい。
【００１０】
本発明の第２の特徴は、前記ＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体（１）の結晶開始温度が前記ＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体（２）の結晶開始温度と同じ、もしくは高いことを特徴とする超電導導体である。
本発明の第３の特徴は、前記の何れかの超電導導体を用いたことを特徴とする超電導・常電導転移抵抗型限流器である。
【００１１】
本発明は常電導転移時の熱的衝撃や大電流を流すことによる電磁力に耐性のある構造をもち、機械的な破壊に強く安定した限流動作などもを長く維持するための超電導導体である。以下、本発明について詳細に説明する。
【００１２】
ＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体（２）でＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体（１）に電流経路を形成することを以下に説明する。ＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体（１）の電流経路を形成するための材料は、高い電気抵抗率をもち、かつ冷却や昇温に対してバルク超電導体（１）と同程度の熱膨張係数をもつことが望まれる。本発明に用いたＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体（２）はバルク超電導体（１）のＲＥをＰｒで置換する量に応じて急激に超電導状態を失い、大きな電気抵抗率を示す。加えて結晶構造がほとんど同じであることから、この非超電導体（２）の熱膨張係数はバルク超電導体（１）とほとんど同じである。この材料を一体形成することで、バルク超電導体（１）の電流経路を長くとることができ、電流経路を長くしたことによる、材料強度の低下を非超電導体（２）で補強することができる。
【００１３】
また該超電導バルク体（１）を該ＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体（２）によって電流経路を形成する場合、（１）および（２）が接する端部部位の角をできるだけ鋭角にせず、できれば丸くしておくと好ましい。これは、例えば非超電導体（２）の端部部位（１２）を図２のような角にしないようにし、図３のように端部部位の角（１３）を丸くし、鋭角とならないように配置することをさす。もし超電導バルク体（１）とＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体（２）とが接する端部部位の角がある場合、端部部位の角には図４のように負荷通電電流が角の部分に集中しやすく、結果としてこの部位で常電導転移を起こしやすい。しかし、この部位は材料強度が弱くなりやすい部分でもあることから、常電導転移による発熱で生じる熱応力、もしくは電流が急激に変化することによる電磁力によって超電導バルク体（１）が破壊されてしまうことがある。それゆえ、端部部位の角をおとして、丸くすることで、上記の障害を回避することができ、電流経路の制限としては好ましい。以上が理由である。
【００１４】
次にＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体（１）の結晶開始温度がＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx非超電導体（２）の結晶開始温度と同じ、もしくは高いことについて説明する。ＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体（１）の結晶開始温度とは、ＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体を高温から徐々に温度を下げていった場合にＲＥＢａ2Ｃｕ3Ｏxの析出が開始する温度を指す。つまり、高温時では、ＲＥ2ＢａＣｕＯ5相とＢａ−Ｃｕ−Ｏを主成分とした液相の共存する半溶融の状態となるが、徐冷することでＲＥＢａ2Ｃｕ3Ｏx相の析出が、ある温度から開始する。結晶開始温度は、この温度を指す。同様にＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体（２）の結晶開始温度とは、ＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体（１）を高温から徐々に温度を下げていった場合にＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx（２）の析出が開始する温度を指す。もし、ＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体（１）の結晶開始温度がＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体（２）の結晶開始温度よりも低いと、ＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体（２）が結晶成長した後に、ＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体（１）が結晶成長しはじめる。この場合、ＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体（１）の結晶成長は電流経路の両側から始まってしまい、中央で両側からの結晶成長面がぶつかり合う。しかし、この結晶成長面のぶつかり合う面では、結晶成長時に取り込めなかったＲＥ2ＢａＣｕＯ5相が析出したり、粒界が発生したりすることが多く、電流経路としての役割を果たすＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体（１）にとって、大きな電流を流すには好ましくない導体となる。しかし逆に、ＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体（１）の結晶開始温度がＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体（２）の結晶開始温度よりも高いと、偏析や粒界が発生するのはＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体（２）であり、大きな電流を流すには好ましい導体となる。以上が理由である。
【００１５】
また、非超電導体（２）のＰｒの割合ｙが０．５以上１．０以下であることについて説明する。ＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体（２）のｙは大きい方が好ましく、具体的には０．５以上が望ましい。これは、ＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体（１）が常電導体となる温度１００Ｋにおいてｙ＝０．５以上の電気抵抗率がｙ＝０．０に比べて少なくとも５倍以上の大きな電気抵抗率を有するという理由による。この高い電気抵抗率によって、ＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体（２）はＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体（１）の電流経路を有効に形成することができる。以上が理由である。
【００１６】
最後に超電導・常電導転移抵抗型限流器について説明する。超電導・常電導転移抵抗型限流器とは、例えば図７のように、超電導導体部（２１）、冷却部（２２）、電流導入部（２３）で構成される送電系統あるいはその末端の電機機器などを保護する装置である。また超電導導体の安定動作のために、一部または全部電流を迂回させる分流部（２４）を備えることも多い。たとえば、上記超電導導体の表面にスパッタ法などにより銀コーティングした限流器も、本発明の超電導・常電導転移抵抗型限流器に含まれる。上記の超電導導体を超電導導体部（２１）に適用することで、高い電気抵抗をもち、常電導転移時の熱的衝撃や大電流を流すことによる電磁力に耐性があり、機械的な破壊に強く安定した限流動作なども長く維持する限流器を得ることができる。以上が理由である。
【００１７】
【実施例】
実施例について以下に図にて説明する。まず以下の実施例におけるＱｕｅｎｃｈ ａｎｄ Ｍｅｌｔ Ｇｒｏｗｔｈ法について説明する。ＲＥＢａ2Ｃｕ3Ｏxの原料粉であるＲＥ2Ｏ3、ＢａＯ2、ＣｕＯ粉体に、微量な白金粉末を加え、混練する。同様にＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏxの原料粉であるＲＥ2Ｏ3、ＢａＯ2、ＣｕＯ粉体に、微量な白金粉末を加え、混練した粉末を作製し、各実施例におけるようなパターンを形成した成形体を作製する。これをＲＥ2ＢａＣｕＯ5相（またはＰｒ2yＲＥ’2-2yＢａＣｕＯ5）とＢａ−Ｃｕ−Ｏを主成分とした液相の共存する半溶融状態まで温度を上げ、その後結晶成長開始温度の高いＲＥ元素を置換したＲＥ2ＢａＣｕＯ5を種結晶として、上記成形体にシーディングをおこない、徐冷させて種結晶から結晶成長させる。以上がＱｕｅｎｃｈ ａｎｄ Ｍｅｌｔ Ｇｒｏｗｔｈ法についての説明である。
【００１８】
（実施例１）
ＰｒyＲＥ' 1-yＢａ2Ｃｕ3Ｏxのｙの変化による電気抵抗率の変化を調べるためＰｒyＲＥ' 1-yＢａ2Ｃｕ3Ｏxバルク超電導体を作製し、電気抵抗率を４端子法にて調べた。試料は最終的に酸素雰囲気中で４００℃で十分アニールされており、ｘの値は６．９２である。
【００１９】
表１はそれぞれの置換量（ｙ）に対する臨界温度（Ｔｃ）と１００ＫにおけるＹＢａ2Ｃｕ3Ｏxの電気比抵抗率を１．０としたときのＰｒyＹ1-yＢａ2Ｃｕ3Ｏx体の電気比抵抗率の大きさを示したものである。この結果よりｙの値で０．５以上を置換したＰｒyＹ1-yＢａ2Ｃｕ3Ｏx系バルク超電導体が非超電導体（２）として有効な組成であるといえる。
【００２０】
【表１】
（実施例２）
試料の超電導導体として、ＲＥをＹとして仕込み組成でＹ2ＢａＣｕＯ5が２５％分散したＹＢａ2Ｃｕ3Ｏx系バルク超電導体（１）のなかに、仕込み組成でＰｒ0.7Ｙ0.3ＢａＣｕＯ5が２５％分散したＰｒ0.7Ｙ0.3Ｂａ2Ｃｕ3Ｏx系非超電導体（２）を図５のように配置した直径６０ｍｍの前駆体を作成し、Ｑｕｅｎｃｈ ａｎｄ Ｍｅｌｔ Ｇｒｏｗｔｈ法で結晶成長させた。種結晶をつけた面から深さ２ｍｍ分を研磨して削り落とし、ダイヤモンドカッターにて厚さ５ｍｍ分を切り取った。これを超電導導体とした。両端部にＡｇを蒸着し、酸素雰囲気中で４００℃で十分アニールした。その後半田にて電流端子と接続した。これを液体窒素に浸した状態で通電を繰り返しおこなったが、安定した通電、限流を確認した。
【００２２】
（実施例３）
試料の超電導導体として、ＲＥをＤｙとして仕込み組成でＤｙ2ＢａＣｕＯ5が３０％分散したＤｙＢａ2Ｃｕ3Ｏx系バルク超電導体（１）のなかに、仕込み組成でＰｒ0.6Ｙ0.4ＢａＣｕＯ5が２５％分散したＰｒ0.6Ｙ0.4Ｂａ2Ｃｕ3Ｏx系非超電導体（２）を図６のように配置した直径６０ｍｍの前駆体を作成し、Ｑｕｅｎｃｈ ａｎｄ Ｍｅｌｔ Ｇｒｏｗｔｈ法で結晶成長させた。種結晶をつけた面から深さ２ｍｍ分を研磨して削り落とし、ダイヤモンドカッターにて厚さ５ｍｍ分を切り取った。これを超電導導体とした。両端部にＡｇを蒸着し、酸素雰囲気中で４００℃で十分アニールした。その後半田にて電流端子と接続した。これを液体窒素に浸した状態で通電を繰り返し、さらに昇温、冷却を繰り返しおこなったが、安定した通電、限流を確認した。
【００２３】
（実施例４）
図７は本発明の第４の発明による超電導・常電導転移抵抗型限流器の一実施例を示す断面図である。超電導導体部（２１）に実施例３で作製した超電導導体を適用した。これにより、常電導転移時にも破壊することなく、安定な限流動作を長く維持する限流器を得ることができた。
【００２４】
【発明の効果】
本発明により、常電導転移時の熱的衝撃や大電流を流すことによる電磁力に耐え安定して限流する効果が得られた。
【図面の簡単な説明】
【図１】 バルク超電導体の電流経路をミアンダ構造にする場合の例を示す図である。
【図２】 非超電導体の端部部位に角をつけた場合の例を示す図である。
【図３】 非超電導体の端部部位を丸くした場合の例を示す図である。
【図４】 非超電導体の端部部位に角がある場合の電流経路を示す図である。
【図５】 実施例２に使用した超電導導体の概略を示す図である。
【図６】 実施例３に使用した超電導導体の概略を示す図である。
【図７】 実施例４に使用した超電導・常電導転移抵抗型限流器の一実施例を示す断面図である。
【符号の説明】
１ ＲＥＢａ2Ｃｕ3Ｏx系バルク超電導体
２ ＰｒyＲＥ’1-yＢａ2Ｃｕ3Ｏx系非超電導体
１１ 非超電導状態である材料（２）を配置する部分
１２ 角をもつ非超電導体（２）の端部部位
１３ 丸みをもつ非超電導体（２）の端部部位
２１ 超電導導体部
２２ 冷却部
２３ 電流導入部
２４ 分流部[0001]
[Industrial application fields]
The present invention relates to a permanent current switch, a superconducting conductor used for a superconducting coil, and a superconducting / normal conducting transition resistance type current limiter.
[0002]
[Prior art]
In the superconducting state and the normal conducting state, the ratio of electrical resistance is close to infinity, and attempts to use this as a switch have been made for a long time. The superconducting / normal conducting transition resistance type fault current limiter uses the normal conducting transition with a certain finite resistance from the superconducting state with zero electrical resistance when a certain overcurrent flows, and the current flows to other bypass paths. It is a device that protects the power transmission system or the electrical equipment at its end by dividing most of the current.
On the other hand, the permanent current switch is provided with a heater attached to the superconductor, and mainly controls the superconducting state and the normal conducting state thermally, and is used as a switch.
[0003]
The material characteristics required for these applications are high resistivity in the normal conducting state with excellent characteristics as a switch. The oxide superconductor, which is one of the YBa 2 Cu 3 O x -based superconductors mentioned in the present invention, generally has a high electrical resistivity in the normal conducting state. In addition, the higher the critical current density, the smaller the cross-sectional area of the current path, so that the electrical resistance in the normal conduction state can be designed to be relatively large. Thus, it is preferable that the critical current density is also high. In particular, the critical current density of the YBa 2 Cu 3 O x -based superconductor is high, and is considered suitable for applications such as current limiters. The position of Y is replaced with one or more elements selected from the group consisting of other La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Hereinafter, it is expressed as REBa 2 Cu 3 O x .
[0004]
As a method for producing this REBa 2 Cu 3 O x , a melting method represented by the Quench and Melt Growth method (patent registration number 01898984 and Japanese Patent Laid-Open No. 5-1993938) can be mentioned. By using this production method, a superconducting material having a high critical current density and a relatively large size can be obtained.
[0005]
However, since the shape obtained by this method is a bulk shape, there is a limit in taking a long linear current path. Therefore, in order to increase the electric resistance in the normal conducting state, a method is adopted in which a zigzag current path (meander structure) is used and the current path as a whole is made longer. Conventionally, when making a meander structure, since the cutting process is performed and manufactured, the strength of the conductor becomes lower as the cross-sectional area becomes smaller. Moreover, since an attractive force acts between adjacent conductors due to energization, there is a possibility of destruction in some cases. For this reason, the meander structure has a weakness and is fragile. In particular, there has been a demand for a structure that is resistant to thermal shock during normal conduction transition and electromagnetic force caused by flowing a large current.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a REBa 2 Cu 3 O x bulk material having a long current path and a structure resistant to electromagnetic force caused by a thermal shock during normal conduction transition or a large current flow.
[0007]
[Means for Solving the Problems and Embodiments]
In order to solve the above problems, the present invention partially replaces the RE composition of the oriented REBa 2 Cu 3 O x based bulk superconductor with Pr, such as a material produced by the Quench and Melt Growth method. Thus, the superconductivity of the portion is lost, a current path of the superconducting current is formed, and as a result, a means for taking a longer current path is provided.
[0008]
A first aspect of the present invention, oriented REBa 2 Cu 3 O x type wherein the interior of the bulk superconductor (1) REBa 2 Cu 3 O x system Pr is integrally formed with the bulk superconductor y RE '1-y Ba The current path in the superconducting state of the bulk superconductor (1) is formed by the 2 Cu 3 O x non-superconductor (2), and the Pr y RE ′ 1-y Ba 2 Cu 3 O x non-superconductor The superconducting conductor is characterized in that the Pr ratio y is 0.5 ≦ y ≦ 1.0. Here, RE represents one or more elements selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. RE ′ represents one or more elements selected from the group consisting of Y, La, Ce, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.
[0009]
The non-superconductor (2) in the present invention refers to a material in a non-conductive state at a temperature (critical temperature) at which the bulk superconductor (1) is in a superconductive state or higher. The fact that the non-superconductor (2) in the present invention forms a current path in the superconducting state means that the current path flowing through the bulk superconductor (1) is the material (2) in the non-superconducting state. It means limiting and lengthening the current path. For example, in the case where the current path of the bulk superconductor (1) has a meander structure, the material (2) in the non-superconducting state may be disposed on the portion (11) in FIG. In addition to the two-dimensional meander structure as shown in FIG. 1, the current path may be formed to have a three-dimensional meander structure as disclosed in JP-A-8-18110.
[0010]
The second feature of the present invention is that the crystal starting temperature of the REBa 2 Cu 3 O x bulk superconductor (1) is that of the Pr y RE ′ 1-y Ba 2 Cu 3 O x nonsuperconductor (2). It is a superconducting conductor characterized by being the same as or higher than the crystal starting temperature.
A third feature of the present invention is a superconducting / normal conducting transition resistance type current limiter characterized by using any one of the above superconducting conductors.
[0011]
The present invention is a superconducting conductor that has a structure that is resistant to electromagnetic force due to a thermal shock and a large current flowing during normal conduction transition, and that maintains a stable current-limiting operation that is strong against mechanical breakdown and long. is there. Hereinafter, the present invention will be described in detail.
[0012]
The formation of a current path in the REBa 2 Cu 3 O x bulk superconductor (1) by the Pr y RE ′ 1-y Ba 2 Cu 3 O x non-superconductor (2) will be described below. The material for forming the current path of the REBa 2 Cu 3 O x bulk superconductor (1) has a high electrical resistivity and the same heat as the bulk superconductor (1) with respect to cooling and temperature rise. It is desirable to have an expansion coefficient. The Pr y RE ′ 1-y Ba 2 Cu 3 O x -based non-superconductor (2) used in the present invention suddenly loses the superconducting state depending on the amount of replacement of RE in the bulk superconductor (1) with Pr. Shows large electrical resistivity. In addition, since the crystal structure is almost the same, the thermal expansion coefficient of the non-superconductor (2) is almost the same as that of the bulk superconductor (1). By integrally forming this material, the current path of the bulk superconductor (1) can be made longer, and the decrease in material strength due to the longer current path can be reinforced by the non-superconductor (2). .
[0013]
Further, when the current path is formed by the Pr y RE ′ 1-y Ba 2 Cu 3 O x -based non-superconductor (2) in the superconducting bulk body (1), the end part where (1) and (2) are in contact with each other It is preferable to make the corners as round as possible. This is because, for example, the end portion (12) of the non-superconductor (2) is not set to the corner as shown in FIG. 2, and the end portion corner (13) is rounded as shown in FIG. It means to place in. If the superconducting bulk body (1) and the Pr y RE ′ 1-y Ba 2 Cu 3 O x -based non-superconductor (2) have corners at the end part, the corners at the end part are shown in FIG. Thus, the load conduction current is likely to concentrate on the corner portion, and as a result, the normal conduction transition is likely to occur at this portion. However, since this part is also a part where the material strength tends to be weak, the superconducting bulk body (1) is destroyed by the thermal stress generated by the heat generation due to the normal conduction transition or the electromagnetic force due to the rapid change of the current. Sometimes. Therefore, by rounding the corners of the end portions, it is possible to avoid the above-mentioned obstacles, which is preferable as a restriction on the current path. This is the reason.
[0014]
Next, the crystal starting temperature of the REBa 2 Cu 3 O x bulk superconductor (1) is the same as or higher than the crystal starting temperature of the Pr y RE ′ 1-y Ba 2 Cu 3 O x non-superconductor (2). explain. REBa The 2 Cu 3 O x type crystal starting temperature of the bulk superconductor (1), when gradually lowering the temperature of REBa 2 Cu 3 O x type bulk superconductor from hot REBa 2 Cu 3 O x Refers to the temperature at which precipitation begins. That is, at a high temperature, the RE 2 BaCuO 5 phase and the liquid phase mainly composed of Ba—Cu—O coexist in a semi-molten state, but the REBa 2 Cu 3 O x phase is precipitated by slow cooling. Start from a certain temperature. The crystal onset temperature refers to this temperature. Similarly, the crystal start temperature of Pr y RE ′ 1-y Ba 2 Cu 3 O x -based non-superconductor (2) is the temperature of REBa 2 Cu 3 O x -based bulk superconductor (1) gradually decreased from a high temperature. In this case, it indicates the temperature at which Pr y RE ′ 1-y Ba 2 Cu 3 O x (2) starts to precipitate. If the crystal start temperature of the REBa 2 Cu 3 O x bulk superconductor (1) is lower than the crystal start temperature of the Pr y RE ′ 1-y Ba 2 Cu 3 O x nonsuperconductor (2), then Pr After the y RE ′ 1-y Ba 2 Cu 3 O x -based non-superconductor (2) grows, the REBa 2 Cu 3 O x -based bulk superconductor (1) begins to grow. In this case, crystal growth of the REBa 2 Cu 3 O x bulk superconductor (1) starts from both sides of the current path, and the crystal growth surfaces from both sides collide with each other in the center. However, the RE 2 BaCuO 5 phase that could not be taken in at the time of crystal growth often precipitates or a grain boundary is generated on the surface where the crystal growth surfaces collide with each other, and REBa 2 Cu 3 that plays a role as a current path. For the O x -based bulk superconductor (1), it becomes an undesired conductor for passing a large current. On the other hand, if the crystal starting temperature of the REBa 2 Cu 3 O x bulk superconductor (1) is higher than the crystal starting temperature of the Pr y RE ′ 1-y Ba 2 Cu 3 O x nonsuperconductor (2), In this case, segregation and grain boundaries occur in the Pr y RE ′ 1-y Ba 2 Cu 3 O x non-superconductor (2), which is a preferable conductor for flowing a large current. This is the reason.
[0015]
The fact that the Pr ratio y of the non-superconductor (2) is 0.5 or more and 1.0 or less will be described. It is preferable that y of the Pr y RE ′ 1-y Ba 2 Cu 3 O x -based non-superconductor (2) is large, specifically 0.5 or more is desirable. This is because the electrical resistivity of y = 0.5 or more is at least 5 times larger than y = 0.0 at a temperature of 100 K at which the REBa 2 Cu 3 O x bulk superconductor (1) becomes a normal conductor. This is because it has electrical resistivity. With this high electrical resistivity, the Pr y RE ′ 1-y Ba 2 Cu 3 O x -based non-superconductor (2) can effectively form the current path of the REBa 2 Cu 3 O x -based bulk superconductor (1). Can do. This is the reason.
[0016]
Finally, the superconducting / normal conducting transition resistance type fault current limiter will be explained. For example, as shown in FIG. 7, the superconducting / normal conducting transition resistance type current limiter is a power transmission system composed of a superconducting conductor (21), a cooling unit (22), and a current introducing unit (23), or an electric machine at the end thereof. It is a device that protects equipment. In addition, for the stable operation of the superconducting conductor, a shunt part (24) for diverting part or all of the current is often provided. For example, a current limiting device in which the surface of the superconducting conductor is silver-coated by sputtering or the like is also included in the superconducting / normal conducting transition resistance type current limiting device of the present invention. By applying the above-mentioned superconducting conductor to the superconducting conductor (21), it has high electrical resistance, is resistant to electromagnetic force due to thermal shock and large current flowing during normal conduction transition, and is resistant to mechanical destruction. A current limiting device that maintains a strong and stable current limiting operation for a long time can be obtained. This is the reason.
[0017]
【Example】
Examples will be described below with reference to the drawings. First, the Quench and Melt Growth method in the following embodiments will be described. A small amount of platinum powder is added to and kneaded with RE 2 O 3 , BaO 2 , and CuO powder, which are raw powders of REBa 2 Cu 3 O x . Similarly, a small amount of platinum powder is added to RE 2 O 3 , BaO 2 , CuO powder, which is a raw powder of Pr y RE ′ 1-y Ba 2 Cu 3 O x , and a kneaded powder is produced. A molded body having a pattern as shown in FIG. The temperature is raised to a semi-molten state in which a liquid phase mainly composed of RE 2 BaCuO 5 phase (or Pr 2y RE ′ 2-2y BaCuO 5 ) and Ba—Cu—O coexists, and then the crystal growth start temperature is high. Using the RE 2 BaCuO 5 substituted with the RE element as a seed crystal, seeding is performed on the molded body, followed by slow cooling and crystal growth from the seed crystal. The above is an explanation of the Quench and Melt Growth method.
[0018]
Example 1
To produce a Pr y RE '1-y Ba 2 Cu 3 O x to examine the change in the electrical resistivity due to the change in y Pr y RE' 1-y
[0019]
Table 1 shows Pr y Y 1-y Ba 2 Cu 3 O x when the critical temperature (Tc) for each substitution amount (y) and the electrical resistivity of YBa 2 Cu 3 O x at 100 K are 1.0. It shows the magnitude of the electrical resistivity of the body. From this result, it can be said that the Pr y Y 1-y Ba 2 Cu 3 O x based bulk superconductor substituted with 0.5 or more in the value of y is an effective composition as the non-superconductor (2).
[0020]
[Table 1]
(Example 2)
In the YBa 2 Cu 3 O x bulk superconductor (1) in which RE is Y and 25% of Y 2 BaCuO 5 is dispersed as a superconducting conductor as a sample superconductor, Pr 0.7 Y 0.3 BaCuO 5 is 25 in the charging composition. A precursor having a diameter of 60 mm in which Pr 0.7 Y 0.3 Ba 2 Cu 3 O x -based non-superconductor (2) dispersed in% was arranged as shown in FIG. 5 was prepared, and crystals were grown by the Quench and Melt Growth method. A 2 mm depth was polished and scraped off from the surface to which the seed crystal was applied, and a 5 mm thickness was cut with a diamond cutter. This was a superconducting conductor. Ag was vapor-deposited on both ends and sufficiently annealed at 400 ° C. in an oxygen atmosphere. After that, the current terminal was connected with solder. While energization was repeated in a state immersed in liquid nitrogen, stable energization and current limiting were confirmed.
[0022]
(Example 3)
In the DyBa 2 Cu 3 O x bulk superconductor (1) in which 30% of Dy 2 BaCuO 5 is dispersed with RE as Dy as the superconductor of the sample, Pr 0.6 Y 0.4 BaCuO 5 is 25 according to the charge composition. A precursor with a diameter of 60 mm in which Pr 0.6 Y 0.4 Ba 2 Cu 3 O x -based non-superconductor (2) dispersed in% was arranged as shown in FIG. 6 was prepared, and crystals were grown by the Quench and Melt Growth method. A 2 mm depth was polished and scraped off from the surface to which the seed crystal was applied, and a 5 mm thickness was cut with a diamond cutter. This was a superconducting conductor. Ag was vapor-deposited on both ends and sufficiently annealed at 400 ° C. in an oxygen atmosphere. After that, the current terminal was connected with solder. While this was immersed in liquid nitrogen, energization was repeated, and the temperature was raised and cooled repeatedly, but stable energization and current limiting were confirmed.
[0023]
Example 4
FIG. 7 is a cross-sectional view showing an embodiment of a superconducting / normal conducting transition resistance type current limiting device according to the fourth invention of the present invention. The superconducting conductor produced in Example 3 was applied to the superconducting conductor part (21). As a result, it was possible to obtain a current limiting device that maintains a stable current limiting operation for a long time without breaking even during normal conduction transition.
[0024]
【The invention's effect】
According to the present invention, the effect of stably withstanding the electromagnetic force due to the thermal shock at the time of the normal conduction transition and the flow of a large current can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example in which a current path of a bulk superconductor has a meander structure.
FIG. 2 is a diagram showing an example in the case where a corner is added to an end portion of a non-superconductor.
FIG. 3 is a diagram showing an example when the end portion of the non-superconductor is rounded.
FIG. 4 is a diagram showing a current path when there is a corner at the end portion of the non-superconductor.
5 is a diagram showing an outline of a superconducting conductor used in Example 2. FIG.
6 is a diagram showing an outline of a superconducting conductor used in Example 3. FIG.
7 is a cross-sectional view showing one embodiment of a superconducting / normal conducting transition resistance type current limiting device used in Embodiment 4. FIG.
[Explanation of symbols]
1 REBa 2 Cu 3 O x type bulk superconductor 2 Pr y RE '1-y Ba 2 Cu 3 O x based
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13747597A JP3943652B2 (en) | 1997-05-13 | 1997-05-13 | Superconducting conductor and superconducting / normal conducting transition resistance type fault current limiter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13747597A JP3943652B2 (en) | 1997-05-13 | 1997-05-13 | Superconducting conductor and superconducting / normal conducting transition resistance type fault current limiter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10316421A JPH10316421A (en) | 1998-12-02 |
| JP3943652B2 true JP3943652B2 (en) | 2007-07-11 |
Family
ID=15199493
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13747597A Expired - Fee Related JP3943652B2 (en) | 1997-05-13 | 1997-05-13 | Superconducting conductor and superconducting / normal conducting transition resistance type fault current limiter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3943652B2 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4550217B2 (en) * | 2000-04-03 | 2010-09-22 | エスアイアイ・ナノテクノロジー株式会社 | Superconducting radiation detector |
| JP2003101089A (en) * | 2001-09-21 | 2003-04-04 | Central Japan Railway Co | Persistent current switch material and manufacturing method therefor |
| DE602004010247T2 (en) * | 2004-07-30 | 2008-10-02 | Nexans | Cylindrically shaped superconducting device and its use as a resistive current limiter |
| GB201705214D0 (en) | 2017-03-31 | 2017-05-17 | Tokamak Energy Ltd | Quench detection in superconducting magnets |
| JP7330152B2 (en) * | 2020-09-15 | 2023-08-21 | 株式会社東芝 | Oxide superconductor and its manufacturing method |
| JP7330153B2 (en) * | 2020-09-15 | 2023-08-21 | 株式会社東芝 | Oxide superconductor and its manufacturing method |
-
1997
- 1997-05-13 JP JP13747597A patent/JP3943652B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH10316421A (en) | 1998-12-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5828291A (en) | Multiple compound conductor current-limiting device | |
| EP0401461B1 (en) | Oxide superconductor and method of manufacturing the same | |
| EP1830446B1 (en) | Electrical device for current conditioning | |
| US5235309A (en) | Resistive current limiter | |
| US6584333B1 (en) | Protected superconducting component and method for producing the same | |
| JP3943652B2 (en) | Superconducting conductor and superconducting / normal conducting transition resistance type fault current limiter | |
| US6344956B1 (en) | Oxide bulk superconducting current limiting element current | |
| US6762673B1 (en) | Current limiting composite material | |
| CA2251488C (en) | High-temperature superconductor arrangement | |
| JPH10136563A (en) | Current-limiting element using oxide superconductor and its manufacturing method | |
| JP2018035015A (en) | Superconducting bulk conjugate and manufacturing method of superconducting bulk conjugate | |
| JPH0883932A (en) | Current limiting element | |
| JPH03226228A (en) | Current limit resistance device | |
| JPH05190918A (en) | Resistive current limiter and manufacture thereof | |
| JP5038603B2 (en) | Superconducting resistive current limiter with shunt resistance | |
| JPH10125966A (en) | Oxide superconductor and its manufacture | |
| EP1898475B1 (en) | Resistive high temperature superconductor fault current limiter | |
| JP4589698B2 (en) | Superconducting bulk material | |
| JPH10125146A (en) | Oxide superconductor current limiter | |
| JP2788240B2 (en) | Current limiting device | |
| CA2177169C (en) | Current-limiting device | |
| JPH1094167A (en) | Current-limiting element using oxide superconductor and its manufacture | |
| DE4244973C2 (en) | Layer arrangement of a high-temperature superconductor, process for its production and use of the arrangement | |
| JP3709531B2 (en) | Manufacturing method of oxide superconductor | |
| JP2892418B2 (en) | Metal-oxide superconductor composite and method for producing the same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| RD02 | Notification of acceptance of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7422 Effective date: 20050908 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20060925 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20061128 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20070126 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20070327 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20070406 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110413 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120413 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130413 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130413 Year of fee payment: 6 |
|
| S531 | Written request for registration of change of domicile |
Free format text: JAPANESE INTERMEDIATE CODE: R313531 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130413 Year of fee payment: 6 |
|
| S533 | Written request for registration of change of name |
Free format text: JAPANESE INTERMEDIATE CODE: R313533 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130413 Year of fee payment: 6 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140413 Year of fee payment: 7 |
|
| LAPS | Cancellation because of no payment of annual fees |