EP0107830B1 - Permanent current switch for short-circuiting at least one superconducting magnet winding - Google Patents

Permanent current switch for short-circuiting at least one superconducting magnet winding Download PDF

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Publication number
EP0107830B1
EP0107830B1 EP83110191A EP83110191A EP0107830B1 EP 0107830 B1 EP0107830 B1 EP 0107830B1 EP 83110191 A EP83110191 A EP 83110191A EP 83110191 A EP83110191 A EP 83110191A EP 0107830 B1 EP0107830 B1 EP 0107830B1
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Prior art keywords
conductor
current switch
pieces
contact piece
contact
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EP83110191A
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German (de)
French (fr)
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EP0107830A1 (en
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Holger Franksen
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Siemens AG
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Siemens AG
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/002—Very heavy-current switches
    • H01H33/004—Very heavy-current switches making use of superconducting contacts

Definitions

  • the invention relates to a continuous current switch for short-circuiting at least one superconducting magnetic winding with at least two contact pieces, each having a plurality of superconducting conductor pieces, which are arranged in parallel with one another and connected to a carrier element, and are cooled by a cryogenic coolant, and with an actuating device for joining the superconducting conductor pieces together with a predetermined contact force.
  • a corresponding permanent current switch is known from DE-A-2 521 328.
  • the magnetic winding can therefore be short-circuited at its ends by means of a low-resistance permanent current switch. The current then flows almost undamped in the short-circuited circuit thus formed, and the power supply required to excite the magnet winding can thus be interrupted.
  • the known continuous current switch contains two contact pieces, each of which has a carrier element made of normally conducting material as a matrix, in which superconducting conductor pieces arranged parallel to one another are embedded.
  • a mechanical actuation device required for opening and closing the switch is designed such that the superconducting conductor pieces of the two contact pieces and their normally conductive parts can be joined together.
  • the contact surfaces are held indirectly by a cryogenic coolant at the operating temperature of the superconducting conductor pieces, since they are arranged in a vacuum chamber in order to be able to exclude contamination of the surfaces.
  • the surface of one contact piece is curved, while the other contact piece can have, for example, a flat or a concave surface.
  • a relatively high contact force is required in addition to an exact guidance of the contact pieces.
  • reproducible resistances in the order of magnitude of 10- 9 ⁇ or even less cannot be easily guaranteed.
  • Resistors of this type are required in particular for superconducting large magnets, such as are to be provided for devices for nuclear fusion or for nuclear spin tomography, for example.
  • This requirement cannot be met with the superconducting contact device known from US-A-3096421.
  • This contact device has two contact pieces with superconducting conductor pieces. In this case, only a single wire-shaped conductor piece is to be fastened to the first contact piece, while the second contact piece, which is designed to be movable, comprises three bow-like conductor pieces which are aligned perpendicularly with respect to the individual conductor piece of the first contact piece and are pressed onto the single conductor piece by means of springs. These bow-shaped conductor pieces of the second contact piece are not connected in parallel, so that in each case only a single contact point between two wires forms a contact.
  • the contact device constructed in this way should be part of a network, for example a computer network.
  • the object of the present invention is therefore to improve the known continuous current switch in such a way that it can be used to easily obtain contact resistances in the order of magnitude mentioned.
  • This object is achieved according to the invention in that on each of the mutually facing surfaces of the contact pieces at least five parallel superconducting conductor pieces are arranged lying in at least largely parallel planes such that the conductor pieces of the first contact piece cross the conductor pieces of the further contact piece, and that the conductor pieces of the first contact piece are firmly attached to the surface of the corresponding support element, while each conductor piece of the further contact piece is held on the associated support element at least above each crossing point with the conductor pieces of the first contact piece by means of a resilient support device.
  • FIGS. 1 and 2 each schematically illustrate a section through an exemplary embodiment of a continuous current switch according to the invention.
  • the continuous current switch indicated in a cross section in FIG. 1 contains two contact pieces 2 and 3 which can be moved or joined together by means of an actuating device which is not shown in the figure.
  • the first contact piece 2 is arranged stationary, while the further, movably designed contact piece 3 can be pressed against the stationary contact piece 2 by means of the actuating device with an actuating force F represented by an arrow.
  • the two contact pieces 2 and 3 are each electrically conductively connected to the ends of the conductors of at least one superconducting magnet winding (not shown in the figure) or directly represent the conductor ends of this winding.
  • the magnet windings can be, for example, the windings of a magnet system for generating the magnetic Basic field of a system for nuclear spin tomography or the winding of a magnet of a nuclear fusion system.
  • The, for example, stationary contact piece 2 contains a flat contact plate 4, on the surface of which faces the movable contact piece 3, a large number of superconducting conductor pieces 5 aligned in parallel with one another is mechanically fixed.
  • at least five superconducting conductor pieces 5 are soldered onto the contact plate 4 which serves as the carrier element.
  • the contact plate 4 advantageously consists of an electrically highly conductive material which is normally conductive at the operating temperature of the superconducting conductor pieces 5, e.g. made of copper or aluminum.
  • the superconducting conductor pieces e.g. have a round or rectangular cross section, it can in particular be a so-called high-current superconductor.
  • These conductor pieces can be both unstabilized and stabilized with normally conductive material, with superconducting conductor parts of these conductor pieces preferably coming to rest at least on the surface side facing the movable contact piece 3.
  • the movable contact piece 3 also contains a large number of individual superconducting conductor pieces 6 aligned parallel to one another. These conductor pieces are arranged transversely with respect to the conductor pieces 5 of the stationary contact piece 2, so that when the conductor pieces 5 and 6 of the two contact pieces 2 are joined together and 3 result in a multiplicity of crossing or contact points 7.
  • the conductor pieces 6 should not be rigidly attached to a movable contact plate 8 connected to the actuating device, corresponding to the conductor pieces 5; rather, a resilient support of the conductor pieces 6 is provided with respect to their contact plate 8 serving as a carrier element.
  • each conductor piece 6 is fastened to the movable contact plate 8 in the areas of its crossing points 7 with each conductor piece 5 of the stationary contact piece 2 via a corresponding support device 9, which also serves to guide and hold the conductor pieces 6.
  • This support device 9 contains a guide rod 11 projecting through a corresponding bore 10 in the contact plate 8, which is attached at one end to the corresponding superconducting conductor piece 6 by means of, for example, a disc-shaped connecting element 12 and which is prevented from slipping out by a stop 13 at its opposite end is secured from the bore 10.
  • a spring 14 enclosing the respective guide rod 11 is clamped with a predetermined spring force.
  • the superconducting conductor pieces 5 and 6 can be arranged directly in a cryogenic medium which ensures their superconductivity, which is in particular the cooling medium of the connected superconducting magnet winding. If necessary, indirect cooling of these conductor sections is also possible (cf. DE-A-2 521 328).
  • the relatively low actuating force F of the continuous current switch not only permits the actuation assumed in FIG. 1 by means of a linkage, but also a pneumatic or hydraulic actuation is possible. Such actuation is known per se (DE-C-2324371).
  • a corresponding exemplary embodiment is indicated in FIG. 2 as a cross section. It is assumed that one of the contact pieces is stationary and corresponds to the contact piece 2 with conductor pieces 5 according to FIG. 1.
  • a large number of superconducting conductor pieces 16 of a further contact piece, designated 17, of this switch is mechanically connected to a stationary, plate-shaped carrier element 19 via a pneumatic or hydraulic support device 18.
  • the support device 18 contains a thin, flat membrane 20 which e.g.
  • This membrane 20 consists of stainless steel and to which the conductor pieces 16 are rigidly attached according to the arrangement of Figure 1.
  • This membrane 20 is fastened to the stationary support element 19 via a bellows 21.
  • the interior 22, which is enclosed by this carrier element 19, the bellows 21 and the membrane 20 holding the conductor pieces 16 in a vacuum-tight manner, can be pressurized via a pressure line 23, so that the conductor pieces 16 have approximately the same contact force K on the conductor pieces 5 arranged transversely to them Contact piece 2 are pressed.
  • gaseous or liquid helium can in particular be provided as the pressure medium.
  • the continuous current switch according to the invention can be provided particularly advantageously for magnetic windings which are wound with superconducting conductor cables made of several superconducting individual conductors.
  • the superconducting individual conductors can form the superconductor pieces of the contact pieces directly from the fanned-out conductor cable.
  • the continuous current switch according to the invention has only two flat contact pieces with conductor pieces to be joined together, the conductor pieces being cushioned on one level above each crossing or contact point.
  • the continuous current switch according to the invention can equally well have more than two levels with line pieces, with resilient support of the conductor pieces being provided for every second level.

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  • Containers, Films, And Cooling For Superconductive Devices (AREA)

Description

Die Erfindung bezieht sich auf einen Dauerstromschalter zum Kurzschliessen mindestens einer supraleitenden Magnetwicklung mit mindestens zwei Kontaktstücken, die jeweils mehrere, parallel untereinander angeordnete und mit einem Trägerelement verbundene, supraleitende, von einem kryogenen Kühlmittel gekühlte Leiterstücke aufweisen, und mit einer Betätigungsvorrichtung zum Aneinanderfügen der supraleitenden Leiterstücke mit einer vorbestimmten Kontaktkraft. Ein entsprechender Dauerstromschalter ist aus der DE-A-2 521 328 bekannt.The invention relates to a continuous current switch for short-circuiting at least one superconducting magnetic winding with at least two contact pieces, each having a plurality of superconducting conductor pieces, which are arranged in parallel with one another and connected to a carrier element, and are cooled by a cryogenic coolant, and with an actuating device for joining the superconducting conductor pieces together with a predetermined contact force. A corresponding permanent current switch is known from DE-A-2 521 328.

Wenn das magnetische Feld einer supraleitenden Magnetwicklung, insbesondere einer Hochfeldmagnetspule, einmal aufgebaut ist, braucht zur Aufrechterhaltung des Feldes der Spule von aussen praktisch keine weitere elektrische Energie mehr zugeführt zu werden. Dann ist lediglich der Energiebedarf der zur Aufrechterhaltung des supraleitenden Zustandes der Wicklung benötigten Kälteeinrichtungen noch zu decken. Zur Speicherung der in die Magnetwicklung eingespeisten elektrischen Energie kann man deshalb die Magnetwicklung an ihren Enden mittels eines möglichst widerstandsarmen Dauerstromschalters kurzschliessen. Der Strom fliesst dann fast ungedämpft in dem so ausgebildeten, kurzgeschlossenen Stromkreis, und die zur Erregung der Magnetwicklung erforderliche Stromversorgung kann somit unterbrochen werden.Once the magnetic field of a superconducting magnetic winding, in particular a high-field magnetic coil, has been built up, practically no further electrical energy needs to be supplied to the coil from the outside in order to maintain the field. Then only the energy requirement of the cooling devices required to maintain the superconducting state of the winding has to be covered. To store the electrical energy fed into the magnetic winding, the magnetic winding can therefore be short-circuited at its ends by means of a low-resistance permanent current switch. The current then flows almost undamped in the short-circuited circuit thus formed, and the power supply required to excite the magnet winding can thus be interrupted.

Der bekannte Dauerstromschalter enthält zwei Kontaktstücke, die jeweils ein Trägerelement aus normalleitendem Material als Matrix aufweisen, in der untereinander parallel angeordnete supraleitende Leiterstücke eingebettet sind. Eine zum Öffnen und Schliessen des Schalters erforderliche mechanische Betätigungsvorrichtung ist so gestaltet, dass jeweils die supraleitenden Leiterstücke der beiden Kontaktstücke sowie ihre normalleitenden Teile aneinandergefügt werden können. Die Kontaktflächen werden dabei indirekt von einem kryogenen Kühlmittel auf der Betriebstemperatur der supraleitenden Leiterstücke gehalten, da sie in einer Vakuumkammer angeordnet sind, um so Verunreinigungen der Oberflächen ausschliessen zu können.The known continuous current switch contains two contact pieces, each of which has a carrier element made of normally conducting material as a matrix, in which superconducting conductor pieces arranged parallel to one another are embedded. A mechanical actuation device required for opening and closing the switch is designed such that the superconducting conductor pieces of the two contact pieces and their normally conductive parts can be joined together. The contact surfaces are held indirectly by a cryogenic coolant at the operating temperature of the superconducting conductor pieces, since they are arranged in a vacuum chamber in order to be able to exclude contamination of the surfaces.

Bei diesem Dauerstromschalter ist die Oberfläche des einen Kontaktstückes gekrümmt gestaltet, während das andere Kontaktstück z.B. eine ebene oder eine konkav geformte Oberfläche aufweisen kann. Um einen geringen Übergangswiderstand zwischen den supraleitenden Leiterstücken der beiden Kontaktstücke zu gewährleisten, ist neben einer exakten Führung der Kontaktstücke auch eine verhältnismässig hohe Kontaktkraft erforderlich. Dennoch kann dabei nicht gewährleistet werden, dass alle entsprechenden supraleitenden Leiterstücke der beiden Kontaktstücke mit etwa gleicher Kontaktkraft aneinandergefügt werden und somit annähernd gleiche Übergangswiderstände hervorrufen. Vielmehr ist davon auszugehen, dass einzelne supraleitende Leiterstücke nur mit verhältnismässig geringer Kontaktkraft aneinanderliegen und somit zu entsprechend hohen Übergangswiderständen führen. Bei dem bekannten Dauerstromschalter lassen sich somit reproduzierbare Widerstände in der Grössenordnung von 10-9 Ω oder noch weniger nicht ohne weiteres gewährleisten. Derartige Widerstände werden insbesondere für supraleitende Grossmagnete, wie sie z.B. für Einrichtungen zur Kernfusion oder zur Kernspin-Tomographie vorzusehen sind, gefordert.In this continuous current switch, the surface of one contact piece is curved, while the other contact piece can have, for example, a flat or a concave surface. In order to ensure a low contact resistance between the superconducting conductor pieces of the two contact pieces, a relatively high contact force is required in addition to an exact guidance of the contact pieces. Nevertheless, it cannot be guaranteed that all corresponding superconducting conductor pieces of the two contact pieces are joined together with approximately the same contact force and thus cause approximately the same contact resistance. Rather, it can be assumed that individual superconducting conductor pieces only lie against one another with a relatively low contact force and thus lead to correspondingly high contact resistances. With the known continuous current switch, reproducible resistances in the order of magnitude of 10- 9 Ω or even less cannot be easily guaranteed. Resistors of this type are required in particular for superconducting large magnets, such as are to be provided for devices for nuclear fusion or for nuclear spin tomography, for example.

Diese Forderung lässt sich auch nicht mit der aus der US-A-3096421 bekannten supraleitenden Kontakteinrichtung erfüllen. Diese Kontakteinrichtung weist zwei Kontaktstücke mit supraleitenden Leiterstücken auf. Dabei soll an dem ersten Kontaktstück nur ein einziges drahtförmiges Leiterstück befestigt sein, während das zweite Kontaktstück, das beweglich gestaltet ist, drei bügelartige Leiterstücke umfasst, die senkrecht bezüglich des einzelnen Leiterstückes des ersten Kontaktstückes ausgerichtet sind und mittels Federn an das einzige Leiterstück angedrückt werden. Diese bügelartigen Leiterstücke des zweiten Kontaktstückes sind nicht parallelgeschaltet, so dass jeweils nur ein einziger Kontaktpunkt zwischen zwei Drähten einen Kontakt bildet. Die so aufgebaute Kontakteinrichtung soll Teil eines Netzwerkes, beispielsweise eines Computernetzwerkes, sein. In solchen Netzwerken fliessen bekanntlich nur sehr geringe Ströme, so dass Übergangswiderstände zwischen den einzelnen Leiterstücken der Kontaktstücke mit Werten im Milliohmbereich ausreichen. Derartige Widerstandswerte sind jedoch für einen Dauerstromschalter zum Kurzschliessen eines supraleitenden Magneten, in dem bekanntlich ganz wesentlich höhere Ströme fliessen, von vornherein nicht zu tolerieren.This requirement cannot be met with the superconducting contact device known from US-A-3096421. This contact device has two contact pieces with superconducting conductor pieces. In this case, only a single wire-shaped conductor piece is to be fastened to the first contact piece, while the second contact piece, which is designed to be movable, comprises three bow-like conductor pieces which are aligned perpendicularly with respect to the individual conductor piece of the first contact piece and are pressed onto the single conductor piece by means of springs. These bow-shaped conductor pieces of the second contact piece are not connected in parallel, so that in each case only a single contact point between two wires forms a contact. The contact device constructed in this way should be part of a network, for example a computer network. As is known, only very low currents flow in such networks, so that contact resistances between the individual conductor pieces of the contact pieces with values in the milliohm range are sufficient. Such resistance values, however, cannot be tolerated from the outset for a continuous current switch for short-circuiting a superconducting magnet, in which, as is known, very much higher currents flow.

Aufgabe der vorliegenden Erfindung ist es deshalb, den bekannten Dauerstromschalter dahingehend zu verbessern, dass mit ihm auf einfache Weise Kontaktwiderstände in der genannten Grössenordnung zu erhalten sind.The object of the present invention is therefore to improve the known continuous current switch in such a way that it can be used to easily obtain contact resistances in the order of magnitude mentioned.

Diese Aufgabe wird erfindungsgemäss dadurch gelöst, dass an jeder der einander zugewandten Oberflächen der Kontaktstücke jeweils mindestens fünf parallelgeschaltete supraleitende Leiterstücke in zumindest weitgehend parallelen Ebenen liegend so angeordnet sind, dass die Leiterstücke des ersten Kontaktstückes die Leiterstücke des weiteren Kontaktstückes kreuzen, und dass ferner die Leiterstücke des ersten Kontaktstückes fest an der Oberfläche des entsprechenden Trägerelementes angebracht sind, während jedes Leiterstück des weiteren Kontaktstückes zumindest über jedem Kreuzungspunkt mit den Leiterstücken des ersten Kontaktstückes mittels einer federnden Abstützungseinrichtung an dem zugehörigen Trägerelement gehalten ist.This object is achieved according to the invention in that on each of the mutually facing surfaces of the contact pieces at least five parallel superconducting conductor pieces are arranged lying in at least largely parallel planes such that the conductor pieces of the first contact piece cross the conductor pieces of the further contact piece, and that the conductor pieces of the first contact piece are firmly attached to the surface of the corresponding support element, while each conductor piece of the further contact piece is held on the associated support element at least above each crossing point with the conductor pieces of the first contact piece by means of a resilient support device.

Mit dieser erfindungsgemässen Ausgestaltung des Dauerstromschalters wird aufgrund einer Vielzahl definierter, kleiner Kontaktflächen mit jeweils annähernd gleicher Flächenpressung vorteilhaft erreicht, dass mit verhältnismässig geringer Gesamtkraft die für gute Kontakte notwendige Flächenpressung ohne weiteres aufzubringen ist. Dabei hat die Parallelschaltung vieler Kontaktpunkte einerseits einen günstigen Einfluss auf den Gesamtwiderstand des Schalters, andererseits kann ohne weiteres eine Anpassung an die geforderte Stromtragfähigkeit des gesamten Leiters durch eine entsprechende Anzahl der Kontaktpunkte vorgenommen werden.With this embodiment of the continuous current switch according to the invention, due to a large number of defined, small contact areas, each with approximately the same surface pressure, it is advantageously achieved that, with a relatively low total force, those necessary for good contacts ge surface pressure is easily applied. The parallel connection of many contact points on the one hand has a favorable influence on the total resistance of the switch, and on the other hand can be easily adapted to the required current carrying capacity of the entire conductor by a corresponding number of contact points.

Vorteilhafte Ausgestaltungen des Dauerstromschalters nach der Erfindung gehen aus den Unteransprüchen hervor.Advantageous embodiments of the continuous current switch according to the invention emerge from the subclaims.

Zur weiteren Erläuterung der Erfindung wird auf die Zeichnung Bezug genommen, in deren Figuren 1 und 2 jeweils ein Schnitt durch ein Ausführungsbeispiel eines erfindungsgemässen Dauerstromschalters schematisch veranschaulicht ist.To further explain the invention, reference is made to the drawing, in which FIGS. 1 and 2 each schematically illustrate a section through an exemplary embodiment of a continuous current switch according to the invention.

Der in Figur 1 in einem Querschnitt angedeutete Dauerstromschalter enthält zwei Kontaktstükke 2 und 3, die mittels einer in der Figur nicht näher ausgeführten Betätigungsvorrichtung relativ zueinander beweglich bzw. aneinanderzufügen sind. Beispielsweise ist das erste Kontaktstück 2 ortsfest angeordnet, während das weitere, beweglich gestaltete Kontaktstück 3 mittels der Betätigungsvorrichtung mit einer durch einen Pfeil dargestellten Betätigungskraft F gegen das ortsfeste Kontaktstück 2 gepresst werden kann.The continuous current switch indicated in a cross section in FIG. 1 contains two contact pieces 2 and 3 which can be moved or joined together by means of an actuating device which is not shown in the figure. For example, the first contact piece 2 is arranged stationary, while the further, movably designed contact piece 3 can be pressed against the stationary contact piece 2 by means of the actuating device with an actuating force F represented by an arrow.

Die beiden Kontaktstücke 2 und 3 sind jeweils mit den Enden der Leiter mindestens einer in der Figur nicht dargestellten supraleitenden Magnetwicklung elektrisch leitend verbunden oder stellen unmittelbar die Leiterenden dieser Wicklung dar. Bei den Magnetwicklungen kann es sich beispielsweise um die Wicklungen eines Magnetsystems zur Erzeugung des magnetischen Grundfeldes einer Anlage zur Kernspin-Tomographie oder um die Wicklung eines Magneten einer Kernfusionsanlage handeln.The two contact pieces 2 and 3 are each electrically conductively connected to the ends of the conductors of at least one superconducting magnet winding (not shown in the figure) or directly represent the conductor ends of this winding. The magnet windings can be, for example, the windings of a magnet system for generating the magnetic Basic field of a system for nuclear spin tomography or the winding of a magnet of a nuclear fusion system.

Das beispielsweise ortsfeste Kontaktstück 2 enthält eine ebene Kontaktplatte 4, auf deren dem beweglichen Kontaktstück 3 zugewandten Oberfläche eine Vielzahl von untereinander parallel ausgerichteten, supraleitenden Leiterstücken 5 mechanisch fest angeordnet ist. Erfindungsgemäss sind mindestens fünf supraleitende Leiterstücke 5 auf der für sie als Trägerelement dienenden Kontaktplatte 4 aufgelötet. Die Kontaktplatte 4 besteht vorteilhaft aus einem elektrisch gut leitenden, bei der Betriebstemperatur der supraleitenden Leiterstücke 5 normalleitenden Material wie z.B. aus Kupfer oder Aluminium. Bei den supraleitenden Leiterstücken, die z.B. runden oder rechteckigen Querschnitt aufweisen, kann es sich insbesondere um sogenannte Hochstromsupraleiter handeln. Diese Leiterstücke können sowohl unstabilisiert als auch mit normalleitendem Material stabilisiert sein, wobei vorzugsweise supraleitende Leiterteile dieser Leiterstücke zumindest an der dem beweglichen Kontaktstück 3 zugewandten Oberflächenseite zu liegen kommen.The, for example, stationary contact piece 2 contains a flat contact plate 4, on the surface of which faces the movable contact piece 3, a large number of superconducting conductor pieces 5 aligned in parallel with one another is mechanically fixed. According to the invention, at least five superconducting conductor pieces 5 are soldered onto the contact plate 4 which serves as the carrier element. The contact plate 4 advantageously consists of an electrically highly conductive material which is normally conductive at the operating temperature of the superconducting conductor pieces 5, e.g. made of copper or aluminum. With the superconducting conductor pieces, e.g. have a round or rectangular cross section, it can in particular be a so-called high-current superconductor. These conductor pieces can be both unstabilized and stabilized with normally conductive material, with superconducting conductor parts of these conductor pieces preferably coming to rest at least on the surface side facing the movable contact piece 3.

Auch das bewegliche Kontaktstück 3 enthält in entsprechender Weise eine Vielzahl von einzelnen, untereinander parallel ausgerichteten supraleitenden Leiterstücken 6. Diese Leiterstücke sind bezüglich der Leiterstücke 5 des ortsfesten Kontaktstückes 2 quer verlaufend angeordnet, so dass sich beim Aneinanderfügen der Leiterstücke 5 und 6 der beiden Kontaktstücke 2 und 3 eine Vielzahl von Kreuzungs- bzw. Kontaktpunkten 7 ergeben. Gemäss der Erfindung sollen dabei die Leiterstücke 6 an einer beweglichen, mit der Betätigungsvorrichtung verbundenen Kontaktplatte 8 nicht entsprechend den Leiterstücken 5 starr befestigt sein; vielmehr ist eine federnde Abstützung der Leiterstücke 6 gegenüber ihrer als Trägerelement dienenden Kontaktplatte 8 vorgesehen. Hierzu ist jedes Leiterstück 6 in den Bereichen seiner Kreuzungspunkte 7 mit jedem Leiterstück 5 des ortsfesten Kontaktstückes 2 über eine entsprechende Abstützungseinrichtung 9, die zugleich zur Führung und Halterung der Leiterstükke 6 dient, an der beweglichen Kontaktplatte 8 befestigt. Diese Abstützungseinrichtung 9 enthält eine durch eine entsprechende Bohrung 10 in der Kontaktplatte 8 hindurchragende Führungsstange 11, die an ihrem einen Ende an dem entsprechenden supraleitenden Leiterstück 6 über ein beispielsweise scheibenförmiges Verbindungselement 12 befestigt ist und die durch einen Anschlag 13 an ihrem gegenüberliegenden Ende gegen ein Herausrutschen aus der Bohrung 10 gesichert ist. Zwischen der Kontaktplatte 8 und dem an dem jeweiligen Leiterstück 6 befestigten Verbindungselement 12 ist eine die jeweilige Führungsstange 11 umschliessende Feder 14 mit vorbestimmter Federkraft eingespannt.Correspondingly, the movable contact piece 3 also contains a large number of individual superconducting conductor pieces 6 aligned parallel to one another. These conductor pieces are arranged transversely with respect to the conductor pieces 5 of the stationary contact piece 2, so that when the conductor pieces 5 and 6 of the two contact pieces 2 are joined together and 3 result in a multiplicity of crossing or contact points 7. According to the invention, the conductor pieces 6 should not be rigidly attached to a movable contact plate 8 connected to the actuating device, corresponding to the conductor pieces 5; rather, a resilient support of the conductor pieces 6 is provided with respect to their contact plate 8 serving as a carrier element. For this purpose, each conductor piece 6 is fastened to the movable contact plate 8 in the areas of its crossing points 7 with each conductor piece 5 of the stationary contact piece 2 via a corresponding support device 9, which also serves to guide and hold the conductor pieces 6. This support device 9 contains a guide rod 11 projecting through a corresponding bore 10 in the contact plate 8, which is attached at one end to the corresponding superconducting conductor piece 6 by means of, for example, a disc-shaped connecting element 12 and which is prevented from slipping out by a stop 13 at its opposite end is secured from the bore 10. Between the contact plate 8 and the connecting element 12 fastened to the respective conductor piece 6, a spring 14 enclosing the respective guide rod 11 is clamped with a predetermined spring force.

Fügt man nun bei einem Schliessen des Dauerstromschalters nach der Erfindung die Kontaktstücke 2 und 3 mit der vorbestimmten Betätigungskraft F aneinander, so wird an den einzelnen Kreuzungspunkten 7 jedes der Leiterstücke 5 mit den Leiterstücken 6 jeweils eine vorbestimmte Kontaktkraft K erzeugt, die aufgrund der von den einzelnen Federn 14 hervorgerufenen Druckkräfte für jeden Kontaktpunkt 7 zwischen den Leiterstücken 5 und 6 zumindest weitgehend gleich gross ist. Auf diese Weise wird erreicht, dass der Übergangswiderstand an jedem Kontaktpunkt entsprechend gleich klein ist. Es ist so möglich, mit einer verhältnismässig geringen Betätigungskraft F die für die Kontakte notwendige hohe Flächenpressung aufzubringen, um so den geforderten niedrigen Übergangswiderstand in der Grössenordnung von 10-9 Ω zwischen den Kontakten zu erreichen. Durch die Parallelschaltung vieler Kontaktpunkte lässt sich einerseits ein entsprechend kleiner Gesamtwiderstand des Dauerstromschalters erreichen; ausserdem kann man mit der Anzahl der Kontaktpunkte die Stromtragfähigkeit des gesamten Dauerstromschalters festlegen.If, when the continuous current switch according to the invention is closed, the contact pieces 2 and 3 with the predetermined actuating force F are joined together, then at the individual crossing points 7 of each of the conductor pieces 5 with the conductor pieces 6, a predetermined contact force K is generated, which is due to the individual springs 14 caused compressive forces for each contact point 7 between the conductor pieces 5 and 6 is at least largely the same size. In this way it is achieved that the contact resistance at each contact point is correspondingly small. It is thus possible to apply the high surface pressure required for the contacts with a relatively low actuating force F, in order to achieve the required low contact resistance of the order of 10- 9 Ω between the contacts. By connecting many contact points in parallel, a correspondingly small overall resistance of the continuous current switch can be achieved; you can also determine the current carrying capacity of the entire continuous current switch with the number of contact points.

Die supraleitenden Leiterstücke 5 und 6 können unmittelbar in einem ihre Supraleitfähigkeit gewährleistenden kryogenen Medium, das insbesondere das Kühlmedium der angeschlossenen supraleitenden Magnetwicklung ist, angeordnet sein. Gegebenenfalls ist aber auch eine indirekte Kühlung dieser Leiterstücke möglich (vgl. DE-A-2 521 328).The superconducting conductor pieces 5 and 6 can be arranged directly in a cryogenic medium which ensures their superconductivity, which is in particular the cooling medium of the connected superconducting magnet winding. If necessary, indirect cooling of these conductor sections is also possible (cf. DE-A-2 521 328).

Die verhältnismässig geringe Betätigungskraft F des Dauerstromschalters gestattet nicht nur die in Figur 1 angenommene Betätigung mittels eines Gestänges, sondern es ist auch eine pneumatische oder hydraulische Betätigung möglich. Eine solche Betätigung ist an sich bekannt (DE-C-2324371). Ein entsprechendes Ausführungsbeispiel ist in Figur 2 als Querschnitt angedeutet. Dabei ist angenommen, dass eines der Kontaktstücke ortsfest ist und dem Kontaktstück 2 mit Leiterstücken 5 gemäss Figur 1 entspricht. Eine Vielzahl supraleitender Leiterstücke 16 eines weiteren, mit 17 bezeichneten Kontaktstückes dieses Schalters ist über eine pneumatische bzw. hydraulische Abstützungseinrichtung 18 mit einem ortsfesten, plattenförmigen Trägerelement 19 mechanisch verbunden. Die Abstützungseinrichtung 18 enthält eine dünne, ebene Membrane 20, die z.B. aus Edelstahl besteht und an der die Leiterstücke 16 entsprechend der Anordnung nach Figur 1 starr befestigt sind. Diese Membrane 20 ist über einen Federbalg 21 an dem ortsfesten Trägerelement 19 befestigt. Der von diesem Trägerelement 19, dem Federbalg 21 und der die Leiterstücke 16 haltenden Membrane 20 vakuumdicht umschlossene Innenraum 22 kann über eine Druckleitung 23 mit Druck beaufschlagt werden, so dass die Leiterstücke 16 mit etwa gleicher Kontaktkraft K auf die quer zu ihnen angeordneten Leiterstücke 5 des Kontaktstücks 2 gepresst werden. Als Druckmittel kann hierzu insbesondere gasförmiges oder flüssiges Helium vorgesehen sein. Bei einer derartigen pneumatischen oder hydraulischen Betätigung lässt sich somit vorteilhaft auf Gestänge und entsprechende Durchführungen, die zu Wärmeeinleitungsverlusten auf die Supraleiterstücke führen, verzichten. Daneben besteht die Möglichkeit, den Schalter auf einfache Weise z.B. in Helium-Atmosphäre oder im Vakuum zu kapseln und so Oxidationen und Langzeitveränderungen des Übergangswiderstandes zu vermeiden.The relatively low actuating force F of the continuous current switch not only permits the actuation assumed in FIG. 1 by means of a linkage, but also a pneumatic or hydraulic actuation is possible. Such actuation is known per se (DE-C-2324371). A corresponding exemplary embodiment is indicated in FIG. 2 as a cross section. It is assumed that one of the contact pieces is stationary and corresponds to the contact piece 2 with conductor pieces 5 according to FIG. 1. A large number of superconducting conductor pieces 16 of a further contact piece, designated 17, of this switch is mechanically connected to a stationary, plate-shaped carrier element 19 via a pneumatic or hydraulic support device 18. The support device 18 contains a thin, flat membrane 20 which e.g. consists of stainless steel and to which the conductor pieces 16 are rigidly attached according to the arrangement of Figure 1. This membrane 20 is fastened to the stationary support element 19 via a bellows 21. The interior 22, which is enclosed by this carrier element 19, the bellows 21 and the membrane 20 holding the conductor pieces 16 in a vacuum-tight manner, can be pressurized via a pressure line 23, so that the conductor pieces 16 have approximately the same contact force K on the conductor pieces 5 arranged transversely to them Contact piece 2 are pressed. For this purpose, gaseous or liquid helium can in particular be provided as the pressure medium. With such a pneumatic or hydraulic actuation, it is thus advantageously possible to dispense with linkages and corresponding bushings, which lead to losses of heat input onto the superconductor pieces. There is also the option of simply switching the switch e.g. encapsulate in a helium atmosphere or in a vacuum to avoid oxidation and long-term changes in contact resistance.

Besonders vorteilhaft kann der Dauerstromschalter nach der Erfindung für Magnetwicklungen vorgesehen werden, die mit supraleitenden Leiterseilen aus mehreren supraleitenden Einzelleitern gewickelt werden. Bei diesem Leitertyp können nämlich die supraleitenden Einzelleiter aus dem aufgefächerten Leiterseil unmittelbar die Supraleiterstücke der Kontaktstücke bilden.The continuous current switch according to the invention can be provided particularly advantageously for magnetic windings which are wound with superconducting conductor cables made of several superconducting individual conductors. With this type of conductor, the superconducting individual conductors can form the superconductor pieces of the contact pieces directly from the fanned-out conductor cable.

In den Ausführungsbeispielen wurde davon ausgegangen, dass der Dauerstromschalter nach der Erfindung nur zwei ebene Kontaktstücke mit aneinanderzufügenden Leiterstücken hat, wobei die Leiterstücke auf einer Ebene über jedem Kreuzungs- bzw. Kontaktpunkt abgefedert sind. Der Dauerstromschalter nach der Erfindung kann jedoch ebensogut auch mehr als zwei Ebenen mit Leitungsstücken aufweisen, wobei dann für jede zweite Ebene eine federnde Abstützung der Leiterstücke vorgesehen wird.In the exemplary embodiments, it was assumed that the continuous current switch according to the invention has only two flat contact pieces with conductor pieces to be joined together, the conductor pieces being cushioned on one level above each crossing or contact point. However, the continuous current switch according to the invention can equally well have more than two levels with line pieces, with resilient support of the conductor pieces being provided for every second level.

Claims (9)

1. A persistent current switch for short-circuiting at least one superconducting magnet winding having at least two contact pieces (2, 3; 2, 17) each having a plurality of parallelly arranged, superconducting conductor elements (5, 6; 5, 16) which are connected to a carrier element (4, 8; 19) and are cooled by a cryogenic coolant, and having an operating means for joining the superconducting conductor elements (5,6; 5,16) with a predetermined contact force, characterised in
a) that on each of the mutually facing surfaces of the contact pieces (2, 3; 2, 17), at least five parallel superconducting conductor pieces (5, 6; 5, 16) which are connected in parallel are arranged in at least largely parallel planes in such a way that the conductor elements (5) of the first contact piece (2) intersect the conductor elements (6; 16) of the further contact piece (3; 17); and
b) that, moreover, the conductor elements (5) of the first contact piece (2) are firmly fixed to the surface of the corresponding carrier element (4), whilst each conductor element (6; 16) of the further contact piece (3; 17) is held on the carrier element (8, 19) allotted thereto, at least above each intersection point (7) with the conductor elements (5) of the first contact piece (2), by means of a resilient supporting device (9; 18).
2. A persistent current switch as claimed in Claim 1, characterised in that the resilient supporting device (9) comprises guiding and retaining rods (11 to 13) which are connected to a carrier element (8) of the further contact piece (3), and a spring (14) which is clamped between the particular conductor member (6) and the carrier element (8).
3. A persistent current switch as claimed in Claim 1, characterised in that the resilient supporting device (18) comprises an elastic bellows (21), which is connected to the carrier element (19) of the further contact piece (17), and a diaphragm (20), to which the conductor members (16) of the further contact piece (17) are secured; and that the interior space (22) enclosed by the carrier element (19), the elastic bellows (21) and the diaphragm (20), is pressurised by means of a gaseous or liquid coolant.
4. A persistent current switch as claimed in Claim 3, characterised by a thin diaphragm (20) made of high quality steel.
5. A persistent current switch as claimed in Claim 3 or Claim 4, characterised in that the coolant for cooling the superconducting magnet winding is provided as a pressurising medium.
6. A persistent current switch as claimed in one of Claims 1 to 5, characterised in that the conductor elements (5, 6; 5, 16) are made of an unstabilized superconducting material.
7. A persistent current switch as claimed in one of Claims 1 to 5, characterised in that the conductor members (5, 6; 5, 16) are stabilized single- or multi-core conductors.
8. A persistent current switch as claimed in Claim 7, characterised in that the conductor members (5, 6; 5, 16) have a superconducting material at least on their surface portions which are to be joined together.
9. A persistent current switch as claimed in one of Claims 1 to 8, characterised in that the conductor pieces (5, 6; 5, 16) of the contact pieces (2, 3; 2,17) are arranged in a vacuum.
EP83110191A 1982-10-28 1983-10-12 Permanent current switch for short-circuiting at least one superconducting magnet winding Expired EP0107830B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19823240019 DE3240019A1 (en) 1982-10-28 1982-10-28 CONTINUOUS CURRENT SWITCH FOR SHORT-CLOSING AT LEAST ONE SUPRAL-CONDUCTING MAGNETIC WINDING
DE3240019 1982-10-28

Publications (2)

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EP0107830A1 EP0107830A1 (en) 1984-05-09
EP0107830B1 true EP0107830B1 (en) 1987-01-28

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US (1) US4623769A (en)
EP (1) EP0107830B1 (en)
JP (1) JPS5994889A (en)
DE (2) DE3240019A1 (en)

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Publication number Priority date Publication date Assignee Title
DE3402828A1 (en) * 1984-01-27 1985-08-01 Siemens AG, 1000 Berlin und 8000 München SWITCHING DEVICE FOR SHORT-CLOSING AT LEAST ONE SUPRAL-CONDUCTING MAGNETIC WINDING
US4872322A (en) * 1988-09-02 1989-10-10 General Electric Company Power operated contact apparatus for superconductive circuit
JP2549137Y2 (en) * 1991-11-06 1997-09-30 和江 三木 Sweat-absorbing pad to put under armpit
US8384504B2 (en) * 2006-01-06 2013-02-26 Quantum Design International, Inc. Superconducting quick switch
US8134434B2 (en) * 2007-01-05 2012-03-13 Quantum Design, Inc. Superconducting quick switch
KR101406947B1 (en) * 2011-10-11 2014-06-12 삼성전자주식회사 Superconducting magnet apparatus and control method thereof

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US3096421A (en) * 1958-04-16 1963-07-02 Walter G Finch Superconducting contact devices
US3349209A (en) * 1966-04-26 1967-10-24 Avco Corp Cryogenic switch
SE323735B (en) * 1967-06-05 1970-05-11 Uddeholms Ab
JPS5533579B2 (en) * 1974-05-15 1980-09-01
JPS5132480A (en) * 1974-09-13 1976-03-19 Mitsubishi Electric Corp
DE2707589C3 (en) * 1977-02-22 1980-02-21 Siemens Ag, 1000 Berlin Und 8000 Muenchen Continuous current switch for short-circuiting a superconducting magnet

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US4623769A (en) 1986-11-18
EP0107830A1 (en) 1984-05-09
DE3240019A1 (en) 1984-05-03
DE3369594D1 (en) 1987-03-05
JPS5994889A (en) 1984-05-31

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