SUPRAL CONDUCTING FAILURE CURRENT LIMITER OR SWITCH

Description

1. Technical field

[0001] The invention relates to a superconducting residual current limiter or switch comprising an armored high-temperature superconducting tape conductor, HTS tape conductor. The HTS tape conductor is further wrapped with several layers of a metal fiber. 2. State of the art

[0002] HTS tape conductors are used in engineering for transporting high currents, e.g., in cables and busbars, for generating high magnetic fields in analytical or medical technology, for beam guidance in accelerators, or for plasma confinement in fusion reactors. Furthermore, the rapid, dynamic transition from the lossless superconducting state to the normal conducting state under overload conditions can be used for fast switches and current limiters.

[0003] In many of these applications, HTS tape conductors are cooled by immersion in a liquid cryogenic medium such as liquid nitrogen (boiling point 77 K), liquid hydrogen (boiling point 21 K), neon (boiling point 27 K), or liquid helium (boiling point 4.2 K). Modern HTS tape conductors (so-called 2nd generation or 2G) comprise a flexible metal substrate coated with the HTS material using chemical or physical processes. This material typically belongs to the so-called 123 material class with the composition RBa₂Cu₃O₇, where R denotes an element or a mixture of elements from the rare earth group (e.g., Nd, Gd, Eu, Dy, Ho, Hf) or yttrium (Y). Since the HTS coating typically takes place at high temperatures (e.g. at T > 650°C), the HTS coating cannot be applied directly to the metal foil.Depending on the manufacturing process used, different intermediate layers, so-called buffer layers, are employed. These serve two purposes: firstly, they act as a diffusion barrier, secondly, they provide crystallographic orientation, and thirdly, they adapt crystal lattice parameters for the epitaxy of the HTS layer. Both the buffer layers and the HTS layer(s) can be deposited using various methods, such as chemical deposition by metal-organic deposition (MOD) of an amorphous precursor material, which is calcined by heat treatment and crystallized into the desired phase; thirdly, metal-organic chemical vapor deposition (MOCVD); and fourthly, various physical vacuum deposition (PVD) processes.

[0004] In further manufacturing steps, the HTS tape conductors are usually encased with thin metal layers of silver or copper. Copper layers with a thickness of 5 to 20 µm are often deposited using electroplating processes, see JP 07335051 A or EP 1 639 609 A2. These circumferential metal layers serve for protection, electrical stabilization, and current supply. However, even these layers are not always 100% free of defects, holes, or channels. Adhesion is often reduced, particularly at the edge, i.e., at the cut edge, and the layers can easily be damaged by scratching against guide rollers during subsequent processing.

[0005] Overall, the thin layers in and around the HTS tape conductor represent a fragile and sensitive system that can be easily damaged by mechanical forces during subsequent processing or use in coils for generating high magnetic fields. Tensile and shear forces can lead to delamination of the layers, while strong compressive forces can cause cracks or local plastic deformations (pressure points) in the layer system.

[0006] To protect and stabilize HTS tape conductors against external forces, a number of techniques are employed. One configuration involves an HTS tape conductor laminated and soldered on both sides with metal foils. An overhang of the foils on both sides creates two channels along the conductor, which can be filled with solder, thus forming a solder bridge laterally. This arrangement is described in EP 1 203 415 B1. A similar method for laminating an HTS tape conductor with electrically insulating plastic film on both sides is described in WO 2013 / 004392 A1. There, the overhang of the thermoplastic film on both sides is welded together by applying heat.

[0007] Further configurations for encasing or sheathing an HTS tape conductor are described in EP 2 940 699 A1 and EP 2 770 513 B1. There, a solder-coated metal foil twice the width of the HTS tape conductor is folded around it and soldered, so that the front and edges are completely covered. The seam on the back of the conductor can also be filled with solder, thus preventing any seepage, for example of coolant, from that side as well.

[0008] To electrically insulate HTS tape conductors without holes, a method was developed in which the conductor is wrapped with a thin, overlapping helical plastic tape. This tape can be made of, for example, polyimide (Kapton™) as described in DE 3 823 938 A1 or polyester (see DE 10 2004 048 439 A1). Polyimide has a low coefficient of thermal expansion, hardly becomes brittle, and is therefore particularly suitable for use at cryogenic temperatures. Conventional, thermally or UV-curable lacquers or resins are also used to provide HTS tape conductors with an electrically insulating coating. Exemplary systems are described in EP 2 801 983 A1, EP 2 731 113 B1, and DE 10 2018 217 480 A1.

[0009] All the methods mentioned are used in practice for encasing HTS tape conductors. However, these methods also present practical difficulties. Tapes are never perfectly straight, but always exhibit a certain curvature, i.e., a deviation from a straight line. This makes the accurate alignment and guidance of three parallel tapes during lamination problematic, which complicates the production of long lengths and affects dimensional accuracy (width tolerance). In fact, the exact position of the inner HTS tape conductor, the so-called "insert," relative to the edge is almost impossible to control. Lateral misalignment can cause the HTS tape conductor to shift completely to one side, resulting in no overlap of the two metal foils and no solder bridge. A resulting problem is that the sandwich can burst at such points.

[0010] The use of soldered metallic tapes does not solve the problem of electrical insulation, and in the event of a brief overload, the solder can become so hot (> 250°C) that its melting point is reached and the sandwich composite breaks down. In this case, the lamination no longer provides any mechanical protection. Thin layers of lacquer, on the other hand, do not offer effective mechanical protection, and wetting the tape edges also poses a problem. When fluoropolymers or polyimides are used for wrapping or as lacquer, surface adhesion is significantly reduced. These surfaces are therefore poorly suited for bonding and subsequent potting.

[0011] The methods described above have in common that the lamination (or wrapping with tapes) significantly increases the thickness of the HTS tape conductor and thus its stiffness (by the cube of its thickness). These conductors are therefore not as flexible to process as unlaminated HTS tape conductors.

[0012] Furthermore, especially in coils used to generate high magnetic fields, enormous mechanical forces occur that act on the surfaces of the windings. To create a mechanically stable winding, such coils are potted and cured with epoxy resins, waxes, or other polymers. Therefore, additional requirements are placed on the HTS tape conductors used in coil construction. These relate to electrical insulation and dielectric strength, as well as the impregnability of the winding spaces; that is, the HTS tape conductor surface must allow for potting and bonding of the individual winding layers. Conductors known from the prior art are only inadequately suited for these and similar applications.

[0013] DE 102 08 139 A1 describes a method for producing a complete encapsulation of an electrical insulating material made of plastic around at least one superconductor, in which a melt tube of molten thermoplastic insulating material is extruded onto the surface of the superconductor. To achieve mechanical reinforcement, a proportion of fibers of a fibrous material is added to the thermoplastic insulating material used.

[0014] DE 3811051 A1 discloses a superconducting cable comprising a rigid inner tube in which at least one superconducting conductor core with an oxide ceramic high-temperature superconducting material is arranged, which is cooled by a suitable cooling medium.

[0015] DE 10 2011 079 323 B3 describes a superconducting coil assembly made of an HTS conductor material mounted on a coil carrier. For mechanical stabilization of the coil assembly, a potting material is provided between each pair of adjacent coil windings and between the coil carrier and the surrounding coil winding.

[0016] AROOJ AKBAR ET AL, "Optical fibre sensing for fast hotspot detection in SFCLs", SUPERCONDUCTOR SCIENCE AND TECHNOLOGY, IOP PUBLISHING, TECHNO HOUSE, BRISTOL, GB, vol. 33, no. 11, doi:10.1088 / 1361-6668 / ABB200, ISSN 0953-2048, (20200921), describes the application of an optical fiber as a measuring line onto an HTS tape conductor.

[0017] JP 2020 136586 A relates to a superconducting coil conductor. The superconducting coil conductor comprises ribbon-shaped superconducting wires consisting of multiple elements with different thermal shrinkage ratios, a fiber whose thermal shrinkage ratio at an absolute temperature of 293 K to 77 K is equal to or less than 0.3% and which is wound around the superconducting wires, and resins that fill the gaps between each adjacent superconducting wire and the fiber, as well as between the other superconducting wire and the fiber.

[0018] The objective of the present invention is therefore to at least partially reduce some of the disadvantages of the prior art described above and, in particular, to make the sensitive HTS tape conductors mechanically robust for further processing and use in demanding applications, and to protect them from destruction. 3. Summary of the invention

[0019] The aforementioned problem is at least partially solved by the subject matter of the independent claims of the present invention. Exemplary embodiments are the subject matter of the dependent claims.

[0020] In one embodiment, the present invention provides a superconducting residual current limiter or switch comprising: a high-temperature superconducting tape conductor, HTS tape conductor, having a width and a thickness; and an armoring formed in that the HTS tape conductor is wrapped with a first layer of at least one fiber of a first type having a substantially round cross-section, wherein the fiber is wound substantially without overlap and butted tightly together, and the HTS tape conductor is wrapped with several layers of a metal fiber.

[0021] In the context of the present invention, the term high-temperature superconductor is to be understood in a technical sense, namely as a piece of electrical conductor which has high-temperature superconducting properties.

[0022] The invention described herein (see also the illustrations below) Figs. 1 to 4bThis allows, for example, the HTS tape conductor to be tightly wrapped with one or more thin, flexible, yet stable fibers. This provides a circumferential protective layer that absorbs and distributes externally acting forces, does not significantly impair the longitudinal bending stiffness, and has gaps that ensure high flexibility and allow impregnation or potting of the HTS tape conductor through capillary action. In particular, such reinforcement only slightly alters the flexibility of the HTS tape conductor, as the windings of the reinforcement can shift relative to one another. This also facilitates the penetration and adhesion of coolant or potting fluid.

[0023] The reinforcement is achieved by wrapping the HTS tape conductor with one or more parallel fibers. Multiple fibers can be wound around the HTS tape conductor in the same direction or in opposite directions. In the latter case, crossovers occur, and the reinforcement consists of a fiber braid. The term "fiber" is used in this description as a collective term and includes not only individual fibers but also fiber bundles or fibers spun into a thread or yarn. The fiber can also consist of a thin, metallic wire.

[0024] Preferably, the fiber exhibits high plastic and / or elastic deformability and is thin enough to achieve a tight fit and good interlocking effect around the thin HTS tape conductor. Furthermore, it should possess sufficient strength and elasticity to be wound under tensile stress around the edges of the HTS tape conductor. Typically, the diameter of a single fiber is determined by the HTS tape conductor thickness and is preferably in the range of 0.2 to 2.5 times the HTS tape conductor thickness to be wrapped. If spun fibers or yarns are used, thicker reinforcements with several times the HTS tape conductor thickness can also be achieved. By winding multiple layers together, very thick reinforcements and coverings can also be produced if required, which are difficult to achieve using other methods, e.g., lamination.

[0025] A wide variety of fiber materials are available. For insulating reinforcements, glass or carbon fibers can be used, as well as textile fibers such as silk, wool, or cotton, or synthetic fibers such as polyamides with trade names like nylon, perlon, and aramid. If reinforcement with metallic (electrical or thermal) conductivity is required, thin metal wire (pure or enameled) can be used, e.g., made of copper, copper alloys, nickel, nickel-chromium alloys, aluminum, tungsten, tantalum, etc.

[0026] In some embodiments, the fiber can be electrically conductive, at least at some points along the HTS tape conductor, and preferably comprises a metallic material. This allows the high-temperature superconductor to be electrically contacted via the armor. Such materials also exhibit high thermal conductivity, which can improve the cooling of the high-temperature superconductor, particularly during local quenching.

[0027] Alternatively or additionally, the fiber can be electrically insulating, at least in some areas of the HTS tape conductor, and preferably comprises one of the following materials: glass fiber, carbon fiber, textile fiber, and synthetic fiber. Such electrically insulated HTS tape conductors can be used, in particular, to manufacture magnetic coils for electric motors or MRI machines.

[0028] Furthermore, the fiber can be configured in such a way that cryogenic liquids can penetrate at least partially into the interior of the fiber. For example, the fiber can have a weave that is at least partially permeable to cryogenic liquids such as liquid nitrogen, liquid hydrogen, and liquid helium.

[0029] If, for example, thicker sheaths are desired, the HTS tape conductor can also be wound with several layers of fibers in succession. Since gaps and channels remain between the individual fibers, which have a substantially round cross-section, these can shift slightly relative to each other when the reinforced HTS tape conductor is deformed, so that the stiffness and the minimum radius of curvature of the HTS tape conductor are only minimally affected. This represents a crucial difference from the prior art, where lamination results in a thicker and stiffer composite tape conductor. Furthermore, the gaps between the fibers create capillary forces when immersed in liquid media, drawing the liquid into the reinforcement, similar to a sponge. This makes it ideally suited for subsequent impregnation and potting, for example, of a coil.

[0030] Since the fiber acts as a framework, a wide range of desired properties can be achieved by combining it with suitable impregnating liquids such as polymers, resins, waxes, oils, or even solder, either through impregnation or after curing. This can affect, for example, mechanical strength, electrical conductivity or dielectric strength, or heat capacity and conductivity. In this case, the reinforcement represents a composite material that allows for very flexible adjustment of the desired properties for the respective application. This expands the spectrum of possible tape conductor coverings far beyond conventional metal or plastic films.

[0031] In some embodiments, the high-temperature superconductor may therefore have a layer of potting, and / or impregnating and / or soldering material that has penetrated at least partially into the fiber and / or into spaces between windings of the fiber and forms a hermetic reinforcement for the HTS tape conductor.

[0032] To further improve these reinforcement properties, the average fiber thickness can be in a range between 0.2 and 2.5 times the thickness D of the HTS tape conductor and / or in a range between 30 µm and 50 µm. Alternatively or additionally, one or more additional layers of the fiber, or another fiber of a different type, can be wound over the first layer, preferably in opposite directions or crosswise, and / or the first layer of the reinforcement can have two or more different fibers of different types. In this way, multi-functional reinforcements can be formed that combine the advantages of different fiber types.

[0033] Thick (e.g., multi-layered) reinforcements also provide a spatial buffer that can compensate for local pressure forces, e.g., from edges or dirt particles, so that these are not pressed into the sensitive HTS tape conductor surface and break the HTS layer.

[0034] The reinforcements described above are particularly useful for tape conductor configurations that feature a composite or laminate of two or more stacked HTS tape conductors or foils. This configuration occurs especially in patch or connection areas, where electrical bridging is achieved through a (face-to-face) laminated second HTS tape conductor. The reinforcement prevents these thicker sections from fraying under mechanical deformation, such as that which occurs during deflection by rollers.

[0035] The reinforcement also allows for the integration and fixing of measuring leads along the HTS tape conductor. Some embodiments can therefore include a measuring lead and / or a coolant line connected to the HTS tape conductor through one of the reinforcement layers. In particular, the measuring lead can incorporate an optical fiber and / or a temperature sensor, enabling simple and robust integration with the HTS tape conductor.

[0036] As mentioned above, in some embodiments of the high-temperature superconductor, several HTS tape conductors can form a multilayer composite and / or be overlapped at their ends and wound together with the fiber. This allows long and / or multilayer high-temperature superconductors to be formed from multiple sub-conductors, where the connection points can be made flexible and mechanically robust by the reinforcement described above.

[0037] In further embodiments, the first layer of the armor can comprise at least one electrically conductive fiber and at least one insulating fiber, wherein the windings of the electrically conductive fiber are preferably insulated from each other. In this way, for example, a measuring cable with inductive behavior or a resistive heating cable can be integrated into the armor without significantly increasing the space requirement.

[0038] The fiber-reinforced high-temperature superconductors described above are particularly suitable for superconducting magnet coils. Thus, a further aspect outside the scope of the present invention relates to a superconducting coil for generating a magnetic field comprising: one or more coil windings of a high-temperature superconductor as described above (and in Section 5 below), wherein the coil windings are connected with a potting material, preferably an epoxy resin.

[0039] The present invention relates to a superconducting fault current limiter or switch comprising: a high-temperature superconductor as described above (and in Section 5 below), wherein the armored HTS tape conductor is furthermore wrapped with several layers of a metal fiber, preferably a copper or refractory metal fiber.

[0040] Such a high-temperature superconductor for a superconducting residual current limiter or switch as described above can be manufactured, for example, using the method specified in claim 6.

[0041] Furthermore, such a procedure may include: creating a hermetic reinforcement by soldering or potting the reinforcement with a solder material and / or a potting material.

[0042] If the fiber is wound onto the HTS conductor with a certain tensile stress and elastic deformation, tensile and shear forces acting on the reinforced HTS conductor from the outside are largely transferred into the fibers of the reinforcement. This significantly reduces the force acting on the interfaces with the HTS conductor and between its layers. The risk of delamination, i.e., the separation of layers over a large area, is thereby reduced. If the fiber winding is not bonded (encapsulated) to the HTS conductor surface, the fiber reinforcement absorbs all forces, as there is no frictional connection at the interface.

[0043] The invention described here leads to armored high-temperature superconductors with significantly improved mechanical, electrical, and thermal properties, which can be manufactured easily and reliably in various dimensions and shapes. Different combinations of fiber types and windings make it possible to adapt and optimize the properties of the armoring for superconducting residual current devices or switches. The present invention thus makes an important contribution to making HTS tape conductor technology practical. 4. Description of the figures

[0044] Certain aspects of the present invention are described below with reference to the attached figures. These figures show: Fig. 1 : a schematic cross-section of an HTS tape conductor structure before wrapping with a fiber; Fig. 2: Top view of a schematic HTS tape conductor structure with single-layer wrapping with a fiber according to an embodiment of the present invention; Fig. 3a : a representation of an HTS tape conductor structure in longitudinal section through the HTS tape conductor with single-layer reinforcement / wrapping according to an embodiment of the present invention; Fig. 3b : a representation of an HTS tape conductor structure in longitudinal section through the HTS tape conductor with double-layered reinforcement according to an embodiment of the present invention; Fig. 3c : a representation of two soldered HTS tape conductors with single-layer armoring according to an embodiment of the present invention; Fig. 4a : a cross-section through an HTS tape conductor assembly with a laterally running, integrated measuring line (e.g. fiber optic cable); Fig. 4b : a cross-section through an HTS tape conductor assembly with a centrally running, integrated measuring line (e.g., fiber optic cable); and Fig. 5: a flowchart of the process steps for manufacturing a reinforced HTS tape conductor. 5. Detailed description of some exemplary implementations

[0045] The following describes some exemplary combinations of features with reference to some exemplary embodiments of the present invention. Naturally, not all features of the described embodiments need to be present to realize the present invention. Furthermore, embodiments can be modified by combining certain features of one embodiment with one or more features of another embodiment – ​​provided this is technically compatible and makes sense – without deviating from the disclosure and scope of protection of the present invention, which is defined solely by the claims.

[0046] Fig. 1Figure 1 shows the structure of an HTS tape conductor 10 based on a thin metal substrate 11, preferably a NiCr alloy such as Hastelloy C276, alloys of Ni with W or Mo, or a sufficiently alloyed stainless steel. The substrate thickness is preferably in the range of 30–150 µm, particularly preferably between 40 and 100 µm. At least one major surface of the metal substrate is coated with one or more buffer layers 12, e.g., MgO, CeO₂, Y₂O₃, LaMnO₃, LaZrO₃, on which the HTS functional layer 13 is deposited. This layer consists essentially of a compound of the group RBa₂Cu₃O₇, where R denotes an element or a mixture of elements of the rare earth group (frequently Nd, Gd, Eu, Dy, Ho, Hf) or yttrium (Y). Other metal oxides, such as BaMO 3, where M stands for elements such as Zr, Hf, Ce, Sn, etc., may also be added as impurities to increase the magnetic field strength.Finally, the HTS tape conductor is typically coated with a thin layer of silver. This can be further reinforced by an additional coating of copper. The in . Fig. 1 The depicted encapsulating metal layer 14, or double layer, acts as a contact layer for current injection, provides adhesion to the substrate edges and the back side, and enables soldering. The encapsulating Ag and / or Cu layer typically has a total thickness of at least 2 µm, preferably between 2 and 10 µm. For electrical stabilization, the HTS tape conductor can also be laminated or encased with a metal foil. The thickness of this foil is preferably between 20 and 150 µm.

[0047] Fig. 2 shows a fiber-reinforced HTS tape conductor 10 according to an embodiment of the present invention in top view. Fig. 3aFigure 1 shows the reinforced high-temperature superconductor in section along the central longitudinal axis. The high-temperature superconductor has an HTS tape conductor 10, which is wound with one or more layers of fiber 15. The fiber is wound tightly together, as shown in Figure 2. Fig. 3a This can be achieved by coordinating the feed rate of the HTS tape conductor and the winding frequency during simple rewinding so that the fiber is offset by one fiber diameter per revolution.

[0048] A wide selection of fibers, textile yarns, or thin metal wires are suitable for the reinforcement material or fiber windings. The tensile stress during winding is preferably in the range of 50–250 MPa. It depends on the specific case, firstly on the material and thickness of the fiber, and secondly on the thickness D and width W of the HTS tape conductor 10. The material and geometric cross-section of the HTS tape conductor determine its bending stiffness. To ensure that the reinforced HTS tape conductor remains as flat as possible and that the reinforcement lies flat on both main surfaces, the tensile stress should be chosen low enough to prevent any additional curvature perpendicular to the conductor. The tensile strength of the fiber and the bending stiffness of the HTS tape conductor thus limit the tensile stress during winding from above and below. Instead of a single fiber, two or more fibers can also be wound in parallel. These parallel fibers can be made of different materials.

[0049] The wrapping process can also be repeated several times in succession to achieve a specific target thickness of the reinforcement. This arrangement is shown as an example in Fig. 3b The diagram illustrates how a second layer of fibers was wound in the same direction onto the HTS tape conductor. Unlike lamination with, for example, films, which significantly impairs the flexural stiffness and thus the processability of the composite, multiple windings allow for the production of virtually any thickness of sheathing without substantially affecting the flexibility of the resulting high-temperature superconductor or its subsequent processing. This makes it possible, for example, to selectively increase the heat capacity of the composite tape conductor for certain applications.

[0050] A special configuration is created when several fibers are wound in opposite directions around the HTS tape conductor. The crossings create a fiber mesh that encases the HTS tape conductor. Both winding methods can be used to reinforce the HTS tape conductor.

[0051] Another configuration involves stacked HTS tape conductors joined at their surface. Such a configuration occurs, for example, at joints between HTS (partial) tape conductors. Very long HTS tape conductors, hundreds or even over a thousand meters in length, are preferably manufactured by joining shorter partial conductors. Ideally, the joints are practically invisible to the end user and behave mechanically like a simple HTS tape conductor. Joining methods are described, for example, in US 7,071,148 or EP 2,835,838 A1. The latter also describes the repair (patching) of a defect similar to EP 2,689,477 A1.

[0052] During the connection process, the HTS tape conductors are first mechanically joined to the substrate, e.g., welded. To ensure current flow across the joint or a local defect, a second HTS tape conductor 10, with its HTS side facing the first (face-to-face), is soldered onto the HTS side of the HTS tape conductor surface as a so-called patch 16. This situation is shown in the longitudinal section in Fig. 3cThis bridging layer is generally significantly thicker than the individual HTS tape conductor. EP 2 835 838 A1 therefore describes how the substrate can be selectively detached from the patch to keep this bridging layer as thin as possible. In any case, however, the joint or repair point represents a sensitive area where the mechanical properties also differ significantly from those of the normal HTS tape conductor. For example, the stiffness increases with the cube of the tape thickness, and during transport over rollers, such points tend to buckle, fray, or delaminate due to the abrupt change in bending stiffness. The reinforcement of such patches or joints according to some embodiments of the present invention is described in Fig. 3cAs illustrated, it holds the assembly together even under severe bending. This eliminates mechanical problem areas in the connections and requires no special care during further handling, greatly simplifying the processing of the conductor.

[0053] In general, the fiber-based reinforcement described here is a suitable means of mechanically holding together and protecting different types of HTS tape conductor stacks as a composite, regardless of whether this stacking is localized or occurs along the entire length. The following section describes some specific embodiments and application examples to demonstrate the wide range of applications for this fiber reinforcement. Example 1:

[0054] An HTS tape conductor with a thin, circumferential copper layer, 70 to 80 µm thick, is wrapped with a single layer of stable, insulating fiber or fiber bundle, such as glass, carbon, or aramid fiber, or a metal wire made of copper or aluminum. The fiber diameter, or thickness of the armoring, is approximately 30 to 50 µm, thus providing very effective edge protection during further processing. Forces, for example, within a coil, can also be dissipated via the armoring at the edges of the HTS tape conductor. Example 2 :

[0055] The reinforced HTS tape conductor from Example 1 can then be impregnated with epoxy resin or polyurethane, preferably at a vacuum < 400 mbar (4 × 10⁴ Pa), and particularly preferably in the range of 100 to 200 mbar (i.e., between 1 × 10⁴ Pa and 2 × 10⁴ Pa), and cured at a suitable temperature (e.g., 150°C). With metallic reinforcement, a solder with a melting point below 250°C can also be applied, e.g., using a solder bath or wave soldering process. This hardens upon cooling and fills the spaces within the reinforcement. In both cases, a hermetically sealed seal is formed, which, when the HTS tape conductor is immersed in cryogenic liquids such as liquid nitrogen, hydrogen, or helium, prevents the liquids from penetrating cavities and from swelling upon heating above the boiling point (so-called thermal shock). Ballooning ) prevented. Example 3

[0056] An HTS tape conductor can be wrapped with one or more layers of a textile fiber, such as cotton, silk, or polyamide. The thickness of the armoring is, for example, 50 µm. The armored HTS tape conductor is wound onto a former (e.g., a cable) or into a coil and cooled with liquid nitrogen or liquid hydrogen, etc. The cooling fluid can thus penetrate almost completely into the armoring, acting as a dielectric and providing electrical insulation for the HTS tape conductor with a dielectric strength of more than 20 kV / mm. Example 4

[0057] An HTS tape conductor several hundred meters long has one or more splice points or patches where a second HTS tape conductor is soldered face-to-face to the HTS side, thus creating an electrical connection. These splice points are wrapped with a high-tensile-strength fiber, such as glass, carbon, or aramid fiber, effectively holding them together mechanically. This eliminates the risk of these splice points fraying during transport of the long HTS tape conductor on reels, allowing the HTS tape conductor to be processed further without any special precautions at the splice points. Example 5

[0058] An HTS tape conductor reinforced with a textile or synthetic fiber is wound into a magnetic coil. This coil is potted with an epoxy resin, polyurethane, or wax at a vacuum of < 400 mbar (4 × 10⁻⁴ Pa). The resins crosslink and cure at temperatures above 100°C, while the wax solidifies upon cooling. This creates a mechanically stable bond with close contact and excellent friction between the HTS tape conductor and the potting compound. Furthermore, this process allows for smooth coil surfaces, enabling good coupling to cooled surfaces, such as copper, and thus effective heat dissipation. The potting compound also provides electrical insulation between the HTS windings of the coil and exhibits a dielectric strength of more than 20 kV / mm. Example 6

[0059] An HTS tape conductor is wound with a metal wire made of copper, NiCr, and / or a refractory metal such as tungsten, molybdenum, or tin. Electrical current pulses through this reinforcement heat the HTS tape conductor and trigger the transition from the superconducting to the normal conducting state. The heating resistance can be adjusted via the effective length of the current path and the contact resistances between the windings. The contact resistance can also be adjusted by impregnation / encapsulation with a conductive filler material, such as solder, silver ink, or metal-filled polymers. High-temperature superconducting switches and triggered current limiters, for example, can be implemented using such an HTS tape conductor. Example 7

[0060] In a superconducting residual current limiter (English: superconducting fault current limiter,In the case of an SFCL or switch, an HTS tape conductor is driven from the superconducting to the normal conducting state within fractions of a second by a strong current overload. To withstand the brief, extremely high energy input without damage, HTS tape conductors with the highest possible heat capacity and high longitudinal resistance are required. A thick metallic sheath with high heat capacity can be formed by wrapping the conductor in multiple layers with thin metal wire, such as copper or refractory metals. Furthermore, good thermal coupling to the armor can be achieved on the surface of the HTS tape conductor 10 by means of a solder layer. The longitudinal resistance of the armor can be controlled, as shown in Example 6. Example 8

[0061] An HTS tape conductor is wound in parallel with a metal wire made of copper, NiCr, or a refractory metal such as tungsten, molybdenum, or tantalum, and one or more electrically insulating fibers. Within the armor, the windings of the metal wire are thus separated by electrically insulating sections, or the metal wire is embedded in an insulating matrix. This wire can be used either as a signal or measuring line, or, similar to Example 6, supplied with current pulses. With this configuration, the effective heating resistance can be varied within even wider limits than with closely spaced metal wires. Example 9

[0062] A measuring line 17 (e.g. an optical waveguide with Bragg gratings) accompanies the HTS tape conductor in the axial direction and is mechanically connected to the HTS tape conductor by the armoring according to the invention (cf. Fig. 4a and Fig. 4bThe measuring lead allows monitoring of the HTS tape conductor during operation, especially when local heating or a quench occurs, i.e., the transition to the normal conducting state. The measuring lead can be installed at the edge of the HTS tape conductor ( Fig. 4a ) or on and along one of the main surfaces of the HTS belt conductor ( Fig. 4b ) arranged and fixed by the reinforcement.

[0063] Fig. 5Figure 510 shows a flowchart of a manufacturing process according to an embodiment of the present invention. In a first step, an HTS tape conductor or several interconnected (e.g., face-to-face) HTS tape conductors—as described above—are wrapped with at least one layer of fiber having a substantially circular cross-section to form an reinforcement, as described in detail above. Subsequently, in some embodiments, a hermetic reinforcement can be created by soldering or potting the reinforcement with a solder material and / or a potting compound (step 520). Further embodiments of such a manufacturing process and suitable fibers and potting compounds are described in detail above, particularly in Section 3. Reference symbol list:

[0064] 10HTS tape conductor ( insert11 Metal substrate 12 Buffer layer(s) 13 HTS layer 14 Enclosing metal layer made of Ag, Ag and Cu or Ag, Cu and solder 15 Fiber reinforcement / wrapping 16 Solder layer between HTS tape conductors 17 Measuring lead (e.g. fiber optic) WHTS tape conductor width DHTS tape conductor thickness

Claims

1. A superconducting fault current limiter or switch comprising: a high temperature superconducting, HTS, tape conductor (10) having a width (W) and a thickness (D); and an armoring formed by wrapping the HTS tape conductor (10) with a first layer of at least one fiber (15) of a first type having a substantially round cross section, wherein the fiber (15) is wrapped substantially without overlap and abutting closely to each other, wherein the HTS tape conductor (10) is wrapped with multiple layers of a metal fiber.

2. The superconducting fault current limiter or switch of claim 1, wherein the metal fiber comprises a copper or refractory metal fiber.

3. The superconducting fault current limiter or switch of claim 1, further comprising a sense line (17), wherein the sense line is located at the edge of the HTS tape conductor or on and along one of the major surfaces of the HTS tape conductor.

4. The superconducting fault current limiter or switch of claim 3, wherein the sense line (17) comprises an optical fiber, preferably a glass fiber.

5. The superconducting fault current limiter or switch of claim 1, wherein a second HTS tape conductor (10) with facing HTS side is soldered as a patch (16) to an HTS side of an HTS tape conductor surface of the HTS tape conductor (10).

6. A method of manufacturing a superconducting fault current limiter or switch comprising: wrapping (510) an HTS tape conductor (10) with at least one layer of a fiber (15) having a substantially round cross section to provide the HTS tape conductor (10) with an armoring; and wrapping the HTS tape conductor (10) with multiple layers of a metal fiber; wherein preferably the tensile stress during wrapping is in the range of 50 to 250 MPa; and wherein a feed of the HTS tape conductor (10) and a wrapping frequency are tuned to each other such that the fiber (15) is offset by one fiber diameter per winding.