AU7181400A - High-temperature superconductor arrangement - Google Patents

High-temperature superconductor arrangement Download PDF

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Publication number
AU7181400A
AU7181400A AU71814/00A AU7181400A AU7181400A AU 7181400 A AU7181400 A AU 7181400A AU 71814/00 A AU71814/00 A AU 71814/00A AU 7181400 A AU7181400 A AU 7181400A AU 7181400 A AU7181400 A AU 7181400A
Authority
AU
Australia
Prior art keywords
layer
arrangement
thermal expansion
coefficient
polymer
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.)
Abandoned
Application number
AU71814/00A
Inventor
Makan Chen
Willi Paul
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB Research Ltd Sweden
Original Assignee
ABB Research Ltd Sweden
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by ABB Research Ltd Sweden filed Critical ABB Research Ltd Sweden
Publication of AU7181400A publication Critical patent/AU7181400A/en
Abandoned legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00Superconducting devices
    • H10N60/30Devices switchable between superconducting and normal states

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  • Containers, Films, And Cooling For Superconductive Devices (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Description

AUSTRALIA
Patents Act 1990 ABB Research Ltd.
ORIGINAL
COMPLETE SPECIFICATION STANDARD PATENT Invention Title: High-temperature superconductor arrangement The following statement is a full description of this invention including the best method of performing it known to us:- I )1 The present invention relates to the field of high-temperature superconductors. It concerns a hightemperature superconductor arrangement according to the precharacterizing clause of patent claim i.
European Patent Application EP-A 0 911 889 discloses a high-temperature superconductor arrangement for use in a current limiter. The arrangement comprises a superconducting layer and a perforated steel plate, designed as an electrical bypass, which forms a composite conductor with the superconducting layer. The bypass is adhesively bonded onto the :superconductor by means of a conductive epoxy resin.
This conducting transitional or intermediate layer, provided for improving the contact resistance between the superconductor and the bypass, makes it possible for the current to change from one layer into the other layer.
The transitional layer referred to consists for example of a conducting polymer composite material which comprises an electrically insulating polymericresin base material and an electrically conducting filler. Metal powders, fibers or flakes as well as metalized small parts or particles come into consideration as the filler. The filler must be used in an adequate proportionate amount by volume, in order that the individual particles or fibers have electrical contact with one another and the composite material produced is conductive.
For cooling to operating temperature, hightemperature superconductors are brought into thermal contact with a cooling medium, preferably with liquid nitrogen LN 2 On account of the different coefficients of thermal expansion of the superconductor and bypass on the one hand and the polymer composite material on the other hand, stresses occur during this cooling.
The layer of polymer composite material in particular, which has a great coefficient of thermal expansion, is 2 subjected to tensile stress by the adjacent layers, contracting to a lesser extent, and forms cracks.
The Patent EP-B 0 257 466 discloses a laminate comprising a metal layer and a layer of a cured polymer-matrix composite material which serves for example for the cooling of electronic components mounted on a printed-circuit board. A reinforcing, heat-conducting material of low thermal expansion in the form of particles, fibers or fabrics is incorporated into the layer of composite material.
This reinforcing layer serves for the heat conduction between the heat source (the electronic components) and the heat sink (metal layer) as well as to balance the coefficients of thermal expansion of the printedcircuit board and the metal layer. The composite layer is electrically nonconducting and designed such that the components which heat up during operation can be *cooled well.
The object of the present invention is to 20 reduce the thermomechanical stresses produced during cooling to operating temperature in an electrically conducting polymer-composite based transitional layer provided between a superconductor and an electrical bypass and prevent the formation of cracks in the transitional layer in a high-temperature superconductor arrangement of the type stated at the beginning. This object is achieved by a high-temperature superconductor arrangement having the features of patent claim 1.
The essence of the invention is to reduce the coefficient of thermal expansion of the transitional layer by the use of suitable means. As a result, said coefficient approaches the unchanged coefficient of thermal expansion of the superconductor and electrical bypass and the tensile stresses occurring in the transitional layer during cooling of the arrangement are reduced.
In a first preferred embodiment, the conducting polymer composite material has a second, electrically nonconducting filler mixed with it. This filler 3 preferably has a coefficient of thermal expansion which is lower than that of the polymer matrix.
In a further embodiment, fibers are additionally added to the polymer composite material to improve the mechanical stability.
Further advantageous embodiments emerge from the dependent patent claims.
The invention is explained in more detail below on the basis of an exemplary embodiment in conjunction with the drawing, in which: Figure 1 shows a high-temperature superconductor arrangement with a polymer-composite transitional layer modified according to the invention.
The designations used in the drawing are S 15 summarized in the list of designations.
Represented in Figure 1 is a detail from a cross section through a high-temperature superconductor arrangement, as is used for example in current limiters. A high-temperature superconductor 1 is 20 connected in an areal manner over a main area to an electrical bypass layer 2 and forms a composite conductor with the latter. Between these two layers 1, 2 there is a transitional layer 3 based on a polymer composite. The latter comprises a polymer matrix 30, a conducting first filling material 31 and a nonconducting second filling material 32.
For the high-temperature superconductor arrangement represented in the drawing and the following description, relating to the latter, a planar geometry has been chosen. This can be symmetrically supplemented, for example by a second bypass layer being provided on a side of the superconductor 1 lying opposite the first bypass layer 2. The invention can be used equally well in the case of cables or wires with a superconducting core which is surrounded by an electrical bypass. In the case of the last-mentioned, axially symmetrical arrangement and in the case of the aforementioned planar configurations with a plane of symmetry, it is ensured that the thermally induced 4 change in length runs in a direction parallel to the axis or plane of symmetry and does not lead to any bimetal-like distortion of the arrangement.
The transitional layer 3 comprises a polymer composite material with a matrix 30 and at least one conducting filling material 31. The matrix systems are preferably three-dimensionally crosslinking thermosetting materials and are based for example on epoxy, silicon or polyester resins. The coefficient of thermal expansion of such a polymer matrix 30 lies in the range of 60-I00.10- 6 in comparison with which the coefficient of thermal expansion of the ceramic :.superconductor 1 is typically approximately 10.10 6
/K,
and that of a bypass 2 of steel is around 1510- 6 /K. 4 15 During the cooling of the arrangement from room temperature or the curing temperature of the polymer matrix 30 to operating temperature (77K), the polymer composite would consequently contract to a much greater extent than the adjacent layers. Since the actually 20 resulting change in length is the same for all the "00i layers of the arrangement, stresses correspondingly build up and, in particular in the case of a number of 0:0. thermal cycles, i.e. repeated heating up and cooling down, may lead to cracks in the transitional layer 3.
To reduce said stresses, it is proposed according to the invention to reduce the coefficient of thermal expansion of the transitional layer 3, preferably to a value which is possibly only 2-3 times greater than that of the steel bypass 2.
The conducting filler 31 comprises for example silver particles and often has itself a low coefficient of thermal expansion. An increase of the particle density of the conducting filler, i.e. the number of silver particles per volume, consequently already brings about a reduction in the coefficient of thermal expansion of the polymer composite. For reasons of cost and so as not to influence the electrical properties of the transitional layer 3 in an uncontrolled way, instead a second, nonconducting 5 filler 32 may be added. This comprises small particles or fibers with a diameter of 1-100 jm, of a material with a small coefficient of thermal expansion of preferably less than 10_10- 6 Quartz (SiO 2 aluminum oxide (A1 2 0 3 or aluminum nitride (AlN) come into consideration, the two last-mentioned additionally being distinguished by their heat-conducting and heatstoring properties.
The mechanical properties of a polymercomposite-based transitional layer of this type can be improved by adding glass, carbon or aramid fibers to it as a reinforcing carrier material in a way similar to a fiber composite layer. A layer modified in this way has, for example, a higher bending strength and 15 consequently serves at the same time for the mechanical stabilization of the composite conductor.
A polymer composite according to the invention .is prepared by mixing between 10 and 40% by volume of silver powder and approximately the same amount of a 20 second, nonconducting filling material with an epoxy resin. The polymer composite is then applied over a large area and uniformly to a first layer of the composite conductor. The layer to become the transitional layer is then brought into congruent alignment with the second layer of the composite conductor and cured under a vacuum. Suitable for applying a viscous layer with a controlled thickness are screen-printing methods or, with the assistance of a solvent, also spray-coating methods.
LIST OF DESIGNATIONS 1 superconductor 2 electrical bypass 3 transitional layer, polymer composite material polymer matrix 31 first filling material, for example silver particles 32 second filling material

Claims (3)

  1. 3. The arrangement as claimed in claim 2, characterized in that the coefficient of thermal expansion of the second filling material is less than the coefficient of thermal expansion of the polymer matrix
  2. 4. The arrangement as claimed in claim 3, characterized in that the polymer matrix is an epoxy resin, and the second filler comprises quartz (Si0 2 aluminum oxide (A1 2 0 3 or aluminum nitride (AlN) The arrangement as claimed in claim 2, characterized in that the coefficient of thermal expansion of the polymer composite material is less than three times the coefficient of thermal expansion of the electrical bypass
  3. 6. The arrangement as claimed in one of the preceding claims, characterized in that the polymer composite material additionally has fibers for mechanical reinforcement. DATED THIS 24 DAY OF NOVEMBER 2000 ABB RESEARCH LTD. Patent Attorneys for the Applicant:- F.B.RICE CO
AU71814/00A 1999-12-02 2000-11-24 High-temperature superconductor arrangement Abandoned AU7181400A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE95/7982 1999-12-02
DE19957982A DE19957982A1 (en) 1999-12-02 1999-12-02 High temperature superconductor arrangement

Publications (1)

Publication Number Publication Date
AU7181400A true AU7181400A (en) 2001-06-07

Family

ID=7931100

Family Applications (1)

Application Number Title Priority Date Filing Date
AU71814/00A Abandoned AU7181400A (en) 1999-12-02 2000-11-24 High-temperature superconductor arrangement

Country Status (5)

Country Link
EP (1) EP1107323A2 (en)
JP (1) JP2001223399A (en)
AU (1) AU7181400A (en)
CA (1) CA2326058A1 (en)
DE (1) DE19957982A1 (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10226390B4 (en) * 2002-06-13 2004-07-22 Siemens Ag Resistive current limiter device with superconducting conductor track and non-superconducting shunt
GB0411035D0 (en) * 2004-05-18 2004-06-23 Diboride Conductors Ltd Croygen-free dry superconducting fault current limiter
JP2009203441A (en) * 2008-02-29 2009-09-10 Denso Corp Composite material, manufacturing method therefor, and composite structure
JP2010255006A (en) * 2010-08-18 2010-11-11 Denso Corp Composite material, production method thereof, and composite structure
JP6046036B2 (en) * 2011-05-24 2016-12-14 古河電気工業株式会社 Superconducting element for superconducting fault current limiter, superconducting element manufacturing method for superconducting fault current limiter, and superconducting fault current limiter

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5761017A (en) * 1995-06-15 1998-06-02 Illinois Superconductor Corporation High temperature superconductor element for a fault current limiter
DE19746976C2 (en) * 1997-10-24 2000-11-30 Abb Research Ltd High temperature superconductor arrangement
EP0942475A3 (en) * 1998-03-13 2002-03-13 Haldor Topsoe A/S Tubular support structure for a superconducting device

Also Published As

Publication number Publication date
CA2326058A1 (en) 2001-06-02
JP2001223399A (en) 2001-08-17
EP1107323A2 (en) 2001-06-13
DE19957982A1 (en) 2001-06-07

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Legal Events

Date Code Title Description
MK1 Application lapsed section 142(2)(a) - no request for examination in relevant period