Patent Grant
7980051
The invention relates to an apparatus and method for forming wound cables, such as Roebel or Rutherford cable, that involves minimal bending of the conductor elements.
Many applications of high Tc superconductors (HTS), such as power transformers and high current magnets, require higher current than the capacity of presently available conductor tape. High currents can be attained by forming cables of multiple subconductors in which the individual conductors or conductor elements are continuously transposed such that each subconductor is electromagnetically equivalent. In this way current is equally shared and AC losses minimised. A spiral arrangement of conductors on the surface of a cylinder achieves this, but with inefficient use of space so that the overall engineering current density of the winding is reduced. The Roebel bar and Rutherford cable are transposed conductor cable configurations which combine high packing density with rectangular cross-section. The Rutherford cable has been used extensively with low Tc superconductors—see for example, M. N. Wilson, “Superconductors and accelerators: the Good Companions”, IEEE Transactions on Applied Superconductivity, Vol. 9, No. 2, June 1999, pages 111-121. The Roebel bar is long established as a high current copper conductor configuration for transformers and has been fabricated using HTS conductor—see J. Nishioka, Y. Hikichi, T. Hasegawa, S. Nagaya, N. Kashima, K Goto, C Suzuki, T Saitoh, “Development of Bi-2223 multifilament tapes for transposed segment conductors”, Physica C volumes, 378-381 (2002) 1070-1072; V Hussennether, M. Oomen, M. Leghissa, H.-W. Neumüller, “DC and AC properties of Bi-2223 cabled conductors designed for high-current applications”, Physica C 401 (2004) 135-139; and Suzuki et. al. “Strain properties of transposed segment conductors for a transmission cable”, Physica C, volumes 392-396, (2003) pages 1186-1191.
In addition to the requirement for high-current conductor most AC applications of HTS demand low AC loss. In general this means that conductors should be transposed, electrically decoupled, and have minimal transverse dimensions. Because of the typically ribbon-like form of HTS conductors, it may be desirable for AC applications to manufacture conductor with narrower subconductor width than the usual DC conductor. An application might be, for example, in parts of windings exposed to appreciable AC fields oriented perpendicular to the face of the conductor. This narrow subconductor conductor will need to be made into a transposed multisubconductor conductor to give adequate current capacity for many applications. The shorter the transposition twist pitch, the lower the effective intersubconductor resistivity can be while still keeping the subconductors magnetically decoupled—see M. N. Wilson, “Superconductors and accelerators: the Good Companions”, IEEE Transactions on Applied Superconductivity, Vol. 9, No. 2, June 1999, pages 111-121, equation 3. Provided decoupling is achieved, lower intersubconductor resistivity improves electrical and thermal stability and facilitates electrical connection to the cable.
There are presently two main HTS tape conductor types in production or development. Multifilament silver or silver alloy-sheathed composite conductor using the superconducting cuprate of composition (Bi,Pb)2.1Sr2Ca2Cu3Ox (otherwise known as Bi-2223) is produced in commercial quantities by a powder-in-tube (PIT) manufacturing process involving drawing, rolling, and thermal treatment processes. A typical conductor will consist of approximately 55 HTS filaments embedded in a silver or silver alloy matrix, will have a cross-section of about 4 mm by 0.2 mm and a critical current at 77 K in self-field of up to 150 A.
Roebel-type cabled conductor made from PIT subconductors has been disclosed in the literature—see J. Nishioka, Y. Hikichi, T. Hasegawa, S. Nagaya, N. Kashirna, K Goto, C Suzuki, T Saitoh, “Development of Bi-2223 multifilament tapes for transposed segment conductors”, Physica C 378-381 (2002) 1070-1072; and V Hussennether, M. Oomen, M. Leghissa, H.-W. Neumüller, “DC and AC properties of Bi-2223 cabled conductors designed for high-current applications”, Physica C 401 (2004) 135-139.
Typically, the formation of a Roebel bar involves sequential steps in which the conductors are in turn laterally bent and then moved vertically. This places strain on the conductors and can damage them.
A method for forming Roebel bar cable by controlled bending of tapes of this type is described in U.S. Pat. No. 6,725,071 to C Albrecht, P Kummeth, P Massek, titled “Fully transposed high Tc composite superconductor, method for producing the same and its use”. This takes account of the sensitivity of PIT tape to deformation-induced damage by imposing minimum limits on the edge-wise (i.e. in the plane of the tape) bending radius and bending zone length respectively of 100 times and 20 times the tape width. The resulting cable pitch for complete transposition is comparatively long.
“Second generation” or 2G HTS conductor is produced as a thin film of YBa2Cu3O7 (Y-123) approximately 1 μm thick on a substrate of a base metal tape coated with various oxide films—see for example A. P. Malozemoff, D. T. Verebelyi, S. Fleshler, D. Aized and D. Yu “HTS Wire: status and prospects”, Physica C, volume 386, (2003) pages, 424-430. Transposed 2G conductor has been disclosed—see Suzuki, Goto, Saitoh and Nakatsuka, “Strain Properties of Transposed Segment Conductors for a Transmission Cable”, Physica C 392-396 (2003) 1186-1191. See also Japanese patent application publications 2003092033 and 2004030907.
Methods have been developed for laminating 2G wire with copper tape or electroplating with copper to protect the tape from thermal-electrical instability and, by locating the HTS film at or near the neutral axis for flat-wise (out-of-plane) bending, from mechanical stress. It is envisaged that standard conductor with around 4 mm width will be slit from the wide conductor. Edge-wise bending of 2G wire to form cables will, like PIT tape, be subject to limits on the minimum bending radius. There is, at present, no published data on the sensitivity of 2G wire to edge-wise bending. However, due to its different mechanical properties compared with silver and silver-alloy sheath material one might expect even more difficulty in edge-wise deformation.
In broad terms, in one aspect, the invention comprises a cable winding machine comprising:
feeding means to move multiple subconductors through the machine in a machine direction as the subconductors are wound together into a cable by the machine,
holding means to hold a first subconductor as it moves forward through the machine,
a winder (herein: first winder) arranged to rotate at least a second subconductor and a third subconductor about the first subconductor as the first, second and third subconductors move through the machine in the machine direction, so that the second subconductor winds with the first subconductor and then the third subconductor winds with the first and second subconductors, after the winder in the machine direction.
The first winder may be arranged to rotate the second and third subconductors and also at least one other subconductor so another subconductor or a first other subconductor winds with the first, second, and third subconductors and thereafter any other subconductors rotated by the first winder wind one after another with the subconductors wound together previously.
The cable winding machine may also include a second winder after the first winder in the machine direction and arranged to rotate at least one further subconductor about the subconductors wound together by the first winder, so that a said further subconductor winds following the second winder with the subconductors wound together by the first winder, or where the second winder is arranged to rotate two or more said further subconductors, so that a first further subconductor winds following the second winder with the subconductors wound together by the first winder, and then any other further subconductors rotated by the second winder wind one after another with the subcondutors wound together previously.
The cable winding machine may also comprise one or more yet further winders after the second winder in the machine direction, each further winder arranged to rotate at least one additional subconductor about the subconductors wound together by the prior winders so that an additional subconductor winds following its further winder with the subconductors wound together by the prior winders, or where each further winder is arranged to rotate two or more additional subconductors, so that a first additional subconductor winds following the further winder with the subconductors wound together by the prior winders, and then any other additional subconductors rotated by the further winder wind one after another with the subconductors wound together previously.
In a preferred form the first winder is arranged to hold said second subconductor for further in the machine direction than said first subconductor and to hold said third subconductor for further in the machine direction than said second subconductor so that said third subconductor winds with the first and second subconductors after in the machine direction the second subconductor winds with the first subconductor.
Where the first winder is arranged to rotate one or more other subconductors it may be arranged to hold each of these other subconductors for further again in the machine direction, so that these other subconductors wind one after another with the subconductors wound together previously.
Where the machine comprises a second winder, in this preferred form the second winder is arranged to hold each further subconductor for different spacings in the machine direction, so that subconductors rotated by the second winder also wind one after another with the subconductors wound together previously.
Where the machine comprises one or more further winders after the second winder then in this preferred form each further winder is arranged to hold each additional subconductor for different spacings in the machine direction, so that subconductors rotated by each further winder wind one after another with the subconductors wound together previously.
In a preferred from the first winder is arranged to hold the first subconductor in a predetermined orientation as it moves through the machine in the machine direction, and the second, third, and any further subconductors wound by the first winder in a predetermined orientation relative to said first subconductor and with each other as the first winder rotates the second, third, and any further subconductors about the first subconductor.
A second winder may be arranged to hold further subconductor(s) which it winds in the predetermined orientation as the further subconductor(s) move(s) forward through the machine in the machine direction and as it rotates these further subconductor(s) about the subconductor(s) wound together by the first winder.
Any further winders may be arranged to hold further subconductor(s) in the predetermined orientation as the further subconductor(s) move forward through the machine in the machine direction and are rotated about the subconductor(s) wound together by the prior winders.
In broad terms in another aspect the invention comprises a cable winding method comprising:
moving multiple subconductors through a cable winding machine in a machine direction as the subconductors are wound together into a cable by the machine,
holding a first subconductor as it moves forward through the machine,
rotating at least a second subconductor and a third subconductor about the first subconductor as the first, second and third subconductors move through the machine, so that the second subconductor winds with the first subconductor and then the third subconductor winds with the first and second subconductors, after the winder in the machine direction.
The method may also include holding the first subconductor in a predetermined orientation as it moves through the machine and the second, third, and any one or more other subconductors in a predetermined orientation relative to the first subconductor and with each while rotating the second, third, and one or more other subconductors about the first subconductor.
The subconductors may each have a width dimension across a longitudinal axis greater than a depth dimension through the longitudinal axis perpendicular to the width direction and holding the subconductors in said predetermined orientation may comprise holding the subconductors with the width dimension of the subconductors parallel as the subconductors move through the machine. The subconductors may have a serpentine shape. The subconductors may comprise a high Tc superconducting layer.
Preferred embodiments of the invention are described by way of example with reference to the accompanying drawings, in which:
Embodiments of the cable winding machine and method are particularly useful for producing composite (transposed) superconducting cable, allowing subconductors to be wound (or transposed) around one another with minimal stress on the subconductors. Superconducting wires typically consist of a flat ribbon-like substrate on which a layer or thin film of HTS crystal is deposited. Stresses on the conductors caused by bending, flexing and twisting during winding of for example Roebel cable can damage the crystal structure of the HTS layer and so reduce conductivity.
A second subconductor 42 and third subconductor 43 unwind from other spools 32 and 33 carried by the spool holder 36. The first subconductor moves through an aperture 58 in the centre of winder 51, aligned with the rotational axis of the winder 51 and the machine axis. The second and third subconductors 42 and 43 are held by and rotated about the first subconductor 41 by the winder 51. A holder 54 in the winder 51 holds the second subconductor 42 as the winder rotates and as the subconductor moves through the winder in the machine direction. Another holder 55 in the winder 51 holds the third subconductor 43 as the winder rotates and as the subconductor 53 moves through the winder in the machine direction. The holders 54 and 55 are spaced radially from the rotational axis of the winder. The second subconductor 42 subsequently winds with the first subconductor 41 at winding point 61. The third subconductor 43 then winds with the first and second subconductors 41 and 42 at winding point 62 spaced from point 61 in the machine direction. To space the winding point 62 from the winding point 61 the holder 55 in the winder 51 is longer in the machine direction than the holder 54 for the second subconductor 42, so that the winder 51 holds the third subconductor 43 for longer in the machine direction than it holds the second subconductor 42.
Fourth and fifth subconductors 44 and 45 unwind from other spools 34 and 35 and pass through apertures in the first winder 51 and are held by holders 56 and 57 in the second winder 52 as the subconductors 44 and 45 move through the winder. After winding together, the first, second and third subconductors 41-43 move through an aperture 59 in the centre of winder 52, aligned with the rotational axis of the winder in the machine direction. Fourth subconductor 44 and fifth subconductor 45 are held and rotated by the second winder 52 about the previously wound together first-third subconductors 41-43, and following the winder 52 in the machine direction first the fourth subconductor 44 winds therewith at winding point 63 and then the fifth subconductor 45 winds on at winding point 64. A longer holder 57 in the second winder 52 holds the fifth subconductor 45 for longer in the machine direction than the holder 56 in the second winder 52 holds the fourth subconductor 44, to space the winding points 64 and 63.
The wound cable is subsequently taken up onto spool 66.
Serpentine subconductors of the type shown in
The winders 51 and 52 may also be arranged to hold the first subconductor 41 in a predetermined orientation about its longitudinal axis as it moves through the machine i.e. so as not to allow it to rotate relative to ground about its longitudinal axis, and the winders may be arranged to also hold the other subconductors in a predetermined orientation relative to ground/to said first subconductor and with each other as they are wound on i.e. as the winders rotate. The subconductors may be in ribbon form i.e. have a width across a longitudinal axis greater than a depth dimension through the longitudinal axis perpendicular to the width direction, and the holders 54-57 may hold the subconductors with the width dimension of the subconductors parallel as the subconductors move through the machine. Where the subconductors comprise a high Tc superconducting layer on serpentine substrate for example, this will avoid bending and potentially damaging the HTS layer as the subconductors are wound into a composite cable. The holders may each comprise a slot guide which counter rotates within the winder as will be further described, where it is desired to maintain the subconductors in a predetermined orientation about their longitudinal axis as they move through the machine.
The embodiment of
As many subconductors as required in a finished cable can be wound by increasing the number of subconductors that are wound on by each winder and/or by increasing the number of winders.
Any of the subconductors can itself be formed from multiple previously wound subconductors.
It is important to maintain a constant angle called the “winding angle” between the central subconductor or group of previously wound subconductors and a next subconductor being wound on, herein after referred to as the “active subconductor”. The crossing point referred to herein is the position at which the active subconductor first contacts the central subconductor or subconductor group.
Referring to
Four spool wheels 73 are coupled to a static shaft by belts. Pulleys 73 are mounted at the ends of shafts journalled through the arms of the rotating spool holder 36 which support each of the subconductor spools 32-35 and a belt 72 passes about the pulleys 73 and couples directly or indirectly to the drive system so that rotation of the spool holder 36 causes counter rotation of each of the spools 32-35 to maintain the spools in a fixed vertical orientation shown throughout 360° rotation of the spool holder 36. The subconductors 42-45 unwound from the spools 32-35 are thus all retained in the same orientation relative to each other (they are retained in this orientation throughout the machine) as they are unwound, and do not twist about their own axis during the winding process and so stress on the subconductors is minimised.
Referring to
A holder 96 (see particularly
The holders 96-100 are mounted in the winder 90 for counter rotation relative to the rotation of the winder, as indicated by arrows C in
The machine embodiment shown in
In a yet alternative embodiment a machine may comprise only a single winder. For example if the winder 52 of the machine of
The preferred embodiment machines described above are arranged to hold the subconductors in a predetermined orientation about their longitudinal axes as the subconductors move through the machine and in particular subconductor tapes in a horizontal orientation. In an alternative embodiment it may not be essential that the machine and winders are arranged to maintain the orientation of each of the conductors about their longitudinal axis. The holders in each winder may be arranged to hold the subconductors sufficiently to rotate them about the centre conductor or group while allowing the subconductors that are rotated to in turn twist about their longitudinal axis.
Preferred forms of the machine are designed for winding Robel cable from subconductors having a serpentine shape, and in which each subconductor is an HTS subconductor comprising a layer of an HTS compound thereon, but in alternative embodiments the machine may be arranged to wind cable from serpentine non-HTS conductors such as serpentine copper conductors for example, or cable from conductors which have a non-serpentine shape.
In the preferred form of machine described with reference to
It is obvious that at set up of the machine rotation of all of the spool holder and winders and the drive unit 120 must be carefully synchronised and the relative rotational position of each of the unwind spools for the subconductors must be relatively positioned where the cable is being wound from serpentine conductor as described, to ensure that the cable is successfully wound as described above.
The foregoing describes the invention including a preferred form thereof. Alterations and modifications as will be obvious to those skilled in the art are intended to be incorporated within the scope hereof as defined in the accompanying claims.
This application is a continuation-in-part of U.S. patent application Ser. No. 11/962,364, filed Dec. 21, 2007, now U.S. Pat. No. 7,788,893 which claims the benefit of U.S. Provisional Application No. 60/871,262, filed Dec. 21, 2006, the entirety of which is incorporated herein by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3360919 | Burr | Jan 1968 | A |
| 4549391 | Toda et al. | Oct 1985 | A |
| Number | Date | Country | |
|---|---|---|---|
| 20090183486 A1 | Jul 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60871262 | Dec 2006 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11962364 | Dec 2007 | US |
| Child | 12341408 | US |
