WO2000039818A1 - Bobine d'induction haute tension - Google Patents

Bobine d'induction haute tension Download PDF

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Publication number
WO2000039818A1
WO2000039818A1 PCT/EP1999/010510 EP9910510W WO0039818A1 WO 2000039818 A1 WO2000039818 A1 WO 2000039818A1 EP 9910510 W EP9910510 W EP 9910510W WO 0039818 A1 WO0039818 A1 WO 0039818A1
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WO
WIPO (PCT)
Prior art keywords
inductor according
coil
electrically insulating
inductor
insulating means
Prior art date
Application number
PCT/EP1999/010510
Other languages
English (en)
Inventor
Udo Fromm
Christian Sasse
Nicholas Warren
Original Assignee
Abb Ab
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
Priority claimed from GBGB9828653.7A external-priority patent/GB9828653D0/en
Priority claimed from GBGB9912609.6A external-priority patent/GB9912609D0/en
Application filed by Abb Ab filed Critical Abb Ab
Priority to AU29038/00A priority Critical patent/AU2903800A/en
Publication of WO2000039818A1 publication Critical patent/WO2000039818A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/28—Coils; Windings; Conductive connections
    • H01F27/32—Insulating of coils, windings, or parts thereof
    • H01F27/324—Insulation between coil and core, between different winding sections, around the coil; Other insulation structures

Definitions

  • This invention relates to a high voltage (HV) inductor, having a cooled coil, preferably, but not exclusively, a cooled, superconducting coil.
  • HV high voltage
  • the term "high voltage” is intended to mean in excess of 2 v and preferably in excess of 10 kV.
  • HN induction devices such as electric machines or HV transformers
  • induction devices based on cables are not suited to handling high voltages in combination with low currents. This is because the electrical insulation thickness of a cable is dependent on the cross-sectional area of the conductors. For small conductor cross-sectional areas (i.e. small currents), the electrical insulation is large and the induction device is therefore uneconomic.
  • the present invention seeks to provide an HN inductor formed from a cable having at least one cooled coil or winding and surrounding electrical insulation.
  • a high voltage inductor comprising a coil having adjacent turns electrically insulated from each other, cooling means for cooling the coil, electrically insulating means surrounding the coil and within which the electric field is contained in use of the inductor, and magnetic material of high magnetic permeability connecting opposite electrically insulated ends of the coil to close the flux path between the opposite coil ends with low reluctance.
  • the present invention preferably uses a solid insulation system, preferably based on extruded technology, with an integrated HV inductor.
  • the HV inductor is conveniently in the form of an electrically insulated HV cable the opposite end portions of which are joined by magnetic material of high magnetic permeability to close the flux path with low reluctance.
  • the main advantage of the invention is that the electrical insulation system in combination with the coil is utilised better when compared to "conventional" cable HV inductors with respect to achieved inductance and magnetic coupling, especially when the coil and is superconducting and is cooled by the cooling means .
  • the electrically insulating means comprises an inner layer of semiconducting material in electrical contact with said coil only at spaced apart intervals along the length of the coil, an outer layer of semiconducting material at a controlled electrical potential along its length and an intermediate layer of electrically insulating material between the said inner and outer layers.
  • semiconductor material means a material which has a considerably lower conductivity than an electric conductor but which does not have such a low conductivity that it is an electrical insulator.
  • a semiconducting material should have a volume resistivity of from 1 to 10 5 ohm. cm, preferably from 1 to 500 ohm. cm and most preferably from 10 to 100 ohm. cm, e.g. 20 ohm. cm.
  • the electrically insulating means is preferably of unitary form with the semiconducting and electrically insulating layers either in close mechanical contact or, more preferably, joined together, e.g. bonded by extrusion.
  • the layers are preferably formed of plastics material having resilient or elastic properties at least during manufacture and assembly at room temperature. This allows the inductor to be flexed and shaped into any desired form. By using for the layers only materials which can be manufactured with few, if any, defects having similar thermal properties, thermal and electric loads within the insulation are reduced.
  • the insulating intermediate layer and the semiconducting inner and outer layers should have at least substantially the same coefficients of thermal expansion (a) so that defects caused by different thermal expansions when the layers are subjected to heating or cooling will not arise. Ideally the layers will be extruded together around the coil.
  • the electrically insulating intermediate layer comprises solid thermoplastics material, such as low or high density polyethylene (LDP ⁇ or HDPE) , polypropylene (PP) , polybutylene (PB) , polymethylpentene (PMP) , ethylene (ethyl) acrylate polymer, cross-linked materials, such as cross -linked polyethylene (XLPE) , or rubber insulation, such as ethylene propylene rubber (EPR) or silicone rubber.
  • the semiconducting inner and outer layers may comprise similar material to the intermediate layer but with conducting particles, such as particles of carbon black or metallic particles, embedded therein. Generally it has been found that a particular insulating material, such as EPR, has similar mechanical properties when containing no, or some, carbon particles.
  • the intermediate layer may be divided into two or more sub-layers by one or more additional intermediate layers of semiconducting material.
  • the electric field generated by the coil is confined within the electrically insulating material, preferably between the semiconducting inner and outer layers on the inside and outside of the insulating intermediate layer.
  • the electric field is substantially radial and confined within the intermediate layer.
  • the semiconducting outer layer is designed to act as a screen to prevent losses caused by induced voltages. Induced voltages in the outer layer could be reduced by increasing the resistance of the outer layer. The resistance can be increased by reducing the thickness of the outer layer but the thickness cannot be reduced below a certain minimum thickness. The resistance can also be increased by selecting a material for the layer having a higher resistivity.
  • the resistivity of the semiconducting outer layer is too great, the voltage potential midway between adjacent spaced apart points at a controlled, e.g. earth, potential will become sufficiently high as to risk the occurrence of partial discharge with consequent erosion of the insulating and semiconducting layers.
  • the semiconducting outer layer is therefore a compromise between a conductor having low resistance and high induced voltage losses but which is easily connected to a controlled potential, typically earth or ground potential, and an insulator which has high resistance with low induced voltage losses but which needs to be connected to the controlled potential along its length.
  • the resistivity p s of the semiconducting outer layer should be within the range P ⁇ __. ⁇ P_ ⁇ P____ ⁇ where p___ a is determined by permissible power loss caused by eddy current losses and resistive losses caused by voltages induced by magnetic flux and p, ⁇ is determined by the requirement for no corona or glow discharge.
  • the semiconducting outer layer may have anisotropic resistive properties, i.e. the resistance in the azimuthal direction is very high to prevent short circuits but is considerably lower in the axial direction.
  • the outer layer of semiconducting material may be at least partly surrounded by a metal sheath in contact with the semiconducting outer layer.
  • the sheath can act both as a means for applying the controlled voltage along the length of the outer layer and for providing rigidity.
  • the metal sheath should not be completely closed in order not to cause an inductive short circuit. It should have at least one interruption in the form of a slit along the main axis of the induction device
  • the metal sheath could completely surround the sheath provided that overlapping sheath portions are electrically insulated from each other. If the surrounding sheath is non-metallic (plastics material) , then it may completely enclose the outer layer of semiconducting material .
  • the coil is wound from elongate electrically conducting means having a surrounding electrical insulation, such as varnish.
  • the electrical insulation is removed at spaced apart regions along the length of the conducting means so that the latter makes electrical contact with the inner layer of semiconducting material.
  • the inner layer of semiconducting material makes electrical contact with regions or points at opposite ends of the coil.
  • the inner layer of semiconducting material also makes electrical contact with the coil at one or more points or regions between the opposite end of the coil.
  • the inner layer of semiconducting material makes electrical contact with the coil at every n turns of the coil ⁇ O.ln turns, where n is typically from 100 to 10,000, typically about 1000.
  • the electrically conducting means has superconducting properties.
  • the invention is not intended to be limited to electrically conducting means having superconducting properties and is intended to cover any electrically conducting means whose electrical conducting properties significantly improve at low temperatures, e.g. at temperatures below 200 K.
  • the electrically conducting means may comprise low temperature superconductors, but most preferably comprise HTS materials, for example electrically insulated HTS wires or tape helically wound, for example, on an inner support tube.
  • a convenient HTS tape comprises silver-sheathed BSCCO-2212 or BSCCO-2223 (where the numerals indicate the number of atoms of each element in the [Bi, Pb] _ Sr 2 Ca 2 Cu 3 O x molecule) and hereinafter such HTS tapes will be referred to as "BSCCO tape(s)".
  • BSCCO tapes are made by encasing fine filaments of the oxide superconductor in a silver or silver oxide matrix by a powder-in-tube (PIT) draw, roll, sinter and roll process. Alternatively the tapes may be formed by a surface coating process. In either case the oxide is melted and resolidified as a final process step.
  • HTS tapes such as TiBaCaCuO (TBCCO-1223) and YBaCuO (YBCO-123) have been made by various surface coating or surface deposition techniques.
  • an HTS wire should have a current density beyond j c ⁇ 10 s Ac "2 at operation temperatures from 65 K, but preferably above 77 K.
  • the filling factor of HTS material in the matrix needs to be high so that the engineering current density j e >_ 10 4 Acm "2 . j c should not drastically decrease with applied field within the Tesla range.
  • the helically wound HTS tape is cooled to below the critical temperature T c of the HTS by a cooling fluid, preferably liquid nitrogen which, for example, may pass through the inner support tube.
  • the coil may be provided with a magnetic core of magnetisable material, such as particulate material, preferably a compound of iron, wire, e.g. iron based, or tape material, e.g. iron based, amorphous or nano- crystalline.
  • the coil may have an air core or a core of other non-magnetisable materials, such as plastics materials or non-magnetisable metals or ceramics.
  • the choice of the magnetic material depends on the application.
  • the core may also be hollow inside to allow a cooling channel of said cooling means to run therethrough. Typically such a cooling channel, especially for cooling superconductors, would carry a cooling medium such as liquid nitrogen to cool the coil down to required superconducting temperatures .
  • the core can be formed in two ways along the main axis of the coil.
  • the potential of the coil at its opposite ends is defined by the voltage applied to the coil.
  • the potential along the coil itself is given by the induced voltage caused by each turn of the coil around the core.
  • the magnetic core will be at equal constant potential all along the length of the coil.
  • the coil however has a potential that depends on the induced voltage, as explained above.
  • the potential difference between the core and the coil will differ along the length of the coil. It is thus necessary to electrically insulate the core sufficiently against the coil so that no local discharges occur.
  • the second possibility for a magnetic core made of magnetisable material is to have no electrical insulation against the core but to provide an electrically insulated coil. This has the advantage of saving insulation material and decreasing the total thickness of the resulting coil.
  • the magnetic core then has to be split up into overlapping "threads" or lengths which are electrically insulated against each other. Since the induced voltage along the coil per meter will typically be less than 1000 Volts, it is sufficient to utilise standard insulation, such as enamel, for the core. It is also possible to use for the magnetic core thin tape of magnetic material or magnetic powder where the particles are insulated with an electrically insulating coating.
  • the core of the coil may have a cooling channel therethrough.
  • a cooling channel especially for cooling superconductors, would carry a cooling medium such as liquid nitrogen to cool the coil down to required superconducting temperatures.
  • the cable from which the coil is formed about a magnetic core may be wound in a helical path around a non-closed magnetic core, such as a toroidal shaped magnetic core having one or more air gaps therein.
  • the current in the cable can be divided into two components, one component flowing in the azimuthal direction with a constant radius and the other component flowing axially along the longitudinal axis of the cable. Since the cable is wrapped around a magnetic core, the effect of the induction is twofold. Firstly as the axial component in the cable, as mentioned above, and secondly as the axial component in the large magnetic core about which the cable is wound.
  • the amount of superconducting means can be optimised.
  • the superconducting coil can be wound as a tight helix or as a loose helix using less superconductor material. Also the "tightness" of the wound cable on the large magnetic core can be adjusted as required.
  • an inductor according to the invention may be formed from a cable having a single coil or winding.
  • An inductor according to the invention may be formed from a cable having at least two series -connected "part coils” or windings arranged coaxially (or concentrically) of each other and each surrounded by a separate "band” of electrically insulating means, each insulation "band” comprising an inner layer of semiconducting material in electrical contact with its associated coil only at spaced apart intervals along the length of the coil, an outer layer of semiconducting material and an intermediate layer of electrically insulating material between the said inner and outer layers. If the cable is grounded or connected to some other controlled potential, the earthing or controlled potential will only be connected to the outermost semiconducting outer layer.
  • the “cooling means” may include separate cooling means associated with the or each part coil or winding.
  • the cooling means may comprise a cryogenic container or the like within which the inductor is contained.
  • the part coils or windings are preferably, but not essentially, superconducting.
  • the winding angles of the part coils or windings may be from just over 0° up to almost 90° to the axial direction of the cable for a tightly wound part coil.
  • the winding angles and/or winding directions of different part coils of the inductor may be different.
  • the winding angle and/or winding direction may be chosen to influence the flexibility of the inductor or to reduce mechanical stress for brittle superconducting means, the winding angle and/or winding direction is primarily selected to influence the magnetic field created by a particular part coil.
  • the winding angles used in the formation of the different part coils are conveniently selected according to how the magnetic fields from each part coil are to be arranged with respect to each other.
  • the respective winding angles and/or winding directions may be chosen so that in certain applications the magnetic fields from adjacent part coils compliment and strengthen each other whereas in other applications the magnetic fields from adjacent part coils oppose each other.
  • Figure 1 is a schematic, sectional view, on an enlarged scale, of a cable of one embodiment of a high voltage inductor according to the invention having an air core;
  • Figure 2A is a schematic view of the inductor shown in Figure 1;
  • Figure 2B is a schematic view, on an enlarged scale, of a part of the inductor shown in Figure 2;
  • Figure 3 is a schematic, sectional view, on an enlarged scale, of part of a cable of another embodiment of a high voltage inductor according to the invention having an air core;
  • Figure 4 is a partly cut away perspective view of yet another embodiment of an inductor according to the invention.
  • Figure 5 is a schematic, partly cut away perspective view of further embodiment of an inductor according to the invention.
  • Figure 6 is a schematic view, on an enlarged scale, of a magnetic core of the inductor shown in Figure 5;
  • Figure 7 is a schematic, partly cut away perspective view of a yet further embodiment of an inductor according to the invention.
  • Figure 8 is a schematic view of a yet further embodiment of an inductor according to the invention.
  • FIGS 1 to 3 show one embodiment of a high voltage (HV) inductor 1 according to the invention.
  • the inductor 1 is in the form of a cable comprising a coil 2 wound from elongate high- temperature (T c ) superconducting (HTS) material, for example BSCCO tape or the like, which is electrically insulated, e.g. with varnish or the like, and wound on a support tube 3.
  • T c high- temperature
  • HTS superconducting
  • a solid electrical insulation system surrounds the coil 2 and comprises an inner layer 4 of semiconducting material, an outer layer 5 of semiconducting material and, sandwiched between these semiconducting layers, an insulating layer 6.
  • the HTS material has its electrical insulation, e.g.
  • the layers 4-6 preferably comprise thermoplastics materials in close mechanical contact or preferably solidly connected to each other at their interfaces. Conveniently these thermoplastics materials have similar coefficients of thermal expansion and are resilient or elastic at least at room temperature. Preferably the layers 4-6 are extruded together around the winding 2 to provide a monolithic structure so as to minimise the risk of cavities and pores within the electrical insulation. The presence of such pores and cavities in the insulation is undesirable since it gives rise to partial discharge in the electrical insulation at high electric field strengths.
  • the solid insulating layer 6 may comprise cross-linked polyethylene (XLPE) .
  • XLPE cross-linked polyethylene
  • the solid insulating layer may comprise other cross-linked materials, low density polyethylene (LDPE) , high density polyethylene (HDPE) , polypropylene (PP) , or rubber insulation, such as ethylene propylene rubber (EPR) , ethylene-propylene-diene monomer
  • LDPE low density polyethylene
  • HDPE high density polyethylene
  • PP polypropylene
  • EPR ethylene propylene rubber
  • semiconducting material may comprise, for example, a base polymer of the same material as the solid insulating layer 6 and highly electrically conductive particles, e.g. particles of carbon black or metallic particles, embedded in the base polymer.
  • the volume resistivity of these semiconductive layers typically about 20 ohm. cm, may be adjusted as required by varying the type and proportion of carbon black added to the base polymer. The following gives an example of the way in which resistivity can be varied using different types and quantities of carbon black.
  • the outer semiconducting layer 5 is connected at spaced apart regions along its length to a controlled potential, e.g. via electrically conductive strips.
  • a controlled potential e.g. via electrically conductive strips.
  • this controlled potential will be earth or ground potential, the specific spacing apart of adjacent earthing points, i.e. the spacing apart of the earthing strips, being dependent on the resistivity of the layer 5, although it is possible to provide a continuous strip, e.g. an earthing strip or wire, along the length of the outer layer 5.
  • the semiconducting layer 5 acts as a static shield and as an earthed outer layer which ensures that the electric field of the coil 2 is retained within the solid insulating layer 6 between the semiconducting layers 4 and 5. Losses caused by induced voltages in the layer 5 are reduced by increasing the resistance of the layer 5. However, since the layer 5 must be at least of a certain minimum thickness, e.g. no less than 0.8 mm, the resistance can only be increased by selecting the material of the layer to have a relatively high resistivity. The resistivity cannot be increased too much, however, else the voltage of the layer 5 mid-way between two adjacent earthing points will be too high with the associated risk of partial discharges occurring.
  • the superconducting coil 2 may be cooled by a cooling fluid, such as liquid nitrogen, to the required superconducting temperatures.
  • a cooling fluid such as liquid nitrogen
  • the liquid nitrogen may be passed along a channel (not shown) , e.g. an annular channel formed between the support tube 3 and an inner, concentrically arranged tube (not shown) spaced from the support tube 3.
  • the cable-like inductor 1 may be enclosed within a cryostat (not shown) to cool the coil to superconducting temperatures.
  • the inductor has an air core but, as described below, the inductor may include a magnetic core.
  • Figures 2A and 2B show how the cable 6 may be arranged, e.g. in a generally cylindrical form.
  • the geometric configuration of the cable itself is not important, but it may be advantageous to wind the cable as a coil as shown.
  • the inductance of the inductor is determined by the air gap between the two ends of the coil. The larger the gap between the coil ends, the smaller the total inductance.
  • the ends of the cable should overlap over a sufficient distance, so that the flux path can be closed with low reluctance.
  • the insulation between the cables is essential, as the potential difference between the opposite ends of the cable is largest.
  • the opposite ends of the coil 2 are embedded in magnetic material of high magnetic permeability. In this way the flux path is closed with small reluctance.
  • FIG 3 schematically shows another embodiment of a high voltage induction device according to the invention comprising an inductor 101.
  • the inductor 101 is in the form of a cable comprising a first coil 102 wound from elongate high- temperature (T c ) superconducting (“HTS”) material, for example BSCCO tape or the like, which is electrically insulated, e.g. with varnish or the like, and helically wound on a tubular support 103.
  • T c high- temperature
  • HTS superconducting
  • the individual turns of the first coil 102 are electrically insulated from each other.
  • Liquid nitrogen, or other cooling fluid may be passed along the tubular support 103 to cool the surrounding superconducting first coil to below its critical superconducting temperature T c .
  • a band 120 of solid electrical insulation surrounds the first coil 102 and comprises inner and outer layers 120a and 120b, respectively, of semiconducting material and an intermediate layer 120c of insulating material.
  • the HTS material has its electrical insulation, e.g. varnish insulation, removed therefrom at its opposite ends and preferably also at spaced intervals along its length so that the surrounding layer 120a is able to make electrical contact with the coil 102 along its length.
  • the outer layer 120b has elongate axial channels 121 formed in its outer surface and is surrounded by a metallic tubular support 122 similar to the support 103.
  • the channels and support 122 define axial cooling ducts for cooling fluid if required.
  • Helically wound electrically insulated elongate HTS material for example BSCCO tape or the like, is wound on the support 122 to form a second coil 123 around the tubular support 122 having its individual turns electrically insulated from each other.
  • the HTS material forming the second coil 123 has its electrical insulation, e.g. varnish insulation, removed therefrom at its opposite ends and preferably also at spaced intervals along its length so that the surrounding layer 125a is able to make electrical contact with the coil 123 along its length.
  • a further band 125 of insulation is positioned around the second coil 123.
  • the band 125 comprises inner and outer layers 125a and 125b of semiconducting material and an intermediate layer 125c of insulating material.
  • the outer layer 125b of the outermost electrical insulation band 125 is grounded at spaced intervals along its length as shown schematically at 127.
  • the layers 120a and 125a can be positioned in contact with the underlying coils 102 and 123, respectively, to ensure electrical contact with the insulation removed portions of the coils.
  • radial gaps 128 and 126 may be provided, respectively, between the band 120 and the layer 114 and the band 125 and the superconducting layer 123. These radial gaps 128 and 126 provide gaps for expansion and contraction to compensate for the differences in the thermal coefficients of expansion (a) between the electrical insulation bands and the superconducting coils.
  • the gaps 128 and 126 may be void spaces or may incorporate foamed, highly compressible material to absorb any relative movement between the superconducting coils and surrounding electrical insulation.
  • the foamed material if provided, may be semiconducting to ensure electrical contact between the coil 102 and layer 120a and the coil 123 and layer 125a. Additionally, or alternatively, metal wires may be provided for ensuring the necessary electrical contact.
  • a cryostat 115 arranged outside the semiconducting layer 125b, comprises two spaced apart flexible corrugated metal tubes 116 and 117. The space between the tubes 116 and 117 is maintained under vacuum and contains thermal superinsulation 118. Instead of the cryostat 115, the induction device may be contained within a thermally insulated, cryogenically cooled container shown schematically at 150.
  • the coils are connected in series.
  • the bands of electrical insulation 120 and 125 are formed in a similar manner to the insulation formed by the corresponding insulation layers described in relation to the embodiment of Figure 1. As described above, the winding angles and/or winding directions of the coils 102 and 123 may be selected as required.
  • Figure 4 shows an alternative design of HV inductor 10 according to the invention and illustrates how an inner magnetic core 11 can be integrated into the design.
  • the inductor 10 is similar to the inductor 1 (or inductor 101) and, where possible, the same reference numerals have been used to designate the same or similar parts.
  • the magnetic core 11 comprises magnetic material which may be particulate, e.g. in the form of particulate iron or compounds of iron; wire, e.g. iron based; or tape, e.g. Fe based, amorphous or nano-crystalline.
  • the potential at opposite ends of the coil 2 of the inductor 10 is defined by the voltage applied to the elongate superconducting material.
  • the potential along the coil 2 is determined by the induced voltage in each turn of the coil around the magnetic core 11. Thus the voltage varies along the length of the coil 2.
  • a controlled potential e.g. ground potential or the high potential of the HV system, is applied to the magnetic core 11 which will have this same constant potential along its length.
  • the coil 2 has a potential that depends on the induced voltage, as explained above, the potential difference between the magnetic core 11 and the coil 2 will also differ along the length of the inductor 10.
  • the first insulation system comprising the inner and outer layers 4 and 5 of semiconducting material and the intermediate layer 6 of insulating material, is positioned radially outside the coil 2. More than one first insulation system will be provided, of course, if an inductor of the type shown in Figure 3 is provided.
  • the second insulation system is positioned radially inside the coil 2 and comprises the insulation layer 12, an outer layer 13 of semiconducting material and an inner layer 14 of semiconducting material. This second insulation system is similar to the first insulation system with the individual layers 12-14 forming a unitary construction.
  • the semiconducting inner layer 4 and semiconducting outer layer 13 should make electrical contact with the coil 2 at opposite ends of the latter and preferably also at spaced apart locations between the coil ends.
  • HV inductor 20 An alternative design of HV inductor 20 is shown in Figures 5 and 6, in which a magnetic core 21 is kept at a "floating" potential along its length which obviates the necessity of having electrical insulation between the magnetic core 21 and the surrounding coil (or coils) 2.
  • the magnetic core 21 is formed of a plurality of overlapping "threads" or core lengths 22 (see Figure 6) which are electrically insulated from each other. Since the induced voltage along the elongate superconducting material from which the coil 2 is wound will be less than 1000 volts per metre, it is sufficient to use standard electrical insulation, e.g. enamel, to insulate the magnetic core.
  • the core lengths 22 can be made from tape of magnetic material or insulated magnetic particles.
  • the coil 2 is wound on a support tube which may be made of electrically insulating material or, alternatively, may be made of semiconducting material which is in electrical contact with the core at least at spaced apart intervals along the length of the magnetic core.
  • the (outermost) outer layer 5 of semiconducting material of an HV inductor 30 may be surrounded by a metal sheath 31. It is important that the sheath 31 is not completely closed so as to prevent the creation of an inductive short circuit.
  • the sheath 31 should therefore have at least one interruption, e.g. in the form of a slit 32, along its length. It is possible for the sheath to extend through more than 360 degrees, although in this case overlapping sheath portions must be electrically insulated from each other.
  • the metal sheath may make electrical contact with the (outermost) outer layer 5 to provide the controlled electric potential, e.g. ground potential, along the length of the layer 5 in addition to providing the mechanical rigidity.
  • rigidity may be provided by a surrounding sheath (not shown) of non- metallic, e.g. plastics, material which may completely enclose the cable.
  • Figure 8 shows an inductor 40 in which the cable 41 may be wound in a helical path around a non-closed magnetic core, such as a toroidal shaped magnetic core 42 having one or more air gaps 43, 44 therein.
  • the current in the cable 41 can be divided into two components, one component flowing in the azimuthal direction with a constant radius and the other component flowing axially along the longitudinal axis of the cable. Since the cable is wrapped around the magnetic core 42, the effect of the induction is twofold. Firstly as the axial component in the cable, as mentioned above, and secondly as the axial component in the magnetic core 42.
  • the amount of superconducting means can be optimised.
  • the superconducting coil or coils of the cable can be wound as a tight helix or as a loose helix using less superconductor material.
  • the "tightness" of the wound cable on the magnetic core 42 can be adjusted as required.
  • the magnetic core 42 is shown as having air gaps 43, 44 these are not essential and the magnetic core could be closed.
  • the toroidal core 42 need not be a true " toroid" since in cross-section, in a plane perpendicular to the plane of Figure 8, it may have a non-circular section, e.g. a D-shaped or oval section. With a D-shaped cross-section, the "straight" part of the D- shape comprises an inner cylindrical wall of the toroidal core.
  • the toroidal core need not be completely annular in shape - i.e. as viewed in Figure 8.
  • An insulation system can be made of an all-synthetic film with inner and outer semiconducting layers or portions made of polymeric thin film of, for example, PP, PET, LDPE or HDPE with embedded conducting particles, such as carbon black or metallic particles and with an insulating layer or portion between the semiconducting layers or portions.
  • a dry, wound multilayer thin film insulation has also good thermal properties and can be combined with a superconducting pipe as an electric conductor and have coolant, such as liquid nitrogen, pumped through the pipe.
  • an electrical insulation system is similar to a conventional cellulose based cable, where a thin cellulose based or synthetic paper or non-woven material is lap wound around a conductor.
  • the semiconducting layers on either side of an insulating layer, can be made of cellulose paper or non-woven material made from fibres of insulating material and with conducting particles embedded.
  • the insulating layer can be made from the same base material or another material can be used.
  • Another example of an insulation system is obtained by combining film and fibrous insulating material, either as a laminate or as co-lapped.
  • An example of this insulation system is the commercially available so-called paper polypropylene laminate, PPLP, but several other combinations of film and fibrous parts are possible. In these systems various impregnations such as mineral oil or liquid nitrogen can be used.

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Abstract

L'invention concerne une bobine d'induction haute tension muni d'un câble (1) comprenant une bobine (2) à spires adjacentes isolées électriquement les une des autres, d'un dispositif de refroidissement servant à refroidir au moins l'une des bobines (2), d'un dispositif d'isolation électrique (4-6) entourant la bobine (2) et contenant le champ électrique de la première bobine pendant l'utilisation du transformateur, enfin d'un matériau magnétique (7) à haute perméabilité magnétique reliant des extrémités opposées de la bobine (2) isolées électriquement, de manière à fermer le chemin du flux entre des extrémités opposées de la bobine à faible réluctance.
PCT/EP1999/010510 1998-12-23 1999-12-23 Bobine d'induction haute tension WO2000039818A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU29038/00A AU2903800A (en) 1998-12-23 1999-12-23 A high voltage inductor

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GBGB9828653.7A GB9828653D0 (en) 1998-12-23 1998-12-23 A high voltage inductor
GB9828653.7 1998-12-23
GB9912609.6 1999-05-28
GBGB9912609.6A GB9912609D0 (en) 1999-05-28 1999-05-28 A high voltage inductor

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WO2000039818A1 true WO2000039818A1 (fr) 2000-07-06

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Application Number Title Priority Date Filing Date
PCT/EP1999/010510 WO2000039818A1 (fr) 1998-12-23 1999-12-23 Bobine d'induction haute tension

Country Status (2)

Country Link
AU (1) AU2903800A (fr)
WO (1) WO2000039818A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009050028A1 (fr) * 2007-10-10 2009-04-23 Mdexx Gmbh Composant électrique, en particulier bobine électrique

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998034245A1 (fr) * 1997-02-03 1998-08-06 Asea Brown Boveri Ab Transformateur d'alimentation/bobine d'induction
GB2332557A (en) * 1997-11-28 1999-06-23 Asea Brown Boveri Electrical power conducting means

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998034245A1 (fr) * 1997-02-03 1998-08-06 Asea Brown Boveri Ab Transformateur d'alimentation/bobine d'induction
GB2332557A (en) * 1997-11-28 1999-06-23 Asea Brown Boveri Electrical power conducting means

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009050028A1 (fr) * 2007-10-10 2009-04-23 Mdexx Gmbh Composant électrique, en particulier bobine électrique

Also Published As

Publication number Publication date
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