Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B7/00—Insulated conductors or cables characterised by their form
  • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
  • H01B7/28—Protection against damage caused by moisture, corrosion, chemical attack or weather
  • H01B7/282—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable
  • H01B7/285—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable by completely or partially filling interstices in the cable
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B7/00—Insulated conductors or cables characterised by their form
  • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
  • H01B7/28—Protection against damage caused by moisture, corrosion, chemical attack or weather
  • H01B7/282—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable
  • H01B7/2825—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable using a water impermeable sheath
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A30/00—Adapting or protecting infrastructure or their operation
  • Y02A30/14—Extreme weather resilient electric power supply systems, e.g. strengthening power lines or underground power cables

Definitions

• the invention relates to a multi-conductor high voltage cable according to claim 1.
• a further problem with prior art high voltage cables is that cables used under extreme conditions with respect to e.g. temperature, pressure, water depth or humidity are often being subjected to extremely expensive and difficult installation.
• the invention relates to an electrical cable
• At least two cable cores being situated within a jacket (10), said jacket (10) being wholly or partly water permeable.
• the open-system cable of the invention provides a unique possibility of adaptive pressure equalization when the high voltage cable is exposed to great pressure from the
• the permeable outer jacket ensures that water is pressed into the cable in the cavity between the lead-sheathed cable cores and the permeable armor ensuring that the high pressure on the armor will be equalized.
• the pressure on the cable will be kept relatively low, and no pressure equalizer is necessary.
• a cable according to the invention may be regarded as a pressure adaptive cable.
• the water barrier may e.g. comprise an extruded lead sheath, corrugated extruded aluminum, stainless steel or other suitable materials or composites of materials.
• An advantage of individual coating of the cores is that the thickness of the necessary water barrier layer may be reduced, thereby obtaining a reduction in material and/or manufacturing costs.
• the support of the barrier especially when the cable is under pressure, improves significantly due to the fact that the barrier may be arranged directly on a circular cable core.
• the choice of individual "lead coating” implies that a pressure equalizer may be filled into the cable which ensures that the desired shape of the cross-section will be maintained under high pressure and that the pressure equalizer does not destroy the insulation material.
• a further advantage of the individual packing of the cable cores is that potential damage or leaks in the water barrier of one of the cores will only affect one core instead of all cores within one common water barrier.
• said jacket comprises permeable bedding and armor layers (10, 1 1, 12, 13, 14), a further advantageous embodiment of the invention has been obtained.
• At least one of said cable cores comprises a conductor (1), and extruded insulation (2) and at least two semi-conducting screens (3, 4),
• said insulation (2) comprises XLPE, a further advantageous embodiment of the invention has been obtained.
• said insulation (2) comprises mass-impregnated paper, a further advantageous embodiment of the invention has been obtained.
• Mass impregnated paper well-known within the art, may be impregnated with high viscosity oil or gel.
• Mass-impregnated cables also called non-draining cables, benefit from the fact that the cable needs no oil feeding. Moreover, there is no oil leakage to the environment if the cable is damaged.
• Interpenetrating network comprises polymer and oil.
• at least one of the water barriers (8) comprises a metal, a further advantageous embodiment of the invention has been obtained.
• metals such as lead benefit from the fact that they may constitute a barrier which offers effective protection of the encapsulated insulation against humidity.
• said metal comprises lead (8), copper, aluminum or steel, a further advantageous embodiment of the invention has been obtained.
• a heat conducting material enclosing e.g. a DC XLPE cable is very advantageous, as XLPE cables would suffer from non-homogenous heating of the XLPE insulation.
• a non-homogenous distribution of the heat over the circumference of the core would result in a non-homogeneous electrical field on the core and consequently a breakdown of the insulation.
• non-homogeneous distribution of heat is a particular problem with multi-core high voltage cables due to the very close arrangement of the cores. Areas of no or little spacing between the cores would result in high non-homogenous temperature distribution over the core.
• fig. 1 shows a cross-section of a preferred embodiment of the invention
• fig. 2 shows a cross-section of a second embodiment of the invention.
• FIG. 1 shows a cross-section of a preferred embodiment of a cable according to the invention.
• the shown flat-type cable is an example of a 150 kV XLPE DC high voltage cable. It should be noted that the invention, although particularly advantageous in relation to DC applications, is not restricted to DC use. AC may also be applicable. Evidently, a traditional cable would comprise three cores.
• the shown cable comprises two copper cores 1.
• the cross-section of each stranded waterproof core 1 is approximately 500 mm 2 .
• the insulation of each of the copper conductors will be described in detail below. Obviously, other core materials may be applicable within the scope of the invention, such as aluminum. Likewise, other cross- sections may be applicable.
• Each conductor 1 is surrounded by an extruded semi-conducting layer 2 such as polyethylene forming the conductor screen.
• the next layer of the cable forms an extruded XLPE insulation 3.
• the insulation layer may also comprise other suitable insulation layers such as mass- impregnated paper, interpenetrating network, i.e. oil and polymer, or other suitable materials.
• the insulation is XLPE.
• An outer semi-conducting layer also called the insulation screen 4 is provided on top of the XLPE insulation layer.
• This layer is adaptive e.g. in order to eliminate ionization on the outer surface of the dielectric.
• the next layer is a humidity barrier in the form of a lead sheath 8.
• the barrier 8 encloses the XLPE insulation completely against ambient humidity.
• the XLPE insulation is very sensitive to even small amounts of humidity, and intruding humidity results in a so-called treeing phenomenon in the insulation. In time, the treeing phenomenon can lead to a breakdown of the insulation.
• the humidity barrier may advantageously comprise other metals such as aluminum, copper or stainless steel.
• the lead sheath is covered with asphalt and subsequently wrapped in bituminized crepe paper 9 in order to eliminate the risk of corrosion of the lead sheath 8.
• the two lead-sheathed cores are subsequently wrapped together with a common galvanized steel tape layer 10 and two layers of asphalt and polypropylene yarn 1 1 , 13 enclosing a galvanized steel armor wire layer 12.
• the final layer of the cable is comprised by chalk 14.
• the galvanized steel tape reduces the mechanical stress on the lead sheath, and the yarn acts as cushion.
• the latter layer 10, 1 1, 12, 13 and 14 forms an armor jacket protecting the inner cable cores and the corresponding insulation and barrier materials against ambient mechanical stress.
• the armor wires are adapted to receiving tensile forces inferred during installation or recovering of the cable.
• the asphalt protects the armor wires against corrosion.
• the outer dimension of the illustrated embodiment of the invention is approximately 78 mm x 135 mm. Other outer dimensions may be applicable within the scope of the invention.
• the layers forming the armor jacket are water permeable. Consequently, water may pass through the armor jacket and form a pressure equalizing filling 20 of the cable under high ambient pressure. This adaptive filling of the inner compartment 20 of the cable prevents the armor from collapsing even under high pressure.
• pressure exercised on a submarine cable may exceed 100 bar or more and that pressure equalization is expected to be vital in such cables.
• the pressure equalizer of the present preferred embodiment is ambient water which has been forced into the inner compartment 20 by the pressure exercised on the cable. This automatic adaptive pressure equalization of the cable is evidently extremely convenient.
• a cable according to the invention is pressure adaptive due to the fact that the inner compartment automatically equalizes the ambient pressure due to the water permeable armor jacket.
• Fig. 2 illustrates a further embodiment of the invention comprising the aforementioned main components of fig. 1.
• the main difference between the cable of fig. 1 and fig. 2 is that the cable of fig. 2 has been fitted with a solid pressure equalizer 10.
• the solid pressure equalizer may comprise extruded polyethylene.
• other choices may be applicable within the scope of the invention.
• the jacket is water permeable.
• a cable according to the invention may be of another type than a sub-marine cable, such as underground cables.

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• Insulated Conductors (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 2001
  • 2001-01-12 EP EP01901122A patent/EP1250706A1/en not_active Withdrawn
  • 2001-01-12 WO PCT/DK2001/000025 patent/WO2001052273A1/en not_active Application Discontinuation
  • 2001-01-12 AU AU2001226642A patent/AU2001226642A1/en not_active Abandoned
• 2002
  • 2002-06-28 NO NO20023157A patent/NO20023157L/no not_active Application Discontinuation

Non-Patent Citations (1)

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