A process for providing a HV-cable joint

Abstract

A process for providing a HV-cable joint between respective end sections of two HV- cable elements, each comprising an inner part surrounded by a metallic sheath (metallic radial water barrier), wherein the inner part comprises a conductor surrounded by polymer containing insulation, wherein the process comprises providing a metallic casing to surround and define an inner part of the joint comprising adjoining end portions of the inner parts of the respective HV-cable elements, and building seals between the metallic casing and the respective metallic sheath at each of the respective end sections of the HV-cable elements, wherein the building of the seals comprises performing a cold deposition process.

Description

[0001] A PROCESS FOR PROVIDING A HV-CABLE JOINT

[0002] FIELD OF THE INVENTION

[0003] The invention relates to process for providing a HV-cable joint between respective end sections of two HV-cable elements.

[0004] BACKGROUND ART

[0005] HV-cables are extensively used in the electricity transmission network. Most HV- cable designs are based on use of polymeric insulation. I.e. a material that is made of or includes a substantial amount of polymers, typically in form of an inner semiconductive layer , surrounded by a thicker insulation layer and at the outside another semiconductive layer. In the following, the conductor itself and the layers of polymeric insulation are referred to as the ‘inner part’ of the HV-cable.

[0006] The insulation and semiconductive materials are sensitive to water absorption, which can lead to detrimental high voltage break-down of HV-cables, an effect also called water-treeing. Hence, most HV-cables, and all submarine HV-cables, have incorporated barriers for longitudinal and radial water penetration into the cable core body.

[0007] The purpose of the longitudinal water barriers is to prevent water penetrating along the inner part of a cable from the broken end in case of a full or partly breakage of a HV-cable, and hence preventing that a significant length of the cable becoming damaged.

[0008] The purpose of the radial protection is to prevent water penetrating through the outer part of the HV-cable into the polymeric insulation and semiconductive layers to avoid risks of water-treeing. The radial protection against water penetration often is provided in the form of a metallic sheath forming a metallic radial water barrier.

[0009] Typical radial water barriers in HV-cables are (see htps: / / encvclopedia.pub / entry / 10308'): extruded lead sheets (figure 2.6); extruded corrugated aluminum tubes (figure 3.1); mm- or below mm-thin folded foils of aluminum foils that are welded (figure 3.2) or laminated (figure 3.3), or mm- or below mm-thin folded foils of copper that are welded or laminated. The radial barriers in form of laminated folded foils of aluminum or copper are only providing a time delay for possible water penetration from the outside into the inner part of the HV-cable since the lamination material is polymeric. Water penetration will take place through such lamination layers, although slowed down since water must penetrate a long way through a thin layer. Laminated folded foils are in most cases not accepted or used as radial water barriers in submarine HV-cables, and some utilities do not accept laminated folded foils for use in underground HV-cables.

[0010] The metallic radial barriers in form of extruded lead sheets, extruded corrugated aluminum tubes, folded and welded foils of aluminum and copper are considered and named to be ‘watertight’ water barriers, assuming they are free of holes.

[0011] There are limits to how long HV-cable lengths that can be produced in one continuous length. Transportation issues, defined by capacity of trucks, of trains, of vessels, and acceptable loads and heights on roads also all set a limit to how long lengths of HV-cables can be brought from production sites to the actual installation fields of HV transmission lines. Hence, there is a need for being able to join HV- cables in the field as well as an advantage of also being able to join HV-cables in the factory. In case of cable failures in the field, there is also a need for being able to make repair joints in the field.

[0012] It is a general aim that joints, whether they are made in the field or in the factory, provides lasting water barriers that prevents water penetrations into the inner part of the joint. Ideally, these barriers have to be of the same quality level as the water barriers of the HV-cable structures themselves. Thus, where the HV-cables are equipped with watertight radial water barriers, it is an aim that the inner parts of the joints shall also be protected for possible water penetration by watertight protections. Typically, for this purpose the inner parts (conductor and insulation) of the joints are surrounded by tubular bodies of metal, often and in here in the following called ‘casings’, that serve as watertight barriers for the joints (figure 4). The main issue for such solutions is then to ‘connect’ these casings to the watertight sheaths of the HV- cables, so the interfaces between these casings and the sheaths of the HV-cable ends being jointed are also providing a watertight water penetration barrier.

[0013] Furthermore, for some applications it will be advantageous if such interfaces also have good electrical conductivity, since the metallic radial water penetration barriers often serve as the bodies or part of bodies for taking care of external fault currents (i.e., HV-cable line protection in case of short circuits etc.). When providing a joint between two HV-cable end sections it is important to ensure a water tight connection between the metallic water barrier sheaths of the two HV-cables at the joint.

[0014] US2019 / 0190245 discloses a method of providing a joint between end sections of two cables, wherein the joint of conductors of the two cables is protected in a metallic protection casing and where transition sleeves are welded to the metallic water barrier sheath of the respective cables and to the metallic protection casing to provide a water tight connection between the metallic sheath of the first cable, the protective casing and the metallic sheath of the second cable without the need for use of lead containing materials.

[0015] Although, this prior art method may provide a water tight connection between HV- cables at a joint location, the method is very time consuming and requires welding technicians with high expertise, whereby the method becomes underside expensive and my result in delay of cable layout and / or repair.

[0016] Therefore there is a need for a process for establishing a HV-cable connection with a good radial barrier, which is relatively fast and ensure a reliable radial water barrier.

[0017] DISCLOSURE OF THE INVENTION

[0018] This invention relates to methods for building and assuring good radial water barriers also at locations of HV-cable connections, where HV-cable end sections need to be connected to other HV-cable end sections or to HV-cable terminations for establishing a full transmission connection or just for the purpose of building longer cable lengths. Such HV cable connections or HV cable links are in the following referred to as joints.

[0019] An objective of the invention is to provide a method for establishing a full metallic watertight solution for HV-cable joints that reduces the risk of, or preferably prevents water penetration into the inner part of the joint and provides a method for interfacing and connecting the casing of the joint to the water tightening metallic sheaths of the two HV-cable ends.

[0020] In an embodiment of the invention, it is an objective to provide a watertight sealed joint where the casing comprises of two or more casing parts. In an embodiment, it is an objective to provide a process for providing a HV-cable joint between respective end sections of two HV-cables, while simultaneously ensuring an effective and reliable radial water barrier.

[0021] In an embodiment, it is an objective to provide a process for providing a HV-cable joint between respective end sections of two HV-cables with a good radial water barrier, which process is relatively fast and which does not require technical expertise.

[0022] In an embodiment, it is an objective to provide a process for providing a HV-cable joint between respective end sections of two HV-cables with a good radial water barrier, which process may be performed at an attractive cost.

[0023] These and other objects have been solved by the invention or embodiments thereof as defined in the claims and / or as described herein below.

[0024] It has been found that the invention or embodiments thereof have a number of additional advantages, which will be clear to the skilled person from the following description.

[0025] The inventors of the present invention have realized that a spraying process may be applied for ensuring a highly reliable radial water barrier a HV-cable joints, which in addition may be performed relatively fast.

[0026] As described above, it is well established to provide the radial water barrier at cable joints by welding the metallic sheaths to the casing containing the joint. However, the inventors of the present invention have realized that it may be beneficial to deviate from such established technique. Thus, it has been realized that the polymeric semiconductive and insulation materials of a HV-cable may be damaged if subjected to high temperatures. Typically, the maximum allowable temperature for insulation materials under operation is about 90°C. If exposed to high temperatures the electrical performance of the polymers may deteriorate and thereby damage the entire HV-cable.

[0027] The invention provides a process for building a metallic interface, that provides a long lasting watertight water barrier between the two HV-cable sheaths and the casing, and preferentially also good electrical conductivity, wherein the process is provided in a way with a very low or even negligible risk of negatively impacting the electrical properties of the HV-cables and the inner part of the joint. A method for providing a solution that does not negatively impact the performance of the insulation layers is therefore a further main objective of this invention.

[0028] It should be emphasized that the term "comprises / comprising" when used herein is to be interpreted as an open term, i.e. it should be taken to specify the presence of specifically stated feature(s), such as element(s), unit(s), integer(s), step(s) component(s) and combination(s) thereof, but does not preclude the presence or addition of one or more other stated features.

[0029] Throughout the description or claims, the singular encompasses the plural and the plural encompasses the singular unless otherwise specified or required by the context.

[0030] The "an embodiment" should be interpreted to include examples of the invention comprising the feature(s) of the mentioned embodiment.

[0031] The term "about" is generally used to include what is within measurement uncertainties. When used in ranges the term "about" should herein be taken to mean that what is within measurement uncertainties is included in the range.

[0032] The term "substantially" should herein be taken to mean that ordinary product variances and tolerances are comprised. All features of the invention and embodiments of the invention as described herein, including ranges and preferred ranges, may be combined in various ways within the scope of the invention, unless there are specific reasons not to combine such features.

[0033] The process of the invention is directed for providing a HV-cable joint between respective end sections of two HV-cable elements, wherein each comprising an inner part surrounded by a metallic sheath providing a metallic radial water barrier, and wherein the inner part comprises a conductor surrounded by polymer containing insulation.

[0034] The conductor may e.g. be a solid conductor or a stranded conductor of any suitable electric conducting material. The process comprises providing a metallic casing to surround and define an inner part of the joint comprising adjoining end portions of the inner parts of the respective HV-cable elements, and building seals between the metallic casing and the respective metallic sheath at each of the respective end sections of the HV-cable elements, wherein the building of the seals comprises performing a cold deposition process. The cold deposition process has been found to be very effective and fast for building watertight seals between the metallic casing and the respective metallic sheath at each of the respective end sections of the HV-cable elements.

[0035] In addition, the risk of leaks or cracks has been found to be very low even negligible low. Further, the cold deposition is relatively simple to perform eve without need for technical expertise.

[0036] In an embodiment, the process providing a HV-cable joint comprises providing a substantially metallic seal by using the cold deposition process and providing a substantially metallic connection and water penetration barrier between the two metallic bodies, such as metallic sheaths and casings or parts of them, that are surrounding the inner parts, i.e. comprising conductors and insulation materials (see e.g. figure 5.5), of HV-cables to be joined or the inner part of the HV-cable joint itself.

[0037] The process may a substantially watertight seal, such as a seal that may also be suitable for subsea use, even under high hydrostatic pressure.

[0038] The two HV-cable elements may independently of each other comprise a HV-cable having a length of 10 m or longer, such as a length of at least 50 m, such as at least 1000 or even longer. The HV-cable elements may e.g. comprise any type of HV- cable, such as a submarine HV-cable, a submarine HV-cable, an oil-filled a submarine HV-cable, a stranded conductor HV-cable, a solid conductor HV-cable, a segmental conductor HV-cable and / or combinations thereof.

[0039] The process advantageously comprises providing the conductor of each of the two HV-cable elements to be electrically connected to each other in the joint.

[0040] The electrical connection of the respective conductors of the HV-cable elements and the application of the metallic casing may be performed by any suitable method such as the method known from prior art.

[0041] The cold deposition process may advantageously be performed at a temperature providing that the temperature of polymer containing insulation of the inner parts at the end sections of two the HV-cable elements is maintained below a selected temperature during the deposition process. The selected temperature may conveniently be selected in depending on the type of the polymer containing insulation, to ensure that the polymer containing insulation is not subjected to damage during the cold deposition, thereby enabling the cold deposition to be fast an relatively simple to perform without risking damaging the insulation. The selected temperature at the outer surface of the insulation layer (see figure 5.2) is advantageously 200 °C or less, preferably 190 °C or less, preferably 180 °C or less, preferably 170 °C or less, preferably 160 °C or less, preferably 150 °C or less, preferably 140 °C or less, preferably 130 °C or less, preferably 120 °C or less, preferably 110 °C or less, preferably 100 °C or less, preferably 90 °C or less, preferably 80 °C or less, or preferably 70 °C or less.

[0042] The process may conveniently be conducted at conditions where it is assured that the process does not lead to such a heating of the polymeric inner parts, i.e. insulation materials of the HV -cables and of the HV-cable joint, that this heating can negatively impact the insulation qualities of the polymeric parts of the HV-cables or the joint (Se figure 5.2).

[0043] In an embodiment, the temperature of the polymeric inner parts of the respective end sections of the two HV-cable elements is maintained below a selected temperature during the deposition process, wherein the selected temperature at the outer surface of the insulation layer advantageously is as described above.

[0044] An optimal temperature may for example be determined by a few experiments of cold deposition adjacent a sample of the insulation to determining a maximal acceptable temperature.

[0045] The cold deposition process may preferably comprise comprises a cold spray process, such as a cold spray process described in US11 ,469,161 and / or US11 ,909,161 .

[0046] Example of a cold spray process is further indicated in figure 5.3.

[0047] The process of cold deposition may in an embodiment comprise the use of particles of a size, weight and with a velocity selected such that the impingement of the deposited particles onto a surface of a deposition area, provides that the particles breaks a potential oxide layers on the surface of the deposition area.

[0048] Advantageously, the deposited particles provide a deposited seal made of a substantially metallic material and where the volume and shape of the seal and the conductivity of the seal material being such, that the deposited seal has a current carrying capacity that is compatible with a current carrying capacity of the metallic sheaths of the HV-cables being connected. Cold spraying may provide such a process that typically, assuming right material composition, high enough speed of particles and particle temperature, breaks the oxide surface layers at the surface of deposition and creates a seal of high electrical conductivity.

[0049] In an embodiment, the cold deposition process comprises deposition of particles comprising metal particles at a deposition area at a velocity sufficiently high to penetrate a potential oxide layer located at the deposition area and preferably to provide the seals in the form of deposited seals. Each of the deposited seals preferably has a volume and a shape that ensures a current carrying capacity that is compatible with a current carrying capacity of the metallic sheaths of the respective end sections of the two HV-cable elements.

[0050] In an embodiment, the method further comprises performing a quality test of the seal, wherein the quality of the seal is proven by a leak test after the cold deposition process has been completed.

[0051] An example of how to perform the leak test is further illustrated in figure 6.

[0052] In an embodiment, the providing of the metallic casing to surround the inner part of the joint comprises providing sections of overlapping layers between opposite ends of the metallic casing and the respective metallic sheaths at the respective end sections of the two HV-cable elements at each end portion of the metallic casing. The step of providing the metallic casing to surround the inner part of the joint may conveniently comprise providing the sections of overlapping layers by arranging the metallic casing to surround or be surrounded by each of the metallic sheaths at the respective end sections of two HV-cable elements.

[0053] Advantageously, the cold deposition is performed while simultaneously reducing or even avoiding risk of penetration of deposition material into the inner parts of HV- cable and / or HV-cable joints:

[0054] In an embodiment, a dust tight shield is built between the two metallic bodies (metallic sheaths of HV-cables and / or metallic casings of joints) to be connected before the cold deposition process is applied.

[0055] Advantageously, the process comprises providing that one of the ends of the metallic shield body is overlapping the end of the other shield body and wherein a gluing or lamination layer is applied at the overlapping area on one of the sides and in between the approaching sides of these two bodies (see figures 7a, b). Conveniently a pressure is then provided on the outermost of these two bodies to thereby building a dust tight seal at the deposition area (see figure 7, c) to enable that the cold deposition process may be performed, while simultaneously reduce the risk of or even avoid the inner parts inside the metallic shields of the HV-cables or HV-cable joint being exposed to dust particles.

[0056] In an embodiment, the process comprises building a dust tight shield at each of the overlapping layers sections prior to building the seals, wherein the building of each of the dust tight shields comprises applying a barrier layer, such as a glue layer and / or a lamination layer between the metallic casing and each of the respective metallic sheaths, followed by applying a pressure on at least one of the metallic casing and the respective metallic sheaths at each of the overlapping layers section, preferably to close any potential passages into the inner part of the joint.

[0057] Advantageously, the process comprises building the metallic casing from two or more casing parts comprising connecting the casing parts using a cold deposition process, preferably using a cold spray process, wherein the two or more casing parts may be of the same or different metals. The cold spray process applied may be as described above.

[0058] The metallic casing may be any metallic casing, such as metallic casings known from prior art. Advantageously, the metallic casing comprises a flexible metallic casing, such as a casing comprising at least one corrugated length section.

[0059] In an embodiment, both of the HV-cable elements are HV-cables each having a metallic sheath comprising or consisting of a common metal, wherein the metallic casing comprises or consists of the common metal and wherein the cold deposition process comprises deposition of particles containing the common metal.

[0060] In an embodiment, both of the HV-cable elements are HV-cables each having a metallic sheath comprising or consisting of aluminium, wherein the metallic casing comprises or consists of aluminum and wherein the cold deposition process comprises deposition of particles containing aluminum particles.

[0061] In an embodiment, both of the HV-cable elements are HV-cables each having a metallic sheath comprising or consisting of cobber, wherein the metallic casing comprises or consists of cobber and wherein the cold deposition process comprises deposition of particles containing cobber particles. In an embodiment, both of the HV-cable elements are HV-cables each having a metallic sheath comprising or consisting of lead, wherein the metallic casing comprises or consists of at least one of lead, aluminum or cobber and wherein the cold deposition process comprises deposition of particles containing particles comprising at least one of cobber, lead and aluminum, such as cobber particles, lead particles and / or aluminum particles.

[0062] In an embodiment, one of the HV-cable elements is a HV-cable comprising a metallic sheath comprising or consisting of a first metal, the other one of the HV- cable elements is a HV-cable comprising a metallic sheath comprising or consisting of a second metal different from the first metal and wherein the metallic casing comprises or consists of one or more metals, preferably comprising at least one of the first and the second metals and optionally a third metal different from the first and the second metal. The cold deposition process may advantageously comprise deposition of particles containing at least one metal, wherein the particles preferably contains particles of at least one of the first, the second or the third metal, optionally the particles contains particles of at least the first and the second metal.

[0063] In an embodiment, one of the HV-cable elements is a HV-cable having a first design and wherein the other one of the HV-cable elements is a HV-cable having a second design, which is different from the first design, e.g. having a different conductor, a different insulation, a different outer shape and / or any other differences.

[0064] In an embodiment, one of the HV-cable elements is a submarine HV-cable and wherein the other one of the HV-cable elements is a submarine cable, an underground HV-cable or a HV-cable termination.

[0065] In an embodiment, one of the HV-cable elements is an underground HV-cable and wherein the other one of the HV-cable elements is a submarine cable, an underground HV-cable or a HV-cable termination.

[0066] In an embodiment, one of the HV-cable elements has a first HV-cable diameter and the other one the HV-cable elements has a second HV-cable diameter, wherein the first HV-cable diameter and the second HV-cable diameter are equal or different, such as slightly different and / or wherein a maximal outer diameter of the metallic sheath in the joint is from 50 % smaller to 50 % larger than an average of the first HV-cable diameter and the second HV-cable diameter, such as from 25 % smaller to 25 % larger, such as from 10 % smaller to 10 % larger, such as from 5 % smaller to 5 % larger than an average of the first HV-cable diameter and the second HV-cable diameter.

[0067] Advantageously, the metallic shields of the HV-cable elements have an average thickness and wherein the metallic casing has a thickness which is from 1 / 10 to 10 times the average thickness of the metallic shields, such as from 1 / 5 to 5 times, such as from 1 / 2 to 2 times the average thickness of the metallic shields.

[0068] In an embodiment, the providing of the metallic casing to surround and define the inner part of the joint comprises building the metallic casing from a metallic foil comprising folding the metallic foil to surround the adjoining end portions of the inner parts of the respective HV-cable elements and to provide lengthwise edge sections of the metallic foil to form an overlapping section extending lengthwise relative to a length of the inner part of the joint, wherein the process comprises build a seal (preferably a metallic seal) between the lengthwise edge sections of the foil using the cold deposition process. Preferably the build a seal (preferably a metallic seal) between the lengthwise edge sections of the foil is performed by the same deposition process applied for building the seals between the metallic casing and the respective metallic sheath.

[0069] In an embodiment, the metallic foil has a length determined along a center axis of the inner part of the joint and wherein the length of the metallic foil is longer than the length of the inner part of the joint, to provide sections of overlapping layers between opposite ends of the metallic casing and the respective metallic sheaths at the respective end sections of two HV-cable elements at each end portion of the metallic casing, preferably to provide the overlapping layers sections by arranging the metallic casing to surround or be surrounded by each of the metallic sheaths at the respective end sections of two HV-cable elements. The process conveniently comprises building the seal between the lengthwise edge sections of the foil and building the seals between the metallic casing and the respective metallic sheaths at each of the respective end sections of the HV-cable elements in a common cold deposition process.

[0070] The process of embodiments of the invention may conveniently be used to connect parts of the shields of a HV-cable joint, where the metal casing, i.e. the water barrier shielding of the joint, is built of more than one metallic tubular body (See figure 8). Advantageously, parts of the metal casing of the joint has flexible structures to make the full joint solution more failure resistant to bending of the joint or to tensile loads on the joint.

[0071] Example is a corrugated part as shown in figure 9.

[0072] In an embodiment, the process of embodiments of the invention is applied in field, in repair of joints and / or in factory / flexible joints.

[0073] The process of embodiments of the invention may for example be used to connect the aluminum based metallic water protection sheaths of two HV-cables in both ends to the two ends of an aluminum based water protection casing of the joint by use of a deposition material, that includes a substantial amount of aluminum,

[0074] In an embodiment, the process of embodiments of the invention is used to connect the copper based metallic water protection sheaths of two HV-cables in both ends to the two ends of a copper based water protection casing of the joint by use of a deposition material that includes a substantial amount of copper.

[0075] In an embodiment, the process of embodiments of the invention is used to connect the lead based metallic water protection sheaths of two HV-cables in both ends to the two ends of a lead, aluminum, or copper based water protection casing of the joint by use of a deposition material, that includes a substantial amount of lead, aluminum or copper.

[0076] In an embodiment, the process of embodiments of the invention is used to connect a metal casing of a joint to the ends of two HV-cables, and where the two HV-cables can are based on dissimilar cable designs or of different materials, and where the radial water protection sheaths of the two HV-cables can include dissimilar types or can be made by use of different metallic materials.

[0077] In an embodiment, the process of embodiments of the invention is used to connect the HV-cable sheaths in a joint used for jointing either two submarine HV-cables or two HV-cables where one is a submarine HV-cable and the other an underground HV-cable or the two cables are both underground HV-cables^

[0078] In an embodiment, the process of embodiments of the invention is used to connect the HV-cable sheaths to the water barrier casing of a termination unit.

[0079] The termination unit could for example be at a HV-cable terminal. In an embodiment, the process of embodiments of the invention is used for a joint where it is desired to have a joint of the conductor, of the polymeric insulation layers and including the metallic water barrier, where the cross section of this joint solution is approximately of the same size or only slightly bigger than that of the HV-cable itself.

[0080] This type of joints are often referred to and named flexible joints or factory joints

[0081] In an embodiment, the process comprises providing the metallic casing of the joint, wherein the metallic casing is built by having a metal foil of same material and approximately same thickness as the metallic sheaths of the HV-cables to be joined, and having an overlength of this foil, and mounting it so that it overlaps the metal shields of the two HV-cable end. Then the process may comprise wrapping the foil around the inner part of the joint, and having a circumferential length of the foil so that an overlap is also created along the length of the foil. Thereby the process may comprise building a metallic seal at the overlapping regions at both HV-cable ends and at the overlapping part of the folded foil along the length of the joint (See figures 10, a, b).

[0082] Advantageously glue or laminating layer is applied or mounted at the overlapping regions to enable a process that avoids the inner part of the HV-cable or HV-cable joint being exposed to dust particles (See figure 7c).

[0083] DECRIPTION OF CERTAIN EMBODIMENT, EXAMPLES AND ELEMENT ILLUSTRATING THE INVENTION

[0084] Brief description of preferred embodiments and elements of the invention.

[0085] The above and / or additional objects, features and advantages of the present invention will be further elucidated by the following illustrative and non-limiting description of embodiments, examples and elements of the present invention, with reference to the appended figures.

[0086] The figures are schematic, are not drawn to scale, and may be simplified for clarity. Throughout, the same reference numerals are used for identical or corresponding parts.

[0087] Figure 1 schematically illustrates an example of a typical underground HV-cable, which may be applied in an embodiment of the process of the invention. Figure 2 schematically illustrates an example of a submarine HV-cable, in this example a co-axial HVDC-cable.

[0088] Figures 3.1 , 3.2 and 3.3 schematically illustrate HV-cables with different types of radial water barriers, which may be applied in an embodiment of the process of the invention.

[0089] Figure 4 schematically illustrates an example of a metallic casing for a joint of a HV- cable, which may be applied in an embodiment of the process of the invention.

[0090] Figure 5 schematically illustrates an example of a cold deposition process for making a watertight seal according to an embodiment of the invention.

[0091] Figure 6 schematically illustrates a system for detecting quality of deposited seals obtained by an embodiment of the process of the invention.

[0092] Figure 7 schematically illustrates an example on how to build a dust tight shield at the deposition interface according to an embodiment of the invention.

[0093] Figure 8 schematically illustrates an example of a water protective casing comprising more than one part, which may be applied in an embodiment of the process of the invention.

[0094] Figure 9 schematically illustrates an example of water protective flexible casing comprising more than one part, which may be applied in an embodiment of the process of the invention.

[0095] Figure 10 schematically illustrates an example of a factory or flexible joint obtainable by the process of an embodiment of the invention.

[0096] The underground HV-cable of figure 1 comprises:

[0097] 1.1 Conductor

[0098] 1.2 Inner semiconductor layer

[0099] 1.3 Insulation

[0100] 1 .4 Outer semiconductor layer

[0101] 1 .5 Semiconductive tape 1.6 Metal sheath for radial water protection and screen for fault currents

[0102] 1 .7 Jacket / protective sheath

[0103] The co-axial HVDC-cable of figure 2 comprises:

[0104] 2.1 Conductor

[0105] 2.2 Inner semiconductor layer

[0106] 2.3 Insulation

[0107] 2.4 Outer semiconductor layer

[0108] 2.5 Semiconductive tape

[0109] 2.6 Metal sheath for radial water protection

[0110] 2.7 Protective sheath

[0111] 2.8 Integrated return conductor

[0112] 2.9 Bedding

[0113] 2.10 Insulation

[0114] 2.11 Armouring

[0115] 2.12 Protective yarn and bitumen layer

[0116] The HV-cables with different types of radial water barriers of figures 3.1 , 3.2 and 3.3 comprise;

[0117] 3.1 . HV-cable with water barrier of corrugated aluminum sheath

[0118] 3.2. HV-cable with water barrier of welded aluminum foil

[0119] 3.3. HV-cable with water barrier of laminated aluminum foil

[0120] The casing for a joint of a HV-cable of figure 4 comprises:

[0121] 4.1. Underground HV-cable

[0122] 4.2. Water protective metal sheath 4.3. Inner part of HV-cable (conductor and semiconductive and insulating polymeric layers

[0123] 4.4. Inner part of joint including metallic connector and insulating polymeric part

[0124] 4.5. Water protective metallic casing

[0125] The cold deposition process setup for making a watertight seal of figure 5 comprises:

[0126] 5.1 Metal sheaths

[0127] 5.2 Semiconductive and insulating polymer layers

[0128] 5.3 Deposition equipment, in case of cold spray the nozzle of the powder gun

[0129] 5.4 Particle or molecular beam

[0130] 5.5 Deposited metallic seal

[0131] The system for detecting quality of deposited seals of figure 6 comprises:

[0132] 6.1 Metal sheaths

[0133] 6.2 Water protective metallic casing

[0134] 6.3 Deposited metallic seal

[0135] 6.4 Inlet for gas (could be He) for leak testing

[0136] 6.5 ‘Sensor-nose’ for detecting gas leakage

[0137] The setup for building a dust tight shield at the deposition interface of figure 7 comprises:

[0138] 7.1 Metal sheath

[0139] 7.2 Lamination layer or glue layer

[0140] 7.3 Pressure applied after lamination layer or glue has been introduced

[0141] 7.4 Deposition equipment with deposition plume

[0142] The water protective casing comprising more than one part of figure 8 comprises:

[0143] 8.1 Metal sheath 8.2 Casing, parti

[0144] 8.3 Casing, part2

[0145] 8.4 Deposited seals

[0146] The water protective flexible casing comprising more than one part of figure 9 comprises:

[0147] 9.1 Metal sheath

[0148] 9.2 Casing, parti

[0149] 9.3 Casing, part2, being flexible

[0150] 9.4 Deposited seals

[0151] The factory or flexible joint obtainable by the process of and shown in figures 10a, 10b comprise:

[0152] 10.1 HV-cable conductor

[0153] 10.2 HV-cable conductor connection

[0154] 10.3 HV-cable insulation layers

[0155] 10.4 Joint insulation layers

[0156] 10.5 HV-cable metallic sheath

[0157] 10.6 Metallic foil wrapped around joint to a water protective casing

[0158] 10.7 Watertight metal seals made by the method

Claims

PATENT CLAIMS1 . A process for providing a HV-cable joint between respective end sections of two HV-cable elements, each comprising an inner part surrounded by a metallic sheath, wherein the inner part comprises a conductor surrounded by polymer containing insulation, wherein the process comprises providing a metallic casing to surround and define an inner part of the joint comprising adjoining end portions of the inner parts of the respective HV-cable elements, and building seals between the metallic casing and the respective metallic sheath at each of the respective end sections of the HV-cable elements, wherein the building of the seals comprises performing a cold deposition process.

2. The process of claim 1 , wherein at least one of the HV-cable elements, is a HV-cable, such as a HV-cable having a length of 10 m or longer, such as a length of at least 50 m, such as at least 1000 or even longer.

3. The process of claim 1 or claim 2, wherein the process comprises providing the conductor of each of the two HV-cable elements to be electric connected to each other in the joint.

4. The process of any one of the preceding claims, wherein the cold deposition process is performed at a temperature providing that the temperature of polymer containing insulation of the inner parts at the end sections of two the HV- cable elements is maintained below a selected temperature during the deposition process, wherein the selected temperature at the outer surface of the insulation layer (drawing 5.2) is 200 °C or less, preferably 190 °C or less, preferably 180 °C or less, preferably 170 °C or less, preferably 160 °C or less, preferably 150 °C or less, preferably 140 °C or less, preferably 130 °C or less, preferably 120 °C or less, preferably 110 °C or less, preferably 100 °C or less, preferably 90 °C or less, preferably 80 °C or less, or preferably 70 °C or less.

5. The process of any one of the preceding claims, wherein the cold deposition process comprises a cold spray process.

6. The process of any one of the preceding claims, wherein the cold deposition process comprises deposition particles comprising metal particles at adeposition area at a velocity sufficiently high to penetrate a potential oxide layer located at the deposition area, preferably to provide the seals in the form of deposited seals, wherein each of the deposited seals preferably has a volume and a shape that ensures a current carrying capacity that is compatible with a current carrying capacity of the metallic sheaths of the respective end sections of the two HV-cable elements.

7. The process of any one of the preceding claims, wherein the providing of the metallic casing to surround the inner part of the joint comprises providing sections of overlapping layers between opposite ends of the metallic casing and the respective metallic sheaths at the respective end sections of the two HV-cable elements at each end portion of the metallic casing, preferably the providing of the metallic casing to surround the inner part of the joint comprises providing the sections of overlapping layers by arranging the metallic casing to surround or be surrounded by each of the metallic sheaths at the respective end sections of two HV- cable elements.

8. The process of claim 7, wherein the process comprises building a dust tight shield at each of the overlapping layers sections prior to building the seals, wherein the building of each of the dust tight shields comprises applying a barrier layer, such as a glue layer and / or a lamination layer between the metallic casing and each of the respective metallic sheaths, followed by applying a pressure on at least one of the metallic casing and the respective metallic sheaths at each of the overlapping layers section, preferably to close any potential passages into the inner part of the joint.

9. The process of any one of the preceding claims, wherein the process comprises building the metallic casing from two or more casing parts comprising connecting the casing parts using a cold deposition process, preferably using a cold spray process, wherein the two or more casing parts may be of the same or different metals.

10. The process of any one of the preceding claims, wherein the metallic casing, comprises a flexible metallic casing, such as a casing comprising at least one corrugated length section.11 . The process of any one of the preceding claims, wherein both of the HV-cable elements are HV-cables each having a metallic sheath comprising orconsisting of aluminum, wherein the metallic casing comprises or consists of aluminum and wherein the cold deposition process comprises deposition of particles containing aluminum particles.

12. The process of any one of the preceding claims 1-10, wherein both of the HV-cable elements are HV-cables each having a metallic sheath comprising or consisting of cobber, wherein the metallic casing comprises or consists of cobber and wherein the cold deposition process comprises deposition of particles containing cobber particles.

13. The process of any one of the preceding claims 1-10, wherein both of the HV-cable elements are HV-cables each having a metallic sheath comprising or consisting of lead, wherein the metallic casing comprises or consists of at least one of lead, aluminum or cobber and wherein the cold deposition process comprises deposition of particles containing particles comprising at least one of cobber, lead and aluminum, such as cobber particles, lead particles and / or aluminum particles.

14. The process of any one of the preceding claims 1-10, wherein one of the HV-cable elements is a HV-cable comprising a metallic sheath comprising or consisting of a first metal, the other one of the HV-cable elements is a HV-cable comprising a metallic sheath comprising or consisting of a second metal different from the first metal and wherein the metallic casing comprises or consists of one or more metals, preferably comprising at least one of the first and the second metals and optionally a third metal different from the first and the second metal, and wherein the cold deposition process comprises deposition of particles containing at least one metal, wherein the particles preferably contains particles of at least one of the first, the second or the third metal, optionally the particles contains particles of at least the first and the second metal.

15. The process of any one of the preceding claims 1-10 and 14, wherein one of the HV-cable elements is a HV-cable having a first design and wherein the other one of the HV-cable elements is a HV-cable having a second design, which is different from the first design.

16. The process of any one of the preceding claims 1-10, wherein one of the HV-cable elements is a submarine HV-cable and wherein the other one of the HV-cable elements is a submarine cable, an underground HV-cable or a HV-cable termination.

17. The process of any one of the preceding claims 1-10, wherein one of the HV-cable elements is an underground HV-cable and wherein the other one of the HV-cable elements is a submarine cable, an underground HV-cable or a HV-cable termination.

18. The process of any one of the preceding claims, wherein one of the HV-cable elements has a first HV-cable diameter and the other one the HV-cable elements has a second HV-cable diameter, wherein the first HV-cable diameter and the second HV-cable diameter are equal or different, such as slightly different and wherein a maximal outer diameter of the metallic sheath in the joint is from 50 % smaller to 50 % larger than an average of the first HV-cable diameter and the second HV-cable diameter, such as from 25 % smaller to 25 % larger, such as from 10 % smaller to 10 % larger, such as from 5 % smaller to 5 % larger than an average of the first HV-cable diameter and the second HV-cable diameter.

19. The process of any one of the preceding claims, wherein the metallic shields of the HV-cable elements have an average thickness and wherein the metallic casing has a thickness which is from 1 / 10 to 10 times the average thickness of the metallic shields, such as from 1 / 5 to 5 times, such as from 1 / 2 to 2 times the average thickness of the metallic shields.

20. The process of any one of the preceding claims, wherein the providing of the metallic casing to surround and define the inner part of the joint comprises building the metallic casing from a metallic foil comprising folding the metallic foil to surround the adjoining end portions of the inner parts of the respective HV-cable elements and to provide lengthwise edge sections of the metallic foil to form an overlapping section extending lengthwise relative to a length of the inner part of the joint, wherein the process comprises build a seal (preferably a metallic seal) between the lengthwise edge sections of the foil using the cold deposition process, preferably the build a seal (preferably a metallic seal) between the lengthwise edge sections of the foil is performed by the same deposition process applied for building the seals between the metallic casing and the respective metallic sheath.21 . The process of claim 20, wherein the metallic foil has a length determined along a center axis of the inner part of the joint and wherein the length of the metallic foil is longer than the length of the inner part of the joint, to provide sections of overlapping layers between opposite ends of the metallic casing and the respective metallic sheaths at the respective end sections of two HV-cable elementsat each end portion of the metallic casing, preferably to provide the overlapping layers sections by arranging the metallic casing to surround or be surrounded by each of the metallic sheaths at the respective end sections of two HV-cable elements, wherein the process comprises building the seal between the lengthwise edge sections of the foil and building the seals between the metallic casing and the respective metallic sheaths at each of the respective end sections of the HV-cable elements in a common cold deposition process.

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