Heating assembly and method for repairing the insulation system of power cables

Abstract

To provide a heating assembly and a method of repairing an insulation system that can mitigate deformation of an insulation system of a power cable.SOLUTION: A heating assembly (1) receiving a power cable (9) for repairing an insulation system of a power cable includes a central pressure and heating structure (3) and first and second lateral structures (5) and (7) provided at respective axial ends of the central pressure and heating structure (3). Each of the first lateral structure (5) and the second lateral structure (7) includes a section extending in an axial direction of the length of at least 20 cm long shaft made mainly of a material having a conductivity of the order of up to 1000 S / m at 20°C.SELECTED DRAWING: Figure 2

Description

Technical Field

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[0001] The present disclosure generally relates to the joining of power cables and equipment for such joining of power cables.

Background Art

[0002] During the manufacture of power cables, it may be necessary to join two cable lengths. This may be the result of limitations regarding the maximum continuous cable length that can be produced in a factory or may be due to an unintended cable cut.

[0003] When two cable lengths are joined in a factory, all cable layers are removed down to the conductors at the cable ends. The conductor ends are then joined, for example by welding, thereby forming a conductor connection. The insulation system around the conductor connection is reconstructed layer by layer. This is usually done by winding a tape layer by layer. The insulation systems of the two cable ends are connected to a joint insulation system. Before this reconstruction process is started, the insulation system at the cable end can be shaped into a pencil shape, i.e., shaped to a tapered conical shape towards the conductor connection. In cases where the cable is damaged during handling and needs to be repaired, the insulation system is repaired in the same manner.

[0004] A device can be used to cross-link the tape layers of the joint insulation system or the repaired insulation system of a damaged cable. In this case, the joint insulation system is placed inside the device and the joint insulation system is heated under pressure, as a result of which the materials in the tape layer melt simultaneously and become interconnected without forming voids.

Summary of the Invention

[0006] A general objective of this disclosure is to provide a method for repairing heating assemblies and power cable insulation systems that solve or at least mitigate problems of the prior art.

[0007] Accordingly, according to a first aspect of the present disclosure, a heating assembly is provided configured to receive a power cable coupling of a power cable for curing an unsecured insulation system layer of the power cable coupling, the heating assembly being a central pressurized heating structure, the central pressurized heating structure comprising a first part having a first central channel configured to receive a portion of the power cable including the power cable coupling, and a second part having a second central channel configured to receive a portion of the power cable including the power cable coupling, the central pressurized heating structure being configured to be set in a closed state with the first central channel facing the second central channel, thereby forming a central heating chamber extending from a first end of the central pressurized heating structure to a second end opposite the first end, the central pressurized heating structure being configured to be pressurized to achieve a first pressure higher than atmospheric pressure inside the central heating chamber when the power cable is arranged in a sealed state within the central heating chamber, and a pressure compensator system, the pressure compensator system being the first The first lateral structure comprises a first lateral structure extending laterally from the end, the first lateral structure having a first lateral channel aligned with a central heating chamber configured to receive a portion of the power cable, and a second lateral structure extending laterally from the second end of the central pressurized heating structure, the second lateral structure having a second lateral channel aligned with a central heating chamber configured to receive a portion of the power cable, wherein the first lateral structure is sealed within the first lateral structure. The first lateral channel is configured to be pressurized to achieve a second pressure higher than atmospheric pressure when arranged in such a manner, and the second lateral structure is configured to be pressurized to achieve a third pressure higher than atmospheric pressure when arranged in such a manner that power cables are sealed within the second lateral structure, and each of the first and second lateral structures has an axially extending section of at least 20 cm in length, made primarily of a material having conductivity on the order of 1000 S / m at 20°C.It includes a pressure compensator system.

[0008] The first and second lateral structures provide counter-pressure to the internal pressure of the central pressurized heating structure. Furthermore, the low conductivity of the material making up the axially extending sections of the first and second lateral structures induces only small currents at most within these structures when high-frequency heating coils are arranged around these structures to heat the power cable conductors to achieve internal heating of the restoration insulation system layer. Consequently, the insulation system inside the first and second lateral structures is not heated to a temperature that would cause the insulation system to melt or reach a viscosity low enough to push the insulation system axially out of these structures.

[0009] The term "primarily" means more than 50%. Therefore, more than 50% of the axially extending sections of the first transverse structure and the second transverse structure are made of a material having a conductivity of up to 1000 S / m at 20°C.

[0010] The percentage of material in a section extending axially relative to the total material may be a volume percentage or a weight percentage.

[0011] The section of the first lateral structure that extends in the axial direction may have a length of at least 30 cm (or at least 40 cm, etc.).

[0012] The axially extending section of the second lateral structure may have a length of at least 30 cm (or at least 40 cm, etc.).

[0013] In one embodiment, the axially extending section of the first transverse structure may be the entire axial length of the first transverse structure. In this example, the first transverse structure is made primarily of a material having a conductivity of up to 1000 S / m at 20°C.

[0014] In one embodiment, the axially extending section of the second transverse structure may be the entire axial length of the second transverse structure. In this example, the second transverse structure is made primarily of a material having a conductivity of up to 1000 S / m at 20°C.

[0015] The material may include, for example, polymers such as epoxy or polyamide, glass fibers and / or carbon fibers, or reinforcing polymers such as glass fiber reinforced polymers or carbon fiber reinforced polymers.

[0016] The terms “interconnected” and “hardened” are used interchangeably herein. Therefore, the terms “interconnected” and “hardened” are also interchangeable.

[0017] According to one embodiment, the material has an electrical conductivity of the order of 100 S / m at 20°C (e.g., 10 S / m (20°C), 1 S / m (20°C), 0.1 S / m (20°C), 0.01 S / m (20°C), 0.001 S / m (20°C), 0.0001 S / m (20°C), etc.).

[0018] According to one embodiment, the material has an electrical conductivity of the order of 10^-4 S / m at 20°C (10^-5 S / m (20°C), 10^-6 S / m (20°C), 10^-7 S / m (20°C), 10^-8 S / m (20°C), 10^-9 S / m (20°C), 10^-10 S / m (20°C), etc.).

[0019] According to one embodiment, the second pressure and the third pressure are each within ±50% of the first pressure (e.g., within ±40% of the first pressure, within ±30% of the first pressure, within ±20% of the first pressure, within ±10% of the first pressure, etc.).

[0020] According to one embodiment, the second pressure and the third pressure are equal to the first pressure.

[0021] According to one embodiment, the first lateral structure and the second lateral structure have smaller radial dimensions than the central pressurized heating structure. This allows each high-frequency (HF) heating coil to be positioned around the first lateral structure and the second lateral structure.

[0022] According to one embodiment, the first pressure is at least one of several bar values, such as 4 bar. The first pressure may be, for example, up to 15 bar (e.g., up to 10 bar).

[0023] According to one embodiment, the central pressurized heating structure mainly comprises metal. The first and second parts may have separate walls, for example, mainly made of metal. The metal may be, for example, steel such as stainless steel or carbon steel, or aluminum.

[0024] According to one embodiment, the axially extending section of the first transverse structure and the axially extending section of the second transverse structure each have walls that are mainly made of the above material having an conductivity of up to 1000 S / m at 20°C.

[0025] According to one embodiment, each wall of the first lateral structure and the second lateral structure contains at least 80% of the above material.

[0026] One embodiment includes a heating device configured to heat a central heating chamber.

[0027] One embodiment comprises an induction heating device having a first high-frequency (HF) heating coil configured to be arranged around a first lateral structure, and a second HF heating coil configured to be arranged around a second lateral structure.

[0028] According to a second aspect of the present disclosure, a method for repairing an insulation system around a conductor of a power cable using the heating assembly of the first aspect is provided. The method includes: a) disposing a power cable joint having a conductor with a repair insulation system layer disposed around the conductor in one of the first central channel and the second central channel; b) disposing the power cable in each of the first lateral structure and the second lateral structure; c) setting the central pressurizing and heating structure to a closed state; d) disposing a first high-frequency HF heating coil around a section extending axially in the first lateral structure and a second HF heating coil around a section extending axially in the second lateral structure; e) pressurizing the central heating chamber to a first pressure, the first lateral channel to a second pressure, and the second lateral channel to a third pressure; and f) heating the repair insulation system layer by external heating inside the central pressurizing and heating structure and by internal heating of the repair insulation system layer by sending a current to the first HF heating coil and the second HF heating coil to induce a current in the conductor.

[0029] Steps a) to e) do not necessarily have to be performed in the order mentioned. For example, step b) may be performed first, followed by step d), step a), step c), step e), and step f), or step a) may be performed first, followed by step c), step e), step b), step d), and finally step f).

[0030] The heating in step f) may be for curing the repair insulation system layer. This may particularly apply when the repair insulation system layer includes a thermosetting polymer.

[0031] The heating in step f) may be for the purpose of melting the repair insulation system layer together with the corresponding layer of the power cable's insulation system. This applies, of course, when the repair insulation system layer contains a thermosetting polymer, but also when the repair insulation system layer contains a thermoplastic material such as polypropylene.

[0032] According to one embodiment, the conductor has a conductor coupling, and in step a), the repair insulation system layer is configured to be arranged around the conductor coupling in one of the central channels, which is either a first central channel or a second central channel.

[0033] The first and second HF heating coils do not induce current or induce only small currents within the first and second lateral structures. Therefore, the first and second lateral structures are not heated to a temperature that would cause the insulation system of the power cable to reach a viscosity low enough to deform the insulation system due to the pressure difference within the interface with the surroundings, which have significantly lower pressure. Furthermore, because the pressure difference between the central heating chamber and the first and second lateral channels is small or equal, no deformation occurs or only negligible deformation occurs within the interface between the first and second lateral structures and the central pressurized heating structure.

[0034] The first HF heating coil can be positioned at a maximum distance of 2 to 2.5 m from the conductor connection (e.g., 1 to 2 m from the conductor connection, 0.8 to 1 m from the conductor connection, etc.).

[0035] The second HF heating coil can be positioned at a maximum distance of 2 to 2.5 m from the conductor connection (e.g., 1 to 2 m from the conductor connection, 0.8 to 1 m from the conductor connection, etc.).

[0036] One embodiment includes performing steps a) to f) in each of a plurality of repair insulation system layers.

[0037] Alternatively, all repair insulation system layers may be provided around the conductor joint, steps a) to f) may be performed simultaneously, with step f) involving simultaneous heating of all repair insulation system layers.

[0038] Typically, the first repair insulation system layer applied to the conductor is the inner semiconductor layer, applied across the conductor joint, or, in the case of repairing the insulation system of a damaged cable, typically across a section of the conductor without using the conductor joint. In the case of repairing the insulation system of a damaged cable, the insulation system is stripped down to the conductor, as it was during the joint before the start of the insulation system repair. The inner semiconductor layer contains a polymer such as polyethylene or polypropylene and conductive particles such as carbon black. The inner semiconductor layer may be made of tape wrapped around the conductor, so that the inner semiconductor layer overlaps with the inner semiconductor layer of each of the two cable length sections that are joined, or, in the case of repairing a damaged power cable, overlaps with the inner semiconductor layer on both sides of the stripped insulation system. The tape may contain a crosslinking agent. Steps a) to d) are then carried out.

[0039] Next, after the first insulation system layer is heated and cooled, a second repair insulation system layer is applied on top of the inner semiconductor layer after the pressurized heating device is opened. The second repair insulation system layer is applied so as to overlap the insulation layer of each of the two cable length sections that are joined, or in the case of repairing a damaged power cable, it is applied so as to overlap the insulation layer on both sides of the stripped insulation system. The insulation layer contains a polymer such as polyethylene or polypropylene. The insulation layer is usually applied by taping. The tape may contain a crosslinking agent. Steps a) to d) are then carried out.

[0040] Finally, after the second insulation system layer is heated and cooled, a third repair insulation system layer is applied on top of the insulation layer after the pressurized heating device is opened. The third repair insulation system layer is an outer semiconductor layer. The outer semiconductor layer contains a polymer such as polyethylene or polypropylene and conductive particles such as carbon black. The outer semiconductor layer may be made of tape that is wrapped around the insulation layer, so that the outer semiconductor layer overlaps with the outer semiconductor layer of each of the two cable length sections that are bonded together, or, in the case of repairing a damaged power cable, overlaps with the outer semiconductor layer on both sides of the stripped insulation system. Steps a) to d) are then carried out. In this way, the insulation system of the power cable is reconstructed.

[0041] Instead of taping, a repair insulation system layer may be formed, for example, by injection molding.

[0042] According to one embodiment, in step f), external heating and internal heating are performed simultaneously. Therefore, heating / curing can be more uniform in the radial direction.

[0043] According to one embodiment, an alternating current having a frequency in the range of kilohertz, such as 1 to 500 kHz or 5 to 300 kHz, is supplied to the first HF heating coil and the second HF heating coil.

[0044] According to one embodiment, before step f), the repair insulation system layer is an uncured insulation system layer, and in step f), external heating and internal heating are for curing the repair insulation system layer.

[0045] In general, all terms used in the claims shall be construed in accordance with their ordinary meaning in the art unless otherwise specified herein. All references to elements, apparatus, components, means, etc., preceded by a / an / the shall be construed as referring non-exclusively to at least one example of such elements, apparatus, components, means, etc., unless otherwise specified herein.

[0046] Next, specific embodiments of the concept of the present invention will be described as examples with reference to the attached drawings. [Brief explanation of the drawing]

[0047] [Figure 1] This is a schematic top view showing the heating assembly in the open state. [Figure 2] This figure shows a longitudinal cross-section of a heating assembly while it is heating the insulation system layer for repairing power cables. [Figure 3] This flowchart shows how to repair the insulation system of a power cable. [Modes for carrying out the invention]

[0048] Next, the concept of the present invention will be described more fully below with reference to the accompanying drawings illustrating exemplary embodiments. However, the concept of the present invention can be embodied in many diverse forms and should not be construed as being limited only to the embodiments described herein. Rather, these embodiments are provided as examples to make this disclosure thorough and complete and to fully convey the scope of the concept of the present invention to those skilled in the art. Throughout this description, similar reference numerals indicate similar elements.

[0049] Figure 1 schematically shows a top view of the heating assembly 1 in the open state. The heating assembly 1 is adapted to heat the insulation system layer of a power cable when repairing the insulation system of a power cable across a conductor joint, or in cases where the power cable has been damaged. In some embodiments, this heating may involve curing the insulation system layer to be repaired.

[0050] The pressurized heating device 1 may be suitable for heating the insulation system layer for repairing medium-voltage or high-voltage AC or DC power cables.

[0051] The heating assembly 1 includes a central pressurized heating structure 3. The central pressurized heating structure 3 includes a first part 3a and a second part 3b.

[0052] The first portion 3a has a first central channel 3c that extends from one end of the first portion 3a to the opposite end of the first portion 3a. The first central channel 3c is straight. The first central channel 3c is configured to receive a power cable, including a power cable connector.

[0053] The second portion 3b has a second central channel 3d extending from one end of the second portion 3b to the opposite end of the second portion 3b. The second central channel 3d is straight. The second central channel 3d is configured to receive a power cable, including a power cable connector.

[0054] The first part 3a and the second part 3b are configured to be assembled together to set the central pressurized heating structure 3 in a closed state. Thus, the central pressurized heating structure 3 is openable and closedable.

[0055] The first part 3a and the second part 3b may be connected, for example, in a hinged manner, or the first part 3a and the second part 3b may be completely separable from each other.

[0056] In the closed state of the central pressurized heating structure 3, the first central channel 3c faces the second central channel 3d. The first central channel 3c is aligned with the second central channel 3d in the axial direction. Thus, the first central channel 3c and the second central channel 3d form a central heating chamber that extends from the first end 4a of the central pressurized heating structure 3 to the second end 4b of the central pressurized heating structure 3 on the opposite side of the first end 4a. Thus, the central heating chamber is configured to surround the power cable, including the power cable connector, in the circumferential direction along the length of the central pressurized heating structure 3.

[0057] The heating assembly 1 may include a heating device 3e configured to heat a central heating chamber to a predetermined temperature. In some embodiments, the predetermined temperature is a curing temperature for curing a thermosetting polymer such as polyethylene. According to some embodiments, the predetermined temperature is a melting temperature for heating a thermoplastic polymer such as polyethylene until it melts.

[0058] According to one embodiment, the central pressurized heating structure 3 may include a heating device 3e. The heating device 3e may be configured to directly heat the central heating chamber by means of, for example, a heating coil or similar means arranged around the first central channel 3c and the second central channel 3d. Alternatively, the heating device may be located outside the central pressurized heating structure 3. In this case, the heating device may be configured to heat a gas, such as a noble gas, introduced into the central heating chamber from the outside.

[0059] The first portion 3a has a wall 3f that mainly contains metal. The second portion 3b has a wall 3g that mainly contains metal.

[0060] The heating assembly 1 includes a pressure compensator system having a first lateral structure 5 and a second lateral structure 7.

[0061] The first lateral structure 5 extends laterally from the first end 4a of the central pressurized heating structure 3.

[0062] The first transverse structure 5 has axially extending sections made primarily of a material having a conductivity of up to 1000 S / m at 20°C. The material may be, or may include, a reinforcing polymer such as a glass fiber reinforced polymer or a carbon fiber reinforced polymer, such as a glass fiber reinforced epoxy or glass fiber reinforced polyamide or a carbon fiber reinforced epoxy or carbon fiber reinforced polyamide.

[0063] The axially extending section is at least 20 cm long, but in one variant, it may be the entire length of the first transverse structure 5, as shown in the embodiment in Figures 1 and 2. In this embodiment, the first transverse structure 5 is mainly made of a material having a conductivity of up to 1000 S / m at 20°C.

[0064] Sections extending axially from the first transverse structure 5 have walls 5a, for example, where at least 80% or at least 90% of them are made of a material having conductivity on the order of 1000 S / m at 20°C (100 S / m (20°C), 10 S / m (20°C), 1 S / m (20°C), 0.1 S / m (20°C), 0.01 S / m (20°C), 0.001 S / m (20°C), 0.0001 S / m (20°C), 10^-4 S / m (20°C), 10^-5 S / m (20°C), 10^-6 S / m (20°C), 10^-7 S / m (20°C), 10^-8 S / m (20°C), 10^-9 S / m (20°C), 10^-10 S / m (20°C), etc.).

[0065] The second lateral structure 7 extends laterally from the second end 4b of the central pressurized heating structure 3. The first lateral structure 5 and the second lateral structure 7 extend away from the central pressurized heating structure 3 in opposite directions.

[0066] The second transverse structure 7 has axially extending sections made primarily of a material having a conductivity of up to 1000 S / m at 20°C. The material may be, or may include, a reinforcing polymer such as a glass fiber reinforced polymer or a carbon fiber reinforced polymer, such as a glass fiber reinforced epoxy or glass fiber reinforced polyamide or a carbon fiber reinforced epoxy or carbon fiber reinforced polyamide.

[0067] The axially extending section is at least 20 cm long, but in one variant, it may be the entire length of the second transverse structure 7, as shown in the embodiment in Figures 1 and 2. In this embodiment, the second transverse structure 7 is mainly made of a material having a conductivity of up to 1000 S / m at 20°C.

[0068] Sections of the second transverse structure 7 extending in the axial direction have walls 7a, for example, where at least 80% or at least 90% of them are made of a material having a conductivity of up to 1000 S / m at 20°C (100 S / m (20°C), 10 S / m (20°C), 1 S / m (20°C), 0.1 S / m (20°C), 0.01 S / m (20°C), 0.001 S / m (20°C), 0.0001 S / m (20°C), 10^-4 S / m (20°C), 10^-5 S / m (20°C), 10^-6 S / m (20°C), 10^-7 S / m (20°C), 10^-8 S / m (20°C), 10^-9 S / m (20°C), 10^-10 S / m (20°C), etc.).

[0069] The first lateral structure 5 may be integrated with the central pressurized heating structure 3. Alternatively, the first lateral structure 5 may be configured to be sealedly connected to or attached to the central pressurized heating structure 3.

[0070] The second lateral structure 7 can be integrated with the central pressurized heating structure 3. Alternatively, the second lateral structure 7 can be configured to be sealed and connected to the central pressurized heating structure 3.

[0071] The first lateral structure 5 may be openable. The first lateral structure 5 may comprise a first lateral structure portion 5b and a second lateral structure portion 5c configured to be assembled with each other. The first lateral structure portion 5b has a straight opening channel 5d extending from one end to the opposite end of the first lateral structure portion 5b. The second lateral structure portion 5c has a straight opening channel 5e extending from one end to the opposite end of the second lateral structure portion 5c. Channels 5d and 5e form a first lateral channel that is closed in the circumferential direction when the first lateral structure portion 5b and the second lateral structure portion 5c are assembled with each other and the first lateral structure 5 is closed. The first lateral channel is configured to receive power cables. The first lateral channel 5c is aligned in the axial direction with the central heating chamber.

[0072] The first lateral structural part 5b and the second lateral structural part 5c may be attached, for example, in a hinged manner, or the first lateral structural part 5b and the second lateral structural part 5c may be completely separable from each other.

[0073] The second lateral structure 7 may be openable. The second lateral structure 7 may comprise a third lateral structure portion 7b and a fourth lateral structure portion 7c configured to be assembled with each other. The third lateral structure portion 7b has a straight opening channel 7d extending from one end to the opposite end of the third lateral structure portion 7b. The fourth lateral structure portion 7c has a straight opening channel 7e extending from one end to the opposite end of the fourth lateral structure portion 7c. Channels 7d and 7e form a second lateral channel that is closed circumferentially when the third lateral structure portion 7b and the fourth lateral structure portion 7c are assembled with each other to close the second lateral structure 7. The second lateral channel is configured to receive power cables. The second lateral channel 7c is aligned axially with the central heating chamber.

[0074] The third lateral structural portion 7b and the fourth lateral structural portion 7c may be attached, for example, in a hinged manner, or the third lateral structural portion 7b and the fourth lateral structural portion 7c may be completely separable from each other.

[0075] Instead of a first lateral structure that can be opened, the first lateral structure may be a disposable tube after use. The first lateral structure may be sawn into two or more pieces for removal, for example, around a power cable.

[0076] Instead of a second lateral structure that can be opened, the second lateral structure may be a disposable tube after use. The second lateral structure may be sawn into two or more pieces for removal, for example, around a power cable.

[0077] Next, with reference to Figures 2 and 3, a method for curing the uncured insulation system layer of a power cable connection using the heating assembly 1 will be described.

[0078] Here, the use of cured assembly 1 is described in the context of bonding operations. This process is also applicable to the case of repairing the insulation system of a damaged power cable. Furthermore, the insulation system being repaired in this embodiment is cured because the repair insulation system layer in this embodiment contains a thermosetting polymer. However, this process is also applicable to cases using thermoplastic materials, except that the temperature used in the heating step may be adapted to match the properties of the thermoplastic material.

[0079] Figure 2 schematically shows a power cable 9 comprising two cable length sections 9a and 9b in the process of being joined inside the heating assembly 1. The central pressurized heating structure 3 is in a closed state, and the power cable 9 extends through the central pressurized heating structure 3 inside the central heating chamber 10.

[0080] The power cable 9 further extends through the first lateral structure 5 and the second lateral structure 7, which are positioned at the axial ends on both sides of the central pressurized heating structure 3.

[0081] In the state shown in Figure 2, the conductors 11a and 11b of the two cable length sections 9a and 9b are joined together, thus creating a conductor joint 11c. Thus, the two conductors 11a and 11b form a single conductor.

[0082] The conductors 11a and 11b may be joined, for example, by welding, brazing, or by using a mechanical connector.

[0083] Each cable length section 9a, 9b has a cone-shaped insulation system 13a, 13b adjacent to the conductor coupling portion 11c. The region including the cone-shaped insulation systems 13a, 13b and the conductor coupling portion 11c constitutes the power cable coupling portion.

[0084] In this way, the coupling insulation system, that is, the insulation system around the conductor coupling portion 11c and between the conical ends of the insulation systems 13a and 13b, is reconstructed layer by layer.

[0085] An uncured first repair insulation system layer 15 is provided around the conductor joint 11c and is configured to overlap with the corresponding insulation layers of the insulation systems 13a and 13b at the conical ends of the insulation systems 13a and 13b. The first repair insulation system layer 15 may be formed, for example, by tape wrapped around the exposed conductor.

[0086] The central heating chamber 10 can be pressurized to a first pressure higher than atmospheric pressure. The first pressure is one of several bar values, such as bar values ​​in the range of 4 bar to 15 bar (e.g., 4 bar to 10 bar).

[0087] During curing, the central heating chamber 10 may be filled with a rare gas to prevent oxidation while rebuilding the insulating system on the conductive joint 11c. The rare gas may be pressurized to a first pressure.

[0088] The first lateral channel 17 of the first lateral structure 5 can be pressurized up to a second pressure. The second pressure is one of several bar values, such as bar values ​​in the range of 3 bar to 15 bar (e.g., 3 bar to 10 bar).

[0089] The second lateral channel 19 of the second lateral structure 7 can be pressurized up to a third pressure. The third pressure is one of several bar values, such as bar values ​​in the range of 3 bar to 15 bar (e.g., 3 bar to 10 bar).

[0090] The second and third pressures are within ±50% of the first pressure (e.g., within ±40%, ±30%, ±20%, ±10%, etc.). In one embodiment, at least one or both of the second and third pressures may be equal to the first pressure.

[0091] In step a), a power cable connector having a conductor, comprising a conductor connector 11c and a repair insulation system layer 15 arranged around the conductor connector, is positioned within one of the central channels, either the first central channel 3c or the second central channel 3d.

[0092] In step b), the power cable 9 is placed inside the first lateral structure 5 and the second lateral structure 7, respectively. At this stage, the first lateral structure 5 and the second lateral structure 7 may be open, and the power cable 9 may be configured to be placed inside channels 5d, 5e, 7d, and 7e.

[0093] Steps a) and b) may be performed simultaneously or substantially simultaneously.

[0094] In step c), the central pressurized heating structure is set to a closed state, where the central heating chamber 10 is formed around the power cable connection. Step c) may further involve setting the first lateral structure 5 and the second lateral structure 7 to their closed states.

[0095] The heating assembly may be equipped with sealing members, such as gaskets, to seal the central heating chamber 10, the first lateral channel 17, and the second lateral channel 19 with respect to the power cable 9.

[0096] As shown in Figure 2, the first lateral structure 17 and the second lateral structure 19 can have smaller radial dimensions than the central pressurized heating structure 3.

[0097] The heating assembly 1 may include an induction heating device comprising a first HF heating coil 21 and a second HF heating coil 23. The induction heating device may include a power supply system configured to supply alternating current having a frequency in the range of kilohertz to the first HF heating coil 21 and the second HF heating coil. The induction heating device may include a water cooling system configured to cool the first HF heating coil 21 and the second HF heating coil 23.

[0098] In step d), the first HF heating coil 21 is positioned around the axially extending section of the first lateral structure 5, and the second HF heating coil 23 is positioned around the axially extending section of the second lateral structure 7. In cases where the first lateral structure 5 further comprises one or more sections made of a material having a higher electrical conductivity than the axially extending section, the first HF heating coil 21 is positioned around the axially extending section at an appropriate distance from the interface between these two materials. In cases where the second lateral structure 7 further comprises one or more sections made of a material having a higher electrical conductivity than the axially extending section, the second HF heating coil 23 is positioned around the axially extending section at an appropriate distance from the interface between these two materials.

[0099] The first HF heating coil 21 and the second HF heating coil 23 may be openable or separable into multiple parts to facilitate their arrangement around the power cable 9 in step d), for example.

[0100] The first HF heating coil 21 and the second HF heating coil 23 may be configured to be positioned at equal axial distances from the conductor coupling portion 11c. This distance may be a maximum of 2 to 2.5 m from the conductor coupling portion 11c (e.g., 1 to 2 m from the conductor coupling portion 11c, 0.8 to 1 m from the conductor coupling portion 11c, etc.).

[0101] In step e), the central heating chamber 10 is pressurized to a first pressure, the first lateral channel 17 is pressurized to a second pressure, and the second lateral channel 19 is pressurized to a third pressure.

[0102] In step f), the repair insulation system layer 15 is heated by external heating of the inside of the central pressurized heating structure 3 by the heating device, and by internal heating of the repair insulation system layer 15 by sending current to the first HF heating coil 21 and the second HF heating coil 23 to induce current in the conductor. In this embodiment, the heating in step f) is accompanied by curing of the repair insulation system layer 15.

[0103] In step f), external and internal heating are typically performed simultaneously.

[0104] Steps a) to f) are typically performed on each of the multiple repair insulation system layers at the power cable connection, for example, each of the multiple repair insulation system layers is uncured before step f). After each repetition of the process, the insulation system layer is cooled to a predetermined temperature, such as 60°C or below.

[0105] The above has primarily described the concept of the present invention with reference to a small number of examples. However, as will be readily apparent to those skilled in the art, other embodiments besides those disclosed above are also possible within the scope of the concept of the present invention as defined by the appended claims.

Claims

1. A heating assembly (1) configured to receive the power cable coupling portion of a power cable (9) for repairing the insulation system of a power cable, wherein the heating assembly (1) - Central pressurized heating structure (3), A first portion (3a) having a first central channel (3c) configured to receive a portion of the power cable (9), and A second portion (3b) comprising a second central channel (3d) configured to receive a portion of the power cable (9) Equipped with The central pressurized heating structure (3) is configured to be set in a closed state such that the first central channel (3c) faces the second central channel (3d), thereby forming a central heating chamber (10) that extends from the first end (4a) of the central pressurized heating structure (3) to the second end (4b) on the opposite side of the first end (4a). The central pressurized heating structure (3) is configured to pressurize the central heating chamber (10) to achieve a first pressure higher than atmospheric pressure when the power cable (9) is arranged in a sealed state within the central heating chamber (10). Central pressurized heating structure (3), - A pressure compensator system, A first lateral structure (5) extending laterally from the first end (4a) of the central pressurized heating structure (3), wherein the first lateral structure (5) has a first lateral channel (17) aligned with the central heating chamber (10) and configured to receive a portion of the power cable (9), and A second lateral structure (7) extending laterally from the second end (4b) of the central pressurized heating structure (3), wherein the second lateral structure (7) has a second lateral channel (19) aligned with the central heating chamber (10) and configured to receive a portion of the power cable (9). Equipped with, The first lateral structure (5) is configured to be pressurized to achieve a second pressure higher than atmospheric pressure in the first lateral channel (17) when the power cable (9) is arranged in a sealed state within the first lateral structure (5), and the second lateral structure (7) is configured to be pressurized to achieve a third pressure higher than atmospheric pressure in the second lateral channel (19) when the power cable (9) is arranged in a sealed state within the second lateral structure (7), Each of the first transverse structure (5) and the second transverse structure (7) has an axially extending section of at least 20 cm in length, which is mainly made of a material having an conductivity of up to 1000 S / m at 20°C. Pressure compensator system and A heating assembly (1) comprising:

2. The heating assembly (1) according to claim 1, wherein the material has an electrical conductivity of the order of 100 S / m at 20°C (e.g., 10 S / m (20°C), 1 S / m (20°C), 0.1 S / m (20°C), 0.01 S / m (20°C), 0.001 S / m (20°C), 0.0001 S / m (20°C), etc.).

3. The heating assembly (1) according to claim 1, wherein each of the second pressure and the third pressure is within ±50% of the first pressure (e.g., within ±40% of the first pressure, within ±30% of the first pressure, within ±20% of the first pressure, within ±10% of the first pressure, etc.).

4. The heating assembly (1) according to claim 1, wherein the second pressure and the third pressure are equal to the first pressure.

5. The heating assembly (1) according to claim 1, wherein the first lateral structure (5) and the second lateral structure (7) have smaller radial dimensions than the central pressurized heating structure (3).

6. The heating assembly (1) according to claim 1, wherein the first pressure is at least one of several bar values, such as 4 bar.

7. The heating assembly (1) according to claim 1, wherein the central pressurized heating structure (3) mainly contains metal.

8. The heating assembly (1) according to claim 1, wherein the axially extending section of the first lateral structure (5) and the axially extending section of the second lateral structure (7) each have walls (3f, 3g) mainly made of the material having an conductivity of up to 1000 S / m at 20°C.

9. The heating assembly (1) according to claim 8, wherein each of the walls (3f, 3g) of the first lateral structure (5) and the second lateral structure (7) contains at least 80% of the material.

10. The heating assembly (1) according to claim 1, comprising a heating device (3e) configured to heat the central heating chamber (10).

11. The heating assembly (1) according to claim 1, comprising an induction heating device having a first high-frequency HF heating coil (21) configured to be arranged around the first lateral structure (5), and a second HF heating coil (23) configured to be arranged around the second lateral structure (7).

12. A method for repairing an insulation system around a conductor of a power cable using a heating assembly (1) according to any one of claims 1 to 10, wherein the method is: a) A power cable coupling having a conductor with a repair insulation system layer (15) arranged around the conductor is placed in one of the central channels, which is either the first central channel (3c) or the second central channel (3d). b) Arranging the power cable (9) within each of the first lateral structure (5) and the second lateral structure (7), c) Setting the central pressurized heating structure (3) to a closed state, d) Arranging the first high-frequency HF heating coil (21) around the axially extending section of the first lateral structure (5) and the second HF heating coil (23) around the axially extending section of the second lateral structure (7), e) Pressurizing the central heating chamber (10) to a first pressure, the first lateral channel (17) to a second pressure, and the second lateral channel (19) to a third pressure, f) Heating the repair insulation system layer (15) by external heating of the inside of the central pressurized heating structure (3) and by internal heating of the repair insulation system layer (15) by sending current to the first HF heating coil (21) and the second HF heating coil (23) to induce current in the conductor. Methods that include...

13. The method according to claim 12, comprising performing steps a) to f) in each of a plurality of repair insulation system layers.

14. The method according to claim 12, wherein in step f), the external heating and the internal heating are performed simultaneously.

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