Pressurized heating device and method for repairing the insulation system of power cables

Abstract

To provide a pressurized heating device that can be repaired without affecting the performance of a power cable insulation system, and a method for repairing the insulation system around a power cable conductor.SOLUTION: A pressurized heating device 1 in a heating assembly 10 comprises: a first portion 3 with a first channel for receiving a portion of a power cable 11; a second portion 5 with a second channel; HF heating coils 19a and 19b for heating a heating chamber 13 to a predetermined temperature; and a section 9 extending axially at least 20 cm long, made mainly of a material having a conductivity of the order of up to 1000 S / m at 20°C, which are set in a closed state forming the heating chamber. The pressurized heating device is pressurized to achieve a pressure greater than atmospheric pressure within the heating chamber when the power cable is arranged to seal inside the heating chamber.SELECTED DRAWING: Figure 2

Description

Technical Field

[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 can be, for example, as a result of limitations regarding the maximum continuous cable length that can be produced in a factory or 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. Then, the conductor ends are joined, for example, by welding, thereby forming a conductor joint. Next, the insulation system around the conductor joint is reconstructed layer by layer. This is usually done by winding 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 of the cable end can be shaped like a pencil, i.e., shaped to have a tapered conical shape towards the conductor joint. 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 arranged 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

[0005] In cases where a high-frequency heating coil is used for internal heating of the insulation system being repaired during curing, in combination with external heating achieved by a pressurized heating device, the insulation system outside the pressurized heating device becomes excessively heated. This is because the high-frequency heating coil, which is configured to be axially separated from the pressurized heating device, induces current in the conductor radially inside the high-frequency heating coil. Consequently, a large portion of the insulation system is heated significantly more than is necessary to cure the insulation system being repaired. This can affect the performance of the insulation system.

[0006] A general objective of this disclosure is to provide a pressurized heating device and a method for repairing the insulation system of a power cable that solves or at least mitigates problems of the prior art.

[0007] Accordingly, according to a first aspect of the present disclosure, a pressurized heating device is provided for repairing the insulation system of a power cable, the pressurized heating device comprising: a first part having a first channel configured to receive a portion of a power cable; and a second part having a second channel configured to receive a portion of a power cable, the pressurized heating device being configured to be set in a closed state with the first channel facing the second channel, thereby forming a heating chamber extending from a first end of the pressurized heating device to a second end opposite the first end, the pressurized heating device being configured to be pressurized to achieve a pressure higher than atmospheric pressure inside the heating chamber when the power cable is arranged to be sealed within the heating chamber, the pressurized heating device having an axially extending section at least 20 cm in length, which is made primarily of a material having a conductivity of up to 1000 S / m at 20°C.

[0008] Due to the low conductivity of the material forming the axially extending section of the pressure-resistant mold, only a small current at most is induced within the axially extending section when a high-frequency heating coil is configured to heat the conductors of the power cable in order to heat the insulation system layer being repaired. Therefore, heating of the insulation system can be concentrated on the insulation system being repaired inside the pressurized heating device. Thus, the temperature profile along the axial direction can be optimized, thereby reducing the problem of waist formation during the curing process.

[0009] Furthermore, the insulating system adjacent to the axial end inside the pressurized heating device cannot be heated to a temperature that would cause the insulating system to melt, or to reach a viscosity low enough that the pressure difference between the ambient pressure and the internal pressure of the pressurized heating device would push the insulating system axially outward from the pressurized heating device. Therefore, the risk of deformation of the insulating system is reduced.

[0010] The term "primarily" means more than 50%. Therefore, more than 50% of the axially extending sections of the pressurized heating device are made of a material having a conductivity of up to 1000 S / m at 20°C.

[0011] The percentage of material in a section extending axially relative to the total material may be a volume percentage or a weight percentage.

[0012] The terms “interconnected” and “hardened” are used interchangeably herein. Therefore, the terms “interconnected” and “hardened” are also interchangeable.

[0013] According to one embodiment, the pressurized heating device may comprise two or more (e.g., two) axially extending sections at least 20 cm in length, primarily made of a material having a conductivity of up to 1000 S / m at 20°C.

[0014] 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.).

[0015] 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.).

[0016] According to one embodiment, the axially extending section is at least 30 cm long (at least 40 cm, at least 50 cm, at least 60 cm, at least 70 cm, at least 80 cm, etc.).

[0017] According to one embodiment, an axially extending section may be centrally located in the axial direction on a pressurized heating device.

[0018] According to one embodiment, the pressurized heating device comprises two axially extending sections that are offset in the axial direction and are arranged symmetrically with respect to the center of the pressurized heating device.

[0019] In one embodiment, the axially extending section may be the entire axial length of the pressurized heating device. In this example, the pressurized heating device is made primarily of a material having a conductivity of up to 1000 S / m at 20°C.

[0020] According to one embodiment, at least 70% (or at least 80%) of an axially extending section is made of a material having an electrical conductivity of up to 1000 S / m at 20°C.

[0021] According to one embodiment, the material includes a fiber-reinforced polymer.

[0022] According to some embodiments, the material can include polymers such as epoxy or polyamide, glass fibers, and / or carbon fibers, or fiber-reinforced polymers such as glass fiber reinforced epoxy or glass fiber reinforced polyamide or carbon fiber reinforced epoxy or carbon fiber reinforced polyamide.

[0023] According to one embodiment, the pressure heating device is configured to be pressurized to a plurality of bar values such as at least 4 bar. The pressure heating device can be configured to be pressurized, for example, up to a maximum of 15 bar (such as a maximum of 10 bar).

[0024] According to one embodiment, the axially extending section has a wall, and at least 80% of the wall is made of a material having a conductivity on the order of up to 1000 S / m at 20°C.

[0025] One embodiment includes a heating device configured to heat a heating chamber.

[0026] One embodiment includes a high-frequency HF heating coil that extends around the heating chamber within an axially extending section when the pressure heating device is in a closed state.

[0027] The HF heating coil can be integrated with the pressure heating device or removably disposed inside the pressure heating device.

[0028] In the case of two axially extending sections, the pressure heating device can include two HF heating coils, and each of the two HF heating coils is disposed within a respective axially extending section.

[0029] According to one embodiment, the HF heating coil extends around the heating chamber at a location within ±30% of the center of the pressure heating device as measured from the first end to the second end.

[0030] According to one embodiment, this range is ±10%.

[0031] According to one embodiment, this range is ±20% or ±40%.

[0032] According to a second aspect of the present disclosure, there is provided a heating assembly including a pressure heating device according to the first aspect and at least one external HF heating coil configured to be disposed around the pressure heating device within an axially extending section.

[0033] The heating assembly can include, for example, two external HF heating coils.

[0034] In the case of two axially extending sections, each external HF heating coil can be disposed within an individual axially extending section.

[0035] According to a third aspect of the present disclosure, there is provided a method for repairing an insulation system around a conductor of a power cable using a pressure heating device according to the first aspect or a heating assembly according to the second aspect, the method including: a) disposing a power cable having a restoration insulation system layer disposed around the conductor within one of a first channel and a second channel; b) setting the pressure heating device to a closed state; c) pressurizing the heating chamber; d) heating the restoration insulation system layer while the heating chamber is pressurized by external heating inside the pressure heating device and by internal heating of the restoration insulation system layer by sending a current through a high-frequency HF heating coil disposed around the heating chamber within an axially extending section for inducing a current in the conductor.

[0036] The heating may be for curing the restoration insulation system layer. This can particularly apply when the restoration insulation system layer includes a thermosetting polymer.

[0037] The heating may be for the purpose of melting the repair insulation system layer along with the corresponding layer of the power cable's insulation system. This is true, 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.

[0038] According to one embodiment, the conductor has a conductor coupling, and in step a), a repair insulation system layer is configured to be arranged around the conductor coupling in one of the channels, a first channel and a second channel.

[0039] The HF coil may 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 to 1 m from the conductor connection, 0 to 0.5 m from the conductor connection, etc.). According to one embodiment, the HF heating coil may be positioned so as to be aligned with the conductor connection in the axial direction.

[0040] One embodiment includes performing steps a) to d) in each of a plurality of repair insulation system layers.

[0041] Alternatively, all repair insulation system layers may be provided around the conductor, steps a) to d) may be performed simultaneously, with step d) involving simultaneous heating of all repair insulation system layers.

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

[0043] According to one embodiment, external and internal heating are performed within a rare gas atmosphere inside the heating chamber. Thus, a rare gas can be introduced into the heating chamber, where heating can be performed within a rare gas atmosphere. The rare gas has a pressure in the range of 2 to 15 bar inside the pressurized heating device (e.g., 4 to 12 bar, 4 to 8 bar). This can eliminate or at least reduce oxidation of the insulating system layer under repair being heated within the pressurized heating device.

[0044] 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 a damaged insulation system, 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.

[0045] 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.

[0046] 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.

[0047] Instead of taping, a repair insulation system layer may be formed, for example, by injection molding.

[0048] 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 HF heating coil.

[0049] According to one embodiment, prior to step d), the repair insulation system layer is an uncured insulation system layer, and in step d), external heating and internal heating are for curing the repair insulation system layer.

[0050] 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.

[0051] 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]

[0052] [Figure 1] This is a schematic top view showing a pressurized heating device in the open state. [Figure 2] Figure 1 is a longitudinal cross-sectional view showing an embodiment of a heating assembly equipped with a pressurized heating device in a state where the insulation system layer for repairing a power cable is being heated. [Figure 3] This is a longitudinal cross-sectional view showing another embodiment of a pressurized heating device heating an insulating system layer for repairing a power cable. [Figure 4] This flowchart shows how to repair the insulation system of a power cable. [Modes for carrying out the invention]

[0053] 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.

[0054] Figure 1 schematically shows a top view of the pressurized heating device 1 in the open position. The pressurized heating device 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 repaired insulation system layer. The pressurized heating device 1 may be suitable for heating the repaired insulation system layer of a medium-voltage or high-voltage AC or DC power cable.

[0055] The pressurized heating device 1 comprises a first part 3 and a second part 5.

[0056] The first portion 3 has a first channel 3a extending from one end of the first portion 3 to the opposite end of the first portion 3. The first channel 3a is straight. The first channel 3a is configured to receive a power cable, including a power cable connector.

[0057] The second portion 5 has a second channel 5a extending from one end of the second portion 5 to the opposite end of the second portion 5. The second channel 5a is straight. The second channel 5a is configured to receive a power cable, including a power cable connector.

[0058] The first part 3 and the second part 5 are configured to be assembled together to set the pressurized heating device 1 in a closed state. Thus, the pressurized heating device 1 is openable and closedable.

[0059] The first part 3 and the second part 5 may be connected, for example, in a hinged manner, or the first part 3 and the second part 5 may be completely separable from each other.

[0060] In the closed state of the pressurized heating device 1, the first channel 3a faces the second channel 5a. The first channel 3a is aligned with the second channel 5a in the axial direction. Thus, the first channel 3a and the second channel 5a form a heating chamber that extends from the first end 4a of the pressurized heating device 1 to the second end 4b of the pressurized heating device 1 on the opposite side of the first end 4a. Thus, the heating chamber is configured to surround the power cable, including the power cable connector, in the circumferential direction along the length of the pressurized heating device 1.

[0061] The pressurized heating device 1 may, according to some embodiments, include a heating device 7 configured to heat the heating chamber to a predetermined temperature. According to 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. The heating device 7 may be configured to heat the heating chamber directly by means of a heating coil or similar means, for example, arranged around a first channel 3a and a second channel 5a.

[0062] Alternatively, the heating device may be located outside the pressurized heating device 1. In this case, the heating device may be configured to heat a gas, such as a noble gas, introduced into the heating chamber from the outside.

[0063] The pressurized heating device 1 has an axially extending section 9 made primarily of a material having a conductivity of up to 1000 S / m at 20°C. The axially extending section 9 is at least 20 cm long (at least 30 cm long, at least 40 cm long, etc.).

[0064] According to one embodiment, the axially extending section 9 may be the entire length of the pressurized heating device 1, that is, the entire length from the first end 4a to the second end 4b.

[0065] According to the examples, the material can have an electrical 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.).

[0066] The material may be, or may include, a glass fiber reinforced polymer or a carbon fiber reinforced polymer, such as glass fiber reinforced epoxy or glass fiber reinforced polyamide, or carbon fiber reinforced epoxy or carbon fiber reinforced polyamide.

[0067] Within an axially extending section 9 of the pressurized heating device 1, each of the first portion 3 and the second portion 5 has a wall 3b, of which at least 70% or at least 80% is made of a material having an conductivity of up to 1000 S / m at 20°C.

[0068] Figure 2 schematically shows a longitudinal cross-section of a heating assembly 10 that includes a pressurized heating device 1 equipped with a power cable 11, including the power cable connection part configured inside.

[0069] The power cable 11 comprises two cable length sections 11a and 11b that are in the process of being coupled inside the pressurized heating device 1. The pressurized heating device 1 is in a closed state, and the power cable 11 extends through the pressurized heating device 1 inside the heating chamber 13.

[0070] In the state shown in Figure 2, the conductors 15a and 15b of the two cable length sections 11a and 11b are joined together, thus creating a conductor joint 15c. The two conductors 15a and 15b form a single conductor.

[0071] The conductors 15a and 15b may be joined, for example, by welding, brazing, or by using a mechanical connector.

[0072] Each cable length section 11a, 11b has a cone-shaped insulation system 17a, 17b adjacent to the conductor coupling portion 15c. The region including the cone-shaped insulation systems 17a, 17b and the conductor coupling portion 15c constitutes the power cable coupling portion.

[0073] The heating assembly 10 comprises an induction heating device. The induction heating device comprises at least one HF heating coil 19a, 19b. At least one heating coil 19a, 19b is configured to be arranged around a section 9 that extends axially of the pressurized heating device 1. Thus, at least one heating coil 19a is configured to be arranged radially outward of the axially extending section 9.

[0074] In this embodiment, the heating assembly 10 comprises two HF heating coils 19a and 19b. Both HF heating coils 19a and 19b are configured to be axially separated around a section 9 that extends axially from the pressurized heating device 1. Alternatively, if the pressurized heating device comprises two axially extending sections, each HF heating coil may be configured to be arranged around an individual axially extending section.

[0075] The HF heating coils 19a and 19b can be configured to be arranged symmetrically on both sides of the conductor coupling portion 15c. Therefore, the HF heating coils 19a and 19b can be configured to be arranged at equal axial distances in their respective axial directions from the conductor coupling portion 15c. 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, 0.1 to 0.5 m from the conductor coupling portion 11c, etc.).

[0076] If only one HF heating coil 19a is used, the HF heating coil 19a may be positioned in the center above the conductor coupling portion 15c.

[0077] The induction heating device may include a power supply. At least one HF heating coil 19a, 19b is powered by the power supply. The power supply is configured to generate an alternating current in the kilohertz range.

[0078] The induction heating device may include a water cooling system configured to cool at least one HF heating coil.

[0079] At least one HF heating coil 19a, 19b may be one or more external HF heating coils, as shown in Figure 2. In this case, at least one HF heating coil 19a, 19b may be provided around the pressurized heating device 1 and may be detached from the pressurized heating device 1. Alternatively, at least one HF heating coil may be integrated with the pressurized heating device 1. In this case, the pressurized heating device 1 comprises at least one HF heating coil, as shown in Figure 3. The same considerations regarding the arrangement mentioned above may also apply to cases where the pressurized heating device 1 comprises one or two integrated HF heating coils.

[0080] Next, with reference to Figures 2 and 4, a method for repairing the insulation system around the conductors of a power cable will be described. In this embodiment, the repair of the insulation system involves curing the uncured insulation system layer at the power cable joint using a pressurized heating device 1 or heating assembly 10. This method can also be used to repair the insulation system of a damaged power cable without involving a joint.

[0081] The coupling insulation system, that is, the insulation system around the conductor coupling portion 15c and between the conical ends of the insulation systems 17a and 17b, is reconstructed layer by layer.

[0082] A first repair insulation system layer 21 is provided around the conductor joint 15c and is configured to overlap with the corresponding insulation layers of the insulation systems 17a and 17b at the conical ends of the insulation systems 17a and 17b.

[0083] An uncured repair insulation system layer 21 may be formed, for example, by tape wrapped around an exposed conductor.

[0084] In the heating process of the repair insulation system layer 21, in step a), a power cable coupling having a conductor, which includes a conductor coupling 15c and a repair insulation system layer 21 arranged around the conductor coupling 15c, is placed in one of the channels of the first channel 3 and the second channel 5.

[0085] In cases where the insulation system of a power cable that needs repair is being restored, a repair insulation system layer is provided around the conductor.

[0086] In step b), the pressurized heating device 1 is set to the closed state. Thus, the heating chamber 10 is formed around the power cable connection.

[0087] The pressurized heating device 1 may be equipped with a sealing member, such as a gasket, to seal the heating chamber 10 away from the power cable 11. The first part 3 and the second part 5 are also sealed to each other.

[0088] In step c), the heating chamber 13 is pressurized. The heating chamber 13 is pressurized to a pressure higher than atmospheric pressure. This pressure is one of several bar values ​​in the range of 4 bar to 15 bar (for example, 4 bar to 10 bar).

[0089] In conjunction with step c), during curing, the heating chamber 13 may be filled with a rare gas to prevent oxidation while rebuilding the insulating system on the conductive joint 15c. The rare gas reaches the pressure present inside the heating chamber 13.

[0090] In step d), the repair insulation system layer 21 is heated. This heating usually involves curing the repair insulation system layer 21, but in the case of a repair insulation system layer 21 made of a thermoplastic material, it may involve melting without curing.

[0091] This heating is achieved by external heating of the repair insulation system layer 21 inside the pressurized heating device 1, and by internal heating of the repair insulation system layer 21 by supplying current to at least one HF heating coil 19a, 19b, 19c configured to be arranged around the heating chamber 13 in an axially extending section 9 to induce current in the conductor.

[0092] At least one HF coil 19a, 19b may be openable or divisible into multiple parts to facilitate placement around the power cable 11, for example, before step d).

[0093] In cases where the pressurized heating device 1 comprises one or more sections made of a material having higher electrical conductivity than the axially extending section 9, at least one HF heating coil 19a, 19b, 19c is positioned around the axially extending section at an appropriate distance from the interface between the two materials.

[0094] In step d), external and internal heating are typically performed simultaneously.

[0095] Steps a) to d) are typically performed on each of the multiple repair insulation system layers at the power cable connection. After each iteration of the process, the heated insulation system layer is cooled to a predetermined temperature, such as 60°C or below.

[0096] 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 pressurized heating device (1) for repairing the insulation system of a power cable (11), wherein the pressurized heating device (1) A first part (3) having a first channel (3a) configured to receive a portion of the power cable (11), A second part (5) having a second channel (5a) configured to receive a portion of the power cable (11), Equipped with, The pressurized heating device (1) is configured to be set in a closed state such that the first channel (3a) faces the second channel (5a), thereby forming a heating chamber (13) that extends from the first end (4a) of the pressurized heating device (1) to the second end (4b) on the opposite side of the first end (4a). The pressurized heating device (1) is configured to pressurize the heating chamber (13) to achieve a pressure higher than atmospheric pressure when the power cable (11) is arranged in a sealed state within the heating chamber (13). The pressurized heating device (1) has an axially extending section (9) 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. When the pressurized heating device (1) is in the closed state, high-frequency HF heating coils (19a, 19b, 19c) extend around the heating chamber (13) within the axially extending section (9), The pressurized heating device (1) includes a heating device (7) configured to heat the heating chamber (13) to a predetermined temperature. Pressurized heating device (1).

2. The pressurized heating device (1) according to claim 1, wherein the material has an electrical conductivity of the order of 100 S / m at 20°C.

3. The pressurized heating device (1) according to claim 1 or 2, wherein the axially extending section (9) has a length of at least 30 cm.

4. The pressurized heating device (1) according to claim 1, wherein at least 70% of the axially extending section (9) is made of a material having an conductivity of up to 1000 S / m at 20°C.

5. The pressurized heating device (1) according to claim 4, wherein the material comprises a fiber-reinforced polymer.

6. The pressurized heating device (1) according to claim 1, wherein the high-frequency HF heating coil (19c) extends around the heating chamber (13) at a location within ±30% of the center of the pressurized heating device, as measured from the first end (4a) to the second end (4b).

7. The pressurized heating device (1) according to claim 6, wherein the range is ±10%.

8. A heating assembly (10) comprising a pressurized heating device (1) as described in claim 1, and at least one external HF heating coil (19a, 19b) configured to be arranged around the pressurized heating device (1) within an axially extending section (9).

9. A method for repairing the insulation system around a conductor of a power cable using the pressurized heating device (1) described in claim 1 or the heating assembly (10) described in claim 8, wherein the method is: a) The power cable having a repair insulation system layer (21) arranged around a conductor is placed in one of the channels, which is either the first channel (3a) or the second channel (5a). b) Setting the pressurized heating device (1) to a closed state, c) Pressurizing the heating chamber (13), d) Heating the repair insulation system layer (21) while the heating chamber is pressurized by external heating of the inside of the pressurized heating device (1), heating the heating chamber (13) to a predetermined temperature by the heating device (7), and internal heating of the repair insulation system layer (21) by supplying current to high-frequency HF heating coils (19a, 19b, 19c) configured to be arranged around the heating chamber (13) in a section (9) that extends axially to induce current in the conductor, and Methods that include...

10. The method according to claim 9, comprising performing steps a) to d) in each of a plurality of repair insulation system layers (21).

11. The method according to claim 9, wherein in step d), the external heating and the internal heating are performed simultaneously.

12. The method according to claim 9, wherein the external heating and the internal heating are carried out in a rare gas atmosphere inside the heating chamber (13).

13. The method according to claim 9, wherein, prior to step d), the repair insulating system layer (21) is an uncured insulating system layer (21), and in step d), the external heating and internal heating are for curing the repair insulating system layer (21).

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