Bushing for an electrical device, electrical device and method for manufacturing a bushing for an electrical device

Abstract

A bushing (1) for an electrical device (100) comprises an electrical conductor (2) and an insulator (5) surrounding the electrical conductor (2), wherein the insulator (5) comprises a first part (6) and a second part (7), wherein the first part (6) is configured to be at least partially positioned at an inner side of the electrical device (100), the second part (7) is configured to be positioned at an outer side of the electrical device (100), the first part (6) is of a single piece and an interface (10) between the first part (6) and the second part (7) is configured to be located at an outer side of the electrical device (100).

Description

[0001] P2024, 1101 WO N / P240208WO01 February 2, 2026

[0002] Description

[0003] BUSHING FOR AN ELECTRICAL DEVICE, ELECTRICAL DEVICE AND METHOD FOR MANUFACTURING A BUSHING FOR AN ELECTRICAL DEVICE

[0004] The present disclosure relates to a bushing for an electrical device. The electrical device may be a transformer, for example, a power transformer. The bushing may be a gas - or liquid- filled bushing. The bushing is configured to lead through a barrier of the electrical device, particularly a wall. The wall may be a tank wall. As an example, the bushing may be an oil - to-air, oil - to-gas, gas - to-air or air - to-air bushing.

[0005] In gas - filled bushings, leakages occurring inside an electrical device can cause unwanted alarms which may be caused by DGA (Dissolved Gas Analysis) of an insulating fluid in the device. Further, gas voids and partial discharge may occur in an insulating liquid of the electrical device, such as e.g. a transformer. In case of strong leakage, deformation due to high pressure may occur. In liquid- filled bushings, contamination of an insulating liquid and other internal parts of the device may occur.

[0006] EP 3 096 334 Bl discloses a liquid- filled bushing for a transformer, wherein the bushing comprises a shell for sealingly containing an insulating liquid, wherein the shell is molded as a single piece from an electrically insulating polymeric material.

[0007] EP 1 134 750 A2 discloses an insulating bushing of the capacitance graded type, wound with a continuous sheet of paper or plastic material and impregnated with liquid orP2024, 1101 WO N / P240208WO01 February 2, 2026

[0008] gaseous insulating fluid. The bushing comprises a monolithic external insulating body in the form of a glass fiber tube.

[0009] CN 201 522 911 U discloses a bushing comprising a conductor arranged inside two parts of the bushing, wherein the lower, oil - filled part of the bushing is attached to a high voltage transformer and wherein the upper, non-oil - filled part extends through a wall of a valve hall.

[0010] CN 115 136 259 A discloses a bushing comprising a capacitor core, which can be manufactured by casting resin around a thin-walled electrically insulating tube from glass - fiber or epoxy. US 11 146 053 B2 discloses an insulating bushing comprising a monolithic glass fiber tube extending along the entire length of the bushing.

[0011] Embodiments of the disclosure relate to an improved bushing for an electrical device and a method for manufacturing a bushing for an electrical device.

[0012] A bushing for an electrical device comprises an electrical conductor and an insulator surrounding the electrical conductor. The insulator comprises a first part and a second part, wherein the first part is configured to be at least partially positioned at an inner side of the electrical device and the second part is configured to be at an outer side of the electrical device. The first part is of a single piece and an interface between the first part and the second part is configured to be located at an outer side of the electrical device.

[0013] Alternatively, but not claimed, the insulator may be of a single piece.P2024, 1101 WO N / P240208WO01 February 2, 2026

[0014] The insulator may be configured for being in direct contact with air when installed.

[0015] It is also possible that the insulator is covered by a further insulation, such as a polymeric and / or elastomeric insulation, that is in direct contact with air. The further insulation may comprise sheds. In case of an insulator with a first part and a second part, the further insulation may cover the second part and parts of the first part which are located in the outer side of an electric device, in particular in air.

[0016] The bushing may be configured to lead through a wall of the electrical device. The wall may be grounded, wherein the conductor is electrically insulated from the wall by the insulator and additional internal insulations if applicable. The insulator may have an elongated shape, extending along a longitudinal axis, wherein the conductor extends centrally through the insulator, along the longitudinal axis. The insulator may have a tubular shape.

[0017] The electrical device may be a transformer, for example, a power transformer. The electrical device may alternatively be another high-voltage device, such as a switchgear or circuit breaker. The electrical device may be filled with an insulating fluid, for example, an insulating oil. In this case, the first part of the insulator is at least partially located within the insulating fluid. An electrical component which is to be electrically contacted by the bushing can be immersed in the insulating fluid.

[0018] The bushing may be filled or configured to be filled with a fluid. In this case, the insulator is configured forP2024, 1101 WO N / P240208WO01 February 2, 2026

[0019] 4

[0020] providing a sealing for the fluid. The fluid may be a gas or a liquid, for example. The fluid may serve to provide electrical insulation and / or dissipates heat generated during operation. The conductor may be surrounded by a condenser core. The condenser core may be a graded condenser core to distribute the electric field and voltage gradient to prevent electrical field concentrations. Insulating papers of the graded condenser core may be impregnated by the fluid.

[0021] Positioning the interface at a side of the bushing which is configured to be located at an outer side of the device, particularly in air, reduces the risk of leakage of the fluid of the bushing inside the device. Such leakage may lead to a contamination of the device, a deterioration of an insulating fluid and / or to unwanted alarms. Furthermore, gas voids and partial discharge may occur. A leakage may also be detrimental for a dry- type device, such as a dry- type transformer, as it leads to contamination of internal parts of the device or deformation due to high pressure. Compared to that, a leakage at an outer side of the device is not as critical as a leakage to the inner side of the device.

[0022] An insulator configured as a single piece as well reduces the risk of leakage, because interfaces are not present in the insulator.

[0023] The interface may be formed by a connection of connection elements at the end of the first part and the second part, respectively. Thereby, a modular design is provided, and the insulator is easy to assemble. The connection elements can be fixed to each other by clamping or via fixing parts. They can be glued to the insulator, particularly in case of a glass -fiber insulator covered with epoxy, or cemented, particularly in the case of a porcelain insulator.P2024, 1101 WO N / P240208WO01 February 2, 2026

[0024] - 5 -

[0025] A modular design with two parts enables using the f irst part or the second part with different other parts and designs, allowing mixing and matching different parts. This enables using the parts for specific designs and / or voltage classes, for example.

[0026] The insulator may comprise or consist of fiberglass or porcelain. In case of an insulator comprising a first part and a second part, at least the first part may comprise or consist of fiberglass or porcelain. The fiberglass or porcelain insulator may be covered by a further insulation. The further insulation may be a polymeric and / or elastomeric insulation, e.g. comprising or consisting of silicone or epoxy. The further insulation may comprise sheds.

[0027] Fiberglass and porcelain have a high chemical resistance to an insulating oil or other chemicals used in electrical devices, such as transformers. Furthermore, such materials have a high dielectric strength, a high mechanical strength and high thermal stability. Using such a material has the advantage that the bushing is compatible with different fluids.

[0028] It is also possible that the insulator comprises or consists of epoxy, in particular epoxy cast. In this case, sheds may be integrally formed with the insulator. When using epoxy, particularly epoxy cast, the bushing may be suitable for a limited range of voltage levels.

[0029] The second part may comprise the same material as the first part. As an example, both the second part or the first part may comprise or consist of fiberglass or porcelain. It is also possible that the first part and the second partP2024, 1101 WO N / P240208WO01 February 2, 2026

[0030] comprises epoxy. It is also possible that the second part comprises a different material than the first part. As an example, the second part may comprise or consist of epoxy while the first part comprises or consists of fiberglass or porcelain or vice versa. In an embodiment with a first part and a second part, the second part is located entirely at an outer side of the device, due to the interface between the first part and the second part being located at an outer side. Therefore, the requirements regarding the chemical resistance are less than for the first part. The material of the second part may be optimized for positioning in air and may be such that additional shapes, such as sheds, may be integrated in the second part.

[0031] The bushing may comprise a flange for mounting at a wall of the device. The flange marks the boundary of the outer side, particularly an air- side, and an inner side, for example, an oil - side of the bushing. The flange may be configured to be fastened to a wall of the device by bolts or screws, for example. The flange may be secured at the insulator. As an example, the flange may be secured by gluing.

[0032] The bushing may comprise a test tap for monitoring and testing electrical properties of the bushing. The test tap may be electrically connected to a graded condenser core, particularly to an outer foil of the graded condenser core. The test tap extends from outside the bushing to an inner side of the bushing.

[0033] The test tap may be located at a position of the bushing which is configured to be positioned at an outer side of the device. In this case, potential leakage through a hole to the inside of the device is prevented.P2024, 1101 WO N / P240208WO01 February 2, 2026

[0034] As an example, the test tap may extend through a hole in the insulator. In an embodiment with a first part and a second part, the test tap may extend through a hole in the first part of the insulator or through a hole in the second part of the insulator or through connection elements at the interface of the parts. The test tap may be located at a position between the interface and the flange, wherein "between" also includes the interface and the flange itself. The test tap may lead through one of the connection elements of the interface. The connection elements may comprise a metal. In this case, forming a hole in the insulating material may not be required in case that the connection elements are formed as an axial extension of the respective parts.

[0035] An electrical device comprises the bushing as described in the forgoing. The electrical device may be a high-voltage device, such as a transformer, circuit breaker or switchgear. The electrical device comprises a wall, wherein the bushing leads through the wall. The wall may comprise a metal. The wall may be grounded. The device may be filled with an insulating liquid, such as an insulating oil or gas. The wall may be a wall of a tank being filled with the insulating liquid.

[0036] The invention also relates to a method for manufacturing a bushing configured to lead through a wall of an electrical device comprises. The bushing may be the bushing described in the foregoing. The bushing comprises a first part and a second part, wherein the first part is configured to be at least partially positioned at an inner side of the electrical device and wherein the second part is configured to be positioned at an outer side of the device. The method comprises providing the insulator and fixing a flange to theP2024, 1101 WO N / P240208WO01 February 2, 2026

[0037] 8

[0038] insulator at an axial position, wherein the axial position is variable.

[0039] Alternatively, but not claimed, the bushing comprises an insulator which is of a single piece.

[0040] The method may comprise the step of selecting the axial position such that a current transformer of a selected length can be accommodated at the side of the insulator which is configured to be at an inner side of the electrical device. Accordingly, the current transformer is positioned between the flange and an internal terminal of the bushing.

[0041] A method of assembling a bushing with an electrical device comprises conducting the method as described in the foregoing, and the further steps of installing the bushing at a wall of the device and positioning a current transformer at the insulator at an inner side of the device.

[0042] The present disclosure comprises several aspects and embodiments. Every feature described with respect to one of the aspects and embodiments is also disclosed herein with respect to the other aspects and embodiments, even if the respective feature is not explicitly mentioned in this context.

[0043] Further features, refinements and expediencies become apparent from the following description of the exemplary embodiments in connection with the figures. In the figures, elements of the same structure and / or functionality may be referenced by the same reference signs. It is to be understood that the embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale.P2024, 1101 WO N / P240208WO01 February 2, 2026

[0044] Figure 1A shows an embodiment of a bushing in a longitudinal sectional view,

[0045] Figure 1B shows the bushing of Fig. 1A in a perspective view,

[0046] Figure 1C shows the bushing of Fig. 1A in a view on the top,

[0047] Figure 2A shows a further example of a bushing in a longitudinal sectional view,

[0048] Figure 2B shows the bushing of Fig. 2A in a perspective view,

[0049] Figure 2C shows the bushing of Fig. 2A in a view on the top,

[0050] Figure 3 shows an embodiment of a transformer with an installed bushing in a conceptional view,

[0051] Figures 4A, 4B and 5A, 5B show an embodiment of a method for manufacturing a bushing in a diagrammatic view.

[0052] Fig. 1A shows an embodiment of a bushing 1 in a longitudinal sectional view. Fig. 1B shows the bushing 1 in a perspective view and Fig. 1C shows the bushing 1 in a cross - sectional view.

[0053] The bushing 1 is configured for installation in the wall of an electric device. The device may be a transformer, particularly a high-voltage transformer. The bushing 1 may also be suitable for electric connection to another electrical device, particularly a high-voltage device. The wall may form a part of an outer housing of the device, wherein one side faces air, which is called air- side or outer side in the following and the opposite side faces an inner side of the device, which is called oil - side or inner side in the following.P2024, 1101 WO N / P240208WO01 February 2, 2026

[0054] 10

[0055] The electrical device can be filled with an insulating fluid, such as oil or an insulating gas. In such devices, an electrical component, such as windings of a transformer, are immersed in the insulating fluid. The outer housing of the device can be a sealed tank that houses the insulating fluid. Alternatively, the bushing 1 can also be used with a dry- type electrical device.

[0056] The bushing 1 serves to provide an electric connection for an electrical component of the device, such as a winding of a transformer, to external electrical lines, such as overhead or underground lines or other components in a power grid. The bushing 1 provides the electric path through the wall, which is usually grounded, the bushing 1 providing suitable electric insulation from the wall.

[0057] The bushing 1 comprises a conductor 2 with an internal terminal 3 at one end for location at an inner side of an electrical device, particularly within an outer housing, and an external terminal 4 at the opposite end for location at an outer side of the device, in particular outside an outer housing, outdoor in air. The terminals 3, 4 may be integral with the conductor 2 or parts connected to the ends of the conductor 2.

[0058] The bushing 1 comprises an insulator 5, wherein the insulator 5 comprises a first part 6 and a second part 7. The first part 6 is configured to be positioned at an inner side of the electrical device 100, particularly immersed in the insulating fluid. The outer surface of the first part 6 may be in direct contact with an insulating fluid in the electrical device. The outer surface of the second part 7 may be in direct contact with air. It is also possible that theP2024, 1101 WO N / P240208WO01 February 2, 2026

[0059] second part 7 is covered by a further insulation (see Fig.3), such as silicone or epoxy, that is in direct contact withair. The further insulation may comprise sheds. As an example, a composite insulator may be formed from fiberglass covered with a polymer and / or elastomer, such as a silicone elastomer. Sheds may be provided on the outer surface of the composite tube.

[0060] The second part 7 is configured to be located at an outer side of the device, particularly in air. The first part 6 is next to the internal terminal 3 and the second part is next 7 to the external terminal 4. Both parts 5, 6 comprise the shape of a tube, extending along an axial direction. The first part 6 may comprise the shape of a cone.

[0061] The first part 6 may comprise or consist of fiberglass or porcelain as a material. Such materials have a high chemical resistance to an insulating oil or other chemicals inside an electrical device. Furthermore, such materials have a high dielectric strength, a high mechanical strength and high thermal stability. The second part 7 may comprise or consist of fiberglass or porcelain. The second part 7 may be covered by a further insulation (see Fig. 3), such as a silicone layer. The further insulation may comprise sheds. It is also possible that the second part 7 comprises or consists of a different material than the first part 6. The second part 7 may not comprise fiberglass or porcelain. As an example, the second part 7 may comprise epoxy as a material. It is also possible that the first part 6 comprises epoxy. In this case, the second part 7 may also comprise epoxy or a different material, such as fiberglass or porcelain.P2024, 1101 WO N / P240208WO01 February 2, 2026

[0062] - 12 -

[0063] The insulator 5 provides sealing of the bushing 1. The bushing 1 may be filled or configured to be filled with a fluid 8, such as oil or gas. The fluid serves to provide electrical insulation and / or dissipates heat generated during operation. The fluid 8 may be provided in a space between the conductor 2 and the insulator 5. The bushing 1 may comprise a graded condenser core 9, wherein insulating papers of the graded condenser core 9 may be impregnated with the fluid 8. Furthermore, a free space between the condenser core 9 and the insulator 5 and towards the internal terminal 3 and the external terminal 4 may be filled with the fluid 8. It is also possible that the bushing 1 does not comprise a condenser core 9 and the fluid fills the entire space between the conductor 2 and the insulator 5. It is further possible that the conductor 2 is not surrounded by condenser core 9 but by a solid insulation layer.

[0064] The bushing 1 may be sealed at the inner side by a bottom flange 15 and at the outer side by a top flange 16. The bottom flange 15 and the top flange 16 may be of metal.

[0065] The insulator 5 ensures that the fluid 8 remains contained inside the bushing 1 and prevents a leakage. Prevention of a leakage inside the electrical device is of particular importance, as leakage may lead to contamination of an insulating fluid in the device, leading to a deterioration of the insulating fluid and / or to unwanted alarms of a dissolved gas analysis. Furthermore, gas voids and partial discharge may occur. A leakage may also be detrimental for a dry- type device as it leads to contamination of internal parts of the device or deformation due to high pressure. Compared to that, a leakage at an outer side of the device is not as critical as a leakage at an inner side of the device.P2024, 1101 WO N / P240208WO01 February 2, 2026

[0066] - 13 -

[0067] For ensuring sealing inside the electrical device and minimizing the risk for leakage and contamination of the inside of the transformer, e. g. of a transformer oil, with media from inside the bushing 1, the insulator 5 does not comprise an interface at an inner side except from the interface at the end of the insulator 5 with the bottom flange 15.

[0068] The first part 6 is of a single piece and is configured to extend to an outer side. Accordingly, an interface 10 to the second part 7, where the first part 6 is connected to the second part 7 is configured to be located at an outer side of the device, particularly outside a tank filled with an insulation fluid. For connection of the first part 6 to the second part 7, the bushing 1 comprises connection elements 11, 12, sealingly connected to each other. The connection elements 11, 12 are shaped as flanges. The connection elements 11, 12 may comprise a metal.

[0069] It is also possible that the insulator 5 comprises more than two parts. However, also in this case, the first part 6 is of a single piece and extends to the outer side. The second part 7 may comprise more than one piece.

[0070] The bushing 1 comprises a flange 13 configured for installation at a wall of an electrical device at the outer side. Accordingly, the flange 13 may abut a wall of the device at the outer side of the wall. The flange 13 may be fixed to the wall by bolts or screws, for example. The flange 13 is fixed to the first part 6 of the insulator 5. The flange 13 may be fixed to the insulator 5 by gluing, for example. In case of a composite insulator, such as anP2024, 1101 WO N / P240208WO01 February 2, 2026

[0071] - 14 -

[0072] insulator 5 formed as a fiberglass tube covered externally by a silicone layer with sheds, the silicone layer may be not present at the location of the flange 13 and the flange 13 may be directly fixed to the insulator 5.

[0073] The flange 13 may comprise or consist of a metal, for example. The flange 13 marks the separation of the outer side and the inner side of the bushing 1. The interface 10 is located at a position towards the external terminal 4 when seen from the flange 13, i. e. at the outer side of the bushing 1.

[0074] When the bushing 1 comprises a graded condenser core 9, the bushing 1 may comprise a test tap 14 for monitoring and testing of the electrical properties. The test tap 14 is connected to the ground foil of the graded condenser core 9. The test tap 14 is positioned at the outer side of the bushing 1. In the shown embodiment, the test tap 14 is positioned in an axial extension of the flange 13 at the outer side of the bushing 1. At this position, the insulator 5 has a hole, through which the test tap 14 passes. Due to the position of the test tap 14 at the outer side, the hole does not lead to a risk of leakage inside the transformer.

[0075] In the shown embodiment the test tap 14 is located at a position below the interface 10, i. e. when seen from the interface 10 in a direction towards the flange 13.

[0076] Accordingly, the hole is provided in the first part 6 of the insulation 5 but at the air- side of the bushing 1.

[0077] It is also possible that the test tap 14 leads through one of the connection elements 11, 12 at the ends of the first part 6 and second part 7, respectively. As an example, the testP2024, 1101 WO N / P240208WO01 February 2, 2026

[0078] - 15 -

[0079] tap 14 may lead through the connection element 11 of the first part 6. In the shown embodiment, the test tap 14 also in this case leads through a hole in the first part 6 of the insulator 5. However, it is also possible that the outer insulation 5 is not present along the entire axial length of the connection elements 11, 12, for example, if the connection elements 11, 12 comprise a sleeve shaped portion connected to ends of the first and second parts 6, 7. In this case, a hole for the test tap 14 may be provided only in the connection element 11 or 12.

[0080] The position at which the flange 13 is secured to the first part 6 of the insulator 5 of the bushing 1 determines the length of the air- side and the length of the device - side of the bushing 1. As long as the first part 6 extends into the air- side, the mounting position of the flange 13 can be chosen such that desired lengths of the air- side and deviceside can be chosen. As an example, the device- side length can be chosen in accordance with a length of a current transformer (CT). A CT may be located outside the bushing 1 or inside the bushing 1. By adjusting the position, different CT lengths can be accommodated. In particular, for longer CTs, the flange 13 will be mounted such that the device- side of the bushing 1 is longer and the air- side is shorter than for shorter CTs.

[0081] Fig. 2A shows a further example of a bushing 1 in a longitudinal sectional view. Fig. 2B shows the bushing 1 in a perspective view and Fig. 2C shows the bushing 1 in a view on the top.

[0082] The bushing 1 distinguishes from the bushing 1 of Fig. 1A in that the insulator 5 is formed as a single piece.P2024, 1101 WO N / P240208WO01 February 2, 2026

[0083] - 16 -

[0084] Accordingly, the bushing 1 does not comprise any interface between parts of the insulator 5. The insulator 5 extends axially between an internal terminal 3 and an external terminal 4. A bottom flange 15 is fixed to a first end of the insulator 5 and a top flange 16 is fixed to the opposite end of the insulator 5.

[0085] The insulator 5 may comprise porcelain or fiberglass as a material, i. e. the materials disclosed for the first part 6 of the embodiment of Fig. 1A. A test tap 14 can be located at an extension of the flange 13 or at any position at the airside of the bushing 1. The test tap 14 leads through a hole in the insulator 5.

[0086] The further features of the bushing 1 are the same as described for the embodiment of Fig. 1A.

[0087] Figure 3 shows an electrical device 100 with an installed bushing 1. The device 100 may be a transformer. The bushing 1 may be the bushing 1 as described in the embodiments of Figs.

[0088] 1A- 1C or 2A- 2C.

[0089] The bushing 1 may be filled by a fluid. The bushing 1 may comprise an insulator 5 with a first part 6 and a second part 7, wherein the first part 6 is positioned at an inner side (device - side) and the second part 7 is positioned at an outer side (air- side) of the device 100. The first part 6 extends from the device- side to the air- side. An interface between the first part 6 and the second part 7 is located in the airside. The bushing 1 is free from an interface between different parts of the insulator 5 in the device- side.

[0090] Thereby, leakage of a fluid into the electrical device 100 can be prevented.P2024, 1101 WO N / P240208WO01 February 2, 2026

[0091] - 17 -

[0092] Alternatively, but not claimed, the insulator 5 of the bushing may be a single piece, extending along the conductor at the device- side and the air- side. The insulator 5 does not comprise any interfaces between different insulating parts. Accordingly, the insulator 5 extends as a single piece from an external end of the bushing to an internal end of the bushing and may be connected at the ends to a top flange and a bottom flange.

[0093] The bushing 1 passes through the wall 101 of the electrical device 100 and electrically contacts an electrical component 102, such as a transformer winding. The electrical component 102 is immersed in an insulating fluid 103, such as oil. In this case, the wall 101 is a wall of a tank 104 filled with the insulating fluid 103.

[0094] The bushing 1 may be used to electrically contact a different electrical device than a transformer, particularly a high-voltage device. For example, the bushing 1 could be utilized with a circuit breaker or a switchgear. It is also possibly the device 100 is a dry- type device.

[0095] The insulator 5 is covered by a further insulation 18 comprising sheds. The further insulation 18 may cover the insulator 5 at the air- side, in particular the second part 7 and the parts of the first part 6 that are located between the flange 13 and the second part 7 in the air- side. The further insulation may be a polymeric and / or elastomeric insulation, e.g. comprising or consisting of silicone or epoxy. The shown further insulation 18 may be present in all embodiments.P2024, 1101 WO N / P240208WO01 February 2, 2026

[0096] Figs. 4A, 4B and Figs. 5A, 5B show steps of a method for manufacturing a bushing. The bushing may be the bushing of any of the foregoing embodiments.

[0097] Figs. 4A and 5A show the step of providing an insulator 5 of the bushing. The insulator 5 may comprise a first part 6 and a second part 7 with an interface 10 between the parts 6, 7. The insulator 5 and the bushing 1 may have some or all features of the first embodiment as shown in Figs. 1A- 1C.

[0098] It is also possible, but not claimed, that the insulator 5 is from a single piece such that an interface is not present. The insulator 5 and the bushing 1 may have some or all features of the first embodiment as shown in Figs. 2A- 2C.

[0099] Figs 4A and 5B show the step of securing a flange 13 to the insulator 5. The axial position of the flange 13 is adjustable and can be chosen such that a current transformer (CT) 17 of a desired length can be positioned at the deviceside of the bushing. In case of a shorter CT 17 as shown in Fig. 4B, the flange 13 is positioned such that the length of the device- side is shorter than in case of a longer CT 17 as shown in Fig. 5B.

[0100] The internal parts of the bushing can be assembled in the insulator 5 before or after mounting the flange 13. Bottom and top flanges can be assembled with the insulator 5 before or after mounting the flange 13 as well. The CT 17 can be installed at the bushing 1 when installing the bushing 1 at the transformer 100.P2024, 1101 WO N / P240208WO01 February 2, 2026

[0101] 19

[0102] Reference Signs

[0103] 1 bushing

[0104] 2 conductor

[0105] 3 internal terminal

[0106] 4 external terminal

[0107] 5 insulator

[0108] 6 first part

[0109] 7 second part

[0110] 8 fluid (in bushing)

[0111] 9 condenser core

[0112] 10 interface

[0113] 11 first connection element 12 second connection element 13 flange

[0114] 14 test tap

[0115] 15 bottom flange

[0116] 16 top flange

[0117] 17 current transformer

[0118] 18 further insulation

[0119] 100 electrical device

[0120] 101 wall

[0121] 102 transformer winding

[0122] 103 insulating fluid

[0123] 104 tank

Claims

P2024, 1101 WO N / P240208WO01 February 2, 202620Claims1. A bushing (1) for an electrical device (100), comprising an electrical conductor (2) and an insulator (5) surrounding the electrical conductor (2),wherein the insulator (5) comprises a first part (6 ) and a second part (7), wherein the first part (6) is configured to be at least partially positioned at an inner side of the electrical device (100), the second part (7) is configured to be positioned at an outer side of the electrical device (100), the first part (6) is of a single piece and an interface (10) between the first part (6) and the second part (7) is configured to be located at an outer side of the electrical device (100),wherein the bushing is filled or configured to be filled with a fluid (8), wherein the fluid is provided in a space between the conductor (2) and the insulator (5), both in the first part (6) and the second part (7) of the insulator (5).

2. The bushing (1) of claim 1,wherein the insulator (5), wherein the first part ( 6) is configured to be at least partially located in an insulating fluid (103 ) of the device (100).

3. The bushing (1) of any of the preceding claims, wherein the insulator (5) comprises fiberglass and / or porcelain.

4. The bushing (1) of any of the preceding claims, wherein the first part (6) comprises the same material as the second part ( 7 ).

5. The bushing (1) of any of claims 1 to 3,P2024, 1101 WO N / P240208WO01 February 2, 2026wherein the first part (6) comprises a different material than the second part (7).

6. The bushing (1) of any of the preceding claims, comprising a flange (13 ) for mounting at a wall (101) of the device (100), wherein the flange (13 ) is secured to the insulator ( 5 ).

7. The bushing (1) of any of the preceding claims, comprising a test tap (14) for monitoring and testing electrical properties of the bushing (1).

8. The bushing (1) of claim 7,comprising a graded condenser core (9 ), wherein the test tap (14) is connected to the graded condenser core (9 ).

9. The bushing (1) of any of claims 7 or 8,wherein the test tap (14) is located at a position of the bushing (1) which is configured to be positioned at an outer side of the device (100).

10. The bushing (1) of claim 9,wherein the test tap (14) is located between the interface (10) and the flange (13 ), including the interface ( 10) and the flange ( 13 ).

11. The bushing (1) of claim 10,wherein the interface (10) is formed by a connection of connection elements (11, 12) at ends of the first part (6) and the second part (7), wherein the test tap (14) leads through one of the connection elements (11, 12).P2024, 1101 WO N / P240208WO01 February 2, 2026- 22 -12. An electrical device (100) comprising the bushing (1) of any of the preceding claims,the device (100) comprising a wall (101), wherein the bushing (1) leads through the wall (101).

13. A method for manufacturing a bushing (1),wherein the bushing (1) comprises an electrical conductor (2) and an insulator (5) surrounding the electrical conductor (2),wherein the insulator (5) comprises a first part (6 ) and a second part (7), wherein the first part (6) is configured to be at least partially positioned at an inner side of the electrical device (100), the second part (7) is configured to be positioned at an outer side of the electrical device (100), the first part (6) is of a single piece and an interface (10) between the first part (6) and the second part (7) is configured to be located at an outer side of the electrical device (100),wherein the method comprises the steps of providing the insulator (5) and providing a flange (13 ) and fixing the flange (13 ) to the insulator (5) at an axial position, wherein the axial position is variable,wherein the bushing is filled or configured to be filled with a fluid (8), wherein the fluid is provided in a space between the conductor (2) and the insulator (5), both in the first part (6) and the second part (7) of the insulator (5).

14. The method of claim 13,comprising the step of selecting the axial position such that a current transformer (17) of a selected length can be accommodated at the side of the insulator (5) which is configured to be located at an inner side of the electrical device (100).

Images