Gas-insulated electrical equipment

Abstract

The present invention relates to a gas-insulated electrical device (1) comprising an enclosure (2), electrical high voltage equipment (3) arranged inside the enclosure (2), and a permeable barrier (5) arranged within the enclosure (2) and circumferentially surrounding the electrical high voltage equipment (3), wherein the enclosure (2) contains an insulating gas (4) comprising at least 70% by volume of CO2 and an elevated predetermined operating gas pressure level, and the permeable barrier (5) comprises a permeable layer (6) surrounded on at least one side by a flow promoting layer (7) and / or a surface activation and / or primer layer (8).

Description

[Technical Field]

[0001] explanation Technical Field The present invention relates to a gas-insulated electrical apparatus comprising an enclosure, electrical high-voltage equipment disposed inside the enclosure, and a permeation barrier disposed within the enclosure and circumferentially surrounding the electrical high-voltage equipment, the enclosure containing an insulating gas comprising at least 70% by volume of CO2 and having an elevated predetermined operating gas pressure level. The present invention further relates to a method of manufacturing a gas-insulated electrical apparatus comprising electrical high-voltage equipment, the method comprising the steps of manufacturing an enclosure for disposing the electrical high-voltage equipment therein. [Background technology]

[0002] Background technology In gas-insulated electrical equipment, such as medium- and high-voltage switchgear or control gear, the electrically active parts are arranged in a gas-tight enclosure or housing. The enclosure or housing defines an insulating space arranged to contain an insulating gas at high pressure, which may be several bar. The insulating space separates the enclosure from the electrically active parts without allowing current to pass through it.

[0003] Insulating gases act as an electrical insulating medium, preventing electrical discharges between the enclosure and the electrical components within. They also act as a cooling medium to suppress temperature rises due to electrical currents. In switchgear, typically comprising circuit breakers and / or disconnectors, insulating gases also act as an arc-extinguishing medium to extinguish arcs that may occur during switching operations. Traditionally, sulfur hexafluoride (SF6) or SF6 gas has been widely used as an insulating gas. However, given the known environmental disadvantages of SF6, the use of other insulating gases, such as carbon dioxide (CO2) or other gases containing CO2, has been proposed.

[0004] Typically, gas-insulated electrical equipment enclosures are filled with insulating gas to a predetermined rated operating gas pressure level before being put into service. The predetermined pressure level can be selected depending on the insulating gas, the switched current / voltage, and / or the switching capacity of the electrical equipment. The pressure level is measured continuously or at predetermined intervals during operation.

[0005] If the gas pressure level falls below a predetermined minimum allowable pressure level, also known as the alarm level, an alarm is generated to the operator. If an alarm is generated, the enclosure must be filled with insulating gas to the predetermined operating gas pressure level. If the enclosure is not refilled, the insulating gas pressure will continue to decrease, resulting in the risk of operational failure.

[0006] Typically, electrical equipment has a predetermined shutoff pressure level, also known as a lockout gas pressure level, and when this level is reached, the gas-insulated electrical equipment is shut off and its function is halted. When the gas-insulated electrical equipment is a switchgear, it is usually configured to react in one of two ways: either the gas-insulated electrical equipment is shut off so that the electrical contacts of the switchgear cannot be opened or closed, or the electrical contacts are forced open and remain open.

[0007] Replenishing and monitoring alarms on electrical equipment is a time-consuming and labor-intensive task, so it is necessary to effectively prevent interruptions to the operation of gas-insulated electrical equipment while reducing the need for maintenance. Summary of the Invention [Problem to be solved by the invention]

[0008] Summary of the Invention The object of the present invention is therefore to maintain as best as possible the properties of the insulating material of the enclosure in order to avoid CO2 leakage. [Means for solving the problem]

[0009] The object of the present invention is solved by the features of the independent claims. Preferred embodiments are detailed in the dependent claims.

[0010] This object is therefore solved by a gas-insulated electrical apparatus comprising an enclosure, an electrical high-voltage equipment arranged inside the enclosure, and a permeation barrier arranged inside the enclosure and circumferentially surrounding the electrical high-voltage equipment, the enclosure contains an insulating gas containing at least 70% by volume of CO2 and having an elevated predetermined operating gas pressure level; The permeation barrier comprises a permeation layer surrounded on at least one side by a flow promoting layer and / or a surface activated and / or primer layer.

[0011] To reduce the global warming potential (GWP), alternative insulating gas mixtures other than SF6 are used, containing molecules such as CO2 with smaller kinetic diameters and / or higher solubility in the respective materials of enclosures made of epoxy-based composites, particularly as insulators. Tests have demonstrated that CO2 alternative insulating gas mixtures penetrate such epoxy-based enclosures at high speeds, resulting in significant pressure drops and ultimately reducing the dielectric and / or current switching behavior of gas-insulated electrical equipment in enclosures made of epoxy-based composites. Furthermore, H2O can penetrate the insulating space defined by the enclosure, potentially leading directly or indirectly to decomposition of the insulating gas, corrosion of components inside gas-insulated electrical equipment, such as electrical high-voltage equipment, or a reduction in the enclosure's dielectric strength.

[0012] Therefore, a key feature of the present invention is the provision of a layer of low-permeability material (LPM) with a very low permeability coefficient, particularly for CO2, as the permeation barrier. To facilitate simple implementation, for example by using wide strips or sheets as the permeation barrier, the described solution proposes providing a flow-promoting layer and / or a surface-activating and / or primer layer on at least one side of the permeation layer. In this way, bubbles and / or cracks that could potentially lead to the failure of the respective epoxy-based composite insulator enclosure under dielectric or environmental stress can be effectively avoided, while simplifying the fabrication of the permeation barrier and thus enabling cost-effective production of gas-insulated electrical equipment. Furthermore, the proposed solution avoids permeation through the respective epoxy-based composite insulator enclosure, avoiding pressure drops within the enclosure and resulting in stable and reliable dielectric and / or current switching behavior.

[0013] The enclosure preferably has a tubular or conical-tubular shape and / or is preferably hermetically sealed. Thus, the insulating gas preferably completely surrounds the electrical high-voltage equipment. The permeation barrier disposed within the enclosure means, in particular, that the permeation barrier is enclosed within the enclosure and is therefore, for example, invisible from the outside or inside of the enclosure. The enclosure may be filled with CO2 as the insulating gas at a volume of at least 70% but may also be completely filled with CO2. The remaining portion of the insulating gas, up to 100% by volume, may contain oxygen O2 or another gas, for example, to an extent of less than 30% by volume. Preferably, the operating gas pressure level is from 1.0 MPa to 1.2 MPa.

[0014] The permeation barrier preferably extends across the entire lateral inner surface of the enclosure. Furthermore, the permeation layer is preferably surrounded by a flow promoting layer and / or a surface activation and / or primer layer over its entire surface or at least a partial surface. This allows the flow promoting layer and / or the surface activation and / or primer layer to be provided on one side of the permeation layer or on both sides of the permeation layer. The enclosure can be sealed with one or more sealants, for example, made of various types of polymeric materials, such as, but not limited to, NBR or EPDM rubber.

[0015] In a preferred embodiment, the permeation layer comprises ethylene vinyl alcohol (EVOH) and / or aluminum oxide foil. Therefore, EVOH provides a barrier not only to CO2 but also to oxygen or hydrocarbons. EVOH is advantageous in that it is highly permeable, weather-resistant, oil- and solvent-resistant, flexible, moldable, recyclable, and printable. EVOH can be applied by coextrusion or lamination. The permeation layer can have a thickness of 0.0001, 0.0005, 0.001, 0.01, 0.1, 0.5, 1, 2, 5, or 10 mm. The aluminum oxide foil can have a thickness of 0.016 mm or 0.024 mm. Additionally, other materials can be used to mitigate insulation gas permeation. Surface activation can result from plasma and / or chemical treatment and / or chemical bonding of the permeation layer. Any suitable material can be used as a primer to prime the enclosure and permeation layer.

[0016] In a further preferred embodiment, the permeation layer, flow promoting layer, and / or surface activation and / or primer layer are provided as sheets and / or strips, preferably as overlapping wrap strips, preferably overlapping axially and / or circumferentially. The strips can be provided as wide strips. Preferably, the sheets and / or strips overlap over the complete axial and / or circumferential extension of the respective layers. In the circumferential extension, the sheets and / or strips may be gapless, gapless, or overlapping.

[0017] In another embodiment, the gas-insulated electrical equipment includes a flow-promoting layer, the flow-promoting layer including fleece and / or mesh. The fleece and / or mesh may include polyester, aramid, synthetic fibers, woven fibers, and / or any mixture thereof. Additional materials may include nylon, Kevlar, Nomex, Trogamid, and polyamides, such as combinations of polyester, polyamide, or polypropylene. The flow-promoting layer may include a thickness of 0.1, 0.3, 0.5, 1, or 2 mm.

[0018] In a further preferred embodiment, the permeation barrier is located within the enclosure, adjacent to the inside of the enclosure and / or closer to the inside than to the outside of the enclosure. Having the permeation barrier closer to the inside has the advantage that there is very little radial material within the enclosure to saturate the insulating gas within the enclosure. Therefore, the permeation barrier is preferably located as close as possible to the inside of the enclosure.

[0019] According to a further preferred embodiment, the gas-insulated electrical equipment comprises a plurality of permeation barriers arranged in the enclosure, particularly spaced apart from one another. Having a plurality of permeation barriers and / or permeation barriers with a greater thickness results in a lower permeation. Therefore, a limit on the thickness of the permeation barriers and / or the number of permeation barriers may be required to ensure that a certain leakage rate is not exceeded, so as to guarantee a certain lifespan before refilling with insulating gas is required.

[0020] In another preferred embodiment, the electrical high-voltage equipment is provided as a high-voltage interrupter. The electrical equipment can be provided as a gas-insulated live-tank circuit breaker, a gas-insulated dead-tank circuit breaker, a bushing, or gas-insulated switchgear. Alternatively, the electrical equipment can be provided as control gear such as a gas-insulated equipment transformer. In any of these devices, there is great value in having equipment that functions reliably for many years without requiring refilling of the insulating gas.

[0021] In a further preferred embodiment, the electrical equipment is provided as outdoor gas-insulated electrical equipment. In this respect, the enclosure can be covered with a silicone shed. Alternatively, if the enclosure is provided as an epoxy-based composite insulator, a layer of insulator can be embedded within the silicone shed according to the same principles described.

[0022] The object is to provide a method for manufacturing gas-insulated electrical equipment comprising electrical high-voltage equipment, the method comprising the steps of: Manufacturing an enclosure for placing electrical high voltage equipment therein; applying a permeation barrier within an enclosure circumferentially surrounding the electrical high voltage equipment during manufacture; The permeation barrier comprises a permeation layer surrounded on at least one side by a flow promoting layer and / or a surface activated and / or primer layer.

[0023] The enclosure is preferably manufactured by impregnating a core with liquid epoxy, which has the negative shape of the enclosure's inner surface. The liquid epoxy should flow and fill all cavities. The proposed flow-promoting and / or surface-activating and / or primer layers help to avoid air bubbles and / or cracks that could otherwise lead to potential failure of the epoxy-based composite insulator and the respective enclosure under dielectric or environmental stress.

[0024] According to a preferred embodiment, the enclosure comprises an epoxy-based composite isolator, the epoxy-based composite isolator comprises wet-wound fabric, and / or the manufacturing includes vacuum impregnating the epoxy-based composite isolator.

[0025] In a preferred embodiment, the method comprises: During manufacture, this involves first applying a flow promoting layer and / or a surface activation and / or primer layer, second applying a permeation layer, and / or third applying another promoting layer and / or another surface activation and / or primer layer.

[0026] In a further preferred embodiment, the method comprises: filling the enclosure with an insulating gas comprising at least 70% by volume of CO2 and at an elevated predetermined operating gas pressure level; and hermetically sealing the enclosure.

[0027] Further embodiments and advantages of the method are directly and clearly derivable by those skilled in the art from the above described device.

[0028] BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0029] The diagram is as follows: [Brief explanation of the drawings]

[0030] [Figure 1a] 1 is a schematic top view of a gas-insulated electrical device with an enlarged portion of the device's enclosure, according to an exemplary embodiment. [Figure 1b] 10 is a schematic top view showing an enlarged portion of the enclosure of the device according to a further exemplary embodiment. [Figure 2] 10 is a schematic top view showing an enlarged portion of the enclosure of the device according to a further exemplary embodiment. [Figure 3] 1 is a schematic side view of a gas-insulated electrical device according to an exemplary embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0031] Description of the Preferred Embodiments FIG. 1 shows a schematic top view of a gas-insulated electrical device 1 according to an exemplary embodiment. The gas-insulated electrical device can provide a gas-insulated circuit breaker, and its application can be, for example, a gas-insulated live-tank circuit breaker, a bushing, or a gas-insulated dead-tank circuit breaker. The gas-insulated electrical device can also be gas-insulated switchgear or control gear such as a gas-insulated potential transformer. The gas-insulated electrical device can be suitable for outdoor use.

[0032] Gas-insulated electrical equipment 1 generally comprises an electrically insulating enclosure 2, generally in the form of a tube shown in top view, with walls made of polymeric and / or composite materials, particularly epoxy-based composites, as an insulator capable of withstanding the pressure within enclosure 1. Enclosure 2 is typically manufactured by wet-wound fabrication and / or by a vacuum impregnation process, thus providing the insulator with high mechanical strength and good dielectric properties. Inside enclosure 2 is located electrical high-voltage equipment 3, which may be a high-voltage interrupter and is shown only diagrammatically in FIG. 1. Enclosure 2 is hermetically sealed and filled with insulating gas 4, which contains at least 70% CO2 by volume, at an elevated predetermined operating gas pressure level ranging from 1.0 MPa to 1.2 MPa.

[0033] Within the enclosure, permeation barriers 5 are provided that circumferentially surround the electrical high-voltage equipment 3. In the circumferential direction, the permeation barriers 5 may have no circumferential gaps, as shown in the upper part of FIG. 2, may have circumferential gaps, as shown in the center of FIG. 2, or may be arranged in a circumferentially overlapping manner, as shown in the lower part of FIG. 2. Without gaps, the permeation barriers 5 each extend completely around the electrical high-voltage equipment 3. The gaps may be 1, 2, 5, or 10 mm wide. In the axial direction shown in FIG. 3, the permeation barriers 5 may also cover the complete axial extension of the enclosure 2, as shown on the left side of FIG. 3. Alternatively, the permeation barriers 5 may be arranged in an overlapping manner, as shown on the right side of FIG. 3. Overlapping means that the electrical high-voltage equipment 3 is always surrounded by one of the various permeation barriers 5 in the radial direction.

[0034] Generally, the permeation barrier 5 may be provided as a sheet and / or as a strip, such as the overlapping wrap strips. Also, as shown in FIG. 1b, multiple layers of individual permeation barriers 5 may be present within the enclosure 2, spaced apart from one another. As shown in FIG. 1b, the permeation barriers 5 are positioned adjacent to the respective inner surfaces of the interior of the enclosure 2. In other words, the permeation barriers 5 are positioned closer to the interior of the enclosure 2 than to the exterior. Each exterior surface of the enclosure 2, i.e., the surface facing the periphery of the enclosure 2, may include multiple sheds (not shown). The sheds may extend along the entire length or a portion of the length of the enclosure.

[0035] In fabricating the enclosure 2, an epoxy composite may be placed around a core that represents the negative shape of the designated enclosure 2's inner surface, followed by placing a permeation barrier 5 over the epoxy composite, and then another layer of epoxy composite up to the designated enclosure 2's outer surface. Once the enclosure 2 has cured, the core may be removed and the electrical high voltage equipment 3 may be placed within the enclosure 2. The enclosure 2 is sealed and filled with an insulating gas 4 to the operating gas pressure level.

[0036] Referring again to FIG. 1 , the permeation barrier 5 comprises a thin layer of a low-permeation material (LPM) as a permeation layer 6, which has a very low permeability coefficient for the respective insulating gas 4. The permeation layer 6 can be applied once to form a single layer or multiple times to increase effectiveness when a very low permeability is required. As previously explained, in the simplest embodiment, the permeation layer 6 can be formed from a sheet of LPM that is wrapped once around the enclosure 2 during manufacturing. For practical reasons, the permeation layer 6 can be made from wide strips instead of a single sheet of LPM. These strips are wrapped with or without overlap, depending on the permeation performance required. The permeation layer 6 can be made of ethylene vinyl alcohol (EVOH) and / or can be provided as aluminum oxide foil or other material suitable for preventing the permeation of the insulating gas 4.

[0037] To achieve sufficient impregnation and / or adhesion with such sheets or wide strips in composite materials, such as epoxy-based composite enclosures, which potentially result in bubbles or cracks leading to failure of the insulating enclosure 2 under dielectric or environmental stress, impregnation is improved by providing a flow promotion layer 7, while adhesion is improved by providing a surface activation and / or primer layer 8. Thus, while both the flow promotion layer 7 and the surface activation and / or primer layer 8 can be present, only one of the flow promotion layer 7 and the surface activation and / or primer layer 8 may also be present. Also, only one of the two sides of the permeation layer 6 can be provided with the flow promotion layer 7 and / or the surface activation and / or primer layer 8.

[0038] The flow promoting layer 7 may comprise fleece and / or mesh, such as polyester, aramid, woven fabric, or any combination thereof. The thickness of the promoting layer 7 may range from 0.3 to 2 mm, preferably 1 mm. The surface activation and / or primer layer 8 may be applied by plasma treatment, chemical bonding, and / or chemical treatment of the permeation layer 6 to activate the surface of the permeation layer 6. The thickness of the surface activation and / or primer layer 8 may range from 0.5 μm to 1 mm, for example, 1 μm. The permeation layer 6 may have a thickness of 0.0001, 0.0005, 0.001, 0.01, 0.1, 0.5, 1, 2, 5, or 10 mm.

[0039] While the invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive, and the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be interpreted as limiting the scope. [Explanation of symbols]

[0040] List of Reference Numbers 1 Electrical equipment 2 Enclosure 3. Electrical high-voltage equipment 4. Insulating gas 5. Permeability Barriers 6 Penetration layer 7 Facilitation layer 8. Surface activation and / or primer layer

Claims

1. A gas-insulated electrical device (1) comprising an enclosure (2), electrical high-voltage equipment (3) arranged inside the enclosure (2), and a permeable barrier (5) enclosed inside the enclosure (2) and circumferentially surrounding the electrical high-voltage equipment (3), The enclosure (2) contains at least 70% by volume of CO ２ and containing an insulating gas (4) containing an elevated predetermined operating gas pressure level; said permeation barrier (5) comprising a permeation layer (6) surrounded on at least one side by a flow promoting layer (7) and / or a surface activated and / or primer layer (8); The permeation layer (6) comprises ethylene vinyl alcohol (EVOH) and / or aluminum oxide foil; the permeation layer (6), the flow promoting layer (7) and / or the surface activation and / or primer layer (8) are provided as overlapping wrap strips; Gas-insulated electrical equipment (1).

2. 2. A gas-insulated electrical device (1) according to claim 1, wherein the wrap strips are provided so as to overlap in the axial and / or circumferential direction.

3. A gas-insulated electrical device (1) comprising an enclosure (2), electrical high-voltage equipment (3) arranged inside the enclosure (2), and a permeation barrier (5) arranged inside the enclosure (2) and circumferentially surrounding the electrical high-voltage equipment (3), The enclosure (2) contains an insulating gas (4) comprising at least 70% by volume of CO2 and having an elevated predetermined operating gas pressure level; said permeation barrier (5) comprising a permeation layer (6) surrounded on at least one side by a flow promoting layer (7) and / or a surface activated and / or primer layer (8); The permeation layer (6) comprises ethylene vinyl alcohol (EVOH) and / or aluminum oxide foil; a plurality of permeation barriers (5) spaced apart from one another within the enclosure (2); Gas-insulated electrical equipment (1).

4. The gas-insulated electrical device (1) according to any one of claims 1 to 3, comprising the flow promoting layer (7), the flow promoting layer (7) comprising fleece and / or mesh.

5. 4. The gas-insulated electrical device (1) according to claim 1, wherein the permeation barrier (5) is arranged within the enclosure (2), adjacent to the inside of the enclosure (2) and / or closer to the inside than to the outside of the enclosure (2).

6. The gas-insulated electrical device (1) according to any one of claims 1 to 3, wherein the electrical high-voltage device (3) is provided as a high-voltage interrupter.

7. The gas-insulated electrical equipment (1) according to any one of claims 1 to 3, wherein the gas-insulated electrical equipment (1) is provided as a gas-insulated live-tank circuit breaker, a gas-insulated dead-tank circuit breaker, a bushing or a gas-insulated switchgear.

8. The gas-insulated electrical equipment (1) according to any one of claims 1 to 3, wherein the gas-insulated electrical equipment (1) is provided as an outdoor gas-insulated electrical equipment.

9. A method for manufacturing a gas-insulated electrical device (1) comprising an electrical high-voltage device (3), comprising the steps of: manufacturing an enclosure (2) for placing said electrical high voltage equipment (3) therein; during manufacture, enclosing a permeation barrier (5) within said enclosure (2) circumferentially surrounding said electrical high voltage equipment (3); said permeation barrier (5) comprising a permeation layer (6) surrounded on at least one side by a flow promoting layer (7) and / or a surface activated and / or primer layer (8); The permeation layer (6) comprises ethylene vinyl alcohol (EVOH) and / or aluminum oxide foil, the permeation layer (6), the flow promoting layer (7) and / or the surface activation and / or primer layer (8) are provided as overlapping wrap strips; method.

10. A method for manufacturing a gas-insulated electrical device (1) comprising an electrical high-voltage device (3), comprising: manufacturing an enclosure (2) for placing said electrical high voltage equipment (3) therein; applying, during manufacture, a plurality of permeation barriers (5) within said enclosure (2) circumferentially surrounding said electrical high voltage equipment (3); a plurality of said permeation barriers (5) comprising a permeation layer (6) surrounded on at least one side by a flow promoting layer (7) and / or a surface activation and / or primer layer (8), and are spaced apart from one another within said enclosure (2); The method, wherein said permeation layer (6) comprises ethylene vinyl alcohol EVOH and / or aluminum oxide foil.

11. 11. The method of claim 9 or 10, wherein the enclosure (2) comprises an epoxy-based composite isolator, the epoxy-based composite isolator comprises wet-wound fabric, and / or the manufacturing comprises vacuum impregnating the epoxy-based composite isolator.

12. During manufacture, firstly applying said flow promoting layer (7) and / or surface activation and / or primer layer (8), secondly applying said permeation layer (6), and / or thirdly applying another promoting layer (7) and / or another surface activation and / or primer layer (8), 11. The method according to claim 9 or 10.

13. At least 70% by volume of CO ２ filling the enclosure (2) with an insulating gas (4) containing an elevated predetermined operating gas pressure level; and hermetically sealing the enclosure (2).

11. The method according to claim 9 or 10.

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