Ground screen structure and power equipment

Abstract

The application discloses a ground screen structure and electric power equipment, wherein the ground screen structure comprises a shielding layer, a first insulating layer and a second insulating layer. The upper end face and the lower end face of the first insulating layer are chamfered, so that the upper end face and the lower end face of the first insulating layer are circular arc-shaped. The upper end of the shielding layer is circular arc-shaped in combination with the upper end face of the first insulating layer, and the lower end of the shielding layer is circular arc-shaped in combination with the lower end face of the first insulating layer, so that the end part of the ground screen structure is arc-shaped, the radius of curvature of the end part of the ground screen is increased, the electric field distribution of the end part of the ground screen is improved, the electric field distribution is homogenized, the problem of electric field concentration of the end part of the ground screen is solved, and the occurrence of partial discharge and insulation breakdown is prevented.

Description

Technical Field

[0001] This application relates to the fields of transformer and reactor technology, and in particular to a grounding shield structure and power equipment. Background Technology

[0002] Currently, in the design and manufacturing of large transformers and reactors, since the core is made of multi-level silicon steel sheets, the core structure has multiple sharp corners, which can cause electric field concentration and partial discharge. Therefore, grounding shields (hereinafter referred to as grounding shields) are usually used to shield the sharp corners of the core to ensure product quality.

[0003] The ends of grounding shields are typically made of metal strips or mesh. These ends are far from the internal conductors of the core column and are relatively independent in space. In an electric field, they function as sharp metal ground electrodes, resulting in a poor electric field shape and greater non-uniformity. This leads to electric field concentration at the ends, far exceeding the allowable electric field strength, posing a safety hazard of partial discharge or breakdown causing insulation failure. Utility Model Content

[0004] This application proposes a grounding shield structure to solve the problem of electric field concentration at the ends of the grounding shield. This application also proposes a power device having the above-described grounding shield structure.

[0005] In a first aspect, this application provides a ground shield structure, including a shielding layer, a first insulating layer, and a second insulating layer;

[0006] The upper and lower surfaces of the first insulating layer are arc-shaped;

[0007] The shielding layer is located on the first side of the first insulating layer away from the iron core, and the second insulating layer is located on the second side of the first insulating layer close to the iron core.

[0008] The upper end of the shielding layer is bent along the upper end of the first insulating layer towards the second side of the first insulating layer, and the lower end of the shielding layer is bent along the lower end of the first insulating layer towards the second side of the first insulating layer;

[0009] The upper and lower surfaces of the first insulating layer are located at both ends of the first insulating layer in the height direction of the core of the transformer or reactor.

[0010] Optionally, in the above-described ground shield structure, along the height direction of the core, the upper end of the second insulating layer is higher than the upper end of the first insulating layer, and the lower end of the second insulating layer is lower than the lower end of the first insulating layer.

[0011] Optionally, the above-mentioned grounding shield structure also includes a third insulating layer;

[0012] The third insulating layer is located on the first side of the first insulating layer, and the shielding layer is located between the first insulating layer and the third insulating layer.

[0013] Optionally, in the above-mentioned ground screen structure, the first insulating layer, the second insulating layer and the third insulating layer are glass fiber cloth layers or pre-impregnated composite insulating layers.

[0014] Optionally, in the above-described grounding shield structure, the first insulating layer is cylindrical;

[0015] The first insulating layer is a cylindrical shape formed by insulating paper, or the first insulating layer is a cylindrical shape formed by multiple arc-shaped insulating plates.

[0016] Optionally, in the above-described ground shield structure, the shielding layer is connected to the first insulating layer by at least one of adhesive bonding and compression bonding.

[0017] Optionally, in the above-described grounding shield structure, the grounding lead connected to the short-circuit band of the shielding layer is a flat lead;

[0018] The plane containing the flat lead is parallel to the plane containing the shielding layer.

[0019] Optionally, in the above-described grounding shield structure, the second insulating layer is provided with a clearance groove at the position corresponding to the grounding lead.

[0020] Optionally, in the above-described ground shield structure, the shielding layer is at least one of a metal strip, a metal mesh, and a semi-conductive paper.

[0021] Secondly, this application also provides an electrical device, including a grounding shield structure, wherein the grounding shield structure is the grounding shield structure described in any of the above-mentioned solutions.

[0022] This application provides a grounding shield structure, including a shielding layer, a first insulating layer, and a second insulating layer. The upper and lower surfaces of the first insulating layer are chamfered, making them arc-shaped. The upper end of the shielding layer is attached to the upper surface of the first insulating layer in an arc shape, and the lower end of the shielding layer is attached to the lower surface of the first insulating layer in an arc shape, thus making the ends of the grounding shield structure arc-shaped. This increases the radius of curvature at the ends of the grounding shield, improves the electric field distribution at the ends of the grounding shield, makes the electric field distribution more uniform, solves the problem of electric field concentration at the ends of the grounding shield, and prevents partial discharge and insulation breakdown.

[0023] This application also discloses a power equipment including a grounding shield structure, which is the grounding shield structure described in any of the above-mentioned solutions. Since the grounding shield structure has the aforementioned technical effects, the power equipment having this grounding shield structure also has the same technical effects. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort, and this application can be applied to other similar scenarios based on the provided drawings. Unless obvious from the linguistic context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0025] Figure 1 This is a schematic diagram of the floor screen structure (not rolled into a cylinder) provided in the embodiments of this application;

[0026] Figure 2 This is a partial side view of the ground screen structure provided in an embodiment of this application;

[0027] Figure 3 This is a schematic diagram of the connection between the grounding shield structure and the grounding lead provided in the embodiments of this application;

[0028] Figure 4 This is a schematic diagram of the structure of the second insulating layer with a clearance groove provided in the embodiment of this application.

[0029] in:

[0030] 1-Shielding layer; 2-First insulating layer; 3-Second insulating layer; 31-Leaving groove; 4-Grounding lead. Detailed Implementation

[0031] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the application and not intended to limit it. The described embodiments are only a part of the embodiments of the present application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without inventive effort are within the scope of protection of the present application.

[0032] It should be noted that, for ease of description, only the parts relevant to the application are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0033] It should be understood that the terms "system," "apparatus," "unit," and / or "module" used in this application are a method of distinguishing different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions.

[0034] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "a," and / or "the" are not specifically singular and may include the plural. Generally, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements. An element defined by the phrase "comprising an..." does not exclude the presence of other identical elements in the process, method, product, or apparatus that includes the element.

[0035] In the description of the embodiments of this application, unless otherwise stated, " / " means "or", for example, A / B can mean A or B; "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more.

[0036] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0037] Grounding shields (or grounding screens) are used to improve electric field distribution, suppress electromagnetic interference, and ensure the safe operation of equipment.

[0038] In related technologies, grounding shields are typically metal strips or meshes. From a microscopic perspective, the ends of a grounding shield are a series of "points" with extremely small radii of curvature. The smaller or sharper the surface curvature radius of a charged conductor, the greater the charge density and the higher the electric field strength on its surface.

[0039] The end of the grounding shield is the boundary of the grounding shield. The grounding shield is at ground potential, i.e., 0 potential. The end of the grounding shield is located in the transition region from 0 potential to high potential, where the potential gradient is very large, causing the end of the grounding shield to become the place where the electric field is most concentrated.

[0040] If the local electric field at the end of the grounding shield exceeds the allowable field strength, partial discharge or even insulation breakdown will occur, causing a short circuit fault.

[0041] Please see Figure 1 and Figure 2 The ground shield structure disclosed in this solution includes a shielding layer 1, a first insulating layer 2, and a second insulating layer 3.

[0042] The upper and lower surfaces of the first insulating layer 2 are chamfered, making them arc-shaped. The angle of the arc is designed according to the requirements of the electric field; that is, the upper and lower surfaces can be chamfered to different sizes according to the requirements of the electric field. As the angle of the arc changes, the thickness of the first insulating layer 2 is also adjusted accordingly.

[0043] It should be noted here that the upper end face and the lower end face of the first insulating layer 2 are the faces located at both ends of the first insulating layer 2 in the height direction of the core of the transformer or reactor.

[0044] The first insulating layer 2 includes a first side and a second side. Optionally, the first side is the side of the first insulating layer 2 away from the iron core, and the second side is the side of the first insulating layer 2 close to the iron core. The first side and the second side are opposite to each other.

[0045] A shielding layer 1 is disposed on the first side of the first insulating layer 2. The upper end of the shielding layer 1 is higher than the upper surface of the first insulating layer 2. The upper end of the shielding layer 1 is bent along the upper surface of the first insulating layer 2 to the second side of the first insulating layer 2, and then bent downward to fit against the second side of the first insulating layer 2. The lower end of the shielding layer 1 is lower than the lower surface of the first insulating layer 2. The lower end of the shielding layer 1 is bent along the lower surface of the first insulating layer 2 to the second side of the first insulating layer 2, and then bent upward to fit against the second side of the first insulating layer 2.

[0046] Continue reading Figure 2 A second insulating layer 3 is disposed on the second side of the first insulating layer 2. The portion of the shielding layer 1 folded to the second side of the first insulating layer 2 is located between the first insulating layer 2 and the second insulating layer 3.

[0047] The upper end of the shielding layer 1 is attached to the upper end face of the first insulating layer 2 in an arc shape, and the lower end of the shielding layer 1 is attached to the lower end face of the first insulating layer 2 in an arc shape, so that the end of the grounding shield structure is arc-shaped, increasing the radius of curvature of the end of the grounding shield, improving the electric field distribution at the end of the grounding shield, making the electric field distribution uniform, solving the problem of electric field concentration at the end of the grounding shield, and preventing partial discharge and insulation breakdown.

[0048] This solution improves the radius of curvature of the end of the ground shield structure formed by folding the shielding layer 1 along the upper and lower surfaces of the first insulating layer 2 into an arc shape. Compared with the related technology that increases the radius of curvature by cutting the edge of the shielding layer 1, this solution is not only easier to implement, but also does not increase costs excessively. More importantly, it has high reliability and significantly improves the quality and stability of the product.

[0049] The first insulating layer 2 may optionally be made of H-class insulation and heat-resistant material, and the first insulating layer 2 is a closed cylindrical tube.

[0050] Optionally, the first insulating layer 2 can be a closed paper tube made of multiple layers of rigid insulating board or a cylindrical shape formed by multiple arc-shaped insulating boards; the first insulating layer 2 can also be a closed cylindrical tube made of glass fiber cloth.

[0051] In the embodiment where the first insulating layer 2 is a cylindrical structure formed by insulating paper, the insulating cylinder has a circumferentially closed structure. In this embodiment, the first insulating layer 2 has good integrity, structural stability, and a small number of connection points.

[0052] In an embodiment where the first insulating layer 2 is a cylinder formed by multiple arc-shaped insulating plates, adjacent arc-shaped insulating plates are interconnected. In this embodiment, the cylinder is composed of multiple arc-shaped plates, and those skilled in the art can combine these plates according to actual needs to obtain cylinders of different diameters, offering good flexibility.

[0053] The second insulating layer 3 is located on the second side of the first insulating layer 2 near the core, and the shape of the second insulating layer 3 is consistent with the shape of the first insulating layer 2. In embodiments where the first insulating layer 2 is cylindrical, the second insulating layer 3 is also cylindrical. The second insulating layer 3 serves as an inner support for the first insulating layer 2. Compared to the method where the first insulating layer 2 is directly surrounded by the support bar or the core support rod, the cylindrical shape of the first insulating layer 2 is more rounded, and it can also prevent the first insulating layer 2 from being unstable and slipping during operation, causing an accident that leads to a short circuit and grounding of the inner winding.

[0054] Along the height direction of the iron core, such as Figure 2 As shown, the upper end of the second insulating layer 3 is higher than the upper surface of the first insulating layer 2, and the lower end of the second insulating layer 3 is lower than the lower surface of the first insulating layer 2. The portion of the second insulating layer 3 that extends beyond the first insulating layer 2 facilitates the making of small holes for binding and also enhances the insulation performance.

[0055] Optionally, the shielding layer 1 is fixed to the first insulating layer 2 by at least one of adhesive bonding and compression to ensure the connection strength between the shielding layer 1 and the first insulating layer 2 and to prevent displacement due to vibration or electrodynamic force.

[0056] Adhesive bonding can achieve a large-area, continuous, and strong bond;

[0057] The compression connection can be achieved by bundling or clamping to compress the shielding layer 1 into the first insulating layer 2.

[0058] In some embodiments, the grounding screen structure disclosed in this application further includes a third insulating layer (not shown in the figure).

[0059] The third insulating layer is located on the first side of the first insulating layer 2, and the shielding layer 1 is located between the first insulating layer 2 and the third insulating layer.

[0060] The third insulating layer is located outside the shielding layer 1. It further optimizes the electric field transition from high potential to low potential, suppresses the generation of partial discharge, and also physically isolates components with different potentials, while playing the role of uniform electric field.

[0061] The third insulating layer also provides mechanical support for the shielding layer 1, preventing displacement, deformation, or wrinkling of the shielding layer 1 during assembly and operation.

[0062] The first insulating layer 2, the second insulating layer 3, and the third insulating layer are insulating paper layers, fiberglass cloth layers, or pre-impregnated composite insulating layers, etc., but are not limited to the above materials.

[0063] In embodiments where the first insulating layer 2, the second insulating layer 3, and the third insulating layer are composed of insulating paper, the first insulating layer 2, the second insulating layer 3, and the third insulating layer include at least one layer of insulating paper.

[0064] The materials of the first insulating layer 2, the second insulating layer 3, and the third insulating layer can be the same or different.

[0065] The fiberglass cloth layer is a fabric woven from extremely fine fiberglass yarns. It has good insulation properties, a low coefficient of thermal expansion, high mechanical strength, and heat resistance.

[0066] The prepreg composite insulation layer can be selected as SHS type prepreg composite insulation material. SHS type prepreg composite insulation material is a soft composite material made of polyimide film and heat-resistant fiber nonwoven fabric, which is impregnated with high-temperature resistant resin and then baked.

[0067] SHS type prepreg composite insulation material has the characteristics of long room temperature storage period, low curing temperature and short curing time. The cured product has excellent electrical properties, adhesion properties and heat resistance properties, with a heat resistance rating of H. It is suitable for interlayer insulation and ground insulation of copper and aluminum foil wrapping of low voltage coils.

[0068] The shielding layer 1 is at least one of a metal strip, a metal mesh, and a semi-conductive paper.

[0069] The metal strip and metal mesh can be copper strip, copper foil, or aluminum foil, etc. Copper strip, copper foil, or aluminum foil have good conductivity, good shielding effect, and are usually about one millimeter thick, with sufficient flexibility to be wrapped on the first insulating layer 2.

[0070] Semiconducting paper is made by adding carbon powder to insulating pulp to make it conductive. If there are tiny air gaps between a pure metallic conductor and the insulating paper, partial discharge can easily occur at the air gaps. The resistance of semiconductor materials can suppress this discharge and better suppress partial discharge.

[0071] In an embodiment where the shielding layer 1 is a metal strip, the length direction of the metal strip is suppressed by the height direction of the iron core, and multiple metal strips are arranged in the circumferential direction of the iron core; or, the length direction of the metal strip is perpendicular to the height direction of the iron core, and multiple iron cores are arranged side by side along the height direction of the iron core.

[0072] The shielding structure also includes a short-circuit strip, which is a metal conductive strip that is riveted to the metal strip of the shielding layer 1 and then vertically welded to electrically short-circuit all the metal strips, ensuring that the shielding layer 1 as a whole is at the same potential and avoiding potential differences between different metal strips.

[0073] The grounding lead 4 is connected to the short-circuit strip. Optionally, the height of the short-circuit strip extends beyond the first insulating layer 2. The short-circuit strip folds over the shielding layer 1 toward the second side of the first insulating layer 2.

[0074] like Figure 3 As shown, after the welding part of the grounding lead 4 and the short-circuit strip is flattened, it is welded to the short-circuit strip folded to the second side of the first insulation layer 2. After welding, the grounding lead 4 is led out upward.

[0075] After the grounding lead 4 is flattened, the plane on which it is located is parallel to the second side of the first insulating layer 2 or the plane on which the shielding layer 1 is located, thereby reducing the thickness of the grounding lead 4 along the plane perpendicular to the second side of the first insulating layer 2, ensuring that there is no significant impact on the protruding structure.

[0076] Optionally, such as Figure 4 As shown, the second insulating layer 3 has a clearance groove at the position corresponding to the grounding lead 4 to ensure that the grounding lead 4 does not lift up the first insulating paper and shielding layer 1, thus optimizing the shape of the grounding shield structure.

[0077] The grounding shield structure disclosed in this solution has a wide range of applications and can be used in reactors without core columns, transformers with irregular core columns, or between some windings.

[0078] Secondly, this application also discloses a power equipment, including a grounding shield structure, wherein the grounding shield structure is the grounding shield structure described in any of the above-mentioned schemes.

[0079] Because the ground shield structure has the aforementioned technical effects, electrical equipment with this ground shield structure also has the same technical effects.

[0080] Optionally, the power equipment may be a transformer or a reactor, etc.

[0081] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed, and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. The scope of this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described application concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A ground screen structure, characterized in that, It includes a shielding layer (1), a first insulating layer (2), and a second insulating layer (3); The upper and lower surfaces of the first insulating layer (2) are arc-shaped; The shielding layer (1) is located on the first side away from the iron core of the first insulating layer (2), and the second insulating layer (3) is located on the second side of the first insulating layer (2) close to the iron core; The upper end of the shielding layer (1) is bent along the upper end of the first insulating layer (2) towards the second side of the first insulating layer (2), and the lower end of the shielding layer (1) is bent along the lower end of the first insulating layer (2) towards the second side of the first insulating layer (2). The upper and lower surfaces of the first insulating layer (2) are the surfaces located at both ends of the first insulating layer (2) in the height direction of the core of the transformer or reactor.

2. The ground screen structure according to claim 1, characterized in that, Along the height direction of the core, the upper end of the second insulating layer (3) is higher than the upper end of the first insulating layer (2), and the lower end of the second insulating layer (3) is lower than the lower end of the first insulating layer (2).

3. The ground screen structure according to claim 2, characterized in that, It also includes a third insulating layer; The third insulating layer is located on the first side of the first insulating layer (2), and the shielding layer (1) is located between the first insulating layer (2) and the third insulating layer.

4. The ground screen structure according to claim 3, characterized in that, The first insulating layer (2), the second insulating layer (3) and the third insulating layer are insulating paper layers, glass fiber cloth layers or pre-impregnated composite insulating layers.

5. The ground screen structure according to any one of claims 1-4, characterized in that, The first insulating layer (2) is cylindrical; The first insulating layer (2) is a cylindrical shape formed by insulating paper, or the first insulating layer (2) is a cylindrical shape formed by multiple arc-shaped insulating plates.

6. The ground screen structure according to any one of claims 1-4, characterized in that, The shielding layer (1) is connected to the first insulating layer (2) by at least one of adhesive bonding and compression bonding.

7. The floor screen structure according to any one of claims 1-4, characterized in that, The grounding lead (4) connected to the short-circuit band of the shielding layer (1) is a flat lead; The plane containing the flat lead is parallel to the plane containing the shielding layer (1).

8. The ground screen structure according to claim 7, characterized in that, The second insulating layer (3) is provided with a clearance groove (31) at the position corresponding to the grounding lead (4).

9. The ground screen structure according to any one of claims 1-4, characterized in that, The shielding layer (1) is at least one of metal strip, metal mesh and semi-conductive paper.

10. An electrical device, characterized in that, Includes a ground screen structure, wherein the ground screen structure is the ground screen structure according to any one of claims 1-9.

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