Dry-type transformer end portion fiber mesh cloth integrated covering structure and method

Abstract

This application discloses an integrated fiber mesh fabric covering structure and method for the end of a dry-type transformer, relating to the field of transformer technology. The integrated fiber mesh fabric covering structure includes a dry-type transformer coil and a fiber mesh fabric. The fiber mesh fabric wraps around the end of the dry-type transformer coil, forming an integral covering layer on the end face of the coil. This integral covering layer penetrates through the air duct holes of the dry-type transformer coil, forming a hole-enclosing layer extending along the inner wall of the air duct holes. This integrated fiber mesh fabric covering structure for the end of the dry-type transformer effectively enhances the mechanical strength of the coil end face, eliminates the hidden dangers of stress concentration and delamination cracking, thereby significantly improving the reliability and service life of the transformer.

Description

Technical Field

[0001] This application relates to the field of transformer technology, and in particular to an integrated fiber mesh fabric covering structure and method for the ends of dry-type transformers. Background Technology

[0002] A dry-type transformer is an electrical device used to transfer electrical energy between different voltage levels, while simultaneously stepping up or down the voltage to meet the needs of specific applications. Compared to traditional oil-immersed transformers, dry-type transformers use dry insulating materials such as resin or fiberglass.

[0003] During transformer operation, the coils generate heat due to the flow of current, causing the coil materials to expand. When the transformer stops operating or cools down, the coil materials contract. This repeated thermal expansion and contraction leads to mechanical stress, especially at the coil end interfaces. The inventors discovered in practice that the coil end interfaces of dry-type transformers are a critical weak point in their structure. This area undergoes cyclical heating and cooling during transformer operation, resulting in thermal expansion and contraction, thus generating mechanical stress. This stress concentration, particularly in the stress-relieving areas of the coil end faces, can lead to insulation fatigue, delamination, and cracking, ultimately causing transformer failure and performance degradation. Summary of the Invention

[0004] The purpose of this application is to provide an integrated fiber mesh fabric covering structure for the ends of a dry-type transformer, which effectively enhances the mechanical strength of the coil end face, eliminates the hidden dangers of stress concentration and delamination cracking, thereby significantly improving the reliability and service life of the transformer. Another purpose of this application is to provide a method for integrated fiber mesh fabric covering the ends of a dry-type transformer.

[0005] To achieve the above objectives, this application provides an integrated fiber mesh fabric covering structure for the end of a dry-type transformer, comprising a dry-type transformer coil and a fiber mesh fabric. The fiber mesh fabric is wrapped around the end position of the dry-type transformer coil, and the fiber mesh fabric forms an integral covering layer on the end face of the dry-type transformer coil. The integral covering layer penetrates through the air passage hole of the dry-type transformer coil and forms a hole surrounding layer extending along the inner wall of the air passage hole.

[0006] In some embodiments, the fiber mesh fabric also forms a bonding cover layer on the end side of the dry-type transformer coil, the bonding cover layer being connected to the integral cover layer, and the angle between the bonding cover layer and the integral cover layer matching the end corner of the dry-type transformer coil.

[0007] In some embodiments, the end side of the dry-type transformer coil is divided into an inner wall region and an outer wall region, and a bonding cover layer is formed on both the inner wall region and the outer wall region.

[0008] The bonding cover layer of the inner wall region is connected to the overall cover layer, and the angle between the bonding cover layer of the inner wall region and the overall cover layer matches the end corner of the lower side of the dry-type transformer coil.

[0009] The bonding cover layer of the outer wall region is connected to the overall cover layer, and the angle between the bonding cover layer of the outer wall region and the overall cover layer matches the end corner of the upper side of the dry-type transformer coil.

[0010] In some embodiments, the bonding cover layer of the inner wall region is parallel to the bonding cover layer of the outer wall region; and / or, the angle between the bonding cover layer of the inner wall region and the overall cover layer is 90°; and / or, the angle between the bonding cover layer of the outer wall region and the overall cover layer is 90°.

[0011] In some embodiments, the fiber mesh includes a substrate, a first side of which has a fiber surface and a second side of which has a mesh surface. The fiber surface is located on the side that is in contact with the dry-type transformer coil, and the mesh surface is located on the side opposite to the side of the dry-type transformer coil that is in contact with the fiber surface.

[0012] This application also provides a method for integrated fiber mesh fabric covering at the end of a dry-type transformer, used to manufacture the aforementioned integrated fiber mesh fabric covering structure at the end of a dry-type transformer. The method for integrated fiber mesh fabric covering at the end of a dry-type transformer includes:

[0013] Select fiber mesh fabric;

[0014] The fiber mesh is wrapped around the end of the dry-type transformer coil, and the fiber mesh forms an integral cover layer on the end face of the dry-type transformer coil.

[0015] The integral cover layer is cut so that it penetrates the air passage hole of the dry-type transformer coil and forms a hole surrounding layer extending along the inner wall of the air passage hole.

[0016] In some embodiments, the step of selecting the fiber mesh fabric includes:

[0017] The selected material is a mesh fabric woven from fiberglass;

[0018] The glass fibers are chopped and spread onto the mesh fabric;

[0019] The needle of the needle-punching machine is used to repeatedly puncture the short-cut fiber material spread on the mesh cloth to obtain a fiber mesh cloth. The side of the fiber mesh cloth with the short-cut fiber material is the fiber side, and the side of the fiber mesh cloth without the short-cut fiber material is the mesh side.

[0020] In some embodiments, the steps of wrapping the fiber mesh fabric around the end position of the dry-type transformer coil and forming an integral cover layer of the fiber mesh fabric on the end face of the dry-type transformer coil include:

[0021] Before winding the dry-type transformer coil, the fiber mesh cloth is pre-placed on the end side of the inner mold used to wind the dry-type transformer coil, so that the first section of the fiber mesh cloth is fixed to the inner mold. The fiber mesh cloth has a fiber surface and a mesh surface. When pre-placing the fiber mesh cloth, the mesh surface is made to fit with the inner mold.

[0022] After the dry-type transformer coil is wound, the fiber mesh cloth is wrapped around the end position of the dry-type transformer coil, so that the second section of the fiber mesh cloth is fixed to the outer wall area of ​​the dry-type transformer coil. At this time, the first section of the fiber mesh cloth is located in the inner wall area of ​​the dry-type transformer coil, and the cloth section between the first and second sections of the fiber mesh cloth is located on the end face of the dry-type transformer coil.

[0023] In some embodiments, the step of cutting the integral cover layer, causing the integral cover layer to penetrate through the air passage hole of the dry-type transformer coil and form a hole-enclosing layer extending along the inner wall of the air passage hole, includes:

[0024] After the step of forming an integral cover layer on the end face of the dry-type transformer coil with the fiber mesh, the integral cover layer is cut with reference to the outline of the air duct plate located at the end of the dry-type transformer coil. The cut opening is smaller than the air duct plate so that the integral cover layer can penetrate the air duct hole shaped in the air duct plate, and leave a margin so that the fiber mesh can form a hole surrounding layer extending along the inner wall of the air duct hole.

[0025] In some embodiments, the mesh fabric has a warp density of 48 threads / 10cm, a weft density of 52 threads / 10cm, a single fiber diameter of 11µm, and a basis weight of 145g / m². 2 The thickness is 0.5mm;

[0026] The length of the chopped fiber material is 30-80 mm;

[0027] The basis weight of the fiber mesh fabric is 360±10 g / m². 2 ;

[0028] The maximum acupuncture frequency of the acupuncture machine is 1200 r / min, the cloth walking speed is 1-12 m / min, the needle density is 4500-5500 needles / m, and the puncture depth is 12-15 mm.

[0029] Compared with the above-mentioned background technology, the dry-type transformer end fiber mesh cloth integrated cover structure provided in this application mainly includes a dry-type transformer coil and a fiber mesh cloth. The fiber mesh cloth is wrapped around the end position of the dry-type transformer coil. The fiber mesh cloth forms an integral cover layer on the end face of the dry-type transformer coil. The integral cover layer penetrates the air passage hole of the dry-type transformer coil and forms a hole surrounding layer extending along the inner wall of the air passage hole.

[0030] This integrated fiber mesh covering structure at the ends of dry-type transformers addresses the problem of mechanical stress at the coil end interface under cyclical heating and cooling, leading to insulation material fatigue, delamination, and cracking. This technical solution effectively avoids the presence of the interface by laying a fiber mesh flat on the transformer coil end face, utilizing its skeletal support and crack resistance. This adds a buffer layer, reduces internal stress, and improves mechanical strength, thereby eliminating end cracking, significantly improving the transformer's product quality and appearance, and enhancing its stability and durability. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0032] Figure 1 A schematic diagram of the integrated fiber mesh cover structure at the end of a dry-type transformer provided in this application embodiment;

[0033] Figure 2 This is a structural diagram of the fiber mesh fabric provided in the embodiments of this application;

[0034] Figure 3 This is a schematic diagram showing the position of the fiber mesh fabric at the end of the dry-type transformer coil, as provided in the embodiments of this application.

[0035] in:

[0036] Dry-type transformer coil 1, end face 101, end side 102, inner wall area 1021, outer wall area 1022, air passage hole 103, fiber mesh cloth 2, substrate 21, fiber surface 22, mesh surface 23, overall cover layer 201, hole surrounding layer 202, combined cover layer 203, air passage plate 3, inner mold 4. Detailed Implementation

[0037] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Please refer to Figures 1 to 3 ,in, Figure 1 This is a schematic diagram of the integrated fiber mesh cover structure at the end of a dry-type transformer provided in an embodiment of this application. Figure 2 This is a structural diagram of the fiber mesh fabric provided in the embodiments of this application. Figure 3 This is a schematic diagram showing the position of the fiber mesh fabric at the end of the dry-type transformer coil, as provided in the embodiments of this application.

[0040] like Figure 1 and Figure 3 As shown, the integrated fiber mesh fabric covering structure at the end of the dry transformer provided in this application embodiment mainly includes a dry transformer coil 1 and a fiber mesh fabric 2, with the fiber mesh fabric 2 wrapped around the end of the dry transformer coil 1.

[0041] like Figure 2 As shown, the fiber mesh 2 forms an integral cover layer 201 on the end face 101 of the dry-type transformer coil 1, combined with... Figure 1 and Figure 3 The overall cover layer 201 penetrates the air passage hole 103 of the dry transformer coil 1 and forms a hole surrounding layer 202 extending along the inner wall of the air passage hole 103.

[0042] In the conventional setup of dry-type transformer coil 1, i.e. without fiber mesh cloth 2, the end interface of dry-type transformer coil 1 is subject to alternating hot and cold temperatures with the outside, and the coil end face is a stress-relieving area, which is a weak area in terms of mechanical strength, making it prone to delamination, cracking and other hidden dangers.

[0043] This integrated fiber mesh fabric covering structure at the ends of dry-type transformers addresses the problem of mechanical stress at the end interface of the coil 1 of dry-type transformers under cyclical hot and cold cycles, leading to insulation material fatigue, delamination, and cracking. This technical solution effectively avoids the existence of the interface by laying fiber mesh fabric 2 flat on the end face of the transformer coil, utilizing its skeleton support and crack resistance properties. This is equivalent to adding a buffer layer, which correspondingly reduces internal stress and improves mechanical strength, thereby eliminating end cracking, significantly improving the product quality and appearance performance of the transformer, and enhancing the stability and durability of the transformer.

[0044] It should be noted that the improvement provided in this embodiment is to add a corresponding process and structure to one step in the processing of the dry transformer coil 1. For example, the fiber mesh cloth 2 is added and the fiber mesh cloth 2 is laid flat at the end of the dry transformer coil 1. Apart from this, the other processing processes and structures of the dry transformer coil 1 are not changed. For example, after the dry transformer coil 1 is obtained by winding the electromagnetic wire in the inner mold 4, epoxy resin is poured and cured. Therefore, apart from the special improvement made to the dry transformer coil 1 in this embodiment, other contents of the dry transformer coil 1 can be referred to the prior art, and will not be repeated here.

[0045] Please continue to refer to this. Figure 3 As can be seen, in addition to the end face 101, the end position of the fiber mesh 2 also has the end side face 102.

[0046] In some embodiments, the fiber mesh fabric 2 also forms a bonding cover layer 203 on the end side 102 of the dry transformer coil 1. The bonding cover layer 203 is connected to the overall cover layer 201, and the angle between the bonding cover layer 203 and the overall cover layer 201 matches the end corner of the dry transformer coil 1.

[0047] In this embodiment, by providing fiber mesh 2 on the end face 101 and end side face 102 at the end of the dry-type transformer coil 1, forming an interconnected integral cover layer 201 and a bonding cover layer 203, this technical solution achieves comprehensive protection for the end of the transformer coil. This design not only enhances the mechanical strength of the end, but also, by matching the angle of the coil end corner, strengthens the bond between the fiber mesh 2 and the dry-type transformer coil 1, improving the overall mechanical strength and thus enhancing the reliability and durability of the transformer. Furthermore, the presence of the bonding cover layer 203 helps to more evenly distribute mechanical stress caused by thermal expansion and contraction, further reducing the risk of delamination and cracking, and improving the long-term operational stability of the transformer.

[0048] Please continue to refer to this. Figure 3As can be seen, at the end position of the fiber mesh 2, apart from the end face 101, the end side 102 on both sides of the end face 101 is divided into an inner wall region 1021 and an outer wall region 1022. A bonding cover layer 203 is formed on both the inner wall region 1021 and the outer wall region 1022. The bonding cover layer 203 can be regarded as two layers, inner and outer.

[0049] In some embodiments, the bonding cover layer 203 of the inner wall region 1021 is connected to the overall cover layer 201, and the angle between the bonding cover layer 203 of the inner wall region 1021 and the overall cover layer 201 matches the end corner on the lower side of the dry-type transformer coil 1. The bonding cover layer 203 of the outer wall region 1022 is connected to the overall cover layer 201, and the angle between the bonding cover layer 203 of the outer wall region 1022 and the overall cover layer 201 matches the end corner on the upper side of the dry-type transformer coil 1.

[0050] In this embodiment, by providing fiber mesh 2 on the end face 101 and end side face 102 (including inner wall region 1021 and outer wall region 1022) of the dry-type transformer coil 1, an integral cover layer 201 and a combined cover layer 203 are formed, achieving all-round protection for the ends of the transformer coil. This design not only significantly enhances the mechanical strength of the ends, but also ensures a tight bond between the fiber mesh 2 and the dry-type transformer coil 1 by precisely matching the angle of the coil end corners, thereby providing enhanced mechanical support in both the inner wall region 1021 and the outer wall region 1022. This structural design allows the combined cover layer 203 to more effectively disperse the mechanical stress caused by thermal expansion and contraction during transformer operation, significantly reducing the risk of delamination and cracking in the end region, and further improving the reliability and durability of the transformer. In addition, this structure of the inner and outer combined cover layers 203 also helps to improve the stability of the transformer during long-term operation, ensuring that the transformer maintains high performance under various operating conditions.

[0051] Furthermore, the bonding cover layer 203 of the inner wall region 1021 is parallel to the bonding cover layer 203 of the outer wall region 1022; and / or, the angle between the bonding cover layer 203 of the inner wall region 1021 and the overall cover layer 201 is 90°; and / or, the angle between the bonding cover layer 203 of the outer wall region 1022 and the overall cover layer 201 is 90°.

[0052] In this embodiment, by designing the combined cover layer 203 of the inner wall region 1021 and the outer wall region 1022 to be parallel and perpendicular to the overall cover layer 201, the fiber mesh cloth 2 is adapted in shape to the annular end of the dry-type transformer coil 1. This technical solution not only ensures a tight bond between the fiber mesh cloth 2 and the dry-type transformer coil 1, providing uniform stress distribution and optimized mechanical support, but also enhances the durability of the transformer end, reduces the risk of cracking, simplifies the manufacturing process, improves heat dissipation performance, and provides a neat and beautiful appearance for the transformer, thereby significantly improving the overall performance and service life of the transformer.

[0053] Please continue to refer to this. Figure 2 In some embodiments, the fiber mesh fabric 2 includes a substrate 21, a first side of which has a fiber surface 22 and a second side of which has a mesh surface 23. The fiber surface 22 is located on the side that is in contact with the dry-type transformer coil 1, and the mesh surface 23 is located on the side opposite to the side of the dry-type transformer coil 1 that is in contact with the fiber surface 22.

[0054] In this embodiment, the fiber surface 22 is directly bonded to the dry-type transformer coil 1. This direct contact provides better mechanical bonding, contributing to improved overall structural stability. The mesh surface 23, located on the opposite side, provides protection. This arrangement not only enhances mechanical bonding and insulation performance but also effectively disperses thermal and mechanical stresses, improving the transformer's heat dissipation efficiency and structural stability. It simplifies manufacturing and maintenance, ensures long-term stable operation of the transformer, and enhances product reliability and durability.

[0055] This application also provides the manufacturing process requirements and performance requirements for the fiber mesh cloth 2 laid flat on the end face of the dry transformer coil 1, so as to ensure that the fiber mesh cloth 2 plays a role in skeleton support and crack resistance.

[0056] In one specific embodiment, this application also provides a method for integrated covering of the fiber mesh fabric 2 at the end of a dry-type transformer, used to manufacture the aforementioned integrated covering structure of the fiber mesh fabric 2 at the end of a dry-type transformer. The method for integrated covering of the fiber mesh fabric 2 at the end of a dry-type transformer includes:

[0057] S1, Select fiber mesh fabric 2;

[0058] S2. Wrap the fiber mesh 2 around the end of the dry-type transformer coil 1, and the fiber mesh 2 forms an integral cover layer 201 on the end face 101 of the dry-type transformer coil 1.

[0059] S3. Cut the overall cover layer 201 so that the overall cover layer 201 penetrates the air passage hole 103 of the dry transformer coil 1 and forms a hole surrounding layer 202 extending along the inner wall of the air passage hole 103.

[0060] In some embodiments, step S1, selecting the fiber mesh fabric 2, includes:

[0061] S11. Select a mesh fabric woven from glass fiber; glass fiber is the preferred material.

[0062] S12. Cut the glass fiber into short pieces and spread it on the mesh fabric;

[0063] S13. The needle of the needle punching machine is controlled to repeatedly puncture the short-cut fiber material spread on the mesh cloth to obtain the fiber mesh cloth 2. The side of the fiber mesh cloth 2 with short-cut fiber material is the fiber side 22, and the side of the fiber mesh cloth 2 without short-cut fiber material is the mesh side 23.

[0064] It should be noted that the chopped glass fiber is mainly spread on the mesh fabric, and the needles of the needle punching machine pierce through it, creating a fluffy effect, which is not related to the size of the transformer selected.

[0065] The mesh fabric is supplied in rolls, with a width of 1040mm. After the fibers are spread on the surface, the thickness is 0.5mm. The mesh fabric is supplied in rolls, and after the fibers are spread and needled, it is also supplied in rolls.

[0066] The needle punching machine can be selected as the 88H needle punching machine. The needle plate is made of a composite of a 15mm aluminum-magnesium alloy plate and a 3mm PU plate, with a width of 300mm. The needles corresponding to the needle holes (Φ1.83mm) are digitally controlled, and the needles are arranged randomly and irregularly. The needle plate is smooth, with enlarged holes at the bottom, and a needle depth gauge is used to display the needle depth. After the mesh fabric is laid out by the web laying machine, it is fed into the needle punching area, where the needle punching machine performs needle punching. The needle plate drives the needles to move up and down at high frequency. The grooves on the needles pierce the fibers scattered on the surface to the other side, creating a fluffy effect. By using thousands of rapidly moving needles to repeatedly pierce the short-cut fiber material scattered on the surface, it is tightly bonded to the mesh fabric.

[0067] Among them, the side of the fiber mesh fabric 2 without fibers is the mesh surface 23. Because the needle-punched fibers are on this surface, it appears as a fine fiber cloth with evenly distributed gaps and a fluffy fibrous structure, showing a full and elastic structure. The side of the fiber mesh fabric 2 with fibers is the fiber surface 22, which shows that the fiber bundles are interwoven and arranged in a staggered manner, forming a felt-like structure with a certain thickness and strength.

[0068] In some embodiments, S2, the step of wrapping the fiber mesh 2 around the end position of the dry transformer coil 1 and forming an integral cover layer 201 of the fiber mesh 2 on the end face 101 of the dry transformer coil 1, includes:

[0069] S21. Before winding the dry-type transformer coil 1, fiber mesh cloth 2 is pre-placed on the end side 102 of the inner mold 4 used for winding the dry-type transformer coil 1, so that the first section of the fiber mesh cloth 2 is fixed to the inner mold 4. The fiber mesh cloth 2 has a fiber surface 22 and a mesh surface 23. When pre-placing the fiber mesh cloth 2, the mesh surface 23 is made to fit with the inner mold 4.

[0070] S22. After the dry-type transformer coil 1 is wound, the fiber mesh cloth 2 is wrapped around the end position of the dry-type transformer coil 1, so that the second section of the fiber mesh cloth 2 is fixed to the outer wall area 1022 of the dry-type transformer coil 1. At this time, the first section of the fiber mesh cloth 2 is located in the inner wall area 1021 of the dry-type transformer coil 1, and the cloth section between the first section and the second section of the fiber mesh cloth 2 is located at the end face 101 of the dry-type transformer coil 1.

[0071] In S21, the inner mold 4 is a cylinder made of galvanized sheet metal. Different inner mold specifications are used for coils of different sizes. The inner mold 4 acts as a tooling mold for the inner coil. After the coil is produced and cured, the inner mold is removed. The pre-placement of the fiber mesh 2 refers to laying it flat on the inner mold 4 and then securing it with fiber tape. For example, a 300*300mm fiber mesh 2 is placed on the surface of the inner mold 4, and then secured with 0.13*30mm fiberglass tape.

[0072] In step S22, after the coil is wound, the fiber mesh 2 is turned over to cover the end, wrapping it from the inner wall of the coil to the outer wall, and then fixed with 0.13*30mm fiberglass tape. The fiber mesh 2 should extend a certain distance from the end face 101 into the inner wall 1021 and outer wall 1022 of the coil, i.e., the end side 102. For example, the fiber mesh 2 should extend 50mm into both the inner and outer walls of the coil, forming a bonding cover layer 203. This facilitates fixing and, since stress concentration is at the end face, a 50mm extension is sufficient to strengthen the end face and resist stress-induced cracking.

[0073] In some embodiments, step S3, cutting the integral cover layer 201, and making the integral cover layer 201 penetrate through the air passage hole 103 of the dry-type transformer coil 1 to form a hole surrounding layer 202 extending along the inner wall of the air passage hole 103, includes:

[0074] S31. After the step of forming an integral cover layer 201 on the end face 101 of the dry transformer coil 1 with fiber mesh 2, the integral cover layer 201 is cut with reference to the outline of the air duct plate 3 located at the end of the dry transformer coil 1. The cut opening is smaller than the air duct plate 3 so that the integral cover layer 201 can penetrate the air duct hole 103 shaped in the air duct plate 3, and leave a margin so that the fiber mesh 2 can form a hole surrounding layer 202 extending along the inner wall of the air duct hole 103.

[0075] In S31, since the air passage hole 103 of the dry-type transformer coil 1 is shaped by the air passage plate 3, the position of the air passage hole 103 can be obtained by referring to the air passage plate 3 before the air passage plate 3 is removed. At this position, the fiber mesh cloth 2 is cut open with a blade, and then the fiber mesh cloth 2 is stuffed into the air passage hole 103 to form a hole surrounding layer 202. Based on the overall cover layer 201 and the hole surrounding layer 202, the curved fiber is integrated, eliminating the end face interface and achieving a strengthening effect.

[0076] Preferably, the mesh fabric has a warp density of 48 threads / 10cm, a weft density of 52 threads / 10cm, a single fiber diameter of 11µm, and a basis weight of 145g / m². 2 The thickness is 0.5mm.

[0077] The length of chopped fiber material is 30-80mm.

[0078] The basis weight of fiber mesh fabric 2 is 360±10 g / m. 2 .

[0079] The maximum needle punching frequency of the needle punching machine is 1200 r / min, the fabric speed is 1-12 m / min, the needle density is 4500-5500 needles / m, and the puncture depth is 12-15 mm.

[0080] It should be noted that the higher the needle-punching density, the more needle holes there are and the more they are distributed, resulting in a denser fiber network structure, meaning more fluffy fibers. The greater the puncture depth, the longer the fiber extends to the other side. Currently, the puncture depth is 12-15mm. The length of the fibers sprinkled on the surface (fiber length varies from about 30-80mm) determines the thickness of the fiber mesh after needle-punching. After the glass fibers sprinkled on the surface of the mesh are needled to the other side, the glass fibers and the mesh are connected as one, without falling off or other phenomena, and are tightly bonded together.

[0081] The main material of fiber mesh fabric 2 is alkali-free glass fiber (100%), with a width of 1040mm and a thickness of 0.5mm; product technical requirements: average weight 360±10g / m². 2 Alkali content <0.8%, combustible material 2%~8%, moisture content ≤0.3%.

[0082] In summary, regarding the structure, this technical solution significantly improves the mechanical strength and durability of the dry-type transformer by employing an integrated fiber mesh fabric structure at the coil ends. The fiber mesh fabric covers both the end face and sides of the coil, simultaneously forming an integral covering layer and a perforation surrounding layer on the end face, effectively preventing stress concentration and delamination cracking caused by alternating hot and cold temperatures. Furthermore, the design of the fiber mesh fabric ensures that its first side adheres to the coil to form a fiber surface, while the second side forms a mesh surface, enhancing structural stability. This solution, by precisely matching the angle of the coil end corners, ensures a tight bond between the fiber mesh fabric and the transformer coil, thereby improving the long-term operational stability and overall performance of the transformer.

[0083] In terms of methodology, this technical solution achieves comprehensive protection of the ends of dry-type transformer coils through pre-placed fiber mesh and precise needle punching technology. The method uses alkali-free glass fiber, ensuring the product's insulation and heat resistance, while simplifying manufacturing steps and improving production efficiency and quality control. The needle punching machine, controlled by a digital program, achieves uniformity in the fiber mesh structure and adaptability to complex shapes, while optimized physical parameter control ensures product stability and reliability, ultimately reducing costs and enhancing the product's market competitiveness.

[0084] It should be noted that many of the components mentioned in this application are general standard parts or components known to those skilled in the art, and their structure and principle can be learned by those skilled in the art through technical manuals or through conventional experimental methods.

[0085] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0086] The integrated fiber mesh covering structure and method for the ends of dry-type transformers provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. An integrated fiber mesh fabric covering structure for the ends of a dry-type transformer, characterized in that, The device includes a dry-type transformer coil and a fiber mesh fabric. The fiber mesh fabric is wrapped around the end of the dry-type transformer coil and forms an integral cover layer on the end face of the dry-type transformer coil. The integral cover layer penetrates through the air passage hole of the dry-type transformer coil and forms a hole-enclosing layer extending along the inner wall of the air passage hole. The fiber mesh fabric includes a substrate. The first side of the substrate has a fiber surface and the second side of the substrate has a mesh surface. The fiber surface is located on the side that is in contact with the dry-type transformer coil, and the mesh surface is located on the side of the substrate opposite to the fiber surface.

2. The integrated fiber mesh cover structure at the end of the dry-type transformer according to claim 1, characterized in that, The fiber mesh fabric also forms a bonding cover layer on the end side of the dry-type transformer coil. The bonding cover layer is connected to the overall cover layer, and the angle between the bonding cover layer and the overall cover layer matches the end corner of the dry-type transformer coil.

3. The integrated fiber mesh cover structure at the end of the dry-type transformer according to claim 2, characterized in that, The end side of the dry-type transformer coil is divided into an inner wall region and an outer wall region, and a bonding cover layer is formed on both the inner wall region and the outer wall region. The bonding cover layer of the inner wall region is connected to the overall cover layer, and the angle between the bonding cover layer of the inner wall region and the overall cover layer matches the end corner of the inner side of the dry-type transformer coil. The bonding cover layer of the outer wall region is connected to the overall cover layer, and the angle between the bonding cover layer of the outer wall region and the overall cover layer matches the end corner of the outer side of the dry-type transformer coil.

4. The integrated fiber mesh cover structure at the end of the dry-type transformer according to claim 3, characterized in that, The bonding cover layer of the inner wall region is parallel to the bonding cover layer of the outer wall region; and / or, the angle between the bonding cover layer of the inner wall region and the overall cover layer is 90°; and / or, the angle between the bonding cover layer of the outer wall region and the overall cover layer is 90°.

5. A method for integrated fiber mesh covering at the ends of a dry-type transformer, characterized in that, For manufacturing an integrated fiber mesh fabric covering structure for the end of a dry-type transformer as described in any one of claims 1 to 4, the method for integrated fiber mesh fabric covering the end of the dry-type transformer includes: Select fiber mesh fabric; The fiber mesh is wrapped around the end of the dry-type transformer coil, and the fiber mesh forms an integral cover layer on the end face of the dry-type transformer coil. The integral cover layer is cut so that it penetrates the air passage hole of the dry-type transformer coil and forms a hole surrounding layer extending along the inner wall of the air passage hole.

6. The method for integrated fiber mesh covering at the ends of a dry-type transformer according to claim 5, characterized in that, The step of wrapping the fiber mesh cloth around the end of the dry-type transformer coil, wherein the fiber mesh cloth forms an integral cover layer on the end face of the dry-type transformer coil, includes: Before winding the dry-type transformer coil, the fiber mesh cloth is pre-placed on the end side of the inner mold used to wind the dry-type transformer coil, so that the first section of the fiber mesh cloth is fixed to the inner mold. The fiber mesh cloth has a fiber surface and a mesh surface. When pre-placing the fiber mesh cloth, the mesh surface is made to fit with the inner mold. After the dry-type transformer coil is wound, the fiber mesh cloth is wrapped around the end position of the dry-type transformer coil, so that the second section of the fiber mesh cloth is fixed to the outer wall area of ​​the dry-type transformer coil. At this time, the first section of the fiber mesh cloth is located in the inner wall area of ​​the dry-type transformer coil, and the cloth section between the first and second sections of the fiber mesh cloth is located on the end face of the dry-type transformer coil.

7. The method for integrated fiber mesh covering at the ends of a dry-type transformer according to claim 5, characterized in that, The step of cutting the integral cover layer so that it penetrates the air passage hole of the dry-type transformer coil and forms a hole-enclosing layer extending along the inner wall of the air passage hole includes: After the step of forming an integral cover layer on the end face of the dry-type transformer coil with the fiber mesh, the integral cover layer is cut with reference to the outline of the air duct plate located at the end of the dry-type transformer coil. The cut opening is smaller than the air duct plate so that the integral cover layer can penetrate the air duct hole shaped in the air duct plate, and leave a margin so that the fiber mesh can form a hole surrounding layer extending along the inner wall of the air duct hole.

8. The method for integrated fiber mesh covering at the ends of a dry-type transformer according to claim 6, characterized in that, The fiber mesh fabric has a warp density of 48 threads / 10cm, a weft density of 52 threads / 10cm, a single fiber diameter of 11µm, and a basis weight of 145g / m². 2 The thickness is 0.5mm; The maximum needle punching frequency of the needle punching machine is 1200 r / min, the fabric speed is 1-12 m / min, the needle density is 4500-5500 needles / m, and the puncture depth is 12-15 mm.

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