A transformer winding insulation layer, a method of winding the same and a transformer winding

Abstract

This invention relates to a transformer winding insulation layer, its winding method, and a transformer winding, belonging to the field of transformer manufacturing technology. The invention provides a transformer winding insulation layer comprising an outer impregnated current-conducting layer, a middle main insulation layer, and an inner hot-melt adhesive layer, sequentially stacked and hot-pressed along the thickness direction. The inner hot-melt adhesive layer has initial tack at room temperature, enabling tape-free pre-positioning, softening and melting under hot pressing, and forming a gap-free interface with in-situ bonding to the conductor after cooling. The outer impregnated current-conducting layer has flow-guiding grooves on its surface to guide the flow of the impregnating medium. Pre-pressed creases are provided on both sides of the insulation layer for folding to form an integrated end insulation. The inner layer surface has anti-slip protrusions. The invention also provides a winding method, including pre-positioning, constant tension laying, online hot-pressing curing, and end-flanging steps. This effectively solves problems of interlayer displacement, air gap residue, uneven impregnation, and end insulation dispersion, improving the reliability and uniformity of winding insulation.

Description

Technical Field

[0001] This invention belongs to the field of transformer manufacturing technology, specifically referring to a transformer winding insulation layer, its winding method, and a transformer winding. Background Technology

[0002] Transformer windings are the core components of a transformer, and the reliability of their interlayer insulation structure directly determines the transformer's electrical life and operational safety. During transformer manufacturing, windings are typically constructed by alternating layers of conductors and interlayer insulation, supplemented by vacuum impregnation or epoxy casting processes to achieve overall insulation curing.

[0003] Currently, sheet-like insulating materials such as adhesive paper, crepe paper, or prepreg are commonly used for interlayer insulation in transformer windings. In actual production, these materials are usually supplied in roll form and are laid layer by layer between conductor layers manually or semi-automatically, relying on mechanical tension control and operator experience to achieve positioning and bonding.

[0004] However, in practical applications, the following drawbacks exist: First, traditional insulation materials have a low surface friction coefficient (typically μ < 0.2) and lack an active bonding mechanism. Under high-speed or high-tension winding conditions, the insulation layer is prone to axial slippage, leading to interlayer misalignment. In severe cases, this results in insufficient end insulation distance, directly affecting the withstand voltage performance of the winding. Second, the winding end insulation typically uses independently molded insulation rings, pads, or end rings, requiring a separate assembly process. This structure has inherent limitations such as low alignment accuracy, weak interface with the main insulation layer, and easy cracking due to mismatched material thermal expansion coefficients, making it a weak link in the transformer insulation system. Summary of the Invention

[0005] In view of the above situation and to overcome the defects of the prior art, the purpose of the present invention is to provide a transformer winding insulation layer to at least partially solve the problems mentioned in the background art.

[0006] The technical solution adopted by the present invention is as follows: On the one hand, a transformer winding insulation layer is proposed, including a main insulation structure for providing electrical insulation; the main insulation structure is a multi-layer composite strip that is stacked and hot-pressed together along the thickness direction, and from the outside to the inside, it includes: an outer impregnation and guiding layer with a loose porous structure for guiding the flow of impregnation medium, an intermediate main insulation layer with high dielectric strength and dimensional stability, and an inner hot-melt adhesive layer; The inner hot melt adhesive layer is dry and solid at room temperature and has initial tack, which is used to achieve tape-free pre-positioning between the insulation layer and the wire. Under conditions of heating to 80℃~150℃ and applying pressure of 0.2MPa~0.5MPa, the inner layer softens and melts, wetting the microstructure of the conductor surface. After cooling, a cross-linked curing interface is formed that bonds the insulation layer and the conductor in situ.

[0007] Preferably, the outer surface of the outer impregnated flow guiding layer is provided with flow guiding grooves, which are formed by embossing process. The groove depth is 1 / 5 to 1 / 3 of the outer layer thickness, the groove width is 0.1 mm to 0.3 mm, and they are distributed in a grid or "rice" shape.

[0008] Preferably, the main insulation structure has pre-pressed creases on both sides of the width direction. The pre-pressed creases are continuous wavy or V-shaped creases with a depth of 0.02mm to 0.05mm. They are used to fold the portion of the insulation layer that exceeds the axial width of the winding along the creases during the winding process and attach it to the end face of the winding to form an integrated end insulation structure.

[0009] Preferably, the inner hot-melt adhesive layer has anti-slip bumps on the surface of the conductor. The anti-slip bumps are arranged in a diamond or mesh array, with a diameter of 0.2mm to 0.4mm, a height of 0.05mm to 0.1mm, and a spherical transition structure at the top.

[0010] Preferably, the material of the inner hot-melt adhesive layer is selected from at least one of epoxy resin film and low-melting-point polyester fiber, wherein the glass transition temperature of the epoxy resin film is 90℃~110℃ and the melting point of the low-melting-point polyester fiber is 120℃~135℃.

[0011] On the other hand, a method for winding the insulation layer of transformer windings is proposed, including the following steps: By utilizing the initial tack of the inner hot melt adhesive layer at room temperature, the first end of the main insulation structure is attached to the surface of the starting wire without tape, thus completing the pre-positioning. The insulation layer is conveyed by a constant tension feeding device with a tension of 5N to 10N and a feeding speed slightly lower than the wire winding speed, so as to achieve constant tension laying and simultaneously remove interlayer air. After each layer of winding is completed, an infrared heating roller or hot air device is immediately used to heat the entire width of the insulation layer at a temperature of 120℃~150℃ and maintain it at a pressure of 0.2MPa~0.5MPa for 20s~60s to soften and melt the inner layer and solidify it in situ. During the final winding process, the excess portion of the insulation layer on both sides is folded 90° along the pre-pressed crease and attached to the winding end face and side face. Then, it is locally cured by short-term heating at 110℃~125℃ to form continuous end insulation.

[0012] Preferably, the constant tension feeding device is set to feed speed of 95% to 99% of the winding linear speed, so that the insulation layer is kept in a taut state during the winding process to remove interlayer air.

[0013] Preferably, in the end-flanging step, the local heating time after folding is 3s to 10s.

[0014] A transformer winding is also provided, including a conductor layer and an insulation layer. The insulation layer is wound alternately with the conductor layer by any of the aforementioned winding methods, and a gapless bonding interface is formed between the insulation layer and the conductor layer by in-situ curing of the inner hot-melt adhesive layer.

[0015] Beneficial effects: Relying on the micro-adhesive properties of the inner hot melt adhesive layer at room temperature, tape-free pre-positioning of the winding head can be achieved. Combined with the mechanical interlocking effect of the anti-slip protrusions, the axial movement of the winding during the winding process can be effectively suppressed.

[0016] The design of pre-compression creases on both sides allows the edge portion of the insulation layer that exceeds the axial width of the conductor layer to be folded during winding, forming an integrated end insulation structure. This replaces the traditional independent end insulation ring, significantly reducing the assembly error and air gap risk of the end insulation, thereby improving the overall dielectric strength and heat dissipation uniformity of the winding. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a transformer winding structure proposed in an embodiment of the present invention; Figure 2 This is a schematic diagram of a transformer winding insulation layer structure according to an embodiment of the present invention; Figure 3 for Figure 2 Schematic diagram of the middle guide layer; Figure 4 for Figure 2 Schematic diagram of the inner thermal fusion adhesive layer of the middle conductor; Figure 5 This is a schematic diagram of a method for winding the insulation layer of a transformer winding according to an embodiment of the present invention.

[0018] Among them, 1. Main insulation structure; 11. Conduction layer; 111. Conduction groove; 112. Pre-compression crease; 12. Main insulation layer; 13. Inner hot melt adhesive layer; 131. Protrusion; 2. Ventilation channel; 3. Conductor layer.

[0019] The accompanying drawings are provided to help readers gain a deeper understanding of this embodiment and are an integral part of the specification. They are used together with this embodiment to illustrate the invention, but do not constitute a limitation on the scope of protection of this embodiment. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection.

[0021] In the description of the embodiments, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments.

[0022] In a first aspect of the present invention, a transformer winding insulation layer is provided, which is mainly used to solve the problems of interlayer displacement between the conductor layer 3 and the insulation layer during the winding process of the transformer winding and uneven impregnation during resin casting, so as to avoid air gap defects and thus significantly improve the overall insulation strength of the winding.

[0023] Example 1 Specifically, in this embodiment, the transformer winding insulation layer includes a main insulation structure 1, which is disposed between the conductor layers 3 and performs the functions of isolation and insulation. Ventilation channels 2 are also provided between adjacent conductor layers 3 to ensure the heat dissipation efficiency of the winding. During manufacturing, the main insulation structure 1 is disposed on both sides of the ventilation channel 2.

[0024] like Figures 1-4 As shown, the main insulation structure 1 provided in this embodiment is a multilayer composite tape that is stacked and hot-pressed together along the thickness direction. From the outside to the inside (i.e., from the side away from the conductor layer 3 to the side closer to the conductor layer 3), it includes: a current-conducting layer 11, a main insulation layer 12, and an inner hot-melt adhesive layer 13.

[0025] In existing technologies, the surface of the insulation layer is smooth and dense, lacking structural features that guide the flow of varnish in a directional manner. This results in slow lateral diffusion of the varnish along the interlayer during vacuum impregnation, especially in the inner layer region of the winding, which easily forms impregnation blind zones, causing a decrease in local insulation performance and a reduction in heat dissipation capacity.

[0026] In this embodiment, the flow guiding layer 11 is made of polypropylene nonwoven fabric with a thickness of 0.2 mm and has a loose porous structure. The flow guiding layer 11 can form a penetrating capillary channel in the subsequent vacuum impregnation stage to guide the impregnating paint liquid to quickly and evenly penetrate into the winding interior.

[0027] like Figure 3As shown, the outer surface of the flow guide layer 11 (i.e., the side away from the main insulation layer 12) is processed by embossing to form flow guide grooves 111. The flow guide grooves 111 are evenly distributed in a "rice" shape on the outer surface of the flow guide layer. The groove width of the flow guide grooves 111 can be set between 0.1 mm and 0.3 mm, preferably 0.15 mm, and the groove depth is 1 / 5 to 1 / 3 of its thickness, preferably 0.05 mm. The flow guide grooves 111 cover the effective width of the entire flow guide layer 11, ensuring unobstructed channels in any direction.

[0028] In the vacuum impregnation stage, the flow guide grooves 111 and the pores of the main body of the flow guide layer 11 form a composite flow guide network: when the impregnation tank is evacuated, the paint liquid preferentially advances rapidly longitudinally along the low-resistance channels under the drive of negative pressure. As shown in relevant experiments and simulation studies, such a flow guide structure can act as a paint liquid circulation channel, accelerating the mold filling process, breaking the limitation that the paint liquid in traditional homogeneous materials only slowly penetrates by capillary action, and at the same time, avoiding "short circuits" or "flow interruption" of the flow channels due to excessive surface tension. In addition, combined with the characteristics of the vacuum impregnation process, a reasonable flow guide structure can avoid problems caused by blindly pursuing high vacuum or high pressure, ensuring the impregnation efficiency and quality.

[0029] The porous structure of the flow guide layer 11 and the surface flow guide grooves 111 work together to form a composite flow guide network. When impregnating with paint, the paint liquid can penetrate efficiently in both longitudinal and transverse directions, improving the thickness uniformity of the paint film.

[0030] Secondly, the main insulation layer 12 is made of a polyimide film with a 0.1 mm thickness and double-sided silicone coating, which has high dielectric strength and dimensional stability. The main insulation layer 12 provides the core electrical isolation and mechanical support functions. Its silicone coating forms a good interfacial bond with the adjacent flow guide layer 11 and the inner heat-melt adhesive layer 13 during the hot pressing and composite process, while maintaining the low hygroscopicity and high insulation resistance of the film itself.

[0031] Finally, the inner heat-melt adhesive layer 13 can be made of an epoxy resin film. The film surface is dry and slightly sticky at 25°C, enabling tape-free pre-positioning between the main insulation structure 1 and the wire layer 3. Among them, the glass transition temperature of the epoxy resin film is 95°C to 105°C, the softening point is 95°C ± 5°C, the curing starting temperature is 115°C ± 5°C, it completely softens and flows and has good wettability above 120°C, and can complete interfacial cross-linking curing by maintaining for 30 seconds at 130°C and 0.3 MPa pressure. After curing, the shear strength ≥ 15 MPa. As Figure 4As shown, the inner hot-melt adhesive layer 13 has anti-slip bumps 131 on its surface facing the conductor layer 3. These anti-slip bumps 131 are formed by micro-gravure roller pressing on the epoxy film surface, arranged in an array with a spacing of 2mm × 2mm. The diameter of the bumps 131 is 0.2mm to 0.4mm, preferably 0.3mm, and the height is 0.05mm to 0.1mm, preferably 0.08mm. The top has a spherical transition structure. The bumps 131 are made of the same material as the inner hot-melt adhesive layer 13, both belonging to the epoxy resin system, ensuring no interface compatibility issues after hot-pressing and curing. During the winding process, the anti-slip bumps 131 are embedded in the microstructure of the paint film on the surface of the conductor layer 3, forming a mechanical interlocking effect and significantly increasing the static friction at the contact interface.

[0032] By utilizing the slight tack of the inner hot-melt adhesive layer 13 at room temperature, tape-free pre-positioning of the first end is achieved. Combined with the mechanical interlocking effect of the anti-slip protrusions 131, axial movement during the winding process can be effectively suppressed. During the winding process, the inner hot-melt adhesive layer 13 undergoes hot-press curing first, allowing the insulation layer and conductor layer 3 to simultaneously complete interfacial cross-linking, avoiding the interlayer stress accumulation caused by traditional post-curing.

[0033] Preferably, after the main insulation structure 1 is composited, pre-compression creases 112 are provided on both sides of its width direction, and the pre-compression creases 112 are symmetrically distributed along the width direction. These pre-compression creases 112 are formed by applying a 0.6MPa linear pressure, a 0.8mm width, and a 0.03mm depth continuous wavy indentation at a distance of 3mm from the edge using a servo rolling mill. The indentation period is 5mm, with alternating peaks and troughs, giving the material controllable bending deformation capability along the crease direction. The crease extension length is consistent with the full width of the main insulation structure 1, covering the entire winding area from the starting end to the ending end. During the winding process, the portion of the insulation layer exceeding the axial width of the winding is folded along the crease and adhered to the winding end face, forming an integrated end insulation structure.

[0034] The design of the pre-compression creases 112 on both sides allows the edge portion of the insulation layer that exceeds the axial width of the conductor layer 3 to be folded during the winding process, forming an integrated end insulation structure to replace the traditional independent end insulation ring. This significantly reduces the end insulation assembly error and air gap risk, and improves the overall dielectric strength and heat dissipation uniformity of the winding.

[0035] The three-layer structure described above is laminated in a hot press at 100°C and 0.8 MPa pressure for 60 seconds to form a complete roll material. The lamination temperature is strictly controlled above the film softening point (approximately 95°C) and below the curing initiation temperature (approximately 115°C) to ensure that the film remains in a flowable viscoelastic state and does not prematurely cross-link. The layers are bonded together by hot pressing without the use of adhesive coating or release paper, ensuring clean interlayer interfaces and uniform thickness.

[0036] like Figure 5As shown, another aspect of this invention provides a method for winding a transformer winding, comprising the following steps: Step 1: Reserve a table After one of the conductor layers 3 is wound, during the winding of subsequent windings, the first end of the main insulation structure 1 is manually and lightly pressed onto the surface of the conductor layer 3 using the slight tack of the inner hot-melt adhesive layer 13 at 25°C. During attachment, ensure that the axial centerline of the main insulation structure 1 is aligned with the axial centerline of the conductor layer 3. This step requires no tape or adhesive application, avoiding tape residue and secondary cleaning processes required in traditional processes.

[0037] Step 2: Constant tension laying A pneumatic constant tension feeding frame is used to transport the main insulation structure 1. The feeding tension is set between 5N and 10N, preferably 7.5N, and the feeding speed is set to 95% to 99% of the winding linear speed, preferably 98%, so that the main insulation structure 1 is always in a slightly stretched state (elongation of about 0.3% to 0.5%) during the winding process, thereby automatically removing interlayer air. The constant tension feeding frame is equipped with a tension sensor and a closed-loop control system, and the tension fluctuation is controlled within ±0.5N to ensure the stability of the laying process.

[0038] The mechanical interlocking effect between the anti-slip protrusions 131 and the surface of the conductor layer 3 enables the main insulation structure 1 to maintain zero slippage under the condition of winding tension fluctuation. The measured axial displacement is ≤0.15mm, and the alignment accuracy between winding layers reaches ±0.2mm.

[0039] Step 3: Online hot pressing curing After each layer of winding is completed, an 80mm diameter infrared heating roller moves along the outer edge of the winding to perform online hot-press curing of the inner hot-melt adhesive layer 13. During the hot-pressing process, infrared radiation penetrates the conductive layer 11 and the main insulation layer 12, directly acting on the inner hot-melt adhesive layer 13. Its heating temperature is controlled within the range of 120℃ to 150℃, causing its temperature to rise rapidly to above 130℃. Under a pressure of 0.3MPa, the molten epoxy resin spreads and penetrates along the gaps formed by the microgrooves and anti-slip protrusions 131 on the surface of the conductor layer 3, filling the tiny gaps between the conductors. Subsequently, under natural cooling or forced air cooling conditions, the epoxy resin undergoes cross-linking and curing, forming a cross-linked cured interface that bonds the main insulation structure 1 and the conductor layer 3 in situ.

[0040] Step 4: End Flanging During the final winding process, the portions of the main insulation structure 1 extending beyond the axial width of the winding on both sides are simultaneously folded 90° along the pre-compression crease 112, so that they fit tightly against the winding end face and sides. After folding, a hot air gun is used to heat the structure at 110°C for a short time of 3 to 10 seconds, preferably 5 seconds, to cause the inner hot-melt adhesive layer 13 to partially melt in the bending area, forming continuous end insulation.

[0041] Example 2 This embodiment provides an insulation layer suitable for dry-type transformer windings. Its structure is basically the same as that of Embodiment 1, with only the material selection being adjusted for compatibility.

[0042] Specifically, the flow guiding layer 11 is made of fiberglass mesh with a thickness of 0.25 mm and a mesh aperture of approximately 0.1 mm. The fiberglass mesh has excellent compatibility with the epoxy resin used in the casting of dry-type transformers, forming a mechanical interlock with the casting resin during vacuum casting, thus enhancing the interfacial bonding strength. Its surface is also provided with the same flow guiding grooves 111, which serve the same function.

[0043] Secondly, the main insulation layer 12 is made of aramid paper, which has a temperature resistance rating of 220℃ (Class C) and is compatible with the insulation system of dry-type transformers. Aramid paper has excellent heat resistance, flame retardancy and mechanical toughness, and forms a good interface bond with glass fiber mesh and inner hot melt adhesive layer 13 during hot pressing and lamination.

[0044] Finally, the inner hot-melt adhesive layer 13 is made of low-melting-point polyester fiber web with an areal density of 15 g / m², a fiber diameter of 20 μm, and a melting point of 125℃±5℃. At room temperature, this fiber web is dry and has a slightly fuzzy feel. It can achieve pre-positioning with the conductor layer 3 by relying on the mechanical interlocking between fibers and van der Waals forces.

[0045] Furthermore, the pre-compression crease 112 in this embodiment is a V-shaped crease.

[0046] Furthermore, such as Figure 1 As shown, transformer windings prepared using the above methods and insulation structures exhibit continuous, gap-free end insulation after vacuum impregnation or epoxy casting and curing. This type of process can fully fill the air gaps within the winding, remove moisture contained in the insulation material, thereby effectively improving the overall dielectric strength, significantly enhancing insulation reliability, and simultaneously improving the winding's moisture resistance, heat resistance, and heat dissipation, while also delaying insulation aging.

[0047] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0048] The embodiments have been described above, and such description is not restrictive. The figures shown are only one embodiment, and the actual structure is not limited to this. In short, if a person skilled in the art is inspired by this description and designs a similar structure and embodiment without departing from the inventive spirit, such design should fall within the scope of protection.

Claims

1. A transformer winding insulation layer, comprising a main insulation structure (1) for providing electrical insulation; characterized in that The main insulation structure (1) includes a multilayer composite tape that is stacked and hot-pressed together along the thickness direction, and from the outside to the inside, it includes: an outer impregnation and flow guiding layer (11) with a loose and porous structure for guiding the flow of the impregnation medium, a middle main insulation layer (12), and an inner hot-melt adhesive layer (13). The inner hot melt adhesive layer (13) is dry and solid at room temperature and has initial tack, which is used to achieve tape-free pre-positioning between the insulation layer and the wire; Under conditions of heating to 80℃~150℃ and applying pressure of 0.2MPa~0.5MPa, the inner layer softens and melts, wetting the microstructure of the conductor surface. After cooling, a cross-linked curing interface is formed that bonds the insulation layer and the conductor in situ.

2. The transformer winding insulation layer of claim 1, wherein, The outer surface of the outer impregnated flow guide layer (11) is provided with flow guide grooves (111). The flow guide grooves (111) are formed by embossing process. The groove depth is 1 / 5 to 1 / 3 of the outer layer thickness, the groove width is 0.1 mm to 0.3 mm, and they are distributed in a grid or "rice" shape.

3. The transformer winding insulation layer of claim 1, wherein, The main insulation structure (1) has pre-pressed creases (112) on both sides of the width direction. The pre-pressed creases (112) are continuous wavy or V-shaped creases with a depth of 0.02mm to 0.05mm. They are used to fold the part of the insulation layer that exceeds the axial width of the winding along the crease during the winding process and attach it to the end face of the winding to form an integrated end insulation structure.

4. The transformer winding insulation layer of claim 1, wherein, The inner hot melt adhesive layer (13) has anti-slip bumps (131) on the surface facing the conductor. The anti-slip bumps (131) are arranged in a diamond or mesh array. The diameter of the bumps (131) is 0.2mm to 0.4mm, the height is 0.05mm to 0.1mm, and the top is a spherical transition structure.

5. The transformer winding insulation layer of claim 1, wherein, The material of the inner hot melt adhesive layer (13) is selected from at least one of epoxy resin film and low melting point polyester fiber, wherein the glass transition temperature of epoxy resin film is 90℃~110℃ and the melting point of low melting point polyester fiber is 120℃~135℃.

6. A method of winding a transformer winding with the insulation layer according to any one of claims 1 to 5, characterized in that Includes the following steps: Using the initial tack of the inner hot melt adhesive layer (13) at room temperature, the first end of the main insulation structure (1) is attached to the surface of the starting wire without tape to complete the pre-positioning; The insulation layer is conveyed by a constant tension feeding device with a tension of 5N to 10N and a feeding speed slightly lower than the wire winding speed, so as to achieve constant tension laying and simultaneously remove interlayer air. After each layer of winding is completed, an infrared heating roller or hot air device is immediately used to heat the entire width of the insulation layer at a temperature of 120℃~150℃ and maintain it at a pressure of 0.2MPa~0.5MPa for 20s~60s to soften and melt the inner layer and solidify it in situ. During the winding of the last layer, the excess portion on both sides of the insulation layer is folded 90° along the pre-pressed crease (112) and attached to the winding end face and side face. Then, it is heated for a short time at 110℃~125℃ to complete local curing and form continuous end insulation.

7. The method of winding a transformer winding insulation layer according to claim 6, characterized in that, The constant tension feeding device is set to feed at 95% to 99% of the winding linear speed, so that the insulation layer is kept taut during the winding process to remove interlayer air.

8. The method of claim 6, wherein the step of winding the transformer winding insulation layer is characterized by, In the end-flanging step, the local heating time after folding is 3s to 10s.

9. A transformer winding, characterized by It includes a conductor layer (3) and a transformer winding insulation layer as described in any one of claims 1 to 5, wherein the insulation layer is wound alternately with the conductor layer (3) by the winding method described in any one of claims 6 to 8, and forms a gapless bonding interface with the winding layer through in-situ curing of the inner hot melt adhesive layer (13).

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