Anti-cracking long circular dry-type transformer coil

Abstract

The utility model discloses an anti-cracking long circular dry-type transformer coil, which comprises a coil body, and the core improvement lies in that: a first composite filling structure is formed by filling first alkali-free and wax-free glass fiber felt and epoxy resin between coil sections; the coil end is filled with alkali-free and wax-free glass fiber band and is higher than the coil body by a distance; second alkali-free and wax-free glass fiber felt is embedded between the coil body and the terminal socket head; a second composite filling structure is formed by arranging three layers of first epoxy resin grid cloth and epoxy resin in the oblique angle region formed by the two; a continuous framework is formed by coating the outer layer of the coil with second epoxy resin grid cloth; and a gas gap-free resin layer is formed on the surface through vacuum casting. The coil can disperse stress in all directions, and the anti-cracking and anti-impact capabilities are significantly improved.

Description

Technical Field

[0001] This utility model relates to dry-type transformer coils, specifically to a crack-resistant oval dry-type transformer coil. Background Technology

[0002] Dry-type transformers are widely used in critical fields such as data centers and rail transportation due to their advantages such as fire resistance, explosion protection, and ease of maintenance. Currently, high-voltage dry-type transformer coils mostly adopt an oblong structure, which consists of a rectangular section in the middle and semi-circular sections at both ends. Combined with an oblong cross-section iron core (both the core column and the yoke are oblong), this can effectively reduce the core window width by 15%-20%, achieving material and energy savings. However, oblong coils face significant technical bottlenecks in practical applications: Stress concentration leads to cracking: Under conditions of transportation vibration or temperature cycling (-40℃~150℃), the epoxy resin on the surface of the coil needs to withstand alternating tensile and compressive stress, which is prone to cracking under long-term action. Brittle fracture in the beveled area: If the beveled part of the coil edge lacks a reinforcing structure, the pure epoxy resin is very prone to cracking under thermal shock or mechanical vibration, which can lead to partial discharge and, in severe cases, inter-turn short circuit, affecting the service life and operational safety of the transformer. Given the shortcomings of the existing technology, it is necessary to improve the structure of the traditional oblong dry-type transformer coil to solve the problem of poor crack resistance. Summary of the Invention

[0003] The purpose of this invention is to overcome the defect of easy cracking of the long oval dry-type transformer coil in the prior art, and to provide a crack-resistant long oval dry-type transformer coil. Through multi-region structural optimization, the coil's stress resistance and impact resistance are improved.

[0004] To solve the above technical problems, the present invention achieves this through the following solution: The present invention provides a crack-resistant elongated oval dry-type transformer coil, including a coil body, wherein the coil segments of the coil body are filled with a first alkali-free and wax-free glass fiber felt, which fills the segment gaps and forms a first composite filling structure with epoxy resin. The coil end of the coil body is filled with alkali-free and wax-free glass fiber tape and extends a certain distance above the coil body; A second alkali-free and wax-free glass fiber felt is embedded between the coil body and the terminal head; An angled region is formed between the area of ​​the second alkali-free and wax-free glass fiber felt and the coil segment, and between the area of ​​the second alkali-free and wax-free glass fiber felt and the coil end. Multiple layers of first epoxy resin mesh are provided in the angled region, and the multiple layers of first epoxy resin mesh and epoxy resin form a second composite filling structure. The outermost layer of the coil body is covered with a second epoxy resin mesh cloth, which covers the entire axial height of the coil body and forms a continuous skeleton structure with the alkali-free and wax-free glass fiber tape on the coil surface and the first epoxy resin mesh cloth. The surface of the coil body is coated with a vacuum resin layer, which makes the surface of the coil body free of air gaps.

[0005] Furthermore, the thickness of the first alkali-free and wax-free glass fiber mat is 0.5-1.2 mm.

[0006] Furthermore, the compression rate of the first alkali-free and wax-free glass fiber mat is 85% ± 2%.

[0007] Furthermore, the first alkali-free and wax-free glass fiber tape fills 105% of the radial height of the coil body, and its width covers the terminal block and extends 2mm above the edge of the terminal block.

[0008] Furthermore, the filling thickness of the second alkali-free and wax-free glass fiber mat is 80%-90% of the height of the terminal head.

[0009] Furthermore, the angle between the outer plane of the oblique region and the transverse central axis plane of the coil body is 45°±5°.

[0010] Furthermore, the multilayer first epoxy resin mesh fabric has three layers.

[0011] Compared with the prior art, the beneficial effects of this utility model are: the dry-type transformer coil of this utility model solves the problem that the epoxy resin of the elongated oval coil cracks due to transportation vibration and temperature changes, resulting in partial discharge and ultimately causing inter-turn short circuit.

[0012] This utility model addresses the problem of coil cracking by improving the structure of five areas: the coil end, the coil section, the terminal head, the oblique angle, and the outer layer of the coil body. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the dry-type transformer coil of this utility model.

[0014] The diagram shows the following markings: 1. Coil segment 2. Coil end 3. Angled area 4. Second alkali-free and wax-free glass fiber felt 5. Terminal head 6. Coil body Detailed Implementation

[0015] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments, so that the advantages and features of the present utility model can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present utility model. Obviously, the embodiments described in this utility model are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0016] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0017] Example 1: The specific structure of this utility model is as follows: Please refer to the appendix. Figure 1 This utility model discloses a crack-resistant elongated oval dry-type transformer coil, comprising a coil body 6. The coil segments 1 of the coil body 6 are filled with a first alkali-free and wax-free glass fiber felt. This first alkali-free and wax-free glass fiber felt fills the segment gaps, forming a first composite filling structure with epoxy resin. The thickness of the first alkali-free and wax-free glass fiber felt is 0.5-1.2 mm, and its compression rate is 85% ± 2%.

[0018] The coil end 2 of the coil body 6 is filled with alkali-free and wax-free glass fiber tape and extends a certain distance above the height of the coil body. Specifically, the first alkali-free and wax-free glass fiber tape is filled to 105% of the radial height of the coil body, and its width covers the edge of the terminal block and extends 2mm above the edge of the terminal block.

[0019] A second alkali-free and wax-free glass fiber mat 4 is embedded between the coil body 6 and the terminal head 5. The filling thickness of the second alkali-free and wax-free glass fiber mat 4 is 80%-90% of the height of the terminal head 5.

[0020] An angled region 3 is formed between the area of ​​the second alkali-free and wax-free glass fiber felt 4 and the coil segment 1, and between the area of ​​the second alkali-free and wax-free glass fiber felt 4 and the coil end 2. Multiple layers of first epoxy resin mesh are provided in the angled region 3, and the multiple layers of first epoxy resin mesh and epoxy resin form a second composite filling structure. Specifically, the multiple layers of first epoxy resin mesh are provided in three layers, and the angle between the outer plane of the angled region 3 and the transverse central axis plane of the coil body 6 is 45°±5°.

[0021] The outermost layer of the coil body 6 is covered with a second epoxy resin mesh cloth, which covers the entire axial height of the coil body 6 and forms a continuous skeleton structure with the alkali-free and wax-free glass fiber tape on the coil surface and the first epoxy resin mesh cloth. After the above filling measures, a vacuum resin layer is cast onto the surface of the coil body 6 through a vacuum resin casting process, allowing the epoxy resin to fully penetrate into the gaps in the mesh fabric. This vacuum resin layer makes the surface of the coil body 6 air-free, forming an air-free integral structure and ensuring uniform distribution of the coil's mechanical strength.

[0022] Example 2: The following is the improvement process of the dry-type transformer coil of this utility model: (See attached diagram) Figure 1 The specific embodiments of this utility model will be described in further detail.

[0023] like Figure 1 As shown, a crack-resistant oblong dry-type transformer coil includes a coil body 6, and its assembly and processing process is as follows: 1. Pre-treatment stage: Material preparation: Cut the first alkali-free and wax-free glass fiber mat (thickness 0.5-1.2mm) according to the gap size between coil segments 1, and control the cutting error within ±0.1mm; cut the alkali-free and wax-free glass fiber tape according to 105% of the coil width height and the edge coverage requirements of the terminal block, and leave a 2mm allowance in width; cut the second alkali-free and wax-free glass fiber mat 4 according to 80%-90% of the height of the terminal head 5; cut the first and second epoxy resin mesh cloths into shapes that match the corresponding coverage areas. 2. Filling process between coil segments: 2.1 Positioning and Fixing: Place the coil body 6 on the winding machine and adjust the winding machine speed to 5-10 r / min to ensure that the gaps between the coil segments 1 are evenly exposed; 2.2 Felt embedding: The cut first alkali-free and wax-free glass fiber felt is embedded into the gap 1 between the coil segments. During the embedding process, the felt is tightly wrapped with alkali-free and wax-free glass fiber tape to ensure that the felt fits tightly against the gap wall without wrinkles.

[0024] Coil end processing: 3.1 Fiber tape winding: Place the coil body 6 on the winding machine and wind the alkali-free and wax-free glass fiber tape around the coil end 2. When winding, start from the bottom of the coil width and control the overlap rate of each turn to 50% until the filling height reaches 105% of the width of the coil body.

[0025] Terminal head embedding processing: 4.1 Gap Measurement: Measure the gap between the coil body 6 and the terminal head 5 to ensure that the second alkali-free and wax-free glass fiber mat 4 is cut to the correct size; 4.2 Felt installation: Insert the second alkali-free and wax-free glass fiber felt 4 into the gap, ensuring that the felt filling thickness is 80%-90% of the height of the terminal head 5, and that there is no offset.

[0026] Enhanced processing of beveled areas: 5.1 Angle Positioning: Determine the location of the oblique angle region 3; 5.2 Placement of the mesh: Set up 3 layers of epoxy resin mesh (increasing from the root of the coil outwards) and fix it with alkali-free and wax-free fiberglass tape. 6. Outer skeleton coating process: 6.1 Coil positioning: Fix the coil body 6 to ensure that the coil axis is horizontal; 6.2 Mesh Covering: The second epoxy resin mesh is wrapped from one end of the coil, ensuring that it covers the entire axial height of the coil and is completely adhered to the coil surface. 7. Vacuum resin casting process: 7.1 Coil Mold Closure: The process of completely closing the coil body 6 into mold; 7.2 Coil drying: Place the coil in a drying oven, raise the oven temperature to 100℃ and hold for 4 hours, then cool it down to 60℃ and wait for casting.

[0027] 3. Resin casting: Slowly inject epoxy resin (pre-degassed under vacuum at 40℃ for 1 hour) into the mold through the pouring port, controlling the pouring rate at 10-15ml / s, until the resin completely submerges the coil and resin overflows from the vent at the top of the mold. 7.4 Curing: After the coil is cast, place it in a curing oven. Hold at 70℃ for 4 hours, 90℃ for 4 hours, and 125℃ for 4 hours, then cool down to 100℃ with the oven (cooling rate ≤3℃ / h). 7.5 Demolding and finishing: Open the mold, grind off excess resin on the coil surface to ensure a smooth surface without burrs or flash, and finally obtain a crack-resistant oval dry-type transformer coil. Through the above implementation method, the crack resistance of the coil is significantly improved. After testing, no cracks were generated on the coil surface after 100 cycles of temperature cycling from -40℃ to 150℃. After simulated transportation vibration (frequency 5-500Hz, acceleration 10m / s²), the coil structure remained intact and there was no partial discharge phenomenon. Moreover, the air gap rate of the coil surface was ≤0.1%, which meets the requirements of high reliability applications.

[0028] In summary, this utility model of a dry-type transformer coil solves the problem of epoxy resin cracking in the elongated oval coil caused by transportation vibration and temperature changes, leading to partial discharge and ultimately inter-turn short circuits. This utility model of a dry-type transformer coil addresses the coil cracking problem through structural improvements in five areas: the coil ends, between coil sections, at the terminal bevels, at the angles, and the outer layer of the coil body.

[0029] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural or procedural transformations made based on the contents of the present utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present utility model.

Claims

1. A crack-resistant oblong dry-type transformer coil, comprising a coil body (6), characterized in that, The coil body (6) is filled with a first alkali-free and wax-free glass fiber felt between the coil segments (1). The first alkali-free and wax-free glass fiber felt fills the segment gaps and forms a first composite filling structure with epoxy resin. The coil end (2) of the coil body (6) is filled with alkali-free and wax-free glass fiber tape and extends a certain distance above the coil body; A second alkali-free and wax-free glass fiber felt (4) is embedded between the coil body (6) and the terminal head (5). An angled region (3) is formed between the area of ​​the second alkali-free and wax-free glass fiber felt (4) and the coil segment (1), and between the area of ​​the second alkali-free and wax-free glass fiber felt (4) and the coil end (2). In the angled region (3), a multilayer first epoxy resin mesh is provided, and the multilayer first epoxy resin mesh and epoxy resin form a second composite filling structure. The outermost layer of the coil body (6) is covered with a second epoxy resin mesh cloth, which covers the entire axial height of the coil body (6) and forms a continuous skeleton structure with the alkali-free and wax-free glass fiber tape on the surface of the coil and the first epoxy resin mesh cloth. The surface of the coil body (6) is coated with a vacuum resin layer, which makes the surface of the coil body (6) free of air gaps.

2. A crack resistant oblong dry-type transformer coil according to claim 1, characterized in that, The thickness of the first alkali-free and wax-free glass fiber mat is 0.5-1.2 mm.

3. The crack-resistant oblong dry-type transformer coil according to claim 1, characterized in that, The compression rate of the first alkali-free and wax-free glass fiber mat is 85% ± 2%.

4. The crack-resistant oblong dry-type transformer coil according to claim 1, characterized in that, The first alkali-free and wax-free glass fiber tape fills 105% of the radial height of the coil body, and its width covers the terminal block and extends 2mm above the edge of the terminal block.

5. The crack-resistant oblong dry-type transformer coil according to claim 1, characterized in that, The filling thickness of the second alkali-free and wax-free glass fiber mat (4) is 80%-90% of the height of the terminal head (5).

6. A crack resistant oblong dry-type transformer coil according to claim 5, wherein The angle between the outer plane of the oblique region (3) and the transverse central plane of the coil body (6) is 45°±5°.

7. A crack resistant oblong dry-type transformer coil according to claim 1, wherein The multilayer first epoxy resin mesh fabric has three layers.

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