A filling method for resisting cracking in the tapping area of ​​a dry-type transformer panel

Abstract

A method for filling and reinforcing the panel tapping area of ​​a dry-type transformer to prevent cracking is disclosed. The method first divides the panel tapping area to be filled and reinforced into the following: corner filling and reinforcement areas on both sides of the panel, a filling and reinforcement area at terminal 2, a panel surface filling and reinforcement area, an insulation wrapping area for terminal lead wires and a terminal surface filling and reinforcement area, and a first and last terminal cavity filling and reinforcement area; then, the corner filling and reinforcement areas on both sides of the panel, the terminal filling and reinforcement areas, the surface filling and reinforcement areas at tangent positions on both sides of the panel, the insulation wrapping area for terminal lead wires and the terminal surface filling and reinforcement area, and the first and last terminal cavity filling and reinforcement areas are reinforced in sequence; the method ensures that the filled and reinforced dry-type transformer can be stored and powered on under the standard requirements of C3 or even C4 climate grade performance, while greatly improving the anti-cracking performance.

Description

Technical Field

[0001] The invention relates to the technical field of transformer construction, and in particular to a method for filling a tapping area of ​​a dry-type transformer panel to prevent cracking. Background Art

[0002] Both IEC 60076-11 and GB / T 1094.11 clearly define the operating conditions for transformers in various climate classes and clearly outline the standard requirements for dry-type transformer climate performance levels. This means that the market for dry-type cast transformers is shifting towards requirements for storage and operation in increasingly stringent climates. Currently, dry-type transformers with C2 climate performance levels struggle to adapt to storage and operation in these harsh climates and are unable to meet the demands of both domestic and international markets.

[0003] As is well known, the most prone areas for cracking in dry-type cast transformers under various climate levels are the panels and panel tap terminals. During thermal shock tests at -40°C to -50°C, the coil panel tap area generates strong traction, resulting in excessively concentrated stress and a high risk of cracking. Existing technology simply pads the panel tap area with glass fiber mesh at the base of the tap lead. This approach only meets the requirements for dry-type transformers stored and operated at -25°C, but cannot guarantee that the cast coil panel tap area will be free of cracks when stored and operated under the performance standards of C3 or even C4 climate levels. Summary of the Invention

[0004] To overcome the deficiencies of the above-mentioned prior art, the present invention aims to provide a method for filling the tap area of ​​a dry-type transformer panel to resist cracking. The method reinforces the panel in a manner that conforms to the shape of the coil, with special reinforcement provided for the corners on both sides of the panel, the glass fiber mesh cloth under the terminals, the insulation wrapping of the terminal lead wires, and the anti-cracking performance of the terminal surface. The filling in the tap area of ​​the panel better conforms to the panel structure, and the glass fiber mesh cloth filling in each part is full and comprehensive, with extremely high crack resistance. It has been verified that it can meet the requirements of C3-C4 climate grade products.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0006] A method for filling the tapping area of ​​a dry-type transformer panel to prevent cracking, specifically comprising the following steps:

[0007] Step 1: Divide the panel tapping area that needs to be filled and reinforced: including the corner filling and reinforcement area on both sides of panel 1, the filling and reinforcement area at terminal 2, the surface filling and reinforcement area at panel 1, the insulation wrapping of terminal 2 lead wire and the filling and reinforcement area on the surface of terminal 2, and the filling and reinforcement area inside the first and last terminal 2 cavities;

[0008] Step 2: Fill and reinforce the corners on both sides of panel 1

[0009] Use filler material to roll into a cylindrical support and place it close to both sides of panel 1 to strengthen the corners where panel 1 and coil 4 are connected and to alleviate the gap at the connection. The width of the roll of filler material is (width of panel 1 - 10) mm and the length is equal to the height of coil 4.

[0010] Step 3: Fill and reinforce the terminal 2 area

[0011] Fill the area around terminal 2 and between tap terminals 3 with a layer of filling material. The thickness should meet the insulation distance requirements of the drawing. The minimum distance between the lead wire of terminal 2 and the outer surface of the outermost layer of wire of coil 4 should be ≥30mm. The minimum distance between the lead wire of tap terminal 3 and the outer surface of the outermost layer of wire of coil 4 should be ≥15mm. The width should not exceed the width of panel 1.

[0012] Step 4: Fill the reinforcement area on the tangent position of both sides of panel 1

[0013] Use filling material 2 to cover panel 1 and the corner filling and reinforcement areas on both sides of panel 1 in step 1. The covering length is equal to the height of coil 4, and the width covers the tangent formed by panel 1 and the corner filling and reinforcement areas on both sides.

[0014] Step 5: Insulate the terminal lead wires and reinforce the terminal surface with reinforced areas.

[0015] Use three half-folds of filler material to wrap the lead wire of terminal 2 and the end of terminal 2 to 2-3 mm near terminal 2, and then wrap it in half a layer for reinforcement;

[0016] Step 6: Fill the reinforcement area in the first and last terminal cavities

[0017] The filling material is cut into a ring shape according to the terminal cavity structure and arranged in each creeping umbrella in the terminal cavity for filling and reinforcement.

[0018] In the step 2 of filling and reinforcing the corners on both sides of the panel 1, the filling material is rolled up and filled and reinforced in sections or in a whole strip axially on both sides of the panel 1.

[0019] In step 6, the filling material is cut into a ring shape according to the terminal cavity structure, and its outer diameter is adapted to the inner diameter of the placement cavity.

[0020] The first filling material is glass fiber mesh cloth.

[0021] The second filling material is a laminated glass fiber chopped strand mat and a glass fiber mesh cloth; the inner layer is the glass fiber chopped strand mat and the outer layer is the glass fiber mesh cloth.

[0022] The third filling material is a laminated glass fiber chopped strand mat and a glass fiber cloth tape; the inner layer is the glass fiber chopped strand mat and the outer layer is the glass fiber cloth tape.

[0023] Compared with the prior art, the present invention has the following technical effects:

[0024] The present invention uses glass fiber mesh cloth to reinforce the panel in a manner that "follows" the coil shape, including corner reinforcement on both sides of the panel, reinforcement of the glass fiber mesh cloth under the terminal, insulation wrapping of the terminal lead wire and special reinforcement of the terminal surface to prevent cracking. Compared with the existing technology, the glass fiber mesh cloth filling in the panel joint area is more in line with the panel structure, and the glass fiber mesh cloth filling in each part is full and comprehensive, which greatly improves the anti-cracking performance.

[0025] The corner reinforcement 1 on both sides of the panel is to use glass fiber mesh cloth rolled into a cylindrical support to strengthen the corners of the plane and the connection area. The width is the panel width a1-10mm, and the filling length is equal to the coil height. This filling method better opens the channel for the fluidity of epoxy resin during the coil casting process, which is convenient for better penetration of resin. The rolled cylindrical structure supports both sides of the panel. There will be no tip discharge in the coil panel after casting. The electrical performance is guaranteed. At the same time, the thicker areas on both sides of the panel are reinforced with grid insulation. The organic combination of epoxy resin and mesh cloth greatly improves the mechanical strength of the panel. Even if the product is operated in an environment of -40℃ or even worse, there will be no cracking problem at this place.

[0026] The terminal part reinforcement 2 is filled with glass fiber mesh cloth. The thickness is mainly 0.6-0.8mm thick glass fiber mesh cloth cut or folded into an insulating block with a total thickness of 15mm or 30mm for padding. Ensure that the head and tail terminals are ≥30mm away from the outer surface of the coil wire, and the tap terminal position is ≥15mm away from the outer surface of the coil wire. The width shall not exceed the panel width. The filling method of the insulating block can effectively ensure the safe distance between the terminals. At the same time, the terminal position is a place where internal stress is more concentrated. The internal stress is too concentrated. During the internal stress release process, it is easy to cause the terminal part to crack due to inadequate insulation filling. The insulation reinforcement here solves the cracking problem caused by internal stress concentration and improves the mechanical strength of the terminal part.

[0027] The surface reinforcement 3 at the tangent position on both sides of the panel is made of glass fiber chopped strands mat and glass fiber mesh cloth as filling materials. The length is equal to the coil height, and the width covers the tangent position for filling and reinforcement. In order to facilitate smooth wiring at the tapping position, the design margin at the tangent position on both sides of the panel is large. At the same time, the resin casting layer at the tangent is thicker. The thicker the resin casting layer, the greater the risk of cracking. The combined filling method of glass fiber chopped strands mat and glass fiber mesh cloth enhances the mechanical strength of the tangent position and improves the anti-cracking performance here.

[0028] The insulation wrapping of the terminal lead wires and the terminal surface reinforcement 4 are reinforced with glass cloth tape and chopped glass mat, which are half-lapped and reinforced. This ensures that the insulation properties meet the requirements while facilitating resin infiltration and improving the mechanical strength of the terminal lead wires. The terminals are also wrapped with glass cloth tape and continuous glass mat. The upper 2-3mm area of ​​the terminal does not need to be wrapped, ensuring good contact surface and conductivity while also improving the crack resistance of the terminal surface.

[0029] The front and rear terminal cavities are reinforced with glass mesh fabric cut into a specific shape to accommodate the circular structure of the terminal cavity. To facilitate the extraction of the terminal lead wires from the cavity, the glass mesh fabric is cut into a ring shape in the middle, with an outer diameter that matches the inner diameter of the cavity. The glass mesh acts as insulation and reinforcement within the terminal cavity, significantly improving the mechanical strength of all parts within the cavity and further enhancing its crack resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 1 is a top view of the panel area filling of the present invention.

[0031] Figure 2 It is the panel area of ​​the present invention that fills the main view.

[0032] Figure 3 It is a side view of the panel area filling of the present invention.

[0033] Figure 4 It is a schematic diagram of the reinforcement of the filling reinforcement area at the terminal 2 of the present invention.

[0034] In the figure: 1. Panel; 2. Terminals; 3. Tap terminals; 4. Coil; DETAILED DESCRIPTION

[0035] The present invention is further described in detail below with reference to the accompanying drawings.

[0036] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0037] See also Figures 1 to 3 A method for filling the tapping area of ​​a dry-type transformer panel to prevent cracking, comprising the following steps:

[0038] Step 1: Divide the panel tapping area that needs to be filled and reinforced: including the corner filling and reinforcement area on both sides of panel 1, the filling and reinforcement area at terminal 2, the surface filling and reinforcement area at panel 1, the insulation wrapping of terminal 2 lead wire and the filling and reinforcement area on the surface of terminal 2, and the filling and reinforcement area inside the first and last terminal 2 cavities;

[0039] Step 2: Fill and reinforce the corners on both sides of panel 1

[0040] Use glass fiber mesh cloth rolled into a cylindrical support and set closely on both sides of panel 1 to strengthen the corners where panel 1 and coil 4 are connected and to alleviate the gap at the connection. The width of the rolled glass fiber mesh cloth is the width of panel 1 minus 10mm, and the length is equal to the height of coil 4.

[0041] Step 3: Fill and reinforce the terminal 2 area

[0042] See also Figure 4 , use glass fiber mesh to fill the area around terminal 2 and between tap terminals 3 in a stacked manner. The thickness should be in accordance with the insulation distance required by the drawing. The minimum distance between the lead wire of terminal 2 and the outer surface of the outermost layer of wire of coil 4 should be ≥30mm. The minimum distance between the lead wire of tap terminal 3 and the outer surface of the outermost layer of wire of coil 4 should be ≥15mm. The width should not exceed the width of panel 1.

[0043] Step 4: Fill the reinforcement area on the tangent position of both sides of panel 1

[0044] Use stacked glass fiber chopped strand mat and glass fiber mesh cloth to cover panel 1 and the corner filling and reinforcement areas on both sides of panel 1 in step 1. The covering length is equal to the height of coil 4, and the width covers the tangent formed by panel 1 and the corner filling and reinforcement areas on both sides.

[0045] Step 5: Insulate the terminal lead wires and reinforce the terminal surface with reinforced areas.

[0046] Use laminated glass fiber chopped strand mat and glass fiber cloth tape to half-wrap the lead wire of terminal 2 and the end of terminal 2 to 2mm near terminal 2, and perform half-wrap reinforcement to ensure good contact surface and conductivity;

[0047] Step 6: Fill the reinforcement area in the first and last terminal cavities

[0048] The glass fiber mesh cloth is cut into a ring shape according to the terminal cavity structure and arranged in each creeping umbrella in the terminal cavity for filling and reinforcement.

[0049] In the step 2 of filling and reinforcing the corners on both sides of the panel 1, the rolled glass fiber mesh panel 1 is filled and reinforced in sections or as a whole along both sides in the axial direction.

[0050] In step 6, the outer diameter of the glass fiber mesh cloth cut into a ring shape according to the terminal cavity structure is adapted to the inner diameter of the placement cavity.

[0051] The present invention uses glass fiber mesh cloth to reinforce the panel in a manner that "follows" the coil shape, including corner reinforcement on both sides of the panel, reinforcement of the glass fiber mesh cloth under the terminal, insulation wrapping of the terminal lead wire and special reinforcement of the terminal surface to prevent cracking. Compared with the existing technology, the glass fiber mesh cloth filling in the panel joint area is more in line with the panel structure, and the glass fiber mesh cloth filling in each part is full and comprehensive, which greatly improves the anti-cracking performance.

Claims

1. A method for filling the tapping area of ​​a dry-type transformer panel to prevent cracking, comprising the following steps: Step 1: Divide the panel tapping area to be filled and reinforced: including the corner filling and reinforcement areas on both sides of the panel (1), the filling and reinforcement area at the terminal (2), the surface filling and reinforcement area at the panel (1), the insulation wrapping of the terminal (2) lead wire and the surface filling and reinforcement area of ​​the terminal (2), and the filling and reinforcement area in the cavity of the first and last terminals (2); Step 2: Fill and reinforce the corners on both sides of the panel (1) Filling material is rolled into a cylindrical support and placed closely on both sides of the panel (1) to strengthen the corners of the connection between the panel (1) and the coil (4) and to alleviate the difference in the connection. The width of the rolled filling material is (panel width - 10) mm, and the length is equal to the height of the coil (4); Step 3: Fill and reinforce the terminal (2) area Filling material is filled in a stacked manner around the terminal (2) and between the tap terminal (3), with a thickness in accordance with the insulation distance required by the drawing. The minimum distance between the lead wire of the terminal (2) and the outer surface of the outermost layer of the coil (4) is ≥30 mm, and the minimum distance between the lead wire position of the tap terminal (3) and the outer surface of the outermost layer of the coil (4) is ≥15 mm. The width shall not exceed the width of the panel (1); Step 4: Fill the reinforcement area on the tangent position of both sides of the panel (1) Using filling material 2, cover the panel (1) and the corner filling reinforcement areas on both sides of the panel (1) in step 1, with the covering length being equal to the height of the coil (4) and the width covering the tangent formed by the panel (1) and the corner filling reinforcement areas on both sides; Step 5: Insulate the terminal lead wires and reinforce the terminal surface with reinforced areas. The lead wire of the terminal (2) and the terminal (2) are wrapped with a filler material three and a half times, and the terminal (2) is wrapped 2-3 mm from the end of the terminal (2) to reinforce the half-fold layer; Step 6: Fill the reinforcement area in the first and last terminal cavities The filling material is cut into a ring shape according to the terminal cavity structure and arranged in each creeping umbrella in the terminal cavity for filling and reinforcement.

2. A method for filling the tap area of ​​a dry-type transformer panel to prevent cracking according to claim 1, characterized in that: In the step 2 of reinforcing the corner filling and reinforcement areas on both sides of the panel (1), the filling material is rolled up and reinforced in sections or in a whole strip axially on both sides of the panel (1).

3. The method for filling the tapping area of ​​a dry-type transformer panel to prevent cracking according to claim 1, characterized in that: In step 6, the filling material is cut into a ring shape according to the terminal cavity structure, and its outer diameter is adapted to the inner diameter of the placement cavity.

4. A method for filling the tap area of ​​a dry-type transformer panel to prevent cracking according to claim 1, 2 or 3, characterized in that: The first filling material is glass fiber mesh cloth.

5. The anti-cracking filling method for the tapping area of ​​a dry-type transformer panel according to claim 1 is characterized in that: The second filling material is a laminated glass fiber chopped strand mat and a glass fiber mesh cloth; the inner layer is the glass fiber chopped strand mat and the outer layer is the glass fiber mesh cloth.

6. The method for filling the tapping area of ​​a dry-type transformer panel to prevent cracking according to claim 1, characterized in that: The third filling material is a laminated glass fiber chopped strand mat and a glass fiber cloth tape; the inner layer is the glass fiber chopped strand mat and the outer layer is the glass fiber cloth tape.

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