High-voltage winding, preparation method therefor, and use thereof

Abstract

The present application relates to the technical field of insulating dry-type transformers, and in particular to a high-voltage winding, a preparation method therefor, and a use thereof. The present application provides a preparation method for a high-voltage winding, comprising the following steps: using a silicone rubber solution to carry out first vacuum casting on an uncast high-voltage winding, and then carrying out first curing molding to obtain primarily cast high-voltage winding; and winding glass fiber mesh fabrics on the inner side and the outer side of the primarily cast high-voltage winding, then using a polyurethane resin solution to carry out second vacuum casting, and carrying out second curing molding to obtain the high-voltage winding. A copper material wrapped in the high-voltage winding can be conveniently recovered.

Description

A high voltage winding and its preparation method and application

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 7, 2023, with application number CN202311475629.7 and invention name “A high-voltage winding, its preparation method and application”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of insulated dry-type transformers, and in particular to a high-voltage winding and a preparation method and application thereof. Background Art

[0003] Traditional epoxy resin dry-type transformers use epoxy resin as the insulation material. The resin is poured and cured in a vacuum, forming a high-strength fiberglass reinforced plastic (FRP) structure. Epoxy resin dry-type transformers offer excellent electrical performance, strong lightning and short-circuit resistance, and are compact and lightweight.

[0004] However, the glass solid formed after the epoxy resin is vitrified is very brittle, with an elongation at break of only 2%. Although a glass fiber network is added inside and outside the coil as a filler, when used in low-temperature and high-temperature environments, photovoltaic fields, wind farms, and energy storage power stations, there will be extreme working conditions such as large load changes, drastic changes in indoor and outdoor working temperatures, and large harmonic content, which will lead to local excessive temperature rise and uneven heating of the resin, causing cracking. At the same time, because the thickness of the resin layer at the tapping part where the insulation is thicker reaches 40 to 80 mm, while the thickness of the wire part where the resin layer is thinner is only 2 to 6 mm. Since the expansion coefficient of copper wire is 17×10 -6 / ℃, the expansion coefficient of epoxy resin is about 60×10 -6 / °C, the shrinkage rates of the two materials are inconsistent, which can easily lead to cracking in the windings. Furthermore, the glassy solid formed after epoxy resin cures is extremely strong. Once the transformer reaches the end of its service life, it is extremely difficult to strip the insulation and recover the copper wire.

[0005] Summary of the Invention

[0006] The purpose of the present application is to provide a high-voltage winding and a preparation method and application thereof, wherein the copper material wrapped in the high-voltage winding is very convenient to recycle.

[0007] In order to achieve the above-mentioned invention objectives, this application provides the following technical solutions:

[0008] The present application provides a method for preparing a high-voltage winding, comprising the following steps:

[0009] After the high-voltage winding before casting is vacuum casted for the first time using silicone rubber solution, the high-voltage winding is first cured and formed to obtain the high-voltage winding after the first casting;

[0010] Glass fiber mesh cloth is wound on both sides of the inner and outer sides of the high-voltage winding after the first casting, and a polyurethane resin solution is used for a second vacuum casting, followed by a second curing molding to obtain the high-voltage winding.

[0011] Preferably, the silicone rubber solution comprises liquid polydimethylsiloxane, polymethyl hydrogensiloxane, platinum vinyl complex, aluminum oxide and boron nitride in a mass ratio of (22-32): (25-31): (25-35): (5-8): (5-10).

[0012] Preferably, the vacuum degree of the first vacuum pouring is 70-100 Pa, the vacuum temperature of the pouring pot during the first vacuum pouring is 80° C., the mold temperature is 70° C., and the pouring time is 40-60 min.

[0013] After the first vacuum pouring is completed, the process further includes placing the mixture under vacuum for 30 to 40 minutes while applying a positive pressure of 0.2 MPa.

[0014] Preferably, the first curing and molding process is: heating the room temperature to 80±5°C and keeping it warm for 5 hours, heating the room temperature to 110±5°C and keeping it warm for 4 hours, heating the room temperature to 130±5°C and keeping it warm for 6-8 hours, and cooling.

[0015] Preferably, the polyurethane resin solution comprises a polyurethane resin and a curing agent;

[0016] The mass ratio of the polyurethane resin to the curing agent is 3:1.

[0017] Preferably, the vacuum degree of the second vacuum pouring is 70-100 Pa, the vacuum temperature of the pouring pot during the second vacuum pouring is 80° C., the mold temperature is 70° C., and the pouring time is 10-15 min.

[0018] After the second vacuum pouring is completed, the process further includes placing the mixture under vacuum for 5 minutes while applying a positive pressure of 0.2 MPa.

[0019] Preferably, the second curing molding process is: heating the room temperature to 80±5°C and keeping it warm for 0.5h, heating the room temperature to 110±5°C and keeping it warm for 1h, heating the room temperature to 130±5°C and keeping it warm for 1.5h, and cooling.

[0020] Preferably, the casting molds used in the first vacuum casting and the second vacuum casting independently include a casting inner mold 1, an end ring 2, a panel 3 and a casting outer mold 4;

[0021] The outer diameter of the inner casting mold used in the second vacuum casting is 5 mm smaller than the inner diameter of the inner casting mold used in the first vacuum casting;

[0022] The outer diameter of the end ring used in the second vacuum casting is 5 mm larger than the outer diameter of the end ring used in the first vacuum casting, and the inner diameter of the end ring used in the second vacuum casting is 5 mm smaller than the inner diameter of the end ring used in the first vacuum casting;

[0023] The width of the panel used in the second vacuum casting is 20 mm greater than the width of the panel used in the first vacuum casting;

[0024] The outer diameter of the outer casting mold used in the second vacuum casting is 5 mm larger than the outer diameter of the outer casting mold used in the first vacuum casting.

[0025] Preferably, before the first vacuum casting, the method further includes: preheating the silicone rubber solution; the preheating process is to place the silicone rubber solution in a 70°C oven for preheating for 3 hours, then control the temperature at 60-65°C and stir for 1-1.5 hours, while evacuating to 120-150Pa.

[0026] Preferably, the Shore hardness of the high-voltage winding after the one-time casting is 60 to 70 degrees.

[0027] Preferably, the glass fiber mesh cloth is an H-grade glass fiber mesh cloth with a thickness of 4 to 6 mm.

[0028] Preferably, the curing agent comprises polymethylene polyphenylene isocyanate and diphenylmethane diisocyanate; the mass ratio of the polymethylene polyphenylene isocyanate to diphenylmethane diisocyanate is 3:1.

[0029] Preferably, before the second vacuum casting, the method further includes: preheating the polyurethane resin solution; the preheating process is to place the polyurethane resin solution in a 70°C oven for preheating for 3 hours, then control the temperature at 60-65°C and stir for 1-1.5 hours, while evacuating to 120-150Pa.

[0030] The present application also provides a high-voltage winding prepared by the preparation method described in the above technical solution, wherein the inner layer of the high-voltage winding is a first polyurethane layer, the outer layer is a second polyurethane layer, and the middle is filled with a silicone rubber layer.

[0031] The present application also provides an application of the high-voltage winding described in the above technical solution in an insulated dry-type transformer.

[0032] Preferably, the insulating dry-type transformer includes a high-voltage winding 9 , a low-voltage winding 10 , an iron core 11 and a clamp 12 .

[0033] The present application provides a method for preparing a high-voltage winding, comprising the following steps: vacuum casting a high-voltage winding before casting with a silicone rubber solution for the first time, followed by a first curing molding to obtain a high-voltage winding after a single casting; winding a glass fiber mesh cloth around the inner and outer sides of the high-voltage winding after the single casting, vacuum casting a polyurethane resin solution for the second time, and then curing molding to obtain the high-voltage winding. The present application adopts two vacuum castings to prepare a polyurethane resin hard shell on the outside and inside of the high-voltage winding, and the middle layer including the conductive material is a silicone rubber material. The silicone rubber material has the characteristics of being relatively soft (having elastic damping effect and slightly low hardness, with a Shore hardness of about 60 degrees), and can be processed by crushing, incineration, and chemical degradation. Therefore, it is very convenient to recycle the copper material wrapped inside, which solves the problem that it is extremely difficult to strip off the insulation material and recycle the copper wire after the service life of the traditional epoxy resin dry-type transformer expires after the epoxy resin is cured. At the same time, the preparation method described in this application has the characteristics of environmental protection and non-toxicity, strong overload capacity, high temperature resistance and outstanding flame retardant performance; and the performance of silicone rubber is outstanding, its hardness is greater than 70 degrees, tensile strength is greater than 1.5MPa, elongation is greater than 50%, flame retardant grade reaches V0 level, breakdown voltage is high voltage 25kV / mm; and it adopts a hard-soft-hard combined redundant insulation structure, which is particularly adaptable to various harsh environments such as plateaus, high cold, high humidity, dust and frequent thunder, and will not cause winding cracking due to excessive changes in load and temperature difference; and the silicone rubber material has elastic damping effect, which can reduce noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a schematic diagram of the overall structure of the casting mold used in the first vacuum casting and the second vacuum casting described in the present application, wherein 1-casting inner mold, 2-end ring, 3-face plate, 4-casting outer mold;

[0035] FIG2 is a schematic structural diagram of the inner casting mold described in this application;

[0036] FIG3 is a schematic structural diagram of the end ring described in this application;

[0037] FIG4 is a schematic structural diagram of the panel described in the present application, wherein 5 is a lead-out hole for the wires;

[0038] FIG5 is a schematic structural diagram of the casting outer mold described in this application;

[0039] FIG6 is a schematic structural diagram of a winding machine used for winding described in this application;

[0040] FIG7 is a schematic diagram of the structure of the comb-shaped stays used in the high-voltage winding before casting in the present application;

[0041] FIG8 is a schematic diagram of the winding process of the high voltage winding before casting in the present application;

[0042] FIG9 is a schematic structural diagram of the high-voltage winding described in the present application, wherein 6 is a first polyurethane layer, 7 is a second polyurethane layer, and 8 is a silicone rubber layer;

[0043] FIG10 is a schematic structural diagram of the insulating dry-type transformer described in this application. DETAILED DESCRIPTION

[0044] The present application provides a method for preparing a high-voltage winding, comprising the following steps:

[0045] After the high-voltage winding before casting is vacuum casted for the first time using silicone rubber solution, the high-voltage winding is first cured and formed to obtain the high-voltage winding after the first casting;

[0046] Glass fiber mesh cloth is wound on both sides of the inner and outer sides of the high-voltage winding after the first casting, and a polyurethane resin solution is used for a second vacuum casting, followed by a second curing molding to obtain the high-voltage winding.

[0047] In the present application, the casting molds used in the first vacuum casting and the second vacuum casting independently include a casting inner mold 1, an end ring 2, a panel 3 and a casting outer mold 4 (the overall structure is shown in Figure 1, and the disassembled diagrams are shown in Figures 2 to 5 respectively).

[0048] In the present application, the inner diameter of the casting inner mold used in the second vacuum casting is preferably 5 mm smaller than the inner diameter of the casting inner mold used in the first vacuum casting; the outer diameter of the end ring used in the second vacuum casting is preferably 5 mm larger than the outer diameter of the end ring used in the first vacuum casting, and the inner diameter of the end ring used in the second vacuum casting is preferably 5 mm smaller than the inner diameter of the end ring used in the first vacuum casting; the width of the panel used in the second vacuum casting is preferably 20 mm larger than the width of the panel used in the first vacuum casting; the outer diameter of the casting outer mold used in the second vacuum casting is preferably 5 mm larger than the outer diameter of the casting outer mold used in the first vacuum casting.

[0049] In the present application, the first vacuum casting process is preferably to place the high-voltage winding before casting between the casting inner mold and the casting outer mold of the casting mold, and then use silicone rubber solution to perform the first vacuum casting on the high-voltage winding before casting.

[0050] In the present application, the process of placing the high-voltage winding before casting between the inner casting mold and the outer casting mold of the casting mold preferably includes:

[0051] 4).

[0052] In this application, the casting mold is preferably completely disassembled before use to check its appearance and dimensions. The end plate and mold contact area should be tightly fitted. Use a grinder and sandpaper to clean burrs and iron filings on the mold. Then, use alcohol to thoroughly clean the mold to remove oil stains and foreign matter. The casting mold is then placed in an electric oven and baked at 180±5℃ for 3 hours. After being removed from the oven, a release agent is evenly applied to the mold while it is still hot. The mold is then placed back in the electric oven at 180±5℃ for 3 hours. The release agent is then wiped off with a pure cotton cloth.

[0053] In the present application, the preparation process of the high voltage winding before casting is preferably:

[0054] Place the casting inner mold (Figure 2) used for the first vacuum casting on a pressure plate padded with a sealing rubber pad, insert the end rings (Figure 3) from top to bottom, and adjust the end rings to both ends (the main directions must be consistent during the insertion process), adjust the primary casting inner mold (Figure 2) to the center position of the lower pressure plate to prevent temporary pressure plate, use 4 pulling screws to fix the casting inner mold 1 (Figure 2) on the lower pressure plate from the inside, insert the transmission square steel, fix the mold, and put it on the winding machine after fixing it to prepare for winding (Figure 6);

[0055] Wrap two layers of H-grade glass fiber mesh cloth of the same height as the coil around the inner casting mold (Figure 1), and evenly distribute comb-shaped stays on the outside in 6 to 8 equal parts (Figure 7), and fix them on the mesh with glass fiber cloth tape;

[0056] Start the winding machine and begin winding. The high-voltage winding uses a pancake-type, continuous coil (Figure 8). The base of each coil is separated from the upper and lower coils by a NOMEX paper slot, which is then wrapped with NOMEX paper tape and secured with 0.12×25mm fiberglass tape. The transition point from one coil to the next is wrapped with two layers of half-lapped NOMEX paper. After the turns are bent, they are wrapped with two layers of H-grade fiberglass mesh cloth, aligned with the coil height.

[0057] If an airway plate is set between coil layers, put a glass cloth sleeve on the POM airway plate with the specifications required by the drawing, tie the two ends with glass cloth tape, place them side by side next to the comb-shaped stays of the specified number of layers (Figure 7), form a circle, and insert the lower end into the positioning stop groove. After the airway plate is placed, measure the outer diameter of the airway plate and continue to wind the turns outside the airway plate. When the coil with multiple wires needs to be transposed, the corresponding transposition should be performed at the position required by the drawing. Use the wire transposition tool to twist the wire out of the transposition S-bend, and wrap it with two layers of 0.13×25mm glass cloth tape half-folded, with a length of 50mm on each side of the S-bend, and then continue winding after transposing the wire;

[0058] After winding is completed, the coil (Figure 8) is unloaded and transported to the terminal welding area for welding the terminal.

[0059] In the present application, the silicone rubber solution preferably includes liquid polydimethylsiloxane, polymethyl hydrogen siloxane, platinum vinyl complex, aluminum oxide and boron nitride; the mass ratio of the liquid polydimethylsiloxane, polymethyl hydrogen siloxane, platinum vinyl complex, aluminum oxide and boron nitride is preferably (22-32): (25-31): (25-35): (5-8): (5-10), more preferably 27:31:31:6:5, 26:27:32:8:7 or 23:26:33:8:10.

[0060] In the present application, the preparation process of the silicone rubber solution is preferably to mix liquid polydimethylsiloxane, polymethylhydrogensiloxane, platinum vinyl complex, aluminum oxide and boron nitride; the present application does not have any special restrictions on the mixing process, and the process well known to those skilled in the art can be used.

[0061] Before the first vacuum casting, the present application also preferably includes preheating the silicone rubber solution; the preheating process is preferably to place the silicone rubber solution in a 70°C oven for preheating for 3 hours, then control the temperature at 60-65°C and stir for 1-1.5 hours, while evacuating to 120-150Pa.

[0062] In the present application, the vacuum degree of the first vacuum pouring is preferably 70-100 Pa, more preferably 80-90 Pa, and most preferably 83-86 Pa; the vacuum temperature of the pouring pot during the first vacuum pouring is preferably 80°C; the mold temperature is preferably 70°C; the pouring time is preferably 40-60 min, more preferably 45-55 min, and most preferably 48-52 min; after the first vacuum pouring is completed, it is also preferred to apply a positive pressure of 0.2 MPa while placing it in a vacuum state for 30-40 min.

[0063] In the present application, the first curing molding process is preferably as follows: the room temperature is raised to 80±5°C and kept for 5 hours, the temperature is raised to 110±5°C and kept for 4 hours, the temperature is raised to 130±5°C and kept for 6-8 hours, and then cooled. In the present application, the cooling is preferably performed by turning off the heating power supply, but not stopping the hot air circulation system, and waiting until the electric oven temperature drops to 80°C.

[0064] After the first curing and molding is completed, the present application also preferably includes taking out the silicone rubber casting body and performing demolding; the demolding is preferably to hang the cured silicone rubber winding to the work site and demold it from the outside to the inside.

[0065] In the present application, the Shore hardness of the high-voltage winding after the primary casting is preferably 60 to 70 degrees.

[0066] After obtaining the high-voltage winding after the first casting, the present application winds glass fiber mesh cloth on the inner and outer sides of the high-voltage winding after the first casting, uses a polyurethane resin solution for a second vacuum casting, and then performs a second curing molding to obtain the high-voltage winding.

[0067] In the present application, the glass fiber mesh is preferably a grade H glass fiber mesh with a thickness of 4 to 6 mm. The present application does not have any special limitation on the winding process, and the process well known to those skilled in the art can be used.

[0068] In the present application, the second vacuum pouring process is preferably to install the high-voltage winding after the first pouring into the pouring mold used for the second vacuum pouring. The installation process is preferably referred to the process of installing the high-voltage winding before pouring into the pouring mold used for the first vacuum pouring, and no further description is given here.

[0069] In the present application, the polyurethane resin solution preferably comprises a polyurethane resin and a curing agent; the mass ratio of the polyurethane resin to the curing agent is preferably 3:1. In the present application, the curing agent preferably comprises polymethylene polyphenylene isocyanate and diphenylmethane diisocyanate; the mass ratio of the polymethylene polyphenylene isocyanate to diphenylmethane diisocyanate is preferably 3:1, more preferably 2.8:1, and most preferably 2.75:1.

[0070] Before performing the second vacuum casting, the present application also preferably includes preheating the polyurethane resin solution; the preheating process is preferably to place the polyurethane resin solution in a 70°C oven for preheating for 3 hours, then control the temperature at 60-65°C and stir for 1-1.5 hours, while evacuating to 120-150 Pa.

[0071] In the present application, the vacuum degree of the second vacuum pouring is preferably 70-100 Pa, more preferably 80-90 Pa, and most preferably 83-86 Pa; the vacuum temperature of the pouring pot during the second vacuum pouring is preferably 80°C; the mold temperature is preferably 70°C; the pouring time is preferably 10-15 min, more preferably 11-14 min, and most preferably 12-13 min; after the second vacuum pouring is completed, it is also preferred to apply a positive pressure of 0.2 MPa while placing it in a vacuum state for 5 minutes.

[0072] In the present application, the second curing molding process is preferably as follows: the room temperature is raised to 80±5°C and kept warm for 0.5 hours, the temperature is raised to 110±5°C and kept warm for 1 hour, the temperature is raised to 130±5°C and kept warm for 1.5 hours, and then cooled. In the present application, the cooling is preferably performed by turning off the heating power supply, without stopping the hot air circulation system, and waiting until the electric oven temperature drops to 80°C.

[0073] After the second solidification molding is completed, the present application also preferably includes removing the casting body and demolding in sequence; the present application does not have any special restrictions on the process of removing the casting body and demolding, and the process well known to those skilled in the art can be used.

[0074] The present application also provides a high-voltage winding prepared by the preparation method described in the above technical solution, wherein the inner layer of the high-voltage winding is a first polyurethane layer, the outer layer is a second polyurethane layer, and the middle is filled with a silicone rubber layer (as shown in Figure 9).

[0075] The present application also provides an application of the high-voltage winding described in the above technical solution in an insulated dry-type transformer.

[0076] In the present application, the insulating dry-type transformer preferably includes a high-voltage winding 9, a low-voltage winding 10, an iron core 11 and a clamp 12 (as shown in FIG10 ).

[0077] In the present application, the preparation process of the insulating dry-type transformer preferably includes the following steps:

[0078] Loosen the side screws and through-core screws of the stacked core, remove the upper clamps and the clamp insulation, remove the upper iron yoke silicon steel sheets in turn, and stack them on the assembly workbench. Remove the pull screws, loosen the side screws and through-core screws, insert the "U"-shaped clips, paying attention to the staggered positions to hold the silicon steel sheets at each level, loosen the disc screws and through-core screws, remove the side screws, remove the through-core screws, remove the upper clamp insulation, remove the upper iron yoke silicon steel sheets in turn, and stack them on the assembly workbench;

[0079] Place the lower pads and shock-absorbing pads on the lower clamp (the shock-absorbing pads are stacked on top of the lower pads). Place four pads under each phase coil, refer to the drawings for their positions. Use a sling to lift the high-voltage coil, keeping it perpendicular to the ground, insert it into the core column, and support it with the lower pads and shock-absorbing pads.

[0080] Use a sling to lift the low-voltage coil, keeping it perpendicular to the ground, insert it into the core column, adjust the concentricity, and use silicone rubber strips to fix the distance between it and the core. Use the cut silicone rubber pads to fix the high and low voltage coils, and adjust the position and height of the high and low voltage coils and the distance between them and the high voltage coil. Try to make the main air gap and the interphase air gap uniform;

[0081] Starting from the main stage, insert the laminations step by step outward, while using a leveling iron to align them. After the laminations are completed, check the alignment of the core lamination holes. Install the through-hole screws, clamp insulation, and upper clamps. Use a finishing block to flatten the core laminations at each level and both ends of the yoke. Slightly tighten the upper yoke, place the side screws, and insert the grounding lugs 50mm from the outside to the inside of the yoke at the 3rd and 4th levels. Check the core column for any arching. If so, address it immediately. Re-adjust the upper yoke until it meets the drawing requirements. Tighten the through-hole screws and side screws.

[0082] Install the pads, shock-proof pads, and compression nuts, starting from the main stage and inserting the pieces outwards step by step, while aligning them with a leveling iron. After inserting the pieces, clamp them with a "U"-shaped clip and check that the holes of the core pieces are aligned. Install the through-core screws, the clamp insulation and the upper clamps, and use the finishing blocks to flatten the core pieces at each level and both ends of the iron yoke. After the upper clamps are installed, adjust the positions of the upper and lower pads so that they are properly positioned and beautiful. Slightly tighten the upper iron yoke, put the side screws in place, and insert the grounding plates at the 3rd and 4th levels from the outside to the inside of the iron yoke. The insertion length is 50mm. Check whether there is any arching of the core column. If there is any, it should be dealt with in time. Arrange the upper iron yoke again and place it in accordance with the requirements of the drawing. Tighten the through-core screws and side screws.

[0083] Prepare the high-voltage coil connection leads according to the drawings and secure the tap to the tap. Prepare a "Y" or "D" connecting copper tube of appropriate length. Punch holes at both ends, then tin the ends of the connecting rod. Cover the remaining portion with black heat shrink tubing. Connect the copper tube to the corresponding lead ends, using yellow, green, and red for the three-phase leads A, B, and C, and tighten them. Place an insulated terminal between the clamp and the lead and secure with bolts.

[0084] Place insulated terminals between the clamps and the low-voltage winding internal lead bars and secure them with bolts. Place the copper bars on the lead bars, bolt them together, and tighten. Place the nameplate, tighten all bolts, and organize the tools. Install the thermostat and fan, check that the wiring is correct, then power on and check that the thermostat and fan are functioning properly.

[0085] After affixing the grounding mark, tap position, high voltage danger mark, rubber plug, phase mark and environmental protection mark, the product assembly is complete.

[0086] The high-voltage winding provided by the present application, its preparation method and application are described in detail below in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present application.

[0087] Example 1

[0088] Disassemble the newly made mold and check whether its appearance and dimensions are qualified. The contact between the end plate and the mold should be tightly fitted. Use a grinder and sandpaper to clean the burrs and iron filings on the mold. Then, clean the mold thoroughly with alcohol to remove oil stains and foreign matter. Then, place the casting mold in an electric oven and bake it at 180±5℃ for 3 hours. After that, remove it from the oven. While it is still hot, evenly apply mold release agent to the mold. Then, place the mold back in the electric oven at 180±5℃ and bake it for 3 hours. Wipe off the mold release agent with a pure cotton cloth.

[0089] Place the casting inner mold (Figure 2) used for the first vacuum casting on a pressure plate padded with a sealing rubber pad, insert the end rings (Figure 3) from top to bottom, and adjust the end rings to both ends (the main directions must be consistent during the insertion process), adjust the primary casting inner mold (Figure 2) to the center position of the lower pressure plate to prevent temporary pressure plate, use 4 pulling screws to fix the casting inner mold 1 (Figure 2) on the lower pressure plate from the inside, insert the transmission square steel, fix the mold, and put it on the winding machine after fixing it to prepare for winding (Figure 6);

[0090] Wrap two layers of H-grade glass fiber mesh cloth of the same height as the coil around the inner casting mold (Figure 1), and evenly distribute comb-shaped stays on the outside in 6 to 8 equal parts (Figure 7), and fix them on the mesh with glass fiber cloth tape;

[0091] Start the winding machine and begin winding. The high-voltage winding uses a pancake-type, continuous coil (Figure 8). The base of each coil is separated from the upper and lower coils by a NOMEX paper slot, which is then wrapped with NOMEX paper tape and secured with 0.12×25mm fiberglass tape. The transition point from one coil to the next is wrapped with two layers of half-lapped NOMEX paper. After the turns are bent, they are wrapped with two layers of H-grade fiberglass mesh cloth, aligned with the coil height.

[0092] If an airway plate is set between coil layers, put a glass cloth sleeve on the POM airway plate with the specifications required by the drawing, tie the two ends with glass cloth tape, place them side by side next to the comb-shaped stays of the specified number of layers (Figure 7), form a circle, and insert the lower end into the positioning stop groove. After the airway plate is placed, measure the outer diameter of the airway plate and continue to wind the turns outside the airway plate. When the coil with multiple wires needs to be transposed, the corresponding transposition should be performed at the position required by the drawing. Use the wire transposition tool to twist the wire out of the transposition S-bend, and wrap it with two layers of 0.13×25mm glass cloth tape half-folded, with a length of 50mm on each side of the S-bend, and then continue winding after transposing the wire;

[0093] After winding is completed, the coil (Figure 8) is unloaded and transported to the welding terminal area to weld the terminal, thus obtaining the high-voltage winding before casting;

[0094] 4).

[0095] Liquid polydimethylsiloxane, polymethylhydrogensiloxane, platinum vinyl complex, aluminum oxide and boron nitride in a mass ratio of 27:31:31:6:5 were mixed and placed in a 70°C oven for preheating for 3 hours. The temperature was then controlled at 65°C and stirred for 1 hour. The mixture was evacuated to 130 Pa for the first vacuum pouring (vacuum degree of 85 Pa; vacuum temperature of the pouring pot during pouring was 80°C; mold temperature was 70°C; pouring time was 50 minutes). The mixture was placed in a vacuum state for 35 minutes, and a positive pressure of 0.2 MPa was applied before taking it out.

[0096] The cast winding is transferred to an electric oven, and the temperature in the oven is gradually increased for the first curing molding (the room temperature is raised to 80±5°C and kept for 5 hours, then raised to 110±5°C and kept for 4 hours, and then raised to 130±5°C and kept for 7 hours. The heating power is turned off, and the hot air circulation system is not stopped until the temperature of the electric oven drops to 80°C). After the first curing is completed, it is taken out and demolded. The cured silicone rubber winding is hoisted to the work site and demolded from the outside to the inside to obtain a high-voltage winding after the first casting (Shore hardness is 65 degrees);

[0097] The inside and outside of the high-voltage winding after sequential casting were wound with H-grade glass fiber mesh cloth with a thickness of 5 mm, and the inner mold, outer mold, end ring and panel for secondary casting were reinstalled; a polyurethane resin and a curing agent with a mass ratio of 3:1 (the curing agent included polymethylene polyphenylene isocyanate and diphenylmethane diisocyanate with a mass ratio of 2:1) were mixed and placed in a 70°C oven for preheating for 3 hours, and then the temperature was controlled at 65°C and stirred for 1 hour, and the mixture was evacuated to 135 Pa, and a second vacuum casting was performed (the vacuum degree was 135 Pa; the vacuum temperature of the pouring pot during pouring was 80°C; the mold temperature was 70°C; and the pouring time was 13 minutes). After that, the mixture was placed in a vacuum state for 5 minutes, a positive pressure of 0.2 MPa was applied, and the mixture was taken out;

[0098] The cast winding is transferred to an electric oven, and the temperature in the oven is gradually increased for the second curing molding (the room temperature is raised to 80±5°C and kept for 0.5h, then raised to 110±5°C and kept for 1h, and then raised to 130±5°C and kept for 1.5h. The heating power is turned off, and the hot air circulation system is not stopped until the temperature of the electric oven drops to 80°C). After the second curing is completed, it is taken out and demolded to obtain the high-voltage winding;

[0099] Loosen the side screws and through-core screws of the stacked core, remove the upper clamps and the clamp insulation, remove the upper iron yoke silicon steel sheets in turn, and stack them on the assembly workbench. Remove the pull screws, loosen the side screws and through-core screws, insert the "U"-shaped clips, paying attention to the staggered positions to hold the silicon steel sheets at each level, loosen the disc screws and through-core screws, remove the side screws, remove the through-core screws, remove the upper clamp insulation, remove the upper iron yoke silicon steel sheets in turn, and stack them on the assembly workbench;

[0100] Place the lower pads and shock-absorbing pads on the lower clamp (the shock-absorbing pads are stacked on top of the lower pads). Place four pads under each phase coil, refer to the drawings for their positions. Use a sling to lift the high-voltage coil, keeping it perpendicular to the ground, insert it into the core column, and support it with the lower pads and shock-absorbing pads.

[0101] Use a sling to lift the low-voltage coil, keeping it perpendicular to the ground, insert it into the core column, adjust the concentricity, and use silicone rubber strips to fix the distance between it and the core. Use the cut silicone rubber pads to fix the high and low voltage coils, and adjust the position and height of the high and low voltage coils and the distance between them and the high voltage coil. Try to make the main air gap and the interphase air gap uniform;

[0102] Starting from the main stage, insert the laminations step by step outward, while using a leveling iron to align them. After the laminations are completed, check the alignment of the core lamination holes. Install the through-hole screws, clamp insulation, and upper clamps. Use a finishing block to flatten the core laminations at each level and both ends of the yoke. Slightly tighten the upper yoke, place the side screws, and insert the grounding lugs 50mm from the outside to the inside of the yoke at the 3rd and 4th levels. Check the core column for any arching. If so, address it immediately. Re-adjust the upper yoke until it meets the drawing requirements. Tighten the through-hole screws and side screws.

[0103] Install the pads, shock-proof pads, and compression nuts, starting from the main stage and inserting the pieces outwards step by step, while aligning them with a leveling iron. After the inserting is completed, clamp it with a "U"-shaped clip and check that the holes of the core pieces are aligned. Install the through-core screws, the clamp insulation and the upper clamps, and use the finishing block to flatten the core pieces at each level and both ends of the iron yoke. After the upper clamps are installed, adjust the position of the upper and lower pads so that the position of the upper and lower pads is appropriate and beautiful. Slightly tighten the upper iron yoke, put the side screws in place, and insert the grounding plate at the 3rd and 4th levels from the outside to the inside of the iron yoke. The insertion length is 50mm. Check whether there is any arching of the core column. If there is, it should be dealt with in time. Arrange the upper iron yoke again until it meets the requirements of the drawing, and tighten the through-core screws and side screws;

[0104] Prepare the high-voltage coil connection leads according to the drawings and secure the tap to the tap. Prepare a "Y" or "D" connecting copper tube of appropriate length. Punch holes at both ends, then tin the ends of the connecting rod. Cover the remaining portion with black heat shrink tubing. Connect the copper tube to the corresponding lead ends, using yellow, green, and red for the three-phase leads A, B, and C, and tighten them. Place an insulated terminal between the clamp and the lead and secure with bolts.

[0105] Place insulated terminals between the clamps and the low-voltage winding internal lead bars and secure them with bolts. Place the copper bars on the lead bars, bolt them together, and tighten. Place the nameplate, tighten all bolts, and organize the tools. Install the thermostat and fan, check that the wiring is correct, then power on and check that the thermostat and fan are functioning properly.

[0106] After affixing the grounding mark, tap position, high voltage danger mark, rubber plug, phase mark and environmental protection mark, the product assembly is completed to obtain an insulated dry-type transformer.

[0107] Although the above embodiment provides a detailed description of the present application, it is only a part of the embodiments of the present application rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present application.

Claims

1. A method for preparing a high voltage winding, characterized in that: The following steps are involved: After the high-voltage winding before casting is subjected to the first vacuum casting with the silicone rubber solution, the first curing and forming is performed to obtain the high-voltage winding after the first casting; Glass fiber mesh cloth is wound around the inner and outer sides of the high-voltage winding after the first pouring, and a polyurethane resin solution is used for a second vacuum pouring, followed by a second curing molding to obtain the high-voltage winding.

2. The preparation method according to claim 1, characterized in that The silicone rubber solution comprises liquid polydimethylsiloxane, polymethyl hydrogensiloxane, platinum vinyl complex, aluminum oxide and boron nitride in a mass ratio of (22-32): (25-31): (25-35): (5-8): (5-10).

3. The preparation method according to claim 1 or 2, characterized in that: The vacuum degree of the first vacuum pouring is 70-100 Pa, the vacuum temperature of the pouring pot during the first vacuum pouring is 80° C., the mold temperature is 70° C., and the pouring time is 40-60 min; After the first vacuum pouring is completed, the process further includes placing the mixture under vacuum for 30 to 40 minutes while applying a positive pressure of 0.2 MPa.

4. The preparation method according to claim 1, characterized in that: The first curing molding process is: the room temperature is raised to 80±5°C and kept for 5 hours, the temperature is raised to 110±5°C and kept for 4 hours, the temperature is raised to 130±5°C and kept for 6-8 hours, and then cooled.

5. The preparation method according to claim 1, characterized in that: The polyurethane resin solution comprises a polyurethane resin and a curing agent; The mass ratio of the polyurethane resin to the curing agent is 3:

1.

6. The preparation method according to claim 1, characterized in that: The vacuum degree of the second vacuum pouring is 70-100 Pa, the vacuum temperature of the pouring pot during the second vacuum pouring is 80° C., the mold temperature is 70° C., and the pouring time is 10-15 min; After the second vacuum pouring is completed, the process also includes placing the mixture under vacuum for 5 minutes while applying a positive pressure of 0.2 MPa.

7. The preparation method according to claim 1 or 5, characterized in that: The second curing molding process is: the room temperature is raised to 80±5°C and kept for 0.5h, the temperature is raised to 110±5°C and kept for 1h, the temperature is raised to 130±5°C and kept for 1.5h, and then cooled.

8. The preparation method according to claim 1, characterized in that: The casting molds used in the first vacuum casting and the second vacuum casting independently include a casting inner mold (1), an end ring (2), a panel (3) and a casting outer mold (4); The outer diameter of the inner casting mold used in the second vacuum casting is 5 mm smaller than the inner diameter of the inner casting mold used in the first vacuum casting; The outer diameter of the end ring used in the second vacuum casting is 5 mm larger than the outer diameter of the end ring used in the first vacuum casting, and the inner diameter of the end ring used in the second vacuum casting is 5 mm smaller than the inner diameter of the end ring used in the first vacuum casting; The width of the panel used in the second vacuum casting is 20 mm greater than the width of the panel used in the first vacuum casting; The outer diameter of the casting outer mold used in the second vacuum casting is 5 mm larger than the outer diameter of the casting outer mold used in the first vacuum casting.

9. The preparation method according to claim 1, characterized in that: Before the first vacuum casting, the method also includes: preheating the silicone rubber solution; the preheating process is to put the silicone rubber solution into a 70°C oven for preheating for 3 hours, then control the temperature at 60-65°C and stir for 1-1.5 hours, and simultaneously evacuate to 120-150Pa.

10. The preparation method according to claim 1 or 2, characterized in that: The Shore hardness of the high-voltage winding after the primary casting is 60 to 70 degrees.

11. The preparation method according to claim 1, characterized in that: The glass fiber mesh cloth is an H-grade glass fiber mesh cloth with a thickness of 4 to 6 mm.

12. The preparation method according to claim 5, characterized in that: The curing agent comprises polymethylene polyphenylene isocyanate and diphenylmethane diisocyanate; the mass ratio of the polymethylene polyphenylene isocyanate to diphenylmethane diisocyanate is 3:

1.

13. The preparation method according to claim 1, characterized in that: Before the second vacuum pouring, the method further includes: preheating the polyurethane resin solution; the preheating process is to place the polyurethane resin solution in a 70°C oven for preheating for 3 hours, then control the temperature at 60-65°C and stir for 1-1.5 hours, and simultaneously evacuate to 120-150Pa.

14. The high voltage winding prepared by the preparation method according to any one of claims 1 to 17, characterized in that: The inner layer of the high-voltage winding is a first polyurethane layer, the outer layer is a second polyurethane layer, and the middle is filled with a silicone rubber layer.

15. Use of the high voltage winding according to claim 18 in an insulated dry-type transformer.

16. The use according to claim 19, characterized in that The insulating dry-type transformer comprises a high-voltage winding (9), a low-voltage winding (10), an iron core (11) and a clamp (12).

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