Low-temperature-resistant dry-type transformer and manufacturing method of high-voltage coil

Abstract

The invention relates to a low-temperature-resistant dry-type transformer and a high-voltage coil manufacturing method, a high-voltage coil comprises a coil inner insulator, an air channel and a coil outer insulator, and multiple layers of electromagnetic wires are wound between the coil inner insulator and the air channel inner insulator and between the air channel outer insulator and the coil outer insulator. An interlayer insulator is arranged between every two adjacent layers of electromagnetic wires, end insulators are arranged at the two ends of the high-voltage coil, the electromagnetic wires are fixed by pouring low-temperature-resistant epoxy resin, and each of the coil inner insulator and the coil outer insulator comprises multiple layers of round-edge gridding cloth. The end insulation comprises end insulation gridding cloth and a first glass fiber continuous felt wrapping the end insulation gridding cloth from the outer side, the interlayer insulation comprises multiple layers of interlayer gridding cloth, a second glass fiber continuous felt is arranged between every two adjacent air channels, and a coil panel is arranged on the front side of the high-voltage coil. And panel filling gridding cloth is arranged between the coil panel and the outer diameter surface of the coil. The device can adapt to low-temperature and severe-cold environmental conditions, and heat preservation cotton and a heating device do not need to be additionally arranged.

Description

Technical Field

[0001] The invention relates to the field of transformers, in particular to a low-temperature resistant dry-type transformer and a method for manufacturing a high-voltage coil. Background Art

[0002] The dry-type transformer coil is manufactured using epoxy resin casting technology, and epoxy resin and air are used as the main insulating medium. When the load of the dry-type transformer increases during operation, heat is generated and the coil temperature increases. When the load of the transformer decreases or stops running, the temperature drops. This temperature change causes the epoxy resin coil to expand and contract. In addition, different materials in the dry-type transformer coil, such as copper wire, aluminum wire, etc., have different volume change coefficients during thermal expansion and contraction. When the temperature changes, the shrinkage or expansion degree of these materials is inconsistent, so stress will be generated.

[0003] In addition, not only the temperature change of the coil itself will cause stress, but also the fluctuation of ambient temperature will cause stress change in the epoxy resin coil. Because dry-type transformers generally use F or H grade insulation, the temperature of the coil itself is relatively high, usually above 100°C. If the ambient temperature is low, the sudden change of the coil surface temperature may cause a large temperature gradient inside the epoxy resin, thereby aggravating the generation of stress.

[0004] If these stresses exceed the bearing capacity of epoxy resin, it will cause the resin to crack, and epoxy resin will become more brittle in low temperature environment, and its toughness and ductility will decrease, which makes it easier to crack when subjected to external force or internal stress. Different types of epoxy resins have different degrees of brittleness in low temperature environment. If the structural design is unreasonable or the operation process is improper, it is more likely to crack. Therefore, in a low temperature environment, if the dry-type transformer is suddenly affected by a sudden temperature change, such as a rapid transfer from a warm indoor to a cold outdoor, or a sudden impact of cold air, the epoxy resin may not be able to adapt to this rapid temperature change and crack. Cracks or microcracks in the epoxy resin will reduce the insulation performance of the coil, and then cause problems such as partial discharge and flashover inside the coil, affecting the safe operation of the transformer.

[0005] In addition, due to the above-mentioned thermal expansion and contraction, the connections between components inside the dry-type transformer may become tighter or looser. If the connection is too tight, it may cause additional pressure on the insulation material and further damage the insulation performance. If the connection is loose, it may cause poor contact and local overheating, which will also have an adverse effect on safe operation.

[0006] In the national standard GB / T1094.11-2007, the most severe temperature-resistant climate level for dry-type transformers is C2, which requires that dry-type transformers can be operated, transported and stored in an environment as low as -25°C. In the latest version of the GB / T1094.11-2022 standard, the application scope of dry-type transformer products has been increased by 4 climate levels, namely C3, C4, C5, and Cxy. Among them, Cxy does not specify the minimum temperature of a specific climate, which needs to be determined through consultation with users and transformer manufacturers based on actual operating conditions. Therefore, according to the latest version of the national standard, there is no limit on the minimum ambient temperature for dry-type transformers. The dry-type transformers produced by the original C2 climate level design concept and manufacturing process can no longer meet the safe operation requirements of the new national standard in low temperature environments.

[0007] Dry-type transformers in the prior art are all selected, designed and manufactured according to the previous standard minimum requirement of -25℃. When the ambient temperature is below -25℃, the transformer is generally equipped with insulation cotton, or an independent power distribution room is built and a heating device is installed to ensure that the ambient temperature of the transformer is maintained above -25℃. For example, the patent CN206249119U discloses a low-temperature resistant transformer low-frequency heating device, in which the heating element and the cooling element heat or cool the low-frequency heating device body according to the control signal, so that it can be used for transformer startup and operation in high-cold or even extremely cold environments. For example, the patent CN209056335U discloses a low-temperature resistant insulating bushing for power transformers, which includes a substrate, and the substrate includes a polyperfluoroethylene propylene insulation layer or a plurality of thermally fused polyperfluoroethylene propylene insulation layers. The bushing does not become brittle at extremely low temperatures, thereby ensuring good insulation performance and strength of the transformer-related components. However, if external insulation measures cannot be set for the transformer in certain special environments and the design of the dry-type transformer does not fully consider the impact of lower temperature environments, or epoxy resins and other materials suitable for low temperature environments are not selected, the transformer will easily experience problems such as resin cracking and mechanical structure fastening failure at low temperatures. Summary of the invention

[0008] The object of the present invention is to provide a low-temperature resistant dry-type transformer and a high-voltage coil manufacturing method, which can adapt to low-temperature and severe cold environmental conditions and can operate safely and reliably throughout the life cycle of the equipment without adding insulation cotton and installing a heating device.

[0009] The objective of the present invention is achieved through the following technical solutions:

[0010] A low-temperature resistant dry-type transformer, comprising an iron core, and a coil assembly is sleeved on the core column of the iron core, the coil assembly comprises a low-voltage coil, an insulating sleeve and a high-voltage coil arranged in sequence from the inside to the outside, wherein the high-voltage coil comprises a coil inner insulation, an airway and a coil outer insulation arranged in sequence from the inside to the outside, and the airway inner insulation is arranged on the inside, and the airway outer insulation is arranged on the outside, multiple layers of electromagnetic wire are wound between the coil inner insulation and the airway inner insulation to form an airway inner coil, multiple layers of electromagnetic wire are wound between the airway outer insulation and the coil outer insulation to form an airway outer coil, interlayer insulation is arranged between adjacent two layers of electromagnetic wire, end insulation is arranged at both ends of the high-voltage coil except for the airway position, and the electromagnetic wire is cast It is fixed with low-temperature resistant epoxy resin, and the inner insulation and outer insulation of the coil both include multiple layers of round-edge mesh cloth, the end insulation includes end insulation mesh cloth and a first glass fiber continuous felt wrapped from the outside of the end insulation mesh cloth, the interlayer insulation includes multiple layers of interlayer mesh cloth, and a second glass fiber continuous felt is provided between two adjacent air ducts, a coil panel connected to the electromagnetic wire lead-out line is provided on the front side of the high-voltage coil, and a panel filling mesh cloth is provided between the coil panel and the outer diameter surface of the coil outside the air duct; the coil assembly is clamped and fixed by an upper clamp and a lower clamp, and an upper pad is provided between the upper clamp and the upper end of the coil assembly, and the lower support plate on the lower side of the upper clamp is connected to the upper pad through a clamping assembly with a disc spring.

[0011] In the coil inner insulation and coil outer insulation, each layer of round-edge mesh cloth is rotated 90° with respect to the previous layer of round-edge mesh cloth and each layer of round-edge mesh cloth is fastened and fixed by glass fiber cloth tape. In the interlayer insulation, each layer of interlayer mesh cloth is rotated 90° with respect to the previous layer of interlayer mesh cloth and placed.

[0012] The first glass fiber continuous felt of the end insulation is provided with an opening along the length direction, and one side of the opening of the first glass fiber continuous felt is bent and tightly wrapped with the corresponding end insulation mesh cloth.

[0013] The second glass fiber continuous felt is reciprocatingly bent to form a plurality of wrapping parts, and each airway is placed in a corresponding wrapping part, and the cross-section of the airway is a trapezoidal shape that is narrow at the top and wide at the bottom, wherein the narrow side of the trapezoid corresponds to the insulating side inside the airway, and the wide side of the trapezoid corresponds to the insulating side outside the airway, and the length difference between the narrow side and the wide side of the trapezoid is equal to the curvature difference between the insulation inside the airway and the insulation outside the airway, and each corner end of the trapezoidal cross-section is a rounded transition.

[0014] A spacing area is formed between the coil panel and the outer diameter surface of the coil outside the airway, and the spacing area includes triangular areas on both sides and a rectangular area in the middle. Panel filling mesh cloths with the same width and height as the coil panel are stacked layer by layer and filled in the rectangular area. Panel filling mesh cloths with decreasing widths cut according to the size of the triangular area are stacked layer by layer and filled in the triangular area.

[0015] The coil panel is provided with connection terminals and tap terminals, wherein the connection terminals are correspondingly connected through conductive rods, the tap terminals are correspondingly connected through tap plates, and the ends of the tap plates are fixedly connected to the corresponding tap terminals through copper bolts.

[0016] The clamping assembly includes a clamping bolt, a disc spring, a clamping nut and a locking nut. The clamping bolt passes through the lower support plate and is connected to the corresponding upper pad. The disc spring, the clamping nut and the locking nut are all sleeved on the clamping bolt, and the disc spring is arranged between the lower support plate and the upper pad. A locking nut is provided on the lower side of the disc spring, and a clamping nut is provided on the upper side of the lower support plate.

[0017] The iron core includes an upper iron yoke and a lower iron yoke, wherein the upper iron yoke is arranged between two upper clamps, and the ends of the two upper clamps are connected by upper side end screws and the middle is connected by an upper side intermediate screw, a lower pad is provided between the lower clamp and the lower end of the coil assembly, the lower iron yoke is arranged between the two lower clamps, and the ends of the two lower clamps are connected by lower side end screws and the middle is connected by a lower side intermediate screw, a hanging plate is provided on the upper side of the upper clamp, and a base is provided on the lower side of the lower clamp.

[0018] An inner lead row and an outer lead row are provided at the upper end of the low-voltage coil, and a sealing copper row is provided on the upper clamp. The inner lead row and the sealing copper row are connected with a copper row locking nut by bolts, and a nylon ring is embedded inside the copper row locking nut.

[0019] A method for manufacturing a high-voltage coil of a low-temperature resistant dry-type transformer comprises the following steps:

[0020] Step 1: placing the inner mold at a set position, and then setting the coil inner insulation on the inner mold;

[0021] Step 2: Winding electromagnetic wires around the outer side of the coil inner insulation to form an airway inner coil, and providing interlayer insulation between two adjacent layers of electromagnetic wires;

[0022] Step 3: Align the inner edge of the uncut side of the first inner glass fiber continuous felt with the corresponding end surface of the insulation inside the coil and place it at the corresponding end of the insulation inside the coil, and then place the end insulation mesh cloth layer by layer on the end insulation positions on the upper and lower sides of the inner coil of the airway until the end insulation height is filled, and then bend the side with the opening of the first inner glass fiber continuous felt to compress and wrap the corresponding end insulation mesh cloth;

[0023] Step 4: Winding the airway insulation on the airway inner coil, and the inner first glass fiber continuous felt is provided with an opening on one side and fixed by the airway insulation;

[0024] Step 5: placing the second glass fiber continuous mat and each airway mold on the airway inner insulation, and the second glass fiber continuous mat is reciprocatingly bent to form a plurality of wrapping parts, each airway mold is respectively placed in the corresponding wrapping part, and after each airway mold is placed along the circumferential direction, the airway outer insulation is wound on the outside;

[0025] Step 6: Winding electromagnetic wires on the outside of the airway outer insulation to form an airway outer coil, and providing interlayer insulation between two adjacent layers of electromagnetic wires;

[0026] Step 7: Align the inner edge of the uncut side of the outer first glass fiber continuous felt with the airway outer insulation height and place it at the corresponding end of the airway outer insulation, then place the end insulation mesh cloth layer by layer on the end insulation positions on the upper and lower sides of the airway outer coil until the end insulation height is filled, and then bend the side with an opening of the outer first glass fiber continuous felt to compress and wrap the corresponding end insulation mesh cloth;

[0027] Step 8: Wind the outer insulation of the coil on the outer coil of the airway, and place the panel filling mesh cloth on the outer diameter surface of the outer coil of the airway according to the position and shape of the coil panel, and then tie the outer insulation of the coil together with the panel filling mesh cloth through the glass fiber cloth tape, and at the same time, fix the opening side of the outer first glass fiber continuous felt through the outer insulation of the coil;

[0028] Step 9: Put the outer mold on the outer insulation of the coil and install the coil panel;

[0029] Step 10: Pour low-temperature resistant epoxy resin between the inner mold and the outer mold. After casting, remove the inner mold, outer mold and airway mold.

[0030] The advantages and positive effects of the present invention are:

[0031] 1. In order to avoid the problem of resin cracking at low temperatures, the present invention adds a composite insulation filling of mesh cloth at the corresponding position of the high-voltage coil, wherein the inner insulation and the outer insulation in the high-voltage coil are both composite insulation structures of round-edge mesh cloth and glass fiber cloth tape, the end insulation of the high-voltage coil adopts a composite insulation structure of end insulation mesh cloth and glass fiber continuous felt, the coil panel on the front side of the high-voltage coil and the outer diameter surface of the high-voltage coil are filled with panel-filled mesh cloth and glass fiber cloth tape to form a composite insulation structure, and the interlayer insulation of each layer of electromagnetic wire of the high-voltage coil is formed by filling the interlayer mesh cloth.

[0032] 2. The present invention improves the shape of the airway mold of the high-voltage coil, changing it to a trapezoidal shape that is narrow at the top and wide at the bottom to ensure that the resin spacing width between two adjacent airways after pouring is consistent, and each corner end of the trapezoid adopts a rounded transition to reduce stress concentration. At the same time, before pouring, the present invention uses a second glass fiber continuous felt to be reciprocatingly bent to form a plurality of wrapping parts, and places the airway mold in the corresponding wrapping parts, so that after pouring, the second glass fiber continuous felt is filled between two adjacent airways, thereby improving the ability of the resin between the two airways to resist cracking in a low temperature environment.

[0033] 3. The present invention utilizes a clamping assembly to connect the lower support plate on the lower side of the upper clamp with the upper pad. The clamping assembly is provided with a disc spring that can increase the coil deformation space. At the same time, the disc spring can also ensure that the transformer can have a good clamping force when the ambient temperature changes greatly from low temperature to high temperature, thereby improving the fastening ability and stability of the transformer mechanical structure.

[0034] 4. The present invention utilizes a copper bar locking nut with a nylon ring embedded inside to connect the inner lead bar of the low-voltage coil with the zero-sealing copper bar. In a low-temperature and severe cold environment, although the nylon material will harden, it can still provide sufficient friction to prevent the nut from loosening, thereby maintaining sufficient anti-loosening capability to prevent the bolts from loosening during long-term expansion and contraction in a low-temperature environment, thereby increasing the contact resistance between the busbars and burning the transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is the front view of the present invention,

[0036] Figure 2 for Figure 1 The left side view of the present invention,

[0037] Figure 3 for Figure 2 Enlarged schematic diagram of the clamping assembly.

[0038] Figure 4 for Figure 1 A top view of the present invention,

[0039] Figure 5 for Figure 4 Schematic diagram of the structure of the locking nut of the copper bar.

[0040] Figure 6 for Figure 1 A cross-sectional view of the coil assembly of the present invention,

[0041] Figure 7 for Figure 6 Top view of medium and high voltage coils.

[0042] Figure 8 for Figure 7Schematic diagram of the mesh filling between the middle coil panel and the outer diameter surface of the high-voltage coil.

[0043] Fig. 9 for Figure 7 Main view of medium and high voltage coils,

[0044] Fig.10 for Fig. 9 Schematic diagram of the terminal insulation manufacturing process at A in the middle.

[0045] Fig.11 for Fig.10 Schematic diagram of the first glass fiber continuous mat,

[0046] Fig.12 for Figure 7 Schematic diagram of the internal structure of the medium and high voltage coil.

[0047] Fig.13 for Fig.12 Schematic diagram of round-edge mesh fabric used for inner and outer insulation.

[0048] Fig.14 This is a schematic diagram of the arrangement of the airway mold used in the high-voltage coil airway casting of the present invention.

[0049] Fig.15 for Fig.14 Enlarged schematic diagram of the middle airway mold.

[0050] Fig.16 for Fig.15 Side view of the mid-airway mold.

[0051] Among them, 1 is the iron core, 101 is the upper iron yoke, 102 is the lower iron yoke, 103 is the core column, 1031 is the silicone rubber rod, 2 is the upper clamp, 201 is the upper pad, 202 is the upper side end screw, 203 is the upper middle screw, 204 is the clamping assembly, 2041 is the clamping bolt, 2042 is the disc spring, 2043 is the clamping nut, 2044 is the locking nut, 205 is the hanging plate, 206 is the lower support plate, 3 is the lower clamp, 301 is the lower pad, 302 is the lower side end screw, 303 is the lower middle screw, 304 is the base, 4 is the high-voltage coil, 401 is the coil panel, 4011 is the terminal, 4012 is the tap terminal, 4013 is the tap sheet, 4014 is the copper bolt, 4015 is the conductive rod, 4016 is the triangle Area, 4017 is a rectangular area, 4018 is a panel filling mesh cloth, 402 is an end insulation, 4021 is an end insulation mesh cloth, 4022 is a first glass fiber continuous felt, 40221 is an opening, 403 is an electromagnetic wire, 404 is an inner mold, 405 is an outer mold, 406 is an inner insulation of the coil, 407 is an outer insulation of the coil, 408 is an airway, 4081 is an inner insulation of the airway, 4082 is an outer insulation of the airway, 409 is an interlayer insulation, 5 is an insulating cylinder, 6 is a low-voltage coil, 601 is an inner lead row, 602 is an outer lead row, 7 is a sealing copper busbar, 701 is a copper busbar locking nut, 7011 is a nylon ring, 8 is an airway mold, 801 is a glass fiber casing, 9 is a round-edge mesh cloth, 10 is a second glass fiber continuous felt, and 11 is a wrapping part. DETAILED DESCRIPTION

[0052] The present invention will be further described below in conjunction with the accompanying drawings.

[0053] like Figures 1 to 16 As shown, the present invention includes an iron core 1, and the iron core 1 includes an upper iron yoke 101, a lower iron yoke 102, and a core column 103 arranged between the upper iron yoke 101 and the lower iron yoke 102, wherein as Figure 6 As shown, a coil assembly is sleeved on the core column 103 , and the coil assembly includes a low-voltage coil 6 , an insulating sleeve 5 and a high-voltage coil 4 arranged in sequence from the inside to the outside, and a silicone rubber rod 1031 is provided between the core column 103 and the low-voltage coil 6 .

[0054] like Fig.12As shown, in this embodiment, the high-voltage coil 4 includes a coil inner insulation 406, an airway 408 and a coil outer insulation 407 which are arranged in sequence from the inside to the outside, wherein an airway inner insulation 4081 is provided on the inside of the airway 408, and an airway outer insulation 4082 is provided on the outside, and multiple layers of electromagnetic wires 403 are wound between the coil inner insulation 406 and the airway inner insulation 4081 to form an airway inner coil, and multiple layers of electromagnetic wires 403 are wound between the airway outer insulation 4082 and the coil outer insulation 407 to form an airway outer coil, and any two adjacent layers of electromagnetic wires 403 are separated by an interlayer insulation 4031, and the electromagnetic wires 403 are fixed by pouring low-temperature resistant epoxy resin, a coil panel 401 is provided on the front side of the high-voltage coil 4, and the wiring led out of the electromagnetic wires 403 are respectively connected to the corresponding terminals on the coil panel 401, and end insulation 402 is provided at both ends of the high-voltage coil 4 except for the airway 408 position.

[0055] Since the high-voltage coil 4 is located at the outermost side of the coil assembly, the present invention mainly modifies the high-voltage coil 4 to avoid the problem of resin cracking at low temperatures. In the above-mentioned high-voltage coil 4 structure, after the electromagnetic wire 403 is wound, it is positioned by pouring low-temperature resistant epoxy resin. After the epoxy resin is poured, although the resin layer can completely encapsulate the electromagnetic wire 403 inside the coil, the resin layer at many positions is very easy to crack at low temperatures. In order to solve the above problem, the present invention adds a composite insulation filling of mesh cloth at the corresponding position of the high-voltage coil 4, specifically:

[0056] 1. The coil inner insulation 406 and the coil outer insulation 407 in the high voltage coil 4 are both composite insulation structures of round edge mesh cloth 9 and glass fiber cloth tape. When manufacturing the high voltage coil 4, Fig.10 As shown, the inner mold 404 and the outer mold 405 are required to define the inner and outer positions of the high-voltage coil 4, wherein the inner insulation 406 of the coil first uses the thinnest layer of round-edge mesh cloth 9 to be placed in a position that fits the inner mold 404, and then the remaining round-edge mesh cloths 9 are stacked layer by layer according to the designed thickness of the inner insulation 406 of the coil until the design requirements are met and bound with glass fiber cloth tape, while the outer insulation 407 of the coil first uses the thinnest layer of round-edge mesh cloth 9 to fit the outer side of the coil outside the airway, and then the remaining round-edge mesh cloths 9 are stacked layer by layer according to the designed thickness of the outer insulation 407 of the coil until the design requirements are met and bound with glass fiber cloth tape. In addition, Fig.13 As shown, each subsequent layer of round-edge mesh cloth 9 needs to be rotated 90° with the previous layer of round-edge mesh cloth 9 to ensure that the thick wires and thin wires of the two adjacent layers of round-edge mesh cloth 9 are arranged vertically. This placement method allows the two adjacent layers of round-edge mesh cloth 9 to support each other, and at the same time, the space between each layer of round-edge mesh cloth 9 can be effectively utilized, so that the resin flows in the coil during subsequent pouring. In this embodiment, Fig.13As shown, the round edge of the round edge mesh cloth 9 is placed at the upper and lower ends of the high-voltage coil 4, and the round edge is reserved 2 to 3 mm from the coil end, which helps prevent the edge of the round edge mesh cloth 9 from contacting the two ends of the high-voltage coil 4, thereby causing the edge of the round edge mesh cloth 9 to be exposed after casting and causing the resin to crack in a low temperature environment. After the subsequent coil winding is completed and the casting resin is positioned, the inner mold 404 and the outer mold 405 will be removed.

[0057] 2. Figures 10-11 As shown, the end insulation 402 of the high-voltage coil 4 is formed of a composite insulation structure using an end insulation mesh cloth 4021 and a first glass fiber continuous felt 4022, wherein the length of the first glass fiber continuous felt 4022 is consistent with the circumference of the high-voltage coil 4, and the width is the thickness of the high-voltage coil 4 in the diameter direction plus L (in this embodiment, L = 300mm), as shown in FIG. Fig.11 As shown, the first glass fiber continuous felt 4022 needs to be cut into openings 40221 along the length direction at intervals of 50 mm in the width direction, and 150 mm is left uncut.

[0058] When making the end insulation 402 on the inner side of the airway, first align the uncut side of the inner first glass fiber continuous felt 4022 with the corresponding end face of the high-voltage coil 4 (that is, the end face of the coil inner insulation 406) and place it on the corresponding end of the coil inner insulation 406, and then wind the airway inner coil on the coil inner insulation 406. After winding, at the end insulation positions on the upper and lower sides of the inner coil of the airway, start placing end insulation mesh cloth 4021 layer by layer according to the height size of the end insulation 402 minus H (in this embodiment, H=5mm) until the height of the end insulation 402 is filled, and then bend and press the end insulation mesh cloth 4021 on the side with the opening 40221 of the inner first glass fiber continuous felt 4022, and then wind the airway inner insulation 4081 on the inner coil of the airway and fix the opening 40221 side of the inner first glass fiber continuous felt 4022.

[0059] When making the end insulation 402 on the outside of the airway, align the uncut side of the first glass fiber continuous felt 4022 on the outside with the corresponding end face of the high-voltage coil 4 (that is, the end face of the airway outer insulation 4082) and place it on the corresponding end of the airway outer insulation 4082, and then wind the airway outer coil on the outside of the airway outer insulation 4082. After the airway outer coil is wound, at the end insulation positions on the upper and lower sides of the airway outer coil, start placing end insulation mesh cloth 4021 layer by layer according to the height size of the end insulation 402 minus H (in this embodiment, H=5mm) until the height of the end insulation 402 is filled, and then bend and press the end insulation mesh cloth 4021 on one side of the first glass fiber continuous felt 4022 on the outside with an opening 40221, and then wind the coil outer insulation 407 on the airway outer coil and fix the opening 40221 side of the first glass fiber continuous felt 4022 on the outside, so that the end insulation 402 on both sides of the airway is completed.

[0060] The end insulation 402 forms an end insulation mesh cloth 4021 structure which is completely wrapped by the first glass fiber continuous felt 4022, which effectively solves the problem that the resin at the end of the high-voltage coil 4 is easy to crack in a low temperature environment due to the low filling rate of the mesh cloth at the end of the high-voltage coil 4.

[0061] 3. Fig. 9 As shown, the coil panel 401 on the front side of the high-voltage coil 4 is provided with a connection terminal 4011 and a tap terminal 4012, and as shown Fig.12 As shown, the lead-out lines of the high-voltage coil 4 are respectively connected to the connection terminals 4011 and the tapping terminals 4012, but as shown in FIG. Figures 7-8 As shown, considering the need for wiring and terminal welding, a spacing area is provided between the coil panel 401 and the outer diameter surface of the high-voltage coil 4, and the spacing area forms an area with triangular areas 4016 on both sides and a rectangular area 4017 in the middle. The rectangular area 4017 is used for the arrangement and welding operation of the electromagnetic wire 403, but there are only a few electromagnetic wires 403 connected to the wiring terminal 4011 and the tap terminal 4012 in the rectangular area 4017, and most of the others are resin filling areas. The triangular area 4016 serves as the connecting area between the rectangular area 4017 and the outer diameter of the high-voltage coil 4. There is no electromagnetic wire 403 inside it, and it is all resin filling areas. These two positions are the key locations for coil resin cracking, and effective insulation filling is required to improve The mechanical properties of the resin are specifically as follows: while a round-edge mesh cloth 9 is wound on the outer coil of the airway to form the outer insulation 407 of the coil, the corresponding panel filling mesh cloth 4018 is placed layer by layer on the outer diameter surface of the outer coil of the airway according to the shape and area according to the position and shape of the coil panel 401, and then the outer insulation 407 of the coil is fastened together with the panel filling mesh cloth 4018 by a glass fiber cloth tape, wherein the corresponding position of the panel filling mesh cloth 4018 needs to be removed according to the position of the electromagnetic wire 403 and the terminal head in the rectangular area 4017, so that the electromagnetic wire 403 etc. can pass through the position where the panel filling mesh cloth 4018 is removed, and the stacking height of the panel filling mesh cloth 4018 is slightly smaller than the gap distance between the coil panel 401 and the outer diameter of the high-voltage coil 4.

[0062] 4. During the coil winding process, the interlayer insulation 4031 of the high-voltage coil 4 is formed by filling the interlayer mesh cloth layer by layer. The width of the interlayer mesh cloth should be greater than the maximum width of the upper and lower conductor layers. At the same time, the outermost turns of the wires on both sides of each layer of wire should be tied together with the middle electromagnetic wire 403 with glass fiber cloth tape to prevent the edge electromagnetic wire 403 from loosening and slipping, thereby causing the interlayer insulation 4031 to fail. Since the warp and weft of the interlayer mesh cloth have a certain interval, if the electromagnetic wire 403 is small in size or a round conductor is used, the electromagnetic wire 403 will be wound in the interval between the warp or weft, resulting in the insulation thickness between the two layers of electromagnetic wires 403 being less than the thickness of the interlayer insulation 4031, which is prone to local discharge. Therefore, the interlayer insulation 4031 should also be stacked with multiple layers of interlayer mesh cloth, and each layer of interlayer mesh cloth needs to be rotated 90° from the warp and weft of the previous layer of interlayer mesh cloth.

[0063] 5. When the high-voltage coil 4 is coiled, after the winding of the coil inside the airway is completed, the airway insulation 4081 is first wound on the outside of the inner coil of the airway, and then the airway mold 8 forming the airway 408 is arranged along the circumferential direction and placed on the airway insulation 4081, and its length direction is parallel to the height direction of the high-voltage coil 4. When the high-voltage coil 4 is finally poured with resin, the airway mold 8 is taken out of the high-voltage coil 4 and the airway 408 is formed to dissipate heat of the high-voltage coil 4. However, in the prior art, the cross-section of the airway 408 usually adopts a symmetrical shape (such as a rectangle, an oblong, etc.) along the center line of the airway 408. Since multiple airways 408 are arranged circumferentially on the outside of the high-voltage coil 4, this will cause the outer spacing distance of two adjacent airways 408 to be greater than the inner spacing distance. In this way, the resin width between the two adjacent airways 408 is inconsistent, which is easy to cause uneven force, and then cause the problem of resin cracking in a low temperature environment.

[0064] like Figures 14 to 16 As shown, in order to solve the above problems, the present invention first improves the shape of the airway mold 8, changing it to a trapezoidal shape that is narrow at the top and wide at the bottom, wherein the narrow side of the trapezoid corresponds to the inner diameter side of the airway 408, and the wide side corresponds to the outer diameter side of the airway 408, and the length difference between the narrow side and the wide side is equal to the curvature difference between the inner diameter side and the outer diameter side of the airway 408. In this way, the resin spacing width between two adjacent airways 408 can be ensured to be consistent, thereby reducing the risk of resin cracking between the airways 408.

[0065] Secondly, each corner of the trapezoidal cross section of the airway mold 8 is rounded. According to the principle of mechanics, stress will be highly concentrated at the corners. This is because the stress line will change sharply at the sharp edge, and the stress concentration coefficient at the corners may be several times higher than other smooth areas. The rounded transition can make the stress more evenly distributed, thereby effectively reducing the stress concentration and further avoiding excessive local stress leading to resin cracking.

[0066] After the airway mold 8 is placed in the airway inner insulation 4081 again, the airway mesh cloth will continue to be wound on the outside of the airway mold 8 to form the airway outer insulation 4082. In addition, a glass fiber sleeve 801 is provided on the outside of the airway mold 8. In this way, the airway mold 8 itself and both sides of the arrangement structure are insulated. However, the insulation between two adjacent airway molds 8 is relatively weak, and the resin here is easy to crack after pouring. Fig.14 As shown, the present invention further adds a second glass fiber continuous felt 10 filling between the inner insulation 4081 and the outer insulation 4082 of the air duct, wherein the second glass fiber continuous felt 10 is reciprocatingly bent to form a plurality of wrapping parts 11, the opening directions of two adjacent wrapping parts 11 are opposite and each air duct mold 8 is respectively placed in the corresponding wrapping part 11, and the wrapping part 11 presses the corresponding air duct mold 8, so that after pouring, the second glass fiber continuous felt 10 is filled between two adjacent air ducts 408, thereby improving the anti-cracking ability of the resin here in a low temperature environment.

[0067] The specific process of placing the airway mold 8 is as follows: first wind an airway mesh cloth around the outside of the coil inside the airway and tie it up to form the airway inner insulation 4081, then fix the starting point of the second glass fiber continuous felt 10 on the airway inner insulation 4081, first place the first airway mold 8 at the starting point of the second glass fiber continuous felt 10, then lift up the second glass fiber continuous felt 10 and place the second airway mold 8 between the second glass fiber continuous felt 10 and the airway inner insulation 4081, then place the third airway mold 8 on the second glass fiber continuous felt 10, then lift up the second glass fiber continuous felt 10 and place the fourth airway mold 8 between the second glass fiber continuous felt 10 and the airway inner insulation 4081, repeat this operation until all the airway molds 8 are placed along the circumferential direction, then place the airway mesh cloth on the outside of the above structure and tie it up to form the airway outer insulation 4082.

[0068] In addition, Figures 1 to 3As shown, the coil assembly is provided with an upper clamp 2 at the upper end and a lower clamp 3 at the lower end, and an upper pad 201 is provided between the upper clamp 2 and the upper end of the coil assembly, and a lower pad 301 is provided between the lower clamp 3 and the lower end of the coil assembly. The upper clamp 2 and the lower clamp 3 are used to clamp and fix the coil assembly. In addition, the upper iron yoke 101 on the upper side of the iron core 1 is provided between the two upper clamps 2, and the ends of the two upper clamps 2 are connected by an upper side end screw 202, and the middle is connected by an upper side middle screw. 203 is connected to achieve the upper iron yoke 101 limiting position, the lower iron yoke 102 on the lower side of the iron core 1 is arranged between the two lower clamps 3, and the ends of the two lower clamps 3 are connected by the lower end screws 302, and the middle is connected by the lower middle screw 303, so as to achieve the lower iron yoke 102 limiting position, the upper side of the upper clamp 2 is provided with a hanging plate 205, the lower side of the lower clamp 3 is provided with a base 304, and the upper clamp 2 and the lower clamp 3 are fixedly connected by a vertical screw to achieve clamping and fixing the coil.

[0069] According to the principle of thermal expansion and contraction, the coil height of the high-voltage coil 4 and the low-voltage coil 6 of the transformer will decrease at low temperatures. When the transformer load increases and the coil heats up, the coil height will increase due to thermal expansion. Figures 2-3 As shown, the present invention connects the lower support plate 206 on the lower side of the upper clamp 2 with the upper pad 201 through a clamping assembly 204, and the clamping assembly 204 includes a clamping bolt 2041, a disc spring 2042, a clamping nut 2043 and a locking nut 2044, wherein the clamping bolt 2041 passes through the lower support plate 206 and is connected to the corresponding upper pad 201, the disc spring 2042, the clamping nut 2043 and the locking nut 2044 are all sleeved on the clamping bolt 2041, wherein the disc spring 2042 is arranged between the lower support plate 206 and the upper pad 201, and a locking nut 2044 is provided on the lower side of the disc spring 2042, and a clamping nut 2043 is provided on the upper side of the lower support plate 206. When the transformer load increases and the coil heats up, the coil height increases due to thermal expansion. At this time, the disc spring 2042 can increase the space for coil deformation, ensuring that after the coil height increases, the coil end will not be pressed too tightly by the increased clamping force, causing the resin to crack. In addition, the disc spring 2042 bears the increased clamping force, and the disc spring 2042 height decreases and stores a certain potential energy. When the transformer load decreases or the ambient temperature decreases, the coil height decreases due to cold shrinkage, the clamping force of the clamping assembly 204 decreases, and the clamping nut 2043 tends to become loose. At this time, the disc spring 27 releases this part of the potential energy stored when the coil expands, that is, the disc spring 2042 height increases to offset the reduced height of the coil, thereby maintaining the pressure of the clamping nut 2043 to meet the clamping requirements. The present invention adopts the above structure to ensure that the transformer has a good clamping force when the ambient temperature changes greatly from low temperature to high temperature, thereby improving the fastening ability and stability of the transformer mechanical structure.

[0070] like Figure 2 As shown, in this embodiment, the upper end of the low-voltage coil 6 is provided with an inner lead row 601 and an outer lead row 602. Figure 4 As shown, the upper clamp 2 is provided with a sealing copper bar 7, the inner lead bar 601 is a neutral point copper bar, which is used for connecting the neutral point of the three-phase low-voltage coil 6, that is, connected to the sealing copper bar 7, the outer lead bar 602 is connected to the external electrical equipment and loads the transmission of electrical energy, and the inner lead bar 601 of the low-voltage coil 6 is connected to the sealing copper bar 7 by bolts and copper bar locking nuts 701, and as shown Figure 5 As shown, a nylon ring 7011 is embedded inside the copper bar locking nut 701. When the bolt is connected to the copper bar locking nut 701, the nylon ring 7011 in the copper bar locking nut 701 will be squeezed and deformed and fit tightly with the bolt thread. Because nylon is a poor conductor of heat, in a low-temperature and severe cold environment, although the nylon material will harden, it can still provide sufficient friction to prevent the nut from loosening, and thus maintain a certain anti-loosening ability to prevent the bolt from loosening during long-term expansion and contraction in a low-temperature environment, resulting in an increase in the contact resistance between the busbars and burning of the transformer.

[0071] like Figure 1 As shown, in this embodiment, the connection terminals 4011 on the coil panel 401 are connected correspondingly through the conductive rods 4015, the tap terminals 4012 on the coil panel 401 are connected through the tap plates 4013, and the ends of the tap plates 4013 are fixedly connected to the corresponding tap terminals 4012 through copper bolts 4014.

[0072] The working principle of the present invention is:

[0073] In the structure of the high-voltage coil 4, after the electromagnetic wire 403 is wound, it is positioned by pouring low-temperature resistant epoxy resin. After the epoxy resin is poured, the resin layer can completely encapsulate the electromagnetic wire 403 inside the coil. However, in order to avoid the problem of resin cracking at low temperatures, the present invention adds a composite insulation filling of mesh cloth at the corresponding position of the high-voltage coil 4, wherein:

[0074] 1. The coil inner insulation 406 and the coil outer insulation 407 in the high voltage coil 4 are both composite insulation structures of round edge mesh cloth 9 and glass fiber cloth tape;

[0075] Second, the end insulation 402 of the high voltage coil 4 uses an end insulation mesh cloth 4021 and a first glass fiber continuous felt 4022 to form a composite insulation structure;

[0076] 3. A composite insulation structure is formed between the coil panel 401 on the front side of the high-voltage coil 4 and the outer diameter surface of the high-voltage coil 4 using a panel filling mesh cloth 4018 and a glass fiber cloth tape;

[0077] 4. The interlayer insulation 4031 between the layers of electromagnetic wires 403 of the high-voltage coil 4 is formed by filling the interlayer mesh cloth layer by layer;

[0078] 5. Improve the shape of the airway mold 8 of the high-voltage coil 4 by changing it to a trapezoidal shape that is narrow at the top and wide at the bottom to ensure that the resin spacing width between two adjacent airways 408 is consistent, and each corner end of the trapezoid adopts a rounded transition to reduce stress concentration. At the same time, before pouring, the second glass fiber continuous felt 10 is reciprocatingly bent to form a plurality of wrapping parts 11, and the airway mold 8 is placed in the corresponding wrapping parts 11, so that after pouring, the second glass fiber continuous felt 10 is filled between two adjacent airways 408.

[0079] The present invention reduces the risk of cracking of the resin at the corresponding position of the high-voltage coil 4 in a low-temperature environment through the above measures.

[0080] In addition, the present invention uses a clamping assembly 204 to connect the lower support plate 206 on the lower side of the upper clamp 2 with the upper pad 201. The clamping assembly 204 is provided with a disc spring 2042 that can increase the coil deformation space. At the same time, it can also ensure that the transformer has a good clamping force when the ambient temperature changes greatly from low temperature to high temperature, thereby improving the fastening ability and stability of the transformer mechanical structure. The present invention also uses a copper bar locking nut 701 with a nylon ring 7011 embedded inside to connect the inner lead bar 601 of the low-voltage coil 6 with the zero-sealing copper bar 7. In a low-temperature and severe cold environment, although the nylon material will harden, it can still provide sufficient friction to prevent the nut from loosening, thereby maintaining a certain anti-loosening ability, preventing the bolts from loosening during long-term expansion and contraction in a low-temperature environment, resulting in an increase in the contact resistance between the busbars and burning the transformer.

[0081] Through the above improvements, the present invention can adapt to low-temperature and severe cold environmental conditions, and can operate safely and reliably throughout the entire equipment life cycle without adding insulation cotton and installing heating devices.

[0082] The high voltage coil 4 winding method of the present invention comprises the following steps:

[0083] Step 1: placing the inner mold 404 at a set position, and then attaching multiple layers of round-edge mesh cloth 9 to the inner mold 404 to form the coil inner insulation 406;

[0084] Step 2: Wind the electromagnetic wire 403 around the outer side of the coil inner insulation 406 to form the airway inner coil, and fill the space between two adjacent layers of electromagnetic wire 403 with interlayer mesh cloth to form interlayer insulation 4031;

[0085] Step 3: Make the end insulation 402 on the inside of the airway, specifically: cut the openings 40221 of the first glass fiber continuous felt 4022 on the inside at equal intervals along the length direction according to the design requirements, then align the inner edge of one side of the first glass fiber continuous felt 4022 (i.e., the bottom end of each opening 40221) without cutting it with the corresponding end surface of the insulation 406 inside the coil and place it on the corresponding end of the insulation 406 inside the coil, then place the end insulation mesh cloth 4021 layer by layer at the end insulation 402 positions on the upper and lower sides of the inner coil of the airway until the height of the end insulation 402 is filled, then bend the side of the first glass fiber continuous felt 4022 on the inside with the opening 4021 to compress and wrap the corresponding end insulation mesh cloth 4021;

[0086] Step 4: Continue to wind the airway mesh cloth on the wound airway inner coil to form the airway inner insulation 4081, and fix the inner first glass fiber continuous felt 4022 with the opening 40221 on one side through the airway inner insulation 4081;

[0087] Step 5: placing the second glass fiber continuous mat 10 and each airway mold 8 on the airway inner insulation 4081, and the second glass fiber continuous mat 10 is reciprocatingly bent to form a plurality of wrapping parts 11, each airway mold 8 is respectively placed in the corresponding wrapping part 11, and after each airway mold 8 is placed along the circumferential direction, an airway mesh cloth is wound on the outside to form the airway outer insulation 4082;

[0088] Step 6: Wind the electromagnetic wire 403 around the outside of the airway outer insulation 4082 to form an airway outer coil, and use interlayer mesh cloth to fill the space between two adjacent layers of electromagnetic wire 403 to form interlayer insulation 4031;

[0089] Step 7: Align the inner edge of the uncut side of the outer first glass fiber continuous felt 4022 with the airway outer insulation 4082 and place it at the corresponding end of the airway outer insulation 4082, and then place the end insulation mesh cloth 4021 layer by layer at the end insulation 402 positions on the upper and lower sides of the airway outer coil until the end insulation 402 height is filled, and then bend the side of the outer first glass fiber continuous felt 4022 with the opening 40221 to compress and wrap the corresponding end insulation mesh cloth 4021;

[0090] Step 8: Continue to wind the round-edge mesh cloth 9 on the outer coil of the airway to form the outer insulation 407 of the coil, and place the panel filling mesh cloth 4018 on the outer diameter surface of the outer coil of the airway according to the position and shape of the coil panel 401, and then tie the outer insulation 407 of the coil together with the panel filling mesh cloth 4018 through the glass fiber cloth tape, and at the same time, fix one side of the opening 40221 of the outer first glass fiber continuous felt 4022 through the outer insulation 407 of the coil;

[0091] Step 9: Put the outer mold 405 on the outer insulation 407 of the coil and install the coil panel 401, so that the insulation at all positions has been filled before pouring;

[0092] Step 10: pour low-temperature resistant epoxy resin between the inner mold 404 and the outer mold 405, and remove the inner mold 404, the outer mold 405 and the airway mold 8 after casting.

Claims

1. A low temperature resistant dry-type transformer, characterized in that: The invention comprises an iron core (1), wherein a coil assembly is sleeved on a core column (103) of the iron core (1), wherein the coil assembly comprises a low-voltage coil (6), an insulating sleeve (5) and a high-voltage coil (4) which are arranged in sequence from the inside to the outside, wherein the high-voltage coil (4) comprises a coil inner insulation (406), an air duct (408) and a coil outer insulation (407) which are arranged in sequence from the inside to the outside, and the air duct (408) is provided with an air duct inner insulation (4081) on the inside and an air duct outer insulation (4082) on the outside, wherein the Multiple layers of electromagnetic wire (403) are wound between the coil inner insulation (406) and the airway inner insulation (4081) to form the airway inner coil, multiple layers of electromagnetic wire (403) are wound between the airway outer insulation (4082) and the coil outer insulation (407) to form the airway outer coil, interlayer insulation (4031) is provided between two adjacent layers of electromagnetic wire (403), end insulation (402) is provided at both ends of the high-voltage coil (4) except the airway (408) position, and the electromagnetic wire (403) is resistant to low temperature by casting The invention relates to a method for manufacturing a high-voltage coil (402) and a high-voltage coil (403) comprising a plurality of glass fibers and a plurality of epoxy resin fixed thereto, wherein the inner coil insulation (406) and the outer coil insulation (407) both comprise multiple layers of rounded mesh cloth (9), the end insulation (402) comprises an end insulation mesh cloth (4021) and a first glass fiber continuous felt (4022) wrapping the end insulation mesh cloth (4021) from the outside, the interlayer insulation (4031) comprises multiple layers of interlayer mesh cloth, a second glass fiber continuous felt (10) is provided between two adjacent air ducts (408), and the front side of the high-voltage coil (4) is provided with a glass fiber continuous felt connected to the electric A coil panel (401) is connected to the lead wire of the magnetic wire (403), and a panel filling mesh cloth (4018) is provided between the coil panel (401) and the outer diameter surface of the coil outside the airway; the coil assembly is clamped and fixed by an upper clamp (2) and a lower clamp (3), and an upper pad (201) is provided between the upper clamp (2) and the upper end of the coil assembly, and the lower support plate (206) on the lower side of the upper clamp (2) is connected to the upper pad (201) through a clamping assembly (204) with a disc spring (2042).

2. The low temperature resistant dry-type transformer according to claim 1, characterized in that: In the coil inner insulation (406) and the coil outer insulation (407), each layer of round-edge mesh cloth (9) is rotated 90 degrees with respect to the previous layer of round-edge mesh cloth (9) and each layer of round-edge mesh cloth (9) is fastened and fixed by a glass fiber cloth belt; in the interlayer insulation (4031), each layer of interlayer mesh cloth is rotated 90 degrees with respect to the previous layer of interlayer mesh cloth and placed.

3. The low temperature resistant dry-type transformer according to claim 1, characterized in that: The first glass fiber continuous felt (4022) of the end insulation (402) is provided with an opening (40221) along the length direction, and one side of the first glass fiber continuous felt (4022) provided with the opening (40221) is bent and pressed to wrap the corresponding end insulation mesh cloth (4021).

4. The low temperature resistant dry-type transformer according to claim 1, characterized in that: The second glass fiber continuous felt (10) is reciprocatingly bent to form a plurality of wrapping parts (11), and each air channel (408) is respectively placed in a corresponding wrapping part (11), and the cross section of the air channel (408) is a trapezoidal shape that is narrow at the top and wide at the bottom, wherein the narrow side of the trapezoid corresponds to one side of the insulation (4081) inside the air channel, and the wide side of the trapezoid corresponds to one side of the insulation (4082) outside the air channel, and the length difference between the narrow side and the wide side of the trapezoid is equal to the curvature difference between the insulation (4081) inside the air channel and the insulation (4082) outside the air channel, and each corner end of the trapezoidal cross section is a rounded transition.

5. The low temperature resistant dry-type transformer according to claim 1, characterized in that: A spacing area is formed between the coil panel (401) and the outer diameter surface of the coil outside the airway, and the spacing area includes triangular areas (4016) on both sides and a rectangular area (4017) in the middle, and panel filling mesh cloth (4018) of the same width and height as the coil panel (401) is stacked layer by layer to fill the rectangular area (4017), and panel filling mesh cloth (4018) of decreasing width cut according to the size of the triangular area (4016) is stacked layer by layer to fill the triangular area (4016).

6. The low temperature resistant dry-type transformer according to claim 1 or 5, characterized in that: The coil panel (401) is provided with a connection terminal (4011) and a tap terminal (4012), wherein the connection terminal (4011) is correspondingly connected via a conductive rod (4015), and the tap terminal (4012) is correspondingly connected via a tap sheet (4013), and the end of the tap sheet (4013) is fixedly connected to the corresponding tap terminal (4012) via a copper bolt (4014).

7. The low temperature resistant dry-type transformer according to claim 1, characterized in that: The clamping assembly (204) comprises a clamping bolt (2041), a disc spring (2042), a clamping nut (2043) and a locking nut (2044); the clamping bolt (2041) passes through the lower support plate (206) and is connected to the corresponding upper pad (201); the disc spring (2042), the clamping nut (2043) and the locking nut (2044) are all sleeved on the clamping bolt (2041); the disc spring (2042) is arranged between the lower support plate (206) and the upper pad (201); the locking nut (2044) is arranged on the lower side of the disc spring (2042); and the clamping nut (2043) is arranged on the upper side of the lower support plate (206).

8. The low temperature resistant dry-type transformer according to claim 1, characterized in that: The iron core (1) comprises an upper iron yoke (101) and a lower iron yoke (102), wherein the upper iron yoke (101) is arranged between two upper clamps (2), and the ends of the two upper clamps (2) are connected by an upper side end screw (202) and the middle is connected by an upper side middle screw (203); a lower cushion block (301) is arranged between the lower clamp (3) and the lower end of the coil assembly; the lower iron yoke (102) is arranged between the two lower clamps (3), and the ends of the two lower clamps (3) are connected by a lower side end screw (302) and the middle is connected by a lower side middle screw (303); a hanging plate (205) is arranged on the upper side of the upper clamp (2), and a base (304) is arranged on the lower side of the lower clamp (3).

9. The low temperature resistant dry-type transformer according to claim 1, characterized in that: The upper end of the low-voltage coil (6) is provided with an inner lead row (601) and an outer lead row (602), and the upper clamp (2) is provided with a zero-sealing copper row (7), the inner lead row (601) and the zero-sealing copper row (7) are connected to the copper row locking nut (701) via bolts, and a nylon ring (7011) is embedded inside the copper row locking nut (701).

10. A method for manufacturing a high voltage coil of a low temperature resistant dry-type transformer according to claim 3, characterized in that: The steps include: Step 1: placing the inner mold (404) at a set position, and then setting the coil inner insulation (406) on the inner mold (404); Step 2: Winding the electromagnetic wire (403) outside the coil inner insulation (406) to form an airway inner coil, and providing interlayer insulation (4031) between two adjacent layers of electromagnetic wire (403); Step 3: align the inner edge of the uncut side of the inner first glass fiber continuous felt (4022) with the corresponding end surface of the coil inner insulation (406) and place it at the corresponding end of the coil inner insulation (406), and then place the end insulation mesh cloth (4021) layer by layer on the end insulation (402) positions on the upper and lower sides of the inner coil of the airway until the height of the end insulation (402) is filled, and then bend the side of the inner first glass fiber continuous felt (4022) provided with the opening (40221) to compress and wrap the corresponding end insulation mesh cloth (4021); Step 4: Winding the airway inner insulation (4081) on the airway inner coil, and fixing the inner first glass fiber continuous felt (4022) with one side having an opening (40221) through the airway inner insulation (4081); Step 5: placing the second glass fiber continuous felt (10) and each airway mold (8) on the airway inner insulation (4081), and the second glass fiber continuous felt (10) is reciprocatingly bent to form a plurality of wrapping parts (11), each airway mold (8) is respectively placed in the corresponding wrapping part (11), and after each airway mold (8) is placed along the circumferential direction, the airway outer insulation (4082) is wound on the outside; Step 6: Winding the electromagnetic wire (403) outside the airway outer insulation (4082) to form an airway outer coil, and providing interlayer insulation (4031) between two adjacent layers of electromagnetic wire (403); Step 7: Align the inner edge of the uncut side of the outer first glass fiber continuous felt (4022) with the airway outer insulation (4082) in height and place it at the corresponding end of the airway outer insulation (4082), and then place the end insulation mesh cloth (4021) layer by layer on the end insulation (402) positions on the upper and lower sides of the airway outer coil until the end insulation (402) height is filled, and then bend the side of the outer first glass fiber continuous felt (40222) provided with the opening (40221) to compress and wrap the corresponding end insulation mesh cloth (4021); Step 8: Winding the coil outer insulation (407) on the airway outer coil, placing the panel filling mesh cloth (4018) on the outer diameter surface of the airway outer coil according to the position and shape of the coil panel (401), and then tying the coil outer insulation (407) together with the panel filling mesh cloth (4018) with a glass fiber cloth belt, and fixing one side of the opening (40221) of the outer first glass fiber continuous felt (4022) through the coil outer insulation (407); Step 9: Put the outer mold (405) on the outer insulation (407) of the coil and install the coil panel (401); Step 10: pouring low temperature resistant epoxy resin between the inner mold (404) and the outer mold (405), and removing the inner mold (404), the outer mold (405) and the airway mold (8) after the casting.

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