Low-temperature-resistant dry-type transformer

Abstract

A high-voltage coil comprises a coil inner insulator, an air channel and a coil outer insulator, 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, and interlayer insulators are arranged between every two adjacent layers of electromagnetic wires. End insulators are arranged at the two ends of the high-voltage coil, the electromagnetic wire is fixed by pouring low-temperature-resistant epoxy resin, the coil inner insulator and the coil outer insulator each comprise a plurality of layers of round edge gridding cloth, each end insulator comprises end insulation gridding cloth and a first glass fiber continuous felt wrapping the end insulation gridding cloth from the outer side, and the interlayer insulators comprise a plurality of layers of interlayer gridding cloth. A second glass fiber continuous felt is arranged between every two adjacent air channels, 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 face of the coil. The heating 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 utility model relates to the field of transformer, concretely is a low temperature resistant dry type transformer. BACKGROUND

[0002] The dry type transformer coil adopts the epoxy resin casting process to manufacture, and the epoxy resin and air are used as the main insulating medium. When the load of the dry type transformer is increased in the operation process, heat is generated and the temperature of the coil is increased, and when the load of the transformer is reduced or the operation is stopped, the temperature is decreased. The change of the temperature causes the thermal expansion and cold contraction of the epoxy resin coil. In addition, different materials in the dry type transformer coil, such as copper wire and aluminum wire, have different volume change coefficients when the thermal expansion and cold contraction occur. When the temperature changes, the contraction or expansion degrees of these materials are inconsistent, and therefore stress is generated.

[0003] In addition, not only the temperature change of the coil itself can generate stress, but also the fluctuation of the environmental temperature can cause the stress change in the epoxy resin coil. Since the dry type transformer generally adopts F or H grade insulation, the temperature of the coil itself is relatively high, and is usually above 100 DEG C. If the environmental temperature is relatively low, the sudden change of the surface temperature of the coil can cause a large temperature gradient in the epoxy resin, and therefore the generation of stress is intensified.

[0004] If the stress exceeds the bearing capacity of the epoxy resin, the resin is cracked, and the epoxy resin becomes more brittle in the low temperature environment, and the toughness and ductility are reduced. This makes it more prone to cracking when subjected to external force or internal stress. The brittleness of different types of epoxy resin in the low temperature environment is different. If the structure design is unreasonable or the operation process is improper, cracking is more likely to occur. Therefore, in the low temperature environment, if the dry type transformer is suddenly subjected to the influence of the sudden temperature change, for example, is quickly transferred from the warm indoor to the cold outdoor, or is suddenly impacted by the cold air, the epoxy resin can not adapt to the rapid temperature change and is cracked. The cracks or micro-cracks of the epoxy resin can reduce the insulation performance of the coil, and further cause the internal partial discharge, flashover and other problems of the coil, and affect the safe operation of the transformer.

[0005] In addition, due to the thermal expansion and cold contraction, the connection of the components inside the dry type transformer can become tighter or looser. If the connection is too tight, additional pressure can be caused to the insulating material, and the insulation performance is further damaged. If the connection is loose, poor contact can be caused, local overheating is generated, and the safe operation is also adversely affected.

[0006] In the national standard GB / T1094.11-2007, the most severe temperature and climate resistance level of dry-type transformer is C2 level, that is, the dry-type transformer can operate, transport and store at the minimum environment of-25℃. In the latest version of GB / T1094.11-2022 standard, the application range of dry-type transformer products is increased by 4 climate levels, namely C3, C4, C5 and Cxy, wherein Cxy does not specify the minimum temperature of the specific climate, and needs to be determined by consultation between the actual operation conditions, the user and the transformer manufacturer. Therefore, according to the latest national standard, there is no limit to the minimum use environment temperature of the dry-type transformer, and the dry-type transformer designed and manufactured according to the previous standard of-25℃ cannot meet the safe operation requirements of the low temperature environment in the new national standard.

[0007] The dry-type transformers in the prior art are all designed and manufactured according to the previous standard of-25℃, and when the environmental temperature is below-25℃, measures such as adding insulation cotton to the transformer, building an independent power distribution room and installing a heating device are generally adopted to ensure that the environmental temperature of the transformer is maintained above-25℃. For example, the patent CN206249119U discloses a low-frequency heating device for low-temperature-resistant transformer, which can be used for starting and running of the transformer in high-cold and even extremely cold environments. For example, the patent CN209056335U discloses a low-temperature-resistant insulation bushing for power transformer, which includes a base body, the base body includes a polytetrafluoroethylene insulation layer or a plurality of hot-fused polytetrafluoroethylene insulation layers, and the bushing does not become brittle at extremely low temperature, thereby ensuring good insulation performance and strength of the related components of the transformer. However, if the external insulation measures of the transformer cannot be set in some special environments, and the design of the dry-type transformer does not fully consider the influence of lower temperature environment, or the epoxy resin and other materials suitable for low temperature environment are not selected, the transformer is prone to problems such as resin cracking and mechanical structure fastening failure at low temperature. Practical new type content

[0008] The purpose of the present application is to provide a low-temperature-resistant dry-type transformer which can adapt to low-temperature and cold environmental conditions and can safely and reliably operate throughout the life cycle of the device without the need to increase insulation cotton and install a heating device.

[0009] The purpose of the present application is achieved by the following technical solutions:

[0010] The low-temperature-resistant dry-type transformer comprises a core, and a coil assembly is sleeved on the core column of the core, the coil assembly comprises a low-voltage coil, an insulating sleeve and a high-voltage coil arranged in sequence from inside to outside, wherein the high-voltage coil comprises coil inner insulation, an air channel and coil outer insulation arranged in sequence from inside to outside, and the air channel is provided with air channel inner insulation on the inner side and air channel outer insulation on the outer side, a plurality of layers of electromagnetic wires are wound between the coil inner insulation and the air channel inner insulation to form an air channel inner side coil, a plurality of layers of electromagnetic wires are wound between the air channel outer insulation and the coil outer insulation to form an air channel outer side coil, interlayer insulation is arranged between adjacent two layers of electromagnetic wires, end insulation is arranged at both ends of the high-voltage coil except the air channel position, the electromagnetic wires are fixed by pouring low-temperature-resistant epoxy resin, and the coil inner insulation and the coil outer insulation each comprise a plurality of layers of round edge glass cloth, the end insulation comprises end insulation glass cloth and a first continuous glass silk felt wrapping the end insulation glass cloth from the outside, the interlayer insulation comprises a plurality of layers of interlayer glass cloth, a second continuous glass silk felt is arranged between adjacent two air channels, a coil panel connected with electromagnetic wire leading wires is arranged on the front side of the high-voltage coil, and panel filling glass cloth is arranged between the coil panel and the outer diameter surface of the air channel outer side coil.

[0011] In the coil inner insulation and the coil outer insulation, each layer of round edge glass cloth is placed at 90° to the previous layer of round edge glass cloth, and each layer of round edge glass cloth is fixed by being tightly tied with glass silk cloth.

[0012] An opening is arranged on the first continuous glass silk felt of the end insulation along the length direction, and the first continuous glass silk felt is bent and tightly wrapped around the corresponding end insulation glass cloth on the side with the opening.

[0013] The second continuous glass silk felt is reciprocally bent to form a plurality of wrapping parts, and each air channel is arranged in the corresponding wrapping part, the air channel has a trapezoidal shape with a narrow upper side and a wide lower side, the narrow side of the trapezoidal shape corresponds to one side of the air channel inner insulation, the wide side of the trapezoidal shape corresponds to one side of the air channel outer insulation, the length difference between the narrow side and the wide side of the trapezoidal shape is equal to the arc difference between the air channel inner insulation and the air channel outer insulation, and each corner end of the trapezoidal cross section is a round corner transition.

[0014] The coil panel and the outer diameter surface of the air channel outer side coil form a spacing area, the spacing area comprises triangular areas on both sides and a rectangular area in the middle, panel filling glass cloth with the same width and height as the coil panel is stacked and filled in the rectangular area layer by layer, and panel filling glass cloth with a width decreasing in turn according to the size of the triangular area is stacked and filled in the triangular area layer by layer.

[0015] The coil panel is provided with wiring terminals and tapping terminals, the wiring terminals are connected correspondingly through conductive rods, the tapping terminals are connected correspondingly through tapping pieces, and the end of the tapping piece is fixed with the corresponding tapping terminal through a copper bolt.

[0016] The pressing assembly comprises a pressing bolt, a disc spring, a pressing nut and a locking nut, the pressing bolt is connected with the corresponding upper cushion block after penetrating through the lower supporting plate, the disc spring, the pressing nut and the locking nut are all sleeved on the pressing bolt, the disc spring is arranged between the lower supporting plate and the upper cushion block, the lower side of the disc spring is provided with the locking nut, and the upper side of the lower supporting plate is provided with the pressing nut.

[0017] The iron core comprises an upper yoke and a lower yoke, the upper yoke is arranged between two upper clamping pieces, the end of the two upper clamping pieces is connected through an upper end screw rod, and the middle of the two upper clamping pieces is connected through an upper middle screw rod, a lower cushion block is arranged between the lower clamping piece and the lower end of the coil assembly, the lower yoke is arranged between two lower clamping pieces, the end of the two lower clamping pieces is connected through a lower end screw rod, and the middle of the two lower clamping pieces is connected through a lower middle screw rod, the upper side of the upper clamping piece is provided with a hanging plate, and the lower side of the lower clamping piece is provided with a base.

[0018] The upper end of the low-voltage coil is provided with an inner lead row and an outer lead row, the upper clamping piece is provided with a zero-seal copper row, the inner lead row and the zero-seal copper row are connected through a bolt and a copper row locking nut, and a nylon ring is embedded in the copper row locking nut.

[0019] The utility model discloses an advantage and positive effect are:

[0020] 1, the utility model discloses in order to avoid the problem of resin cracking under low temperature to increase the composite insulation filling of mesh cloth in the corresponding position of high voltage coil, wherein the inner insulation and outer insulation in high voltage coil are the composite insulation structure of round edge mesh cloth and glass silk cloth strip, the end insulation of high voltage coil adopts the composite insulation structure of end insulation mesh cloth and glass silk continuous felt, the coil panel between the coil panel of high voltage coil front side and the outer diameter surface of high voltage coil adopts panel filling mesh cloth and glass silk cloth strip to form the composite insulation structure, and the interlayer insulation of each layer electromagnetic wire of high voltage coil uses interlayer mesh cloth to fill and form insulation.

[0021] 2, the utility model discloses the shape of the air channel mold of high voltage coil is improved, which is changed into a trapezoidal shape with narrow upper side and wide lower side to ensure that the resin interval between two adjacent air channels after pouring is uniform, and each corner end of the trapezoid adopts a round corner transition to reduce stress concentration. Meanwhile, the utility model discloses that a plurality of wrapping parts are formed by reciprocating bending of the second glass silk continuous felt before pouring, and the air channel mold is placed in the corresponding wrapping part. In this way, the second glass silk continuous felt is filled between two adjacent air channels after pouring, thereby improving the anti-cracking ability of the resin between the two air channels in a low temperature environment.

[0022] 3. The utility model discloses a lower support plate of upper clamp lower side is connected with upper cushion block through the compression assembly, the compression assembly is equipped with disc spring that can increase the coil deformation space, and the disc spring can also guarantee that the transformer can have very good compression force when the environmental temperature changes greatly between low temperature and high temperature, and further improve the fastening capacity and stability of transformer mechanical structure.

[0023] 4. The utility model discloses that the copper bar locking nut with nylon ring embedded in the inside is used to connect the inside lead wire row of low voltage coil with zero copper bar, in the low temperature severe cold environment, although nylon material can be hard, but still can provide enough friction to prevent the nut loosening, and further can maintain enough anti-loosening capacity, prevent the bolt loosening in the long-term expansion in the low temperature environment and lead to the contact resistance between busbar increase, burn out the transformer. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is the front view of the utility model,

[0025] Figure 2 It is Figure 1 It is the left view of the utility model,

[0026] Figure 3 It is Figure 2 It is the enlarged schematic view of compression assembly,

[0027] Figure 4 It is Figure 1 It is the plan view of the utility model,

[0028] Figure 5 It is Figure 4 It is the structure schematic diagram of copper bar locking nut,

[0029] Figure 6 It is Figure 1 It is the sectional view of coil assembly of the utility model,

[0030] Figure 7 It is Figure 6 It is the plan view of high voltage coil,

[0031] Figure 8 It is Figure 7 It is the mesh cloth filling schematic diagram between coil panel and high voltage coil outer diameter surface,

[0032] Figure 9 It is Figure 7 It is the front view of high voltage coil,

[0033] Figure 10 It is Figure 9 It is the end insulation manufacturing process state schematic diagram of A,

[0034] Figure 11 It isFigure 10 Schematic view of first glass filament continuous mat,

[0035] Figure 12 For Figure 7 Schematic view of internal structure of high-voltage coil,

[0036] Figure 13 For Figure 12 Schematic view of round edge mesh cloth used for internal and external insulation,

[0037] Figure 14 Schematic view of air channel mold arrangement used during air channel pouring of high-voltage coil of the utility model,

[0038] Figure 15 For Figure 14 Schematic view of air channel mold,

[0039] Figure 16 For Figure 15 Side view of air channel mold.

[0040] Wherein, 1 is iron core, 101 is upper yoke, 102 is lower yoke, 103 is core column, 1031 is silicone rubber rod, 2 is upper clamp, 201 is upper pad, 202 is upper side end screw rod, 203 is upper side middle screw rod, 204 is pressing assembly, 2041 is pressing bolt, 2042 is disc spring, 2043 is pressing nut, 2044 is locking nut, 205 is hanging plate, 206 is lower support plate, 3 is lower clamp, 301 is lower pad, 302 is lower side end screw rod, 303 is lower side middle screw rod, 304 is base, 4 is high-voltage coil, 401 is coil panel, 4011 is terminal, 4012 is tapping terminal, 4013 is tapping piece, 4014 is copper bolt, 4015 is conductive rod, 4016 is triangular area, 4017 is rectangular area, 4018 is panel filling mesh cloth, 402 is end insulation, 4021 is end insulation mesh cloth, 4022 is first glass filament continuous mat, 40221 is opening, 403 is electromagnetic wire, 404 is inner mold, 405 is outer mold, 406 is coil internal insulation, 407 coil is external insulation, 408 is air channel, 4081 is air channel internal insulation, 4082 is air channel external insulation, 409 is interlayer insulation, 5 is insulation cylinder, 6 is low-voltage coil, 601 is inner side lead row, 602 is outer side lead row, 7 is zero sealing copper row, 701 is copper row locking nut, 7011 is nylon ring, 8 is air channel mold, 801 is glass filament sleeve, 9 is round edge mesh cloth, 10 is second glass filament continuous mat, and 11 is wrapping part. DETAILED DESCRIPTION

[0041] The utility model will be further described in detail below in combination with the drawings.

[0042] For example, Figures 1 to 16As shown, the core 1 is provided with a coil assembly, and the coil assembly comprises a low-voltage coil 6, an insulating sleeve 5 and a high-voltage coil 4 arranged in sequence from inside to outside, and a silicon rubber rod 1031 is arranged between the core 103 and the low-voltage coil 6. Figure 6 As shown, the core 103 is provided with a coil assembly, and the coil assembly comprises a low-voltage coil 6, an insulating sleeve 5 and a high-voltage coil 4 arranged in sequence from inside to outside, and a silicon rubber rod 1031 is arranged between the core 103 and the low-voltage coil 6.

[0043] As shown, Figure 12 As shown in the embodiment, the high-voltage coil 4 comprises a coil inner insulation 406, an air channel 408 and a coil outer insulation 407 arranged in sequence from inside to outside, wherein the air channel inner insulation 4081 is arranged on the inner side of the air channel 408, the air channel outer insulation 4082 is arranged on the outer side of the air channel 408, a plurality of layers of electromagnetic wires 403 are arranged between the coil inner insulation 406 and the air channel inner insulation 4081 to form an air channel inner coil, a plurality of layers of electromagnetic wires 403 are arranged between the air channel outer insulation 4082 and the coil outer insulation 407 to form an air channel outer coil, the adjacent two layers of electromagnetic wires 403 are separated by the interlayer insulation 4031, the electromagnetic wires 403 are fixed by pouring low-temperature resistant epoxy resin, the high-voltage coil 4 is provided with a coil panel 401 on the front side, the wires led out from the electromagnetic wires 403 are connected to the corresponding terminals on the coil panel 401, and the end insulation 402 is arranged at both ends of the high-voltage coil 4 except the position of the air channel 408.

[0044] Since the high-voltage coil 4 is located at the outermost side of the coil assembly, the high-voltage coil 4 is mainly transformed to avoid the problem of resin cracking at low temperature. In the structure of the high-voltage coil 4, after the electromagnetic wires 403 are wound, the low-temperature resistant epoxy resin is poured for positioning, and after the pouring of the epoxy resin is completed, although the resin layer can completely encapsulate the electromagnetic wires 403 inside the coil, the resin layer at many positions is prone to cracking at low temperature. In order to solve the above problem, the mesh cloth composite insulation filling is added at the corresponding position of the high-voltage coil 4, and the specific is:

[0045] One, the coil inner insulation 406 and the coil outer insulation 407 in the high-voltage coil 4 are both composite insulation structures of the round edge mesh cloth 9 and the glass silk cloth belt, wherein when the high-voltage coil 4 is manufactured, as shown, Figure 10As shown, the inner mold 404 and outer mold 405 are used to define the inner and outer positions of the high-voltage coil 4. The inner insulation 406 of the coil requires the thinnest layer of round-edged mesh fabric 9 to be placed against the inner mold 404. Then, the remaining round-edged mesh fabric 9 is layered according to the designed thickness of the inner insulation 406 until the design requirements are met, and then bound with fiberglass tape. Similarly, the outer insulation 407 of the coil requires the thinnest layer of round-edged mesh fabric 9 to be attached to the outer side of the coil outside the air passage. Then, the remaining round-edged mesh fabric 9 is layered according to the designed thickness of the outer insulation 407 until the design requirements are met, and then bound with fiberglass tape. Additionally, as shown... Figure 13 As shown, each subsequent layer of rounded mesh fabric 9 needs to be rotated 90° relative to the previous layer to ensure that the thick lines of adjacent layers are perpendicular to each other and the thin lines are perpendicular to each other. This placement method allows adjacent layers of rounded mesh fabric 9 to support each other and effectively utilizes the space between each layer, facilitating resin flow within the coil during subsequent pouring. In this embodiment, as... Figure 13 As shown, the rounded edges of the mesh fabric 9 are placed at the upper and lower ends of the high-voltage coil 4, with a 2-3 mm margin between the edge of the rounded edge and the coil end. This helps prevent the edge of the mesh fabric 9 from contacting the two ends of the high-voltage coil 4, thus preventing the edge of the mesh fabric 9 from being exposed after casting and causing resin cracking in low-temperature environments. After the coil is wound and the resin is cast and positioned, the inner mold 404 and outer mold 405 will be removed.

[0046] II. Figures 10 to 11 As shown, the end insulation 402 of the high-voltage coil 4 adopts a composite insulation structure formed by end insulation mesh cloth 4021 and first glass fiber continuous felt 4022. The length of the first glass fiber continuous felt 4022 is the same as the circumference of the high-voltage coil 4, and its width is the diameter thickness of the high-voltage coil 4 plus L (in this embodiment, L = 300 mm). Figure 11 As shown, the first continuous glass fiber felt 4022 needs to be cut with openings 40221 in the width direction every 50mm along the length direction, and 150mm should be left uncut.

[0047] When the end insulation 402 of the inner side of the air passage is made, the first glass fiber continuous felt 4022 of the inner side is not cut on one side, and is aligned with the end face of the high-voltage coil 4 corresponding to the coil inner insulation 406 (that is, the end face of the coil inner insulation 406), and is placed on the corresponding end of the coil inner insulation 406. Then, the air passage inner coil is wound on the coil inner insulation 406. After the winding is completed, the end insulation position on the upper and lower sides of the air passage inner coil, the end insulation grid cloth 4021 is placed layer by layer starting from the height dimension of the end insulation 402 minus H (in this embodiment, H = 5 mm), until the height of the end insulation 402 is filled. Then, the first glass fiber continuous felt 4022 of the inner side is bent and pressed to fix the end insulation grid cloth 4021 on one side of the opening 40221, and then the air passage inner insulation 4081 is wound on the air passage inner coil and the opening 40221 on one side of the first glass fiber continuous felt 4022 of the inner side is fixed.

[0048] When the end insulation 402 of the outer side of the air passage is made, the first glass fiber continuous felt 4022 of the outer side is not cut on one side, and is aligned with the end face of the high-voltage coil 4 corresponding to the air passage outer insulation 4082 (that is, the end face of the air passage outer insulation 4082), and is placed on the corresponding end of the air passage outer insulation 4082. Then, the air passage outer coil is wound on the outer side of the air passage outer insulation 4082. After the winding of the air passage outer coil is completed, the end insulation position on the upper and lower sides of the air passage outer coil, the end insulation grid cloth 4021 is placed layer by layer starting from the height dimension of the end insulation 402 minus H (in this embodiment, H = 5 mm), until the height of the end insulation 402 is filled. Then, the first glass fiber continuous felt 4022 of the outer side is bent and pressed to fix the end insulation grid cloth 4021 on one side of the opening 40221, and then the coil outer insulation 407 is wound on the air passage outer coil and the opening 40221 on one side of the first glass fiber continuous felt 4022 of the outer side is fixed. In this way, the end insulation 402 of the inner and outer sides of the air passage is completed.

[0049] The end insulation 402 forms an end insulation grid cloth 4021 structure completely wrapped by the first glass fiber continuous felt 4022, which effectively solves the problem that the end resin of the high-voltage coil 4 is prone to cracking in a low-temperature environment due to low grid cloth filling rate of the end of the high-voltage coil 4.

[0050] III. As shown in Figure 9 The coil panel 401 of the front side of the high-voltage coil 4 is provided with a wiring terminal 4011 and a tapping terminal 4012, and as shown in Figure 12 The lead lines of the high-voltage coil 4 are respectively connected to the wiring terminal 4011 and the tapping terminal 4012, but as Figures 7 to 8As shown, considering the welding requirements of the wires and terminals, the coil panel 401 is provided with a spacing area between the outer diameter surface of the high-voltage coil 4, and the spacing area forms a region 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 only a few electromagnetic wires 403 connected with the wire terminals 4011 and the tapping terminals 4012 in the rectangular area 4017, and the rest is mostly resin filling area, the triangular area 4016 is used as a connecting area between the rectangular area 4017 and the outer diameter of the high-voltage coil 4, and there is no electromagnetic wire 403 inside, and it is all resin filling area, these two positions are the key parts of the coil resin cracking, and effective insulation filling is needed to improve the mechanical properties of the resin, specifically: while winding the circular edge mesh cloth 9 on the outside of the air channel to form the coil outer insulation 407, according to the position and shape of the coil panel 401, the corresponding panel filling mesh cloth 4018 is placed on the outer diameter surface of the air channel outside the coil according to the shape and area, and then the coil outer insulation 407 is tightened together with the panel filling mesh cloth 4018 through the glass silk cloth belt, wherein the panel filling mesh cloth 4018 needs to be removed at the corresponding position according to the position of the electromagnetic wire 403 and the wire head in the rectangular area 4017, so that the electromagnetic wire 403 and the like can pass through the removed position of the panel filling mesh cloth 4018, 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.

[0051] Four, during the winding process of the coil, the interlayer insulation 4031 of the high-voltage coil 4 is formed by layer-by-layer filling of interlayer mesh cloth, the width of the interlayer mesh cloth is greater than the maximum width of the upper and lower two layers of conductors, and the outermost turn of conductors on both sides of each layer of conductors is bound together with the electromagnetic wire 403 in the middle by a glass silk cloth belt, so as to prevent the edge electromagnetic wire 403 from loosening and falling, and further 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 adopts a circular conductor, the electromagnetic wire 403 will be wound in the interval of the warp or weft, resulting in that the insulation thickness between the two layers of electromagnetic wires 403 is less than the thickness of the interlayer insulation 4031, and local discharge is easily generated. Therefore, the interlayer insulation 4031 should also be stacked by multiple layers of interlayer mesh cloth, and each layer of interlayer mesh cloth needs to be placed with the warp and weft of the previous layer of interlayer mesh cloth rotated by 90°.

[0052] Fifth, when winding the high-voltage coil 4, after winding the air channel inside coil, the air channel inside insulation 4081 is wound outside the air channel inside coil, then the air channel mold 8 forming the air channel 408 is arranged on the air channel inside insulation 4081 along the circumferential direction, the length direction is parallel to the height direction of the high-voltage coil 4, and when the resin pouring of the high-voltage coil 4 is completed, the air channel mold 8 is taken out from the high-voltage coil 4 and forms the air channel 408 for heat dissipation of the high-voltage coil 4, but in the prior art, the air channel 408 section usually adopts a symmetrical shape (such as a rectangle, an oblong, etc.) along the center line of the air channel 408, and because a plurality of air channels 408 are arranged in a circle outside the high-voltage coil 4, the interval distance between the outside of the two adjacent air channels 408 is greater than the interval distance between the inside, so that the resin width between the two adjacent air channels 408 is not uniform, which easily causes uneven stress and further causes resin cracking in a low-temperature environment.

[0053] As shown in Figures 14 to 16 To solve the above problems, the utility model first improves the shape of the air channel mold 8 to a trapezoidal shape with a narrow upper side and a wide lower side, wherein the narrow side corresponds to the inner diameter side of the air channel 408, the wide side corresponds to the outer diameter side of the air channel 408, and the length difference between the narrow side and the wide side is equal to the arc difference between the inner diameter side and the outer diameter side of the air channel 408, so that the resin interval width between the two adjacent air channels 408 is uniform, thereby reducing the risk of resin cracking between the air channels 408.

[0054] Secondly, each corner end of the trapezoidal section of the air channel mold 8 adopts a round corner transition. According to the principle of mechanics, stress is highly concentrated at the corners, because the stress line changes sharply at the sharp edge, and the stress concentration coefficient at the corner may be several times higher than that in other smooth areas. The round corner transition can make the stress more uniformly distributed, thereby effectively reducing the stress concentration and further avoiding resin cracking caused by excessive local stress.

[0055] Thirdly, after the air channel mold 8 is placed on the air channel inside insulation 4081, the air channel mesh cloth is continuously wound outside the air channel mold 8 to form the air channel outside insulation 4082, and the glass filament sleeve 801 is arranged outside the air channel mold 8, so that the air channel mold 8 itself and the arrangement structure on both sides are insulated, but the insulation between the two adjacent air channel molds 8 is relatively weak, and the resin at this position is prone to cracking after pouring, therefore Figure 14As shown, the utility model discloses further increase the second glass silk continuous felt 10 filling between air channel inner insulation 4081 and air channel outer insulation 4082, wherein the second glass silk continuous felt 10 reciprocating bending forms multiple wrapping parts 11, and the opening direction of adjacent two wrapping parts 11 is opposite, and each air channel mold 8 is placed in the corresponding wrapping part 11 respectively, the wrapping part 11 compresses the corresponding air channel mold 8, so that the second glass silk continuous felt 10 fills between adjacent two air channels 408 after pouring, thereby improving the anti-cracking ability of the resin at low temperature environment.

[0056] The specific process of placing the air channel mold 8 is as follows: first, wind the air channel grid cloth outside the air channel inner coil and tighten to form the air channel inner insulation 4081, then fix the starting head of the second glass silk continuous felt 10 on the air channel inner insulation 4081, place the first air channel mold 8 at the starting head of the second glass silk continuous felt 10, then lift the second glass silk continuous felt 10 and place the second air channel mold 8 between the second glass silk continuous felt 10 and the air channel inner insulation 4081, then place the third air channel mold 8 on the second glass silk continuous felt 10, then lift the second glass silk continuous felt 10 again and place the fourth air channel mold 8 between the second glass silk continuous felt 10 and the air channel inner insulation 4081, and repeat the operation until each air channel mold 8 is placed along the circumferential direction, then place the air channel grid cloth outside the above structure and tighten to form the air channel outer insulation 4082.

[0057] In addition, as Figures 1 to 3 As shown, the upper clamp 2 is arranged at the upper end of the coil assembly, the lower clamp 3 is arranged at the lower end of the coil assembly, the upper pad 201 is arranged between the upper clamp 2 and the upper end of the coil assembly, the lower pad 301 is arranged between the lower clamp 3 and the lower end of the coil assembly, the upper clamp 2 and the lower clamp 3 are used for clamping and fixing the coil assembly, the upper yoke 101 on the upper side of the iron core 1 is arranged between the two upper clamps 2, the end portions of the two upper clamps 2 are connected through the upper end screw 202 and the middle portions are connected through the upper middle screw 203, so as to realize the limiting of the upper yoke 101, the lower yoke 102 on the lower side of the iron core 1 is arranged between the two lower clamps 3, the end portions of the two lower clamps 3 are connected through the lower end screw 302 and the middle portions are connected through the lower middle screw 303, so as to realize the limiting of the lower yoke 102, the hanging plate 205 is arranged on the upper side of the upper clamp 2, the base 304 is arranged on the lower side of the lower clamp 3, and the upper clamp 2 and the lower clamp 3 are fixedly connected through the vertical screw to realize the clamping and fixing of the coil.

[0058] According to the principle of thermal expansion and cold contraction, the coil height of the high-voltage coil 4 and the low-voltage coil 6 of the transformer will decrease in the low-temperature state, and the coil height will increase due to thermal expansion when the transformer load increases and the coil generates heat, aiming at this problem, as Figures 2 to 3As shown, the utility model discloses the lower side of upper clamp piece 2 lower side's lower support plate 206 is connected with upper cushion block 201 through compression assembly 204, the compression assembly 204 includes compression bolt 2041, disc spring 2042, compression nut 2043 and locking nut 2044, wherein the compression bolt 2041 passes through the lower support plate 206 and is connected with the corresponding upper cushion block 201, disc spring 2042, compression nut 2043 and locking nut 2044 are all set on the compression bolt 2041, wherein the disc spring 2042 is located between the lower support plate 206 and upper cushion block 201, and the lower side of the disc spring 2042 is equipped with locking nut 2044, the upper side of the lower support plate 206 is equipped with compression nut 2043. When the coil height is increased due to thermal expansion after the transformer load increases, the disc spring 2042 can increase the space of the coil deformation, ensure that the coil end is not too tight due to the increased compression force after the coil height is increased, and the resin is cracked, in addition, the disc spring 2042 bears the increased compression force, and the height of the disc spring 2042 is reduced and a certain potential energy is stored. When the transformer load decreases or the ambient temperature decreases, the coil height is reduced due to cold shrinkage, the compression force of the compression assembly 204 decreases, and the compression nut 2043 has a tendency to relax, at this time the disc spring 2042 releases the part of the potential energy stored when the coil expands, that is, the height of the disc spring 2042 increases to offset the height of the coil shrinkage, thereby maintaining the pressure of the compression nut 2043 to meet the compression requirement. The utility model adopts the above structure, which can ensure that the transformer has good compression force when the ambient temperature changes greatly from low temperature to high temperature, thereby improving the fastening ability and stability of the mechanical structure of the transformer.

[0059] As Figure 2 shown, in the embodiment, the upper end of the low-voltage coil 6 is provided with an inner lead row 601 and an outer lead row 602, as Figure 4 shown, the upper clamp piece 2 is provided with a zero-seal copper bar 7, the inner lead row 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 with the zero-seal copper bar 7, the outer lead row 602 is connected with an external electrical equipment and loads to transmit electric energy, the inner lead row 601 of the low-voltage coil 6 is connected with the zero-seal copper bar 7 by a bolt and a copper bar locking nut 701, and as Figure 5 shown, the copper bar locking nut 701 is embedded with a nylon ring 7011, when the bolt is connected with the copper bar locking nut 701, the nylon ring 7011 in the copper bar locking nut 701 is extruded and deformed and tightly combined with the bolt thread, because nylon is a poor conductor of heat, therefore, in a low-temperature cold environment, although the nylon material will become hard, it can still provide enough friction to prevent the nut from loosening, thereby maintaining a certain anti-loosening ability, preventing the bolt from loosening in the long-term expansion in the low-temperature environment, causing the contact resistance between the busbars to increase, and burning the transformer.

[0060] AsFigure 1 As shown in the embodiment, the wiring terminal 4011 on the coil panel 401 is connected through the conductive rod 4015, the tapping terminal 4012 on the coil panel 401 is connected through the tapping piece 4013, and the end of the tapping piece 4013 is fixedly connected with the corresponding tapping terminal 4012 through the copper bolt 4014.

[0061] The working principle of the utility model is as follows:

[0062] In the high-voltage coil 4 structure, after the electromagnetic wire 403 is wound, low-temperature resistant epoxy resin is used for pouring and positioning, and after the pouring of the epoxy resin is completed, the resin layer can completely encapsulate the electromagnetic wire 403 inside the coil, but in order to avoid the problem of resin cracking at low temperature, the utility model adds a composite insulation filling of mesh cloth at the corresponding position of the high-voltage coil 4, wherein:

[0063] One, 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 silk cloth belt;

[0064] Two, the end insulation 402 of the high-voltage coil 4 adopts a composite insulation structure formed by the end insulation mesh cloth 4021 and the first glass silk continuous felt 4022;

[0065] Three, 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 adopt a composite insulation structure formed by the panel filling mesh cloth 4018 and the glass silk cloth belt;

[0066] Four, the interlayer insulation 4031 between the electromagnetic wires 403 of each layer of the high-voltage coil 4 is formed by layer-by-layer filling of interlayer mesh cloth;

[0067] Five, the shape of the air channel mold 8 of the high-voltage coil 4 is improved to be a trapezoidal shape with the upper part being narrow and the lower part being wide, so as to ensure that the resin spacing width between the adjacent two air channels 408 is consistent, and each corner end of the trapezoid adopts a round corner transition to reduce stress concentration, and before pouring, the second glass silk continuous felt 10 is reciprocally bent to form a plurality of wrapping parts 11, and the air channel mold 8 is placed in the corresponding wrapping part 11, so that after pouring, the second glass silk continuous felt 10 is filled between the adjacent two air channels 408.

[0068] The utility model 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.

[0069] In addition, the utility model discloses utilize the compression assembly 204 to connect the lower support plate 206 of upper clamp piece 2 downside with upper cushion block 201, be equipped with the disc spring 2042 of coil deformation space can be added in compression assembly 204, can also guarantee the compression force of transformer when environmental temperature is from low temperature to high temperature between big change is very good, thereby improved the fastening ability and stability of transformer mechanical structure. The utility model discloses still utilize the copper bar locking nut 701 that nylon ring 7011 is embedded in the inside with the inner lead line row 601 of low voltage coil 6 is connected with zero copper bar 7, in low temperature severe cold environment, although nylon material can be hard, but still can provide enough friction to prevent the nut loosening, thereby can maintain certain anti-loose ability, prevent the loosening of bolt in long -term expansion in low temperature environment, lead to the contact resistance between busbar increases, burn down transformer.

[0070] Through the above-mentioned improvement, the utility model can adapt to the environmental conditions of low temperature and severe cold, and can be safely and reliably operated in the whole equipment life cycle without increasing the heat preservation cotton and installing the heating device.

[0071] The winding method of the high-voltage coil 4 of the utility model comprises the following steps:

[0072] Step one: place the inner mold 404 at a designated position, and then adhere a plurality of layers of circular edge mesh cloth 9 to the inner mold 404 to form a coil inner insulation 406;

[0073] Step two: wind the electromagnetic wire 403 outside the coil inner insulation 406 to form an air passage inner coil, and fill the space between the adjacent two layers of electromagnetic wire 403 with interlayer mesh cloth to form interlayer insulation 4031;

[0074] Step three: make the end insulation 402 of the air passage inner side, specifically: cut the openings 40221 of the first glass fiber continuous felt 4022 on the inner side according to the design requirements along the length direction at equal intervals, then align the inner side of the first glass fiber continuous felt 4022 on the uncut side (i.e. the bottom end of each opening 40221) with the corresponding end face of the coil inner insulation 406 and place it on the corresponding end of the coil inner insulation 406, then place the end insulation mesh cloth 4021 layer by layer on the position of the end insulation 402 on both sides of the air passage inner coil until the end insulation 402 is filled to the height, then bend the side of the first glass fiber continuous felt 4022 provided with the openings 40221 to tightly wrap the corresponding end insulation mesh cloth 4021;

[0075] Step four: continue to wind the air passage mesh cloth on the wound air passage inner coil to form air passage inner insulation 4081, and the side of the first glass fiber continuous felt 4022 provided with the openings 40221 is fixed through the air passage inner insulation 4081;

[0076] Step five: place the second glass fiber continuous felt 10 and each air channel mold 8 on the air channel inner insulation 4081, and the second glass fiber continuous felt 10 is reciprocatingly bent to form a plurality of wrapping parts 11, each air channel mold 8 is placed in the corresponding wrapping part 11, and each air channel mold 8 is placed along the circumferential direction and then wound with air channel mesh cloth outside to form air channel outer insulation 4082;

[0077] Step six: wind the electromagnetic wire 403 outside the air channel outer insulation 4082 to form an air channel outer coil, and use the interlayer mesh cloth between the adjacent two layers of electromagnetic wire 403 to fill and form an interlayer insulation 4031;

[0078] Step seven: align the inner side of the uncut side of the outer first glass fiber continuous felt 4022 with the height of the air channel outer insulation 4082 and place it on the corresponding end of the air channel outer insulation 4082, and then place the end insulation mesh cloth 4021 on the end insulation 402 on the upper and lower sides of the air channel outer coil layer by layer until the end insulation 402 is filled to the height, and then the side of the outer first glass fiber continuous felt 4022 provided with the opening 40221 is bent to press the corresponding end insulation mesh cloth 4021;

[0079] Step eight: continue to wind the round edge mesh cloth 9 on the air channel outer coil to form a coil outer insulation 407, and place the panel filling mesh cloth 4018 on the outer diameter surface of the air channel outer coil according to the position and shape of the coil panel 401, then tighten the coil outer insulation 407 together with the panel filling mesh cloth 4018 by glass fiber cloth tape, and the opening 40221 side of the outer first glass fiber continuous felt 4022 is fixed through the coil outer insulation 407;

[0080] Step nine: fit the outer mold 405 on the coil outer insulation 407 and install the coil panel 401, so that the insulation at all positions has been filled before pouring;

[0081] Step ten: 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 air channel mold 8 after pouring and forming.

Claims

1. A low temperature resistant dry-type transformer, characterized by: The application relates to a coil assembly, which comprises a core (1), and a coil assembly is sleeved on a core column (103) of the core (1), the coil assembly comprises a low-voltage coil (6), an insulating sleeve (5) and a high-voltage coil (4) arranged in sequence from inside to outside, the high-voltage coil (4) comprises coil inner insulation (406), an air channel (408) and coil outer insulation (407) arranged in sequence from inside to outside, air channel inner insulation (4081) is arranged on the inner side of the air channel (408), air channel outer insulation (4082) is arranged on the outer side of the air channel (408), a plurality of layers of electromagnetic wires (403) are wound between the coil inner insulation (406) and the air channel inner insulation (4081) to form an air channel inner side coil, a plurality of layers of electromagnetic wires (403) are wound between the air channel outer insulation (4082) and the coil outer insulation (407) to form an air channel outer side coil, layer-to-layer insulation (4031) is arranged between adjacent two layers of electromagnetic wires (403), end insulation (402) is arranged at both ends of the high-voltage coil (4) except the air channel (408) position, the electromagnetic wires (403) are fixed by pouring low-temperature resistant epoxy resin, the coil inner insulation (406) and the coil outer insulation (407) each comprise a plurality of layers of round-edge glass cloth (9), the end insulation (402) comprises end insulation glass cloth (4021) and first glass filament continuous felt (4022) which wraps the end insulation glass cloth (4021) from the outside, the layer-to-layer insulation (4031) comprises a plurality of layers of layer-to-layer glass cloth, second glass filament continuous felt (10) is arranged between adjacent two air channels (408), a coil panel (401) connected with electromagnetic wire (403) lead-out wires is arranged on the front side of the high-voltage coil (4), and panel filling glass cloth (4018) is arranged between the coil panel (401) and the outer diameter surface of the air channel outer side coil; the coil assembly is fixed by upper clamping pieces (2) and lower clamping pieces (3), upper cushion blocks (201) are arranged between the upper clamping pieces (2) and the upper end of the coil assembly, and lower supporting plates (206) on the lower side of the upper clamping pieces (2) are connected with the upper cushion blocks (201) through compression assemblies (204) with disc springs (2042).

2. The cryogenically tolerant dry-type transformer of claim 1, wherein: In the coil inner insulation (406) and the coil outer insulation (407), each layer of round-edge glass cloth (9) is placed in rotation of 90 DEG with the previous layer of round-edge glass cloth (9), and each layer of round-edge glass cloth (9) is fixed by being tightly tied with glass filament cloth belts; in the layer-to-layer insulation (4031), each layer of layer-to-layer glass cloth is placed in rotation of 90 DEG with the previous layer of layer-to-layer glass cloth.

3. The cryogenic dry-type transformer of claim 1, wherein: The first glass filament continuous felt (4022) of the end insulation (402) is provided with openings (40221) along the length direction, and the first glass filament continuous felt (4022) is bent and tightly wrapped around the corresponding end insulation glass cloth (4021) on the side provided with the openings (40221).

4. The cryogenic dry-type transformer of claim 1, wherein: The second glass fiber continuous felt (10) is reciprocatingly bent to form a plurality of wrapping parts (11), and each air duct (408) is arranged in a corresponding wrapping part (11), the air duct (408) has a trapezoidal shape with a narrow top and a wide bottom, wherein the narrow side of the trapezoid corresponds to one side of the air duct inner insulation (4081), the wide side of the trapezoid corresponds to one side of the air duct outer insulation (4082), and the length difference between the narrow side and the wide side of the trapezoid is equal to the curvature difference between the air duct inner insulation (4081) and the air duct outer insulation (4082), and each corner end of the trapezoidal section is a rounded corner transition.

5. The cryogenic dry-type transformer of claim 1, wherein: The coil panel (401) and the outer diameter surface of the air duct outer coil form a spacing area, and the spacing area includes triangular areas (4016) on both sides and a rectangular area (4017) in the middle, the panel filling mesh cloth (4018) with the same width and height as the coil panel (401) is stacked and filled in the rectangular area (4017), and the panel filling mesh cloth (4018) with a width decreasing in turn is cut according to the size of the triangular area (4016) and is stacked and filled in the triangular area (4016).

6. The cryogenic dry-type transformer of claim 1 or 5, wherein: The coil panel (401) is provided with a wiring terminal (4011) and a tapping terminal (4012), wherein the wiring terminal (4011) is connected by a conductive rod (4015), the tapping terminal (4012) is connected by a tapping piece (4013), and the end of the tapping piece (4013) is fixed to the corresponding tapping terminal (4012) by a copper bolt (4014).

7. The cryogenic dry-type transformer of claim 1, wherein: The compression assembly (204) includes a compression bolt (2041), a disc spring (2042), a compression nut (2043), and a locking nut (2044), the compression bolt (2041) passes through the lower support plate (206) and is connected to the corresponding upper cushion block (201), the disc spring (2042), the compression nut (2043), and the locking nut (2044) are all sleeved on the compression bolt (2041), the disc spring (2042) is arranged between the lower support plate (206) and the upper cushion block (201), the lower side of the disc spring (2042) is provided with the locking nut (2044), and the upper side of the lower support plate (206) is provided with the compression nut (2043).

8. The cryogenic dry-type transformer of claim 1, wherein: The iron core (1) includes an upper yoke (101) and a lower yoke (102), wherein the upper yoke (101) is arranged between two upper clamping pieces (2), the end portions of the two upper clamping pieces (2) are connected by an upper end screw (202), and the middle portions are connected by an upper middle screw (203), a lower cushion block (301) is arranged between the lower clamping piece (3) and the lower end of the coil assembly, the lower yoke (102) is arranged between two lower clamping pieces (3), the end portions of the two lower clamping pieces (3) are connected by a lower end screw (302), and the middle portions are connected by a lower middle screw (303), the upper clamping piece (2) is provided with a hanging plate (205) on the upper side, and the lower clamping piece (3) is provided with a base (304) on the lower side.

9. The cryogenic dry-type transformer of claim 1, wherein: The low-voltage coil (6) upper end is provided with inner side lead row (601) and outer side lead row (602), the upper clamp (2) is provided with zero-sealing copper bar (7), the inner side lead row (601) is connected with zero-sealing copper bar (7) through bolt and copper bar locking nut (701), and the copper bar locking nut (701) is embedded with nylon ring (7011) inside.

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