Static induction machine coils

Abstract

To effectively prevent a clearance from being formed between inter-layer unwoven fabrics in a configuration that a step-up part or lead wire of an insulation electric wire is disposed in a notched portion formed in the inter-layer unwoven fabric.SOLUTION: A stationary induction apparatus coil according to an embodiment is configured by including a plurality of winding layers each of which is formed by cylindrically winding an insulation electric wire, from the inside to the outside while disposing an inter-layer unwoven fabric between the layers and by providing a cooling duct between the inner and outer winding layers. A step-up part or a lead wire of the insulation electric wire to the next winding layer is disposed in a notched portion formed in the inter-layer unwoven fabric, and an unwoven fabric support made of an insulation material for preventing a peripheral part of the notch from falling toward the duct is provided on inner and outer peripheral surfaces of the notched portion in the inter-layer unwoven fabric.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE An embodiment of the present invention relates to a coil for a stationary induction machine. [Background technology]

[0002] For example, as a coil used in a transformer for high-voltage power receiving and distribution equipment, a resin molded coil is adopted in which an insulating layer is impregnated with epoxy resin and then hardened (see, for example, Patent Document 1). In manufacturing this type of resin molded coil, for example, a cylindrical winding frame is used, and an insulated electric wire is wound cylindrically in the axial direction, one turn at a time, to form one winding layer. An interlayer nonwoven fabric, which is made of several overlapping thin nonwoven fabrics, is wound around the inner and outer peripheral sides of each winding layer. Furthermore, a plurality of duct pieces are provided between the inner and outer winding layers to provide a duct extending in the axial direction.

[0003] When the winding work for one layer is completed, a step-up portion is provided, and the winding work for the next layer is repeated. After multiple layers, for example four layers, are obtained, the coil is impregnated with epoxy resin, and the interlayer nonwoven fabric portion is impregnated with resin and hardened to obtain a molded coil in which the gaps inside the coil and the outer surface portion are covered with a molded resin layer. At this time, the insulated electric wire has lead wires at the start and end of the winding, and a step-up portion is provided at the portion from the winding layer to the next winding layer. An insulating tape is wound spirally in multiple layers around the lead wires and the step-up portions of the insulated electric wire to form a thick insulating layer around the conductor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-120558 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, when the step-up portion or the lead wire of the insulated electric wire is passed to the next layer or drawn out during the above-mentioned coil winding operation, a cut of a certain length is made in the interlayer nonwoven fabric with a cutter or the like, and the step-up portion or the lead wire is arranged so as to be stored along the cut portion. Here, FIG. 9 shows a cross section showing the positional relationship between the cut 42 formed in the interlayer nonwoven fabric 41 and the insulated electric wire 43 of the step-up portion. The interlayer nonwoven fabric 41 is formed by stacking multiple nonwoven fabrics 41a. In this case, it is desirable to have the ideal state shown on the left side of FIG. 9, but in reality, as shown on the right side of FIG. 9, the cut end of the nonwoven fabric 41a is deformed so as to open toward the duct side by the lead wire 43. Therefore, gaps are easily formed in the interlayer nonwoven fabric 41, and there is a risk that voids will be generated during resin molding, thereby reducing the insulation.

[0006] Therefore, the present invention provides a coil for a stationary induction device that is configured so that the stepped portion or the lead wire of the insulated electric wire is placed in a cut portion formed in the interlayer nonwoven fabric, thereby effectively preventing the formation of gaps between the interlayer nonwoven fabric. [Means for solving the problem]

[0007] A coil for a stationary induction device according to an embodiment has a winding layer formed by winding an insulated electric wire into a cylindrical shape, with interlayer nonwoven fabric disposed between the layers, and has a cooling duct disposed between the inner and outer winding layers, and is configured so that a step-up portion or an outlet wire of the insulated electric wire to the next winding layer is disposed in a cut portion formed in the interlayer nonwoven fabric, and nonwoven fabric supports made of an insulating material are provided on the inner and outer peripheral surfaces of the cut portion of the interlayer nonwoven fabric to prevent the surrounding portion of the cut from dropping toward the duct. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a front view showing a schematic overall configuration of a transformer according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing a schematic configuration of the winding layers of the secondary winding. [Diagram 3] A perspective view (part 1) showing the coil winding process [Figure 4] A diagram showing the state in which a cut is made in the interlayer nonwoven fabric. [Diagram 5] A perspective view (part 2) showing the coil winding process [Figure 6] FIG. 1 is a perspective view showing the appearance of an insulating pipe; [Figure 7] FIG. 1 is a cross-sectional view of a cut portion of an interlayer nonwoven fabric. [Figure 8] FIG. 11 is a perspective view showing the second embodiment, and is a schematic view showing a state during a coil winding operation. [Figure 9] This is a diagram showing a conventional example, in which the ideal state (left) and the actual state (right) of the cross-sectional configuration of the cut portion of the interlayer nonwoven fabric are shown side by side. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (1) First embodiment Hereinafter, a first embodiment in which the present invention is applied to a molded coil of a three-phase molded transformer used as a stationary induction device, for example, in a high-voltage receiving and transforming facility for 66 kV or 77 kV, will be described with reference to Fig. 1 to Fig. 7. First, Fig. 1 shows a schematic configuration of a molded transformer body 1, and this transformer body 1 is configured by mounting three molded coils 3 of U, V, and W phases on an iron core 2.

[0010] The iron core 2 is, for example, a laminated iron core, and is configured to have upper and lower yoke parts and three leg parts that connect them vertically. The molded coil 3 is cylindrical and is attached to each of the leg parts so as to be lined up in the left-right direction in the figure. The upper and lower yoke parts of the iron core 2 are fixed by an upper clamp 4 and a lower clamp 5, respectively. Although not shown in detail, each of the molded coils 3 is configured by arranging a primary winding on the inner periphery side, providing a main cooling duct that extends vertically in the middle, and arranging a secondary winding 6 (see FIG. 2) on the outer periphery side. The molded coil 3 is entirely molded with a molded resin layer 7 such as epoxy resin.

[0011] 2 shows a schematic configuration of the secondary winding 6 of the molded coil 3. The secondary winding 6 is provided with, for example, four winding layers 11, numbered from the first layer to the fourth layer, arranged from the inner periphery to the outer periphery on the outer periphery of a cylindrical winding frame 10. Each winding layer 11 is formed by winding an insulated electric wire 12 formed by insulating the outer periphery of a conductor such as copper. At this time, the inner and outer periphery portions and both upper and lower end faces of each winding layer 11 are covered with an interlayer nonwoven fabric 13. The interlayer nonwoven fabric 13 is formed as a layer in which a plurality of nonwoven fabrics 13a (see FIG. 7, etc.) are stacked.

[0012] Ducts 14, which serve as paths for cooling fluid such as gas or liquid, are provided between the reel 10 and the first winding layer 11, and between the winding layers 11. As shown in Figures 3 and 5, these ducts 14 are formed by disposing a plurality of duct pieces 15 as spacers intermittently in the circumferential direction between the layers, i.e., between the interlayer nonwoven fabrics 13. The duct pieces 15 are made of an insulating material, such as plastic, and have a rod-like shape with a cross section that is roughly drum-shaped, and are disposed so as to extend in the entire axial direction.

[0013] When forming the winding layer 11, winding starts from one axial end, i.e., from the lead wire 16 at the winding start part at the top in FIG. 2, and the insulated wire 12 is wound so that it is shifted in the axial direction, i.e., from top to bottom in FIG. 2, one turn at a time. When the winding of the first winding layer 11 is completed, a step-up portion 17 is provided at the lower end of the winding layer 11, and the winding of the second winding layer 11 is performed from bottom to top in the figure. The step-up portion 17 is provided so as to extend in the circumferential direction and pass through the layers of the duct 14 to the next winding layer 11 on the outer periphery. When the winding of the second winding layer 11 is completed, a step-up portion 17 is similarly provided at the upper end, and the winding of the third winding layer 11 is performed from top to bottom in the figure.

[0014] When the winding of the third winding layer 11 is completed, a step-up portion 17 is similarly provided at the lower end, and the winding of the fourth winding layer 11 is performed from bottom to top in the figure. When the winding of the fourth winding layer 11 is completed, an output wire 18 at the winding end portion is provided so as to be led out. As for the output wire 16, each step-up portion 17, and output wire 18, as shown in Figures 3, 7, etc., insulating tape 19 is wound multiple times in a spiral shape around the outer periphery of the insulated wire 12 so as to form a thick insulating layer around the conductor.

[0015] To obtain the above-mentioned molded coil 3, the insulated wire 12 is wound around the winding frame 10 while arranging the duct piece 15 and the interlayer nonwoven fabric 13, to obtain a coil body having four winding layers 11. Then, an immersion process is performed in which the coil body is placed in an impregnation tank and liquid epoxy resin is injected, so that the epoxy resin is impregnated into the interlayer nonwoven fabric 13 and the gaps between the insulated wires 12. After the immersion process, a curing process is performed in which the coil body is heated in a heating furnace (not shown), and the impregnated epoxy resin is cured to obtain the molded resin layer 7. As a result, the molded resin layer 7 is provided so as to fill the gaps inside the coil body and cover the entire outer surface of the coil body, thereby obtaining the molded coil 3.

[0016] In the molded coil 3 of this embodiment, when providing the step-up portion 17 to the winding layer 11 or leading out the lead wires 16, 18 during winding of the insulated wire 12, a slit 20 is formed in the interlayer nonwoven fabric 13 as shown in Fig. 4 etc. The step-up portion 17 or the lead wires 16, 18 are configured to be accommodated and disposed along the slit 20. In this case, the slit 20 for the step-up portion 17 extends in the circumferential direction of the interlayer nonwoven fabric 13 and is formed with a width such that the step-up portion 17 fits into it.

[0017] Further, a nonwoven fabric support made of an insulating material is provided on the inner and outer peripheral surfaces of the slits 20 of the interlayer nonwoven fabric 13 to prevent the surroundings of the slits 20 from dropping toward the duct 14. In this embodiment, as shown in Fig. 7, a glass mesh 21 is provided as the nonwoven fabric support so as to be applied to the inner and outer peripheral surfaces of the slits 20 of the interlayer nonwoven fabric 13. As shown in Fig. 3, the glass mesh 21 is, for example, a net-like structure in which glass fibers are arranged lengthwise and widthwise, and is arranged so as to cover the region of the interlayer nonwoven fabric 13 including the slits 20 (in this case, a rectangular region that is somewhat long in the circumferential direction).

[0018] Furthermore, in this embodiment, as shown in Figures 5 and 7, a hollow insulating pipe 22 is provided as a nonwoven fabric support inserted in the duct 14. As shown in Figure 6, this insulating pipe 22 is formed by cutting a circular tubular pipe 22a made of plastic, for example glass epoxy resin, to a relatively short length and wrapping a nonwoven fabric 23 around the pipe to adjust the outer diameter. The outer diameter of the insulating pipe 22 corresponds to the diameter of the duct 14.

[0019] A plurality of insulating pipes 22 are inserted from the end side into the duct 14, i.e., between adjacent duct pieces 15, in the region corresponding to the portion where the slits 20 are formed in the interlayer nonwoven fabric 13. This makes it possible for the insulating pipes 22 arranged in the duct 14 to support the interlayer nonwoven fabric 13. Since the insulating pipes 22 are hollow, it is possible to ensure the flow of the cooling fluid in the axial direction in the duct 14.

[0020] More specifically, an example will be described in which a stepped portion 17 is provided in the lower portion of the coil body, connecting the first winding layer 11 to the second winding layer 11. As shown in Fig. 3, a plurality of duct pieces 15 are arranged on the outer periphery of the first interlayer nonwoven fabric 13, and the stepped portion 17 is drawn out from the first winding layer 11 to the outer periphery through the spaces between the duct pieces 15. At this time, an insulating pipe 22 is arranged in the gaps between the duct pieces 15, in the region where the stepped portion 17 is arranged.

[0021] Then, the glass mesh 21 cut to a required size is arranged on the outer periphery of the duct piece 15. The glass mesh 21 is provided with holes 21a for passing the stepped portion 17 through. Meanwhile, as shown in Fig. 4, a cut 20 is formed, for example with a cutter, in the bundle of nonwoven fabrics 13a stacked so as to make up half the total thickness on the inner periphery side of the second interlayer nonwoven fabric 13, extending in the circumferential direction and having a length and width required for the stepped portion 17 to be fitted and arranged therein.

[0022] 5, the bundle of nonwoven fabric 13a with the slits 20 formed therein is placed around the outer periphery of the duct piece 15 and the glass mesh 21, and is arranged so that the stepped portion 17 passes through the slits 20. The bundle of nonwoven fabric 13a that forms the inner periphery of the second layer of interlayer nonwoven fabric 13 is arranged around the entire outer periphery of the duct piece 15. Thereafter, although not shown in detail, the insulated wire 12 is wound around the bundle of nonwoven fabric 13a to form the second layer of winding layer 11. After the winding layer 11 is formed, the bundle of nonwoven fabric 13a with the remaining half of the thickness is wound around the outer periphery of the bundle of nonwoven fabric 13a, and the second layer of interlayer nonwoven fabric 13 is formed.

[0023] In this bundle of nonwoven fabrics 13a, slits 20 are also formed for drawing out the next step-up portion 17, and a glass mesh 21 is arranged at a required position on the outer circumferential surface of the interlayer nonwoven fabric 13, i.e., the drawing position of the step-up portion 17. A duct piece 15 is arranged on the outer circumferential surfaces of the interlayer nonwoven fabric 13 and the glass mesh 21, and an insulating pipe 22 is arranged at a required position. Thereafter, the third and fourth winding layers 11 and interlayer nonwoven fabrics 13 are provided in a similar manner, and the end wire 18 at the winding end is drawn out from the interlayer nonwoven fabric 13 located at the outermost periphery. Thereafter, resin molding is performed as described above, and a molded coil 3 on which a molded resin layer 7 is formed is obtained.

[0024] As a result, as shown in Fig. 7, a stepped portion 17 is arranged at the slit 20 of the interlayer nonwoven fabric 13, and the cut end of the interlayer nonwoven fabric 13 is pressed down by arranging the glass mesh 21 and the insulating pipe 22 on both the inner and outer circumferential sides of the interlayer nonwoven fabric 13. Note that, although the stepped portion 17 has been described in Figs. 3 to 5 above, a similar configuration is adopted for the lead wires 16 and 18, in which a nonwoven fabric support is provided to prevent the slit 20 of the interlayer nonwoven fabric 13 from dropping into the duct 14. A cooling fluid such as air, gas, or insulating oil flows through the duct 14, and the insulating pipe 22 does not impede the flow of the cooling fluid.

[0025] As described above, according to this embodiment, the following actions and effects can be obtained. That is, in this embodiment, as described above, the stepped up portion 17 or the lead wires 16, 18 of the insulated electric wire 12 are arranged in the slit 20 formed in the interlayer nonwoven fabric 13, and a glass mesh 21 and an insulating pipe 22 are provided on the inner and outer periphery of the slit 20 of the interlayer nonwoven fabric 13 as a nonwoven fabric support made of an insulating material to prevent the surrounding portion of the slit 20 from dropping toward the duct 14. As a result, as shown in Fig. 7, the slit end of the interlayer nonwoven fabric 13 is pressed, and deformation of the end so as to open toward the duct 14 is suppressed, unlike the conventional example shown in Fig. 9.

[0026] Therefore, according to the molded coil 3 of this embodiment, it is possible to obtain the excellent effect of effectively preventing the formation of gaps in the slits 20 of the interlayer nonwoven fabric 13 during resin molding. As a result, it is possible to reduce the generation of voids in the molded resin layer 7, and in turn, to prevent the deterioration of insulation caused by the generation of voids.

[0027] In this embodiment, a glass mesh 21 is provided as a nonwoven fabric support, which is applied to the incision 20 of the interlayer nonwoven fabric 13. The glass mesh 21 holds the interlayer nonwoven fabric 13, preventing deformation such as the edge of the incision 20 dropping into the duct 14. In this case, the use of the glass mesh 21 provides the strength and insulation required to hold the interlayer nonwoven fabric 13, and excellent resin permeability during resin molding, making it suitable as a nonwoven fabric support.

[0028] Furthermore, in this embodiment, the nonwoven fabric support includes a hollow insulating pipe 22 inserted and disposed in the duct 14. By disposing the insulating pipe 22 in the duct 14, the interlayer nonwoven fabric 13 is supported so as to maintain its shape, and the edge of the slit 20 is prevented from dropping toward the duct 14. In this case, the insulating pipe 22 can be made to have sufficient strength to support the interlayer nonwoven fabric 13, and the insulating pipe 22 can be provided while ensuring the function of the duct 14 without increasing the size of the entire coil. In particular, by combining with the glass mesh 21, deformation of the interlayer nonwoven fabric 13 is more effectively prevented.

[0029] (2) Second embodiment and other embodiments FIG. 8 shows the second embodiment. The second embodiment differs from the first embodiment in the configuration of the duct 31. That is, the duct 31 is configured by disposing a spacer 32 made of an insulating material between the interlayer nonwoven fabrics 13 of the winding layers 11 adjacent to each other on the inner and outer periphery. The spacer 32 is configured in a corrugated or corrugated shape in the circumferential direction, and also serves as a nonwoven fabric support. In this embodiment, a glass mesh 21 (not shown) is provided on the inner and outer periphery of the slits 20 of the interlayer nonwoven fabric 13 as the nonwoven fabric support, and a hollow insulating pipe 22 is inserted and disposed inside the duct 31, i.e., between the waves of the spacer 32.

[0030] According to the second embodiment, as in the first embodiment, it is possible to effectively prevent the formation of gaps at the edge portions of the incisions 20 of the interlayer nonwoven fabric 13 during resin molding, thereby reducing the generation of voids in the molded resin layer 7 and thus preventing the deterioration of insulation caused by the generation of voids. In particular, since the spacer 32 for forming the duct 31 also serves as the nonwoven fabric support, no additional parts are required and the structure can be simplified. By combining with the glass mesh 21 and the insulating pipe 22, it is more effective in preventing the deformation of the interlayer nonwoven fabric 13.

[0031] In the first embodiment described above, both the glass mesh 21 and the insulating pipe 22 are provided as the nonwoven fabric support, but either one of them may be provided. In addition, in each of the above embodiments, the coil is cylindrical, but it may be rectangular. The number of winding layers is also merely an example, and can be changed as appropriate. In addition, the stationary induction device is not limited to a three-phase molded transformer, and may be a single-phase transformer.

[0032] The above-described embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0033] In the drawings, reference numeral 1 denotes a transformer body (static induction device), 2 denotes an iron core, 3 denotes a molded coil (coil), 7 denotes a molded resin layer, 11 denotes a winding layer, 12 denotes an insulated wire, 13 denotes an interlayer nonwoven fabric, 13a denotes a nonwoven fabric, 14 and 31 denote ducts, 15 denotes duct pieces (spacers), 16 and 18 denote outlet wires, 17 denotes a stepped portion, 20 denotes a notch, 21 denotes a glass mesh, 22 denotes an insulating pipe, and 32 denotes a spacer.

Claims

1. A coil for a stationary induction device, comprising a plurality of winding layers, each of which is formed by winding an insulated electric wire into a cylindrical shape, from the inside to the outside, with interlayer nonwoven fabric disposed between the layers, and a cooling duct provided between the inner and outer winding layers, A step-up portion or an outlet wire of the insulated electric wire to a next winding layer is arranged in a cut portion formed in the interlayer nonwoven fabric, A coil for a stationary induction device, wherein nonwoven fabric supports made of insulating material are provided on the inner and outer peripheral surfaces of the cut portions of the interlayer nonwoven fabric to prevent the surrounding portions of the cuts from dropping toward the duct.

2. 2. A coil for a stationary induction machine according to claim 1, wherein said nonwoven fabric support includes a glass mesh applied to the cut portions of said interlayer nonwoven fabric.

3. 3. A coil for a stationary induction device according to claim 1, wherein the nonwoven fabric support includes a hollow insulating pipe inserted in the duct.

4. 4. The coil for a stationary induction device according to claim 1, wherein a spacer for forming the duct also serves as the nonwoven fabric support.

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