Static induction machine

Abstract

To improve the insulation of a neutral wire lead portion drawn out from a molded coil.SOLUTION: A stationary induction apparatus according to an embodiment includes an iron core, a molded coil attached to the iron core, a neutral wire lead drawn out from the molded coil, a barrier insulator protruding from the outer peripheral surface of the molded coil, and a lead support insulator that is held apart from the outer peripheral surface of the molded coil by the barrier insulator and that supports the neutral lead.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a stationary induction machine. [Background technology]

[0002] For example, transformers used in 66 kV or 77 kV high-voltage substation equipment employ molded coils that are entirely molded with, for example, epoxy resin. In a Y-connected three-phase transformer, the neutral point lead wires drawn from each of the three phase molded coils are Y-connected, supported, for example, by a lead support insulator at the top of the coil (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 58-66621 Summary of the Invention [Problem to be solved by the invention]

[0004] In three-phase transformers like the one described above, impulse voltages are sometimes applied to the molded coils during testing and inspection, for example. However, in such cases, a voltage higher than the applied voltage may be generated at the neutral point of the transformer's Y-connection. If the lead wires located near the outer surface of the molded coil are not sufficiently insulated, high voltage may flow from the neutral point to the coil surface, potentially causing creepage breakdown and dropping to the earth part of the iron core. Ensuring sufficient insulation performance is particularly important for high-voltage transformers and those that use dry air for cooling.

[0005] Therefore, a stationary induction device is provided that can improve the insulation of the neutral wire lead portion drawn out from the molded coil. [Means for solving the problem]

[0006] The stationary induction device of the embodiment comprises an iron core, a molded coil attached to the iron core, a neutral wire lead connected to the outlet wire of the molded coil, a barrier insulator protruding from the outer peripheral surface of the molded coil, and a lead support insulator that is held apart from the outer peripheral surface of the molded coil by the barrier insulator and supports the neutral wire lead. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 10 is an enlarged vertical cross-sectional side view showing the configuration of a barrier insulator portion of a molded coil according to the first embodiment. [Figure 2] Enlarged front view of the barrier insulator part of the molded coil [Figure 3] Enlarged top view of the barrier insulator part of the molded coil [Figure 4] FIG. 1 is a front view showing the overall configuration of a transformer body; [Figure 5] An enlarged perspective view showing the support portion of the neutral wire lead above the molded coil DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of a static induction device applied to a three-phase molded transformer used in, for example, a 66 kV or 77 kV high-voltage power receiving and transforming facility will be described with reference to the drawings. Although not shown as a whole, this molded transformer is composed of a molded transformer body 1 (see FIG. 4), a sealed container that houses this molded transformer body 1, a heat exchanger provided outside this sealed container, etc. In the following description, when directions are mentioned, for convenience, the states of FIGS. 2 and 4 will be used as front views.

[0009] First, the overall structure of the transformer body 1 will be described with reference to Figure 4. The transformer body 1 is configured by attaching three molded coils 3 for U, V, and W phases to an iron core 2. The iron core 2 is, for example, a laminated iron core, and is configured with upper and lower yoke sections and three leg sections that vertically connect them. The molded coils 3 are cylindrical and are attached to each of the leg sections so that they are aligned horizontally in the figure. The upper and lower yoke sections of the iron core 2 are fixed by an upper clamp 4 and a lower clamp 5, respectively. At this time, multiple coil-holding insulators (not shown) are provided between the upper clamp 4 and the top surface of each coil 3.

[0010] Although not shown in detail, each of the molded coils 3 has a primary winding arranged on the inner periphery, a cooling duct extending vertically in the middle, and a secondary winding arranged on the outer periphery, and the entire structure is molded with a molded resin layer 7 such as epoxy resin. In this embodiment, as shown in Fig. 3 and other figures, a cylindrical air channel 8 made of, for example, plastic is provided on the outer periphery of the molded coil 3, and an outer periphery duct for flowing cooling gas in the axial direction, i.e., the vertical direction, is formed between the outer periphery and the outer surface of the molded coil 3. In this case, the air channel 8 has a flange 8a extending circumferentially at its upper end and is provided in a height range excluding the upper end of the molded coil 3.

[0011] As is well known, the molded coil 3 is obtained by winding a conductor made of a metal material such as copper, the outer periphery of which is covered with insulating tape, into a cylindrical shape, and then covering the inner and outer peripheries of the conductor with an impregnated base material to form the coil body. The impregnated base material is made of a nonwoven fabric, for example, a sheet of fibrous material such as synthetic fiber or synthetic resin, and is configured as a narrow strip. It is wound around the outer periphery of the wound conductor so as to overlap the outer periphery. At this time, as shown in FIG. 1 , a fixture 23 made of an insulating material for attaching a barrier insulator 22 (described later) is fixed so that its base end is bound by the impregnated base material and embedded in the molded resin layer 7, and its tip end is positioned on the outer periphery of the molded coil 3.

[0012] Then, although not shown, an immersion step is carried out in which liquid epoxy resin is poured into an impregnation tank while the coil body is placed in the tank, and after the immersion step, a curing step is carried out in which the coil is heated in a heating furnace (not shown) to harden the impregnated epoxy resin and obtain a molded resin layer 7. As a result, the molded resin layer 7 fills gaps inside the coil body and is provided so as to cover the entire outer surface of the coil body, thereby obtaining a molded coil 3.

[0013] As shown in Figures 2 and 5, end-of-winding lead wires 11 extend radially outward from the outer peripheral surface of the upper end of the secondary side of the molded coil 3 of each phase. The three end-of-winding lead wires 11 extending from each molded coil 3 are connected to a neutral lead 12 made of a KIP wire to form a Y connection, and the neutral lead 12 is connected, for example, to earth. A pleated insulation 13 is provided on the outer periphery of the connection between the end-of-winding lead wires 11 and the neutral lead 12. Furthermore, a start-of-winding lead wire 14 extends from the upper surface of the secondary side of the molded coil 3 of each phase and is connected to a connecting conductor 15 made of a KIP wire. A pleated insulation 16 is provided on the outer periphery of the connection between the start-of-winding lead wire 14 and the connecting conductor 15. Although not shown in detail, each connecting conductor 15 is connected to a bushing provided in the sealed container for connection to the outside.

[0014] Although not shown, the transformer body 1 is housed in a sealed container. At this time, the sealed container is filled with, for example, dry air as a cooling and insulating gas. For example, a blower fan device is provided inside the sealed container, and by driving the blower fan device, relatively low-temperature dry air is supplied toward the bottom of the transformer body 1, and by passing through the cooling duct and the air tunnel 8, i.e., the outer duct, it rises, thereby contributing to cooling the molded coil 3. The high-temperature dry air is cooled by heat exchange with the outside in a heat exchanger, and this process is repeated again to contribute to cooling the molded coil 3, etc.

[0015] In this embodiment, the neutral wire leads 12 connected to the winding end output wires 11 of the three molded coils 3 are supported by lead support rods 21, which serve as lead support insulators, and are connected to each other while extending laterally across the front surface of the molded coils 3. At this time, barrier insulators 22 are provided on the upper front surface of the outer periphery of each molded coil 3, protruding forward in the drawing, and the lead support rods 21 are held by these barrier insulators 22. This holding structure will be described below with reference to Figures 1 to 3 and 5.

[0016] That is, as shown in FIG. 1 , a fixture 23 for attaching the barrier insulator 22 is provided on the front surface of the upper end of each molded coil 3. This fixture 23 is made of an insulating material, such as plastic, and is shaped like a rectangular thin plate bent into a U-shape with its sides facing inward. As described above, during the manufacture of the molded coil 3, this fixture 23 is positioned so that its base end faces the upper outer surface of the coil body, and the impregnated base material is wound around the outer periphery of the coil body. As a result, the base end of the fixture 23 is fixed and bound by the impregnated base material, and in this state, the molded resin layer 7 is formed, thereby fixing the fixture to the molded coil 3. In this case, the tip side of the fixture 23 is positioned to protrude forward of the molded coil 3.

[0017] As shown in Fig. 1, the fixtures 23 are fixed at two positions, one above the other, slightly spaced apart, and the tip surfaces of both fixtures 23, 23 are arranged above and below the front surface of the molded coil 3. A vertically long rectangular mounting plate 24 is fixed between the two fixtures 23 by insulating bolts 25 or the like. The barrier insulator 22 is attached to the front surface of the mounting plate 24.

[0018] In this case, the barrier insulator 22 is made of an insulating material, such as FRP, and is configured by integrating two small-diameter disks 22a as the small-diameter portion and one large-diameter disk 22b as the large-diameter portion, with the large-diameter disk 22b sandwiched between them on the same axis. Thus, the barrier insulator 22 has a shape in which large-diameter portions and small-diameter portions alternate in the direction of protrusion toward the outer circumferential surface of the molded coil 3. The barrier insulator 22 is fixed to the front surface of the mounting plate 24 with insulating bolts 25.

[0019] The lead support rod 21 is made of an insulating material, such as wood, and is shaped like a square beam, long enough to span almost horizontally across the three molded coils 3. As shown in Figures 2 and 5, the lead support rod 21 is fixed to the front faces of the barrier insulators 22 of the three molded coils 3 with insulating bolts 25, respectively. The neutral wire lead 12 is arranged along the lead support rod 21 and is supported by being bound to the lead support rod 21 at multiple points with strings 26 made of insulating material.

[0020] As a result, the lead support rod 21 is held by the barrier insulator 22 in a state spaced forward from the outer peripheral surface of the molded coil 3, and therefore the neutral lead 12 is held in a state spaced forward from the molded coil 3. As shown in Figures 2 and 4, the barrier insulator 22 is provided at the upper end, which is located above the air tunnel 8 on the front side of the molded coil 3. At the same time, as shown in Figures 3 and 5, the tip of the barrier insulator 22 is positioned outer than the air tunnel 8, i.e., the outer duct, and the lead support rod 21 and neutral lead 12 are positioned above the flange 8a of the air tunnel 8.

[0021] According to this embodiment, the following actions and effects can be obtained. That is, in this embodiment, a barrier insulator 22 is provided in a protruding shape on the front portion, which is the outer peripheral surface of the molded coil 3, and a lead support rod 21, which supports the neutral conductor lead 12, is held at the tip of the barrier insulator 22. This keeps the lead support rod 21, and therefore the neutral conductor lead 12, apart from the outer peripheral surface of the molded coil 3. Therefore, a long creepage distance can be secured by the insulator from the neutral conductor lead 12 to the molded coil 3, and creepage breakdown can be suppressed when, for example, an impulse voltage is applied.

[0022] As a result, this embodiment has the excellent effect of improving the insulation of the neutral wire lead 12 portion drawn out from the molded coil 3. In this case, particularly in this embodiment, the barrier insulator 22 has a shape in which discs 22a as small diameter portions and discs 22b as large diameter portions are alternately arranged in the direction of protrusion toward the outer circumferential surface of the molded coil 3, so that a longer creepage distance can be secured in the barrier insulator 22, which is more effective in improving the insulation.

[0023] In this embodiment, a rod-shaped lead support rod 21 that extends across three molded coils 3 is provided as the lead support insulator, and the neutral lead 12 is bound and supported by the lead support rod 21. This allows the neutral lead 12 to be bound at multiple locations to one rod-shaped lead support rod 21, making it possible to reduce the number of parts and simplify the configuration.

[0024] In this embodiment, the mounting fixture 23 made of insulating material for mounting the barrier insulator 22 on the front surface of the molded coil 3 is configured so that its base end is fastened by the impregnated base material during the winding operation of the impregnated base material and fixed within the molded resin layer 7. This allows the mounting fixture 23 made of insulating material for mounting the barrier insulator 22 to be mounted reliably and firmly during the manufacture of the molded coil 3, eliminating the need for troublesome post-processing.

[0025] Furthermore, in this embodiment, the molded coil 3 is provided with an air tunnel 8 on its outer periphery, and the barrier insulator 22 is provided at the axial upper end of the molded coil 3 that is outside the air tunnel 8. This prevents the barrier insulator 22 from adversely affecting the flow of cooling gas in the air tunnel 8, ensuring a good flow of cooling gas in the air tunnel 8. In addition, because the tip of the barrier insulator 22 is located on the outer periphery of the air tunnel 8, the lead support rod 21 and neutral lead 12 can be provided without interfering with the air tunnel 8. Since dry air is supplied as the cooling gas, an inexpensive and simple dry-type transformer can be constructed, and the provision of the barrier insulator 22 can compensate for the deterioration of insulation that accompanies the use of dry air.

[0026] In the above embodiment, the barrier insulator 22 is configured with three layers of small-diameter discs 22a and large-diameter discs 22b, but it may be configured with four or more layers. The barrier insulator may be configured from a square plate or the like instead of a disc shape. The lead support insulator is not limited to a rod-like shape with a substantially square cross section, but may be a round rod or a thin plate. The structure for holding the neutral wire lead 12 may be secured with a clip instead of binding with a string. The structure for attaching a fixture to the outer circumferential surface of the molded coil may also be attached with an adhesive after the molded resin layer 7 is formed, for example.

[0027] In the above embodiment, the air channel 8 is provided around the outer periphery of the molded coil 3. However, the present invention can be applied to a configuration without an air channel. Furthermore, instead of using dry air as the cooling gas, other insulating gases or insulating oils may be used. Furthermore, the specific materials for the resin constituting the molded resin layer, the barrier insulator, the lead support insulator, etc., described in the above embodiment are merely examples, and various modifications can be made. Furthermore, the overall configuration of the transformer can of course be modified in various ways.

[0028] The above-described embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0029] In the drawing, 1 is the transformer body, 2 is the iron core, 3 is the molded coil, 8 is the winding tunnel, 8a is the flange, 11 is the end-of-winding lead wire, 12 is the neutral wire lead, 14 is the start-of-winding lead wire, 15 is the connecting conductor, 21 is the lead support rod (lead support insulator), 22 is the barrier insulator, 22a is the small diameter disc, 22b is the large diameter disc, 23 is the mounting fixture, 24 is the mounting plate, 25 is the insulating bolt, and 26 is the string.

Claims

1. Iron core and a molded coil attached to the iron core; a neutral wire lead connected to an output wire of the molded coil; a barrier insulator provided in a protruding shape on the outer peripheral surface of the molded coil; a lead support insulator that is held apart from the outer peripheral surface of the molded coil by the barrier insulator and supports the neutral wire lead; The molded coil is configured by winding and stacking a strip-shaped impregnated base material around the outer periphery of a conductor and then molding it with resin, a stationary induction device in which a mounting fixture made of an insulating material for mounting the barrier insulator is provided so that its base end is fastened by the impregnated base material and fixed in the molded resin layer during the winding operation of the impregnated base material, and its tip end is positioned on the outer periphery of the molded coil.

2. 2. The stationary induction device according to claim 1, wherein said barrier insulator has a shape having alternating large diameter portions and small diameter portions in a direction of protrusion toward the outer circumferential surface of said molded coil.

3. 3. The stationary induction device according to claim 1, wherein the lead support insulator is rod-shaped and extends across a plurality of coils, and the neutral wire lead is supported by being bound to the lead support insulator.

4. a wind tunnel for flowing a cooling gas is provided on the outer periphery of the molded coil; 4. The stationary induction device according to claim 1, wherein the barrier insulator is provided at an axial end of the molded coil that is outside the wind tunnel.

5. 5. The stationary induction device according to claim 4, wherein the tip of the barrier insulator is positioned on the outer periphery side of the wind tunnel.

6. 6. The stationary induction device according to claim 4, wherein dry air is supplied into the wind tunnel as a cooling gas.

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