Static induction circuit

Abstract

To realize a static induction electric device that can suppress winding deformation during short circuits at a low cost. [Solution] A static induction electric appliance having an iron core, a low-voltage winding wound around the magnetic legs of the iron core, and a high-voltage winding wound around the low-voltage winding, having an inner electrode that leads the low-voltage winding on the inner side and an outer electrode that leads the low-voltage winding on the outer side, wherein when the radius of the inner end of the low-voltage winding is r1, the distance from the center point of the low-voltage winding to the outer surface of the inner electrode is r3, the radius of the outer end of the low-voltage winding is r2, and the distance from the center point of the low-voltage winding to the inner surface of the outer electrode is r4, the relationship r1≦r3 and r2≦r4 is satisfied.

Description

Technical Field

[0001] The present invention relates to a static induction electrical apparatus.

Background Art

[0002] Examples of static induction electrical apparatuses include transformers and reactors. These have a core made of a soft magnetic material such as electromagnetic steel sheets or amorphous materials, and windings wound around the core. And not only when rated current or voltage is applied, but also when an accident such as a short circuit occurs on the connected load side or in the static induction electrical apparatus itself, mechanical and electrical resistance are required.

[0003] For example, in a transformer in which a high-voltage winding and a low-voltage winding are wound around a core, when a problem occurs where the load side connected to the low-voltage winding is short-circuited, currents several times to dozens of times the rated current instantaneously flow through the windings of the transformer. This can also be called a short-circuit current. Then, according to Fleming's left-hand rule, an electromagnetic force acts as a Lorentz force in the inner direction on the low-voltage winding and in the outer direction on the high-voltage winding, which may lead to deformation or even significant destruction of the windings and the structures of the transformer. Therefore, for transformers, short-circuit test conditions, for example, are specified by standards according to their power capacity. And it is necessary to ensure mechanical strength so that the deformation of windings and the like does not exceed the allowable range.

[0004] Patent Document 1 discloses a technique related to a resistance structure against electromagnetic force during short circuit acting on the low-voltage winding of a transformer. As an example, it discloses a configuration in which a bobbin has a polygonal shape exceeding a quadrilateral.

[0005] Patent Document 2 discloses a method of forming windings on a bobbin.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

[0007] The bobbin described in Patent Document 1 has the problem of increased manufacturing costs due to its complex shape. Patent Document 2 discloses an efficient manufacturing method in which the winding is routed by rotating the bobbin. However, even when Patent Documents 1 and 2 are combined, the problem of increased manufacturing costs due to the inherent complexity of the bobbin shape in Patent Document 1 remains.

[0008] Therefore, the objective of this invention is to provide a static induction electric device that can suppress winding deformation during a short circuit at low cost. [Means for solving the problem]

[0009] A static induction electric appliance having an iron core, a low-voltage winding wound around the magnetic legs of the iron core, and a high-voltage winding wound around the low-voltage winding, having an inner electrode that leads the low-voltage winding on the inner side and an outer electrode that leads the low-voltage winding on the outer side, wherein when the radius of the inner end of the low-voltage winding is r1, the distance from the center point of the low-voltage winding to the outer surface of the inner electrode is r3, the radius of the outer end of the low-voltage winding is r2, and the distance from the center point of the low-voltage winding to the inner surface of the outer electrode is r4, the relationship r1≦r3 and r2≦r4 is satisfied. [Effects of the Invention]

[0010] The present invention provides a static induction electric device that can suppress winding deformation during short circuits at a low cost.

[0011] Further means and effects of the present invention will become apparent throughout the entire specification below. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view of a transformer in one embodiment. [Figure 2]This is a cross-sectional view of the transformer magnetic leg in one embodiment. [Figure 3] This is a cross-sectional view of the transformer magnetic leg in another embodiment. [Figure 4] This is a longitudinal cross-sectional view of the transformer magnetic leg in another embodiment. [Figure 5] This is a cross-sectional view of the transformer magnetic leg in another embodiment. [Figure 6] This is a cross-sectional view of the transformer magnetic leg in another embodiment. [Figure 7] This is a longitudinal cross-sectional view of the transformer magnetic leg in another embodiment. [Figure 8] This is a longitudinal cross-sectional view of the transformer magnetic leg in another embodiment. [Figure 9] This is a cross-sectional view of the transformer magnetic leg in a comparative example. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described below with reference to the drawings. [Examples]

[0014] Figure 1 is a perspective view of an example of a transformer. The width direction is defined as x, the height direction as y, and the depth direction as z when the transformer is stationary and viewed from the front. The transformer consists of a single-phase tripod-type core 30, which has two sets of roughly rectangular wound cores, each made by winding thin strips of magnetic material in layers, adjacent to each other in the x-direction; a low-voltage winding 10 with a circular cross-section wound around the magnetic legs of the core; and a high-voltage winding 20 with a circular cross-section wound around its outer circumference. The low-voltage winding 10 is provided with an inner electrode 11 and an outer electrode 12 above the portion exposed to the outside of the core 30. Although not shown, electrodes of the high-voltage winding 20 are provided above the portion exposed to the outside of the core 30 on the opposite side of electrodes 11 and 12.

[0015] The transformer shown in Fig. 1 is merely an example, and the present invention is also applicable to a transformer using a laminated core formed by laminating plate-shaped magnetic materials in the z direction. Further, the present invention is of course applicable not only to a single-phase transformer having one set of low-voltage windings and high-voltage windings, but also to a three-phase transformer having three sets.

[0016] Fig. 2 is a cross-sectional view of the magnetic leg portion of the transformer. It corresponds to the cross-sectional view in plane A of Fig. 1. However, only half of the inner peripheral side electrode 11 and the outer peripheral side electrode 12 side are shown.

[0017] In Fig. 2, since the core 30 is composed of a plurality of wound cores having different widths, the cross-section is polygonal. An insulating cylinder 13 is provided at a position corresponding to the circumscribed circle of the cross-section of the core 30. The insulating cylinder 13 can also be referred to as a bobbin. The low-voltage winding 10 is wound on the outside thereof, and the high-voltage winding 20 is wound further outside thereof.

[0018] The dimensions r1 and r2 shown in Fig. 2 are the radii of the innermost peripheral part and the outermost peripheral part of the low-voltage winding 10, respectively, and are also the distances from the center point 110.

[0019] Here, the feature of this embodiment is that the distance r3 from the center point 110 to the outer surface of the inner peripheral side electrode 11 in the cross-section of the low-voltage winding 10 is r1 or more, and the distance r4 from the center point 110 to the inner surface of the outer peripheral side electrode 12 is r2 or more. Further, the low-voltage winding 10, and the electrodes 11 and 12 are arranged so as to have such an arrangement.

[0020] Fig. 9 is a comparative example corresponding to Fig. 2. The effect of the configuration of Fig. 2 will be described while comparing Fig. 2 and Fig. 9.

[0021] The low-voltage winding 10, constructed by winding conductive material such as flat wire, ideally has a circular cross-section. Due to the effect of the current flowing concentrically through the low-voltage winding 10 and the magnetic flux flowing inside and around the iron core 30 in the direction perpendicular to the plane of the paper (y-direction), an electromagnetic force (Lorentz force) acts on the conductive material constituting the low-voltage winding 10 in the radially inward direction. If the conductive material is wound in a circular shape, the direction of this electromagnetic force is towards the center of the circular cross-section of the winding, and therefore can be supported by the physical strength of the conductive material. However, the windings of transformers used in practical applications need to be equipped with electrodes 11 and 12.

[0022] The conductive material in the electrode section is susceptible to distortion due to its physical thickness, the means of electrically connecting the conductive material to the electrode, and the structural materials. As schematically shown in Figure 9, it may deform into a partially linear shape rather than being an ideal circle. For example, this can occur when the Lorentz force causes electrode 11 to shift towards the center, and as a result, electrode 12 also shifts towards the center.

[0023] In this case, the distance r3 from the center point in the cross-section of the low-voltage winding 10 to the outer surface of the inner electrode 11 may be smaller than the radius r1 of the inner end of the low-voltage winding 10. Also, the distance r4 from the center point in the cross-section of the low-voltage winding 10 to the inner surface of the outer electrode 12 may be smaller than the radius r2 of the outer end of the low-voltage winding 10.

[0024] In such a case, the electromagnetic force acting on the conductive material at the location of electrodes 11 and 12 is aligned downwards (-z direction) from the plane of the paper, exceeding the physical strength of the conductive material and potentially causing deformation or destruction of the low-voltage winding 10.

[0025] To address these concerns, this embodiment is characterized by the conditions r1 ≤ r3 and r2 ≤ r4. This makes it possible to provide a static induction electric device that can suppress winding deformation during short circuits. [Examples]

[0026] This embodiment is an example of a structure that realizes the relationship described in Embodiment 1, namely r1 ≤ r3 and r2 ≤ r4.

[0027] Figure 3 is a cross-sectional view of the transformer magnetic leg corresponding to Figure 2. Figure 4 is a cross-sectional view in plane B of Figure 1, when the structure of Figure 3 is applied to Figure 1. To show 30, the cross-section is taken at a position slightly offset from the center of Figure 1. As with Figure 2, the illustration is shown up to about half the position of 30.

[0028] In Figure 3, an insulating cylinder 13 is provided at a position corresponding to the circumscribed circle of the iron core 30. A low-voltage winding 10 is wound around the outside of the insulating cylinder 13, and a high-voltage winding 20 is wound around the outside of that. Multiple sheets of plate-shaped insulating material 14 are stacked and filled into the gap between the iron core 30 and the insulating cylinder 13, and are arranged to fill the gap. With this configuration, a distance is maintained between the insulating cylinder 13 and the iron core 30 by the insulating material 14, preventing deformation toward the inner circumference. The inner circumference electrode 11 of the low-voltage winding 10 is positioned so as to be pressed against the insulating cylinder 13, preventing deformation toward the inner circumference.

[0029] In the vertical cross-sectional view of the transformer's magnetic leg section in Figure 4, the low-voltage winding 10 is constructed by winding a rectangular cross-section flat wire as a conductive material. The inner circumference electrode 11 of the low-voltage winding 10 is connected to the tip 101 of the conductive material located at the lowest part of the inner circumference and extends to the upper end. As an example, fastening fittings 40 are provided at the upper and lower ends of the transformer's iron core 30 to fasten and fix the low-voltage winding 10 and the high-voltage winding 20.

[0030] The inner electrode 11 may be bent outward as appropriate to avoid interference with the fastening fitting. The outer electrode 12 of the low-voltage winding 10 is connected to the tip 102 of the conductive material located at the uppermost part of the outer circumference and extends to the upper end. In this embodiment, an insulating material 15 is provided between the electrodes 11 and 12 extending from the upper end of the low-voltage winding 10 to ensure and fix the distance between the two electrodes.

[0031] By adopting the above configuration, it becomes possible to maintain the distance of the inner electrode 11 of the low-voltage winding 10 from the winding center to be greater than or equal to the radius of the inner end of the low-voltage winding 10, via the iron core 30, the insulating material 14, and the insulating cylinder 13. Furthermore, it becomes possible to maintain the distance of the outer electrode 12 of the low-voltage winding 10 from the winding center to be greater than or equal to the radius of the outer end of the low-voltage winding 10, via the inner electrode 11 and the insulating material 15. In this embodiment and all embodiments described thereafter, it is preferable to use dielectric materials such as pressboard, wood, or resin for the insulating cylinder 13, insulating material 14, and insulating material 15.

[0032] In this embodiment, a static induction electric device can be provided that can suppress winding deformation during a short circuit. Furthermore, since a bobbin with a complex structure like that of Patent Document 1 is not required, it can be manufactured at a low cost. [Examples]

[0033] This embodiment is another example of a structure that realizes the relationship described in Embodiment 1, namely r1 ≤ r3 and r2 ≤ r4. Therefore, the same explanation as in Embodiment 2 will be omitted.

[0034] Figure 5 corresponds to Figure 3.

[0035] In Figure 5, while the insulating material 14 in Figure 3 is made up of multiple layers of plate-shaped insulating material, a single-piece insulating material is constructed to match the cross-sectional shape of the gaps, and this is arranged to fill multiple gaps. Therefore, the insulating material 14 in this embodiment is a molded body of a dielectric material such as pressboard, wood, or resin. Consequently, the outer circumference of the insulating material 14 in this embodiment corresponds to the shape of the insulating cylinder 13 and has an arc shape.

[0036] In this embodiment, the insulating material 14 is preferably a resin composition formed by resin injection, both from the viewpoint of ease of manufacturing and in relation to the hardness of the insulating material 14 itself.

[0037] In this embodiment, the positions of electrodes 11 and 12 of the low-voltage winding can be fixed more firmly than in Embodiment 2, thus ensuring and fixing the distance between the two electrodes more reliably. [Examples]

[0038] This embodiment is another example of a structure that realizes the relationship described in Embodiment 1, namely r1 ≤ r3 and r2 ≤ r4. Therefore, the same explanation as in Embodiment 3 will be omitted.

[0039] Figure 6 corresponds to Figure 5.

[0040] In this embodiment, a groove is provided in the portion of the insulating material 14 that fills the gap between the iron core 30 and the insulating cylinder 13 that faces the inner circumference electrode 11 of the low-voltage winding, and the electrode 11 is fitted into the groove. With this configuration, the insulating cylinder 13 faces the iron core 30 via the insulating material 14 integrated with the electrode 11, so deformation toward the inner circumference can be prevented.

[0041] Figure 7 corresponds to Figure 4 and is a longitudinal cross-sectional view of the transformer magnetic leg in the case of Figure 6. The low-voltage winding 10 is constructed by winding a rectangular cross-section flat wire as a conductive material. The inner-circumferential electrode 11 of the low-voltage winding 10 is connected to the tip 101 of the conductive material located at the lowest part of the inner circumference and is drawn out to the inner circumference side via the lower end of the insulating cylinder 13. It is further drawn out to the upper end of the electrode via the portion fitted to the insulating material 14. The outer-circumferential electrode 12 of the low-voltage winding 10 is connected to the tip 102 of the conductive material located at the highest part of the outer circumference and is drawn out to the upper end. In this embodiment, an insulating material 15 is provided between the electrodes 11 and 12 extending from the upper end of the low-voltage winding 10 to fix the distance between the two electrodes.

[0042] By adopting the above configuration, it becomes possible to maintain, via the iron core 30, insulating material 14, and insulating cylinder 13, that the distance from the winding center to the inner circumference end of the low-voltage winding 10 is greater than or equal to the radius of the inner circumference end of the low-voltage winding 10.

[0043] In this embodiment, the inner electrode 11 of the low-voltage winding 10 is positioned inside the insulating cylinder 13, but the cross-sectional shape of the low-voltage winding is maintained as circular. Furthermore, via the inner electrode 11 and the insulating material 15, it becomes possible to maintain the distance of the outer electrode 12 of the low-voltage winding 10 from the winding center to be greater than or equal to the radius of the outer edge of the low-voltage winding 10.

[0044] Furthermore, this also prevents misalignment of the inner electrode 11 in the left-right direction. [Examples]

[0045] This embodiment is another example of a structure that realizes the relationship described in Embodiment 1, namely r1 ≤ r3 and r2 ≤ r4. Therefore, the same explanation as in Embodiment 3 will be omitted.

[0046] Figure 8 corresponds to Figure 4 or Figure 7.

[0047] In this embodiment, a conductive sheet material is used as the conductive material constituting the low-voltage winding 10 of the transformer, and it is constructed by winding it in the radial direction. The insulating material 14 includes cases where multiple sheets of plate-shaped insulating material 14 are stacked together as shown in Figure 3, or cases where a resin insulating material is charged as shown in Figures 5 and 6.

[0048] Furthermore, the conductive material constituting the low-voltage winding 10 may include cases where a circular or elliptical conductor is used.

[0049] The inner electrode 11 of the low-voltage winding 10 is electrically connected to the conductive material 101 located at the innermost circumference, and the outer electrode 12 is electrically connected to the conductive material 102 located at the outermost circumference, by means of welding, brazing, or other means. At this time, electrodes 11 and 12 are extended in both directions from the upper and lower ends of the winding, and an insulating material 15 is provided between the extended electrodes to fix the distance between the two electrodes.

[0050] By adopting the above configuration, it becomes possible to maintain the distance of the inner electrode 11 of the low-voltage winding 10 from the winding center to be greater than or equal to the radius of the inner end of the low-voltage winding 10, via the iron core 30, the insulating material 14, and the insulating cylinder 13. Furthermore, it becomes possible to maintain the distance of the outer electrode 12 of the low-voltage winding 10 from the winding center to be greater than or equal to the radius of the outer end of the low-voltage winding 10, via the inner electrode 11 and the two insulating materials 15 provided at the upper and lower ends of the low-voltage winding 10.

[0051] Furthermore, since the insulating material 15 is placed on both ends of the inner electrode 11 and the outer electrode 12, meaning that multiple insulating materials are placed, it becomes possible to more reliably maintain the distance between the inner electrode 11 and the outer electrode 12. [Examples]

[0052] This embodiment is an additional configuration to be used in combination with any of Examples 1 to 5.

[0053] A key feature of this embodiment is that the width of the outer electrode 12 is wider than the width of the inner electrode 11. This reduces the force or pressure applied per unit area of ​​the outer electrode 12 toward the inner circumference, suppresses deformation, and ensures a more reliable distance between the inner electrode 11 and the outer electrode 12. [Examples]

[0054] This embodiment is an example of use in combination with any of Examples 1 to 6.

[0055] A key feature of this embodiment is that the inner electrode 11 or the outer electrode 12 is configured to have a curvature directed inward. The shape of the curvature can be visualized as if a part of the insulating cylinder 13 had been cut out.

[0056] This prevents the inner electrode 11 or outer electrode 12 from making point contact with respect to the insulating material 14, allowing them to make surface contact. This prevents high pressure from being generated at specific contact points, and as a result, deformation suppression and position retention can be achieved more reliably. [Examples]

[0057] This embodiment is an example of use in combination with any of Examples 1 to 7.

[0058] This embodiment is a static induction electric device characterized by having an iron core made of an amorphous metal laminate and a capacity of 2 MVA or more. In particular, it is an amorphous transformer with a capacity of 2 MVA or more.

[0059] Amorphous transformers, which use a laminate of amorphous metals in an iron core, are gaining popularity as an environmental solution due to their high conversion efficiency. However, because amorphous metal laminates are softer than non-amorphous electrical steel sheets, they are inevitably prone to deformation. In particular, for large transformers with high power capacity, the thickness and size of the amorphous metal laminate increase, making countermeasures against deformation an even greater challenge for practical application.

[0060] In this embodiment, a static induction electric device or amorphous transformer in which the iron core is a laminate of amorphous metal can be realized by applying any of Examples 1 to 7, thereby realizing a static induction electric device or amorphous transformer with a capacity of 2 MVA or more.

[0061] In this embodiment, for example, it is possible to provide a large amorphous transformer capable of handling conversion from commercial power in a main-line system, as an amorphous transformer with excellent environmental performance.

[0062] The multiple embodiments described above may be combined in any way.

[0063] Furthermore, the idea and concept of the present invention have been explained using various embodiments. Of course, examples realized by combining the embodiments are also included within the scope of the present invention. Moreover, modifications and similar examples thereof, as long as they utilize the disclosed ideas and concepts, are also included within the scope of the present invention.

[0064] Furthermore, static induction electrical equipment includes either a single-phase transformer in which one set of low-voltage and high-voltage windings are wound around one magnetic leg of the iron core, or a three-phase transformer in which three sets of low-voltage and high-voltage windings are wound around three magnetic legs of the iron core. Furthermore, the iron core of a static induction electric device also includes cases where multiple wound iron cores, each having a roughly rectangular outer shape and formed by winding thin strip-shaped magnetic material in layers, are combined.

[0065] Furthermore, the core of a static induction electric device may also be composed of a laminated core made of stacked plate-shaped magnetic material.

[0066] Furthermore, an example of the present invention described using the above embodiments can also be expressed as follows.

[0067] <Part 1> It has an iron core, a low-voltage winding wound around the magnetic legs of the iron core, and a high-voltage winding wound around the low-voltage winding. The system includes an inner-circumferential electrode that draws out the low-voltage winding on the inner side, and an outer-circumferential electrode that draws out the low-voltage winding on the outer side. Let r1 be the radius of the inner end of the low-voltage winding. Let r3 be the distance from the center point of the low-voltage winding to the outer surface of the inner circumference electrode. Let r2 be the radius of the outer end of the low-voltage winding. If the distance from the center point of the low-voltage winding to the inner surface of the outer electrode is r4, A static induction electromagnet that satisfies the relationships r1 ≤ r3 and r2 ≤ r4. <Part 2> A static induction electric device according to <Part 1>, having an insulating cylinder inside the low-voltage winding and a filling member that fills the gap between the insulating cylinder and the iron core. <Part 3> The aforementioned filling member is a static induction electric device as described in <Part 2>, comprising a stack of multiple filling members. <Part 4> The static induction electric device according to <3>, wherein the filling member is one of press board, wood, or resin. <Part 5> The aforementioned filling member is a resin, and is integrally filled in the static induction electric device as described in <Part 2>. <Part 6> The static induction electric device described in <Part 5>, wherein the filling member is provided with a groove as a recess in the winding axis direction of the low-voltage winding, and the inner circumference electrode is fitted into the groove. <Part 7> The static induction electric device described in <Part 2>, wherein the cross-section of the low-voltage winding is rectangular, circular, or elliptical. <Part 8> The static induction electric device according to <Part 2>, having an insulating member provided outside the low-voltage winding and between the inner circumferential electrode and the outer circumferential electrode. <Part 9> The aforementioned low-voltage winding is composed of a wound plate-shaped conductive material, as described in <Part 2>, for the static induction electric device. <Part 10> The static induction electric device according to <9>, wherein the inner circumferential electrode and the outer circumferential electrode extend above and below the low-voltage winding, respectively, and each of the upper and lower sides has an insulating member provided between the inner circumferential electrode and the outer circumferential electrode. <Part 11> The static induction electric device described in <Part 2>, wherein the width of the outer circumferential electrode is wider than the width of the inner circumferential electrode. <Part 12> The stationary induction electric device according to <Part 2>, wherein either the inner electrode or the outer electrode has curvature toward the center point. <Part 13> The static induction electric device according to any one of items <1> to <12>, wherein the iron core is composed of a laminate of amorphous metal and has a capacity of 2 MVA or more. <Part 14> The static induction electric device described in <Part 13> is an amorphous transformer with a capacity of 2 MVA or more. [Explanation of symbols]

[0068] 10: Low-voltage winding 11: Inner electrode 12: Outer peripheral electrode 13: Insulating tube 14, 15: Insulating material 20: High-voltage winding 30: Iron Heart 40: Fastening hardware 101: The inner end of the low-voltage winding 102: Outer end of low-voltage winding 110: Center point in the cross-section of a low-voltage winding r1: Radius of the inner end in the cross-section of the low-voltage winding r2: Radius of the outer edge in the cross-section of the low-voltage winding r3: Distance from the center point in the cross-section of the low-voltage winding to the outer surface of the inner circumference electrode. r4: Distance from the center point in the cross-section of the low-voltage winding to the inner surface of the outer electrode.

Claims

1. It has an iron core, a low-voltage winding wound around the magnetic legs of the iron core, and a high-voltage winding wound around the low-voltage winding. The system includes an inner-circumferential electrode that draws out the low-voltage winding on the inner side, and an outer-circumferential electrode that draws out the low-voltage winding on the outer side. Let r1 be the radius of the inner end of the low-voltage winding. Let r3 be the distance from the center point of the low-voltage winding to the outer surface of the inner circumference electrode. Let r2 be the radius of the outer end of the low-voltage winding. When the distance from the center point of the low-voltage winding to the inner surface of the outer electrode is r4, A static induction electromagnet that satisfies the relationships r1 ≤ r3 and r2 ≤ r4.

2. The static induction electric device according to claim 1, having an insulating cylinder inside the low-voltage winding and a filling member that fills the gap between the insulating cylinder and the iron core.

3. The static induction electric device according to claim 2, wherein the filling member is composed of a stack of multiple filling members.

4. The static induction electric device according to claim 3, wherein the filling member is one of press board, wood, or resin.

5. The static induction electric device according to claim 2, wherein the filling member is made of resin and is integrally filled.

6. The static induction electric device according to claim 5, wherein the filling member is provided with a groove as a recess in the winding axis direction of the low-voltage winding, and the inner circumference electrode is fitted into the groove.

7. The static induction electric device according to claim 2, wherein the cross-section of the low-voltage winding is rectangular, circular, or elliptical.

8. The static induction electric device according to claim 2, further comprising an insulating member provided outside the low-voltage winding and between the inner circumferential electrode and the outer circumferential electrode.

9. The static induction electric device according to claim 2, wherein the low-voltage winding is composed of a wound plate-shaped conductive material.

10. The static induction electric device according to claim 9, wherein the inner circumferential electrode and the outer circumferential electrode extend above and below the low-voltage winding, respectively, and each of the upper and lower sides has an insulating member provided between the inner circumferential electrode and the outer circumferential electrode.

11. The static induction electric device according to claim 2, wherein the width of the outer peripheral electrode is wider than the width of the inner peripheral electrode.

12. The static induction electric device according to claim 2, wherein either the inner electrode or the outer electrode has curvature toward the center point.

13. The static induction electric device according to any one of claims 1 to 12, wherein the iron core is composed of a laminate of amorphous metal and has a capacity of 2 MVA or more.

14. The static induction electric device according to claim 13, wherein the static induction electric device is an amorphous transformer with a capacity of 2 MVA or more.

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