Static induction circuit

Abstract

To provide a static induction electrometer that can control the horizontal position of the iron core. [Solution] A static induction electric device having a winding and an iron core, wherein the winding has an inner winding and an outer winding, and the static induction electric device has a winding support plate that holds both the inner winding and the outer winding.

Description

Technical Field

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

Background Art

[0002] Static induction electric apparatuses are widely used as voltage conversion means. One form thereof is a so-called transformer. An example thereof is disclosed in Patent Document 1. It is a transformer having windings and a core.

[0003] Since both the core and the windings used in a static induction electric apparatus or a transformer are made of metallic materials, they have mass due to their size and specific gravity.

[0004] Patent Document 1 discloses a method for avoiding the self-weight of the windings and the self-weight of the core from being applied to the outer covering portion of the windings.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Patent Document 1 discloses a technical idea of avoiding the self-weight of the core from being applied to the outer covering portion of the windings by receiving the mass of the core 32 with insulating members 28 to 31 and then receiving it with upper core clamping fittings 16 and 18. That is, it suppresses the deformation of the windings caused by the core of the transformer.

[0007] However, when the winding is energized as a static induction device, current flows through the winding, creating a magnetic field. The interaction between the leakage flux and the winding current generates a Lorentz force. This force is generated as an electromagnetic mechanical force. The winding generally has a vertically elongated shape, as disclosed in the figure of reference 1, for example. Therefore, the number of turns in the winding is oriented vertically. Consequently, this electromagnetic force generates a vertical force in the winding.

[0008] Therefore, the present invention aims to provide a means for suppressing winding deformation when energized as a static induction electric device.

[0009] Furthermore, a further objective is to achieve a balance between this and measures to prevent temperature increases. [Means for solving the problem]

[0010] A static induction electric device having a winding and an iron core, wherein the winding has an inner winding and an outer winding, and the static induction electric device has a winding support plate that holds both the inner winding and the outer winding. [Effects of the Invention]

[0011] According to the present invention, it is possible to realize a static induction device in which winding deformation is suppressed when energized as a static induction device. Furthermore, it is possible to achieve this while also addressing the issue of temperature rise.

[0012] Further means and effects of the present invention will become apparent throughout the entire specification below. [Brief explanation of the drawing]

[0013] [Figure 1A] This is a top view of an example of a winding. [Figure 1B] This is a top view of an example of a winding section. [Figure 1C] Figure 1B is a schematic cross-sectional view along line AA. [Figure 2A] This diagram corresponds to Figure 1B and illustrates the winding support plate. [Figure 2B]It is a schematic cross-sectional view taken along the line A-A of FIG. 2A. [Figure 3A] It is an explanatory diagram when other members of the iron core are installed with respect to the winding of FIG. 2A. [Figure 3B] It is a schematic cross-sectional view taken along the line B-B of FIG. 3A. [Figure 3C] It is a diagram corresponding to FIG. 3A and showing lead-out lines. [Figure 3D] It is a schematic cross-sectional view explaining the arrangement of the lead-out lines. [Figure 4A] It is an explanatory diagram of a part of the cross-sectional components in a region of FIG. 3A. [Figure 4B] It is an explanatory diagram of a part of the cross-sectional components in a region of FIG. 3A. [Figure 5A] It is an explanatory diagram of an example of the planar shape of the winding support plate. [Figure 5B] It is an explanatory diagram of an example of the planar shape of the winding support plate. [Figure 5C] It is an explanatory diagram of an example of the planar shape of the winding support plate. [Figure 5D] It is an explanatory diagram of an example of the planar shape of the winding support plate. [Figure 5E] It is a diagram showing only the planar shape of the winding support plate from FIG. 5D. [Figure 5F] It is an explanatory diagram of an example of the planar shape of the winding support plate. [Figure 5G] It is a schematic cross-sectional view taken along the line C-C of FIG. 5F. [Figure 5H] It is an explanatory diagram of an example of the planar shape when a common support plate is provided with respect to FIG. 5F. [Figure 5I] It is an example of a schematic cross-sectional view taken along the line D-D of FIG. 5H. [Figure 5J] It is an example of a schematic cross-sectional view taken along the line D-D of FIG. 5H.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment

[0015] To help you understand the structure, we will explain it by adding and describing the components one by one.

[0016] As an example of static induction electrical equipment, we will explain using the example of a transformer.

[0017] Figure 1A is a top view of the transformer windings. 1 represents a winding. Winding 1, for example, has an outer winding 1A and an inner winding 1B. While it is customary for the outer winding 1A to be the high-voltage side, this is not a limitation.

[0018] Figure 1B is an addition to Figure 1A, showing the inner insulating cylinder 30 and the outer insulating cylinder 31. The inner insulating cylinder 30 and the outer insulating cylinder 31 contribute to maintaining the shape of the inner winding 1B and the outer winding 1A, respectively. In addition, they have the effect of preventing contact with the winding during the manufacturing process and avoiding deformation of the winding.

[0019] Furthermore, when the inner insulating cylinder 30 and the outer insulating cylinder 31 are constructed from insulating materials, the insulation performance of the static induction device can be improved. Suitable materials in this case include pressboard and resin.

[0020] In the following explanation, the static induction electric device will be illustrated and described using an example that includes an inner insulating cylinder 30 and an outer insulating cylinder 31. However, the technical concept described below can also be applied to cases where there is no inner insulating cylinder 30 and an outer insulating cylinder 31. For this reason, configurations without an inner insulating cylinder 30 and an outer insulating cylinder 31 are also included within the scope of disclosure and claims of this application.

[0021] Figure 1C is a schematic cross-sectional view of the section along line AA in Figure 1B. Only a portion of the upper part of the winding cross-section is shown. This is because, due to the elongated shape of the winding, displaying the entire section would require a much larger drawing.

[0022] In the diagram, the left and right sides are arranged in the following order from the center outwards: inner insulating cylinder 30, space, inner winding 1B, space, outer winding 1A, space, and outer insulating cylinder 31.

[0023] Figure 2A is a diagram illustrating the planar shape of the winding support plate, which is a feature of the present invention. Compared to Figure 1B, it has a structure in which winding support plates 50 and 51 are provided. Winding support plates 50 and 51 are represented by different shaded lines for identification purposes. Furthermore, the positions of the outer winding 1A and inner winding 1B below them are shown as a top perspective view.

[0024] In Figure 2A, a gap of 200 is provided between the winding support plate 50 and the winding support plate 51.

[0025] Figure 2B is a schematic cross-sectional view of the section indicated by line AA in Figure 2A. It corresponds to Figure 1C. The difference from Figure 1C is that a winding support plate 51 is placed on the outer winding 1A, and a winding support plate 50 is placed on the inner winding 1B. These winding support plates 50 and 51 suppress deformation of the windings of the inner winding 1B and outer winding 1A when energized as a static induction device.

[0026] Furthermore, a gap 200 is provided between the winding support plate 50 and the winding support plate 51. This allows the heat generated from the winding when the static induction device is energized to dissipate through this gap 200. As a result, the heat dissipation issues that may arise from the addition of the winding support plates 50 and 51 can be avoided in advance.

[0027] This gap 200 functions as a circulation path over the thermal fluid in air-cooled or gas-cooled static induction electrical devices. In oil-filled static induction electrical devices, it functions as a circulation path over the thermal fluid in the insulating oil.

[0028] In Figure 2B, the winding support plate 50 is positioned on top of the inner insulating cylinder 30, and the winding support plate 51 is positioned on top of the outer insulating cylinder 31. In this case, the winding support plate 50 and the inner insulating cylinder 30 provide more reliable shape retention for the inner winding 1B, and the winding support plate 51 and the outer insulating cylinder 31 provide more reliable shape retention for the outer winding 1A. Furthermore, contact with the windings during work can be more reliably avoided.

[0029] Furthermore, even in a configuration without an inner insulating cylinder 30 and an outer insulating cylinder 31, the effects of the winding support plates 50 and 51 can be achieved in the same way.

[0030] Figure 3A is an explanatory diagram showing the installation of the core and other components on the winding shown in Figure 2A. The core 2 is positioned on top of the winding 1. The weight of the core is supported by the upper support plate 11, as in Patent Document 1, so that its mass does not directly affect the winding. In particular, since the shapes of the winding 1 and the core 2 are different, if the mass of the core 2 were to be directly applied to the winding 1, an uneven load would be applied to the winding 1, causing large deformation in some areas.

[0031] The upper support plate 11 is fixed to the upper support member 3, and the weight of the iron core 2 rests on the upper support member 3. The upper support members 3 are positioned on both the left and right sides of the iron core 2, and they share the burden of supporting the iron core 2.

[0032] The left and right upper support members 3 are positioned horizontally by fastening means 4.

[0033] Figure 3B is a schematic cross-sectional view along line BB in Figure 3A. Note that core 2 is excluded from the diagram.

[0034] A retaining member 70 is positioned between the upper support member 3 and the winding support plate 50. This applies a controlled and appropriate load to the winding support plate 50. As a result, the shape of the inner winding 1B is more reliably maintained. Furthermore, deformation of the inner winding 1B due to electromagnetic force during energization is suppressed.

[0035] A retaining member 71 is positioned between the upper support member 3 and the winding support plate 51. This applies a controlled and appropriate load to the winding support plate 51. As a result, the shape of the outer winding 1A is more reliably maintained. Furthermore, deformation of the outer winding 1A due to electromagnetic force during energization is suppressed.

[0036] As described above, this embodiment makes it possible to realize a static induction device in which winding deformation is suppressed when energized as a static induction device. Furthermore, it is also possible to achieve this while simultaneously addressing the issue of temperature rise. [Examples]

[0037] This embodiment is basically identical to Embodiment 1. The difference from Embodiment 1 lies in the arrangement of the lead wires from the inner winding 1B and the outer winding 1A.

[0038] Figure 3C is a modified version of Figure 3A with the addition of lead wires 100 and 101. It shows that lead wires 100 and 101 are drawn out from the gap between the inner winding 1B and the outer winding 1A.

[0039] Figure 3D is a schematic cross-sectional view illustrating the arrangement of the lead wires. Wiring for external connection from the outer winding 1A is drawn out from the gap 200 on the left side of the figure via lead wire 101. Wiring for external connection from the inner winding 1B is drawn out from the gap 200 on the right side of the figure via lead wire 100.

[0040] In this way, by providing a gap 200 between the winding support plate 50 and the winding support plate 51, external connection wiring can be pulled out through the gap 200, which has the advantage of making wiring easier to pull out.

[0041] This advantage is particularly greater in configurations having an inner insulating tube 30 and an outer insulating tube 31. This is because the distance between the inner insulating tube 30 and the inner winding 1B, and the distance between the outer insulating tube 31 and the outer winding 1A, are usually short, and drawing out wiring for external connections from these points requires labor and time during manufacturing.

[0042] Therefore, by providing a gap 200 between the winding support plate 50 and the winding support plate 51, the work of pulling out wiring for external connections is facilitated, thereby improving the production efficiency of static induction electrical equipment.

[0043] Furthermore, by routing the lead wires 100 and 101 from different locations, as shown in Figure 3C or Figure 3D, the wiring routing process during manufacturing can be further simplified. Additionally, sufficient insulation distance can be ensured between the lead wires.

[0044] Furthermore, by leading out wires 100 and 101 so that they face each other, as shown in Figure 3C or Figure 3D, the wiring work during manufacturing is further simplified. This also contributes to reducing wiring errors during subsequent connection work, as it becomes easier to determine which leading wire corresponds to which winding. [Examples]

[0045] This embodiment is basically identical to Embodiment 2. The difference from Embodiment 2 is that one or both of the inner winding 1B and the outer winding 1A are cylindrical windings.

[0046] Cylindrical winding is a winding structure in which the winding is wound sequentially from bottom to top, then from top to bottom, and then again from bottom to top, and so on.

[0047] Cylindrical winding structures offer advantages such as compatibility with automated winding, excellent mass production capabilities, and high production efficiency.

[0048] On the other hand, there is a problem in that there are constraints on where the windings can be brought out to the outside.

[0049] As disclosed in Example 2, by using a structure in which lead wires 100 and 101 are drawn out from the gap between the inner winding 1B and the outer winding 1A, the arrangement of lead wires can be simplified even in a cylindrical winding structure.

[0050] Furthermore, by providing a gap 200 between the winding support plate 50 and the winding support plate 51, external connection wiring can be pulled out through the gap 200, which has the advantage of making wiring easier to install. [Examples]

[0051] This embodiment shows the configuration for supporting the weight of the iron core in Examples 1 to 3.

[0052] Figure 4A is an explanatory diagram of a part of the cross-sectional components in one region of Figure 3A. The iron core 2 is shaped by the side support brackets 10 and placed on the upper support plate 11. The upper support plate 11 is fixed by the upper support member 3 and the fastening member 12. As a result, the mass of the iron core 2 is supported by the upper support member 3. 5 is the iron core regulating member.

[0053] Figure 4B is an explanatory diagram of a part of the cross-sectional components in a region of Figure 3A. It is a diagram of a different region than Figure 4A.

[0054] The difference from Figure 4A is that the upper support member 3 is positioned by the upper and lower support members 15. Therefore, the weight of the iron core 2 ultimately rests on the upper and lower support members 15.

[0055] In this way, the position of the upper support member 3 is secured, and by appropriately designing the height or thickness of the pressing member 70 and pressing member 71 as described in Embodiment 2, the force applied to the winding support plate 50 and winding support plate 51 can be adjusted, making it possible to press the winding with the appropriate force. [Examples]

[0056] In this embodiment, various shapes of the winding support plate in Examples 1 to 4 will be described.

[0057] Figure 5A is an explanatory diagram illustrating an example of the planar shape of the winding support plate. Corresponding to Figure 2A, this diagram specifically explains the planar structure of the winding support plate 50, the winding support plate 51, and the gap 200.

[0058] In Figure 5A, the winding support plate 50 and the winding support plate 51 are each constructed in an arc shape. A gap 200 is positioned between them.

[0059] Figure 5B is an explanatory diagram of an example of the planar shape of the winding support plate. Compared to Figure 5A, the winding support plate 50 and the winding support plate 51 are integrated into a single component, forming the winding support plate 52. However, it has a gap 200 for the purpose of heat dissipation and wiring outlets.

[0060] Gap 200 has an arc shape, or an elongated structure with curvature, or an elongated structure with a radius (R).

[0061] Figure 5C is an explanatory diagram of an example of the planar shape of the winding support plate. Compared to Figure 5B, the winding support plate 52 has a structure with numerous holes. This structure improves heat dissipation.

[0062] Alternatively, the winding support plate 52 can be constructed as a flat structure with a mesh-like shape instead of holes.

[0063] Figure 5D is an explanatory diagram of an example of the planar shape of the winding support plate. Compared to Figure 5B, the winding support plate 52 is divided into upper, lower, left, and right sections, and is composed of four winding support plates 53A, 53B, 53C, and 53D, forming the winding support plate 53. In Figure 5D, the lower side of the winding support plate is also shown. Therefore, Figure 5E is a diagram showing only the winding support plate 53. The winding support plate 53 is composed of four winding support plates 53A, 53B, 53C, and 53D. It is shown that each winding support plate has a gap of 200 and is separated from each other.

[0064] As described above, this embodiment has explained various shapes of winding support plates. By using these winding support plates, it is possible to realize a static induction device in which winding deformation is suppressed during energization operation. Furthermore, it is possible to achieve compatibility with thermal management in this process.

[0065] In Figure 5D, an example with four divisions is used, but the number of divisions is not limited to two or more. However, considering the manufacturing process, too many divisions increase the workload, so it is desirable to limit the number of divisions to a maximum of eight. The best balance is achieved with four divisions. [Examples]

[0066] Similar to Example 5, this embodiment describes various shapes of winding support plates.

[0067] Figure 5F is a diagram corresponding to Figure 5A. The difference from Figure 5A is that the winding support plate 50 and the winding support plate 51 are divided into four sections.

[0068] In this embodiment, the winding support plate 50 is divided into four parts: 50A, 50B, 50C, and 50D. Similarly, the winding support plate 51 is divided into four parts: 51A, 51B, 51C, and 51D.

[0069] Figure 5G is a schematic cross-sectional view along line CC in Figure 5F. A retaining member 70 is positioned between the winding support plate 50 and the upper support member 3. A retaining member 71 is positioned between the winding support plate 51 and the upper support member 3. As a result, the outer winding 1A is held down by the winding support plate 50 via the retaining member 70. Similarly, the inner winding 1B is held down by the winding support plate 51 via the retaining member 71.

[0070] Therefore, it is possible to realize a static induction device that suppresses winding deformation during energized operation. Furthermore, since there is a gap between the winding support plates in the lateral direction, it is also possible to achieve compatibility with heat countermeasures.

[0071] Furthermore, the structure in Figure 5G corresponds to the separate winding support plates in Figure 5F. Therefore, a total of four retaining parts similar to those in Figure 5G are arranged relative to Figure 5F. [Examples]

[0072] This embodiment is a modification of Embodiment 6.

[0073] Figure 5H is a diagram corresponding to Figure 5F. The difference from Figure 5F is that it has a common support plate 80.

[0074] The common support plate 80 is positioned across both the winding support plate 50 and the winding support plate 51. Figure 5I is a schematic cross-sectional view taken along the line DD in Figure 5H. It can be seen that the common support plate 80 is positioned across both the winding support plate 50 and the winding support plate 51.

[0075] In Figure 5G, there were two retaining members, 70 and 71. Or rather, it was essential to have two. However, in Figure 5I, which has a common support plate 80, only one retaining member is needed. That is, retaining members 70 and 71 can be integrated and arranged as retaining member 72. This reduces the number of parts in the retaining member, contributing to cost reduction, and also contributes to reducing the man-hours required for assembly.

[0076] However, this does not mean that the provision of retaining members 70 and 71, as shown in Figure 5J, is excluded.

[0077] Furthermore, the winding support plate 50 is configured as a relatively large component, with a planar area larger than that of the pressing members 70 and 71 or 72. This expands the area where pressure is applied from the pressing members to the winding support plate 50 and winding support plate 51, thereby preventing tilting or lifting of the winding support plate 50 and winding support plate 51.

[0078] Furthermore, the flatness of the winding support plates 50 and 51 on the winding can also be improved, thereby further enhancing the winding support capability.

[0079] In Figure 5H, an example was shown with four divisions, but the number of divisions is not particularly limited as long as it is two or more. However, considering the manufacturing process, too many divisions increase the workload, so it is desirable to limit it to a maximum of eight. The best balance is achieved with four divisions.

[0080] The above embodiments can be used individually or in combination.

[0081] Furthermore, the materials used for the winding support plates and common support plates must be insulating materials. Examples include pressboard, resin, plastic, wood, and birch.

[0082] Furthermore, in the embodiments described above, the winding support plate, common support plate, and various other components were explained in relation to the upper side of the static induction electric device, but the same structure may be used on the lower side as well. This will allow the same effects to be achieved on the lower side as well.

[0083] Furthermore, the technical concept of this application is not limited to the embodiments described above, and modifications and applications are also equivalent to the disclosure in this application as long as the technical concept is applied.

[0084] Furthermore, an example of the present invention described using the above embodiments can also be expressed as follows.

[0085] <Part 1> In a static induction electric device having windings and an iron core, The winding has an inner winding and an outer winding, A static induction electric device having a winding support plate that holds both the inner winding and the outer winding. <Part 2> The winding support plate has a gap between the inner winding and the outer winding as described in <Part 1> of the static induction electric device. <Part 3> The aforementioned gap is arc-shaped, or has a curved, elongated shape, or has an R-shaped portion, as described in <Part 2>, for the static induction electric device. <Part 4> The winding support plate has a shape with numerous holes or a mesh shape as described in <Part 3>, a static induction electric device. <Part 5> The winding support plate has a portion on the inner winding and a portion on the outer winding, and a portion of the inner winding portion and the outer winding portion are connected. Static induction electric device as described in <Part 2>. <Part 6> The static induction electric device described in <Part 2>, wherein the winding support plate has a portion on the inner winding and a portion on the outer winding, and each of the portions on the inner winding and the outer winding is divided into multiple parts. <Part 7> The winding support plate has no connecting portion between the portion on the inner winding and the portion on the outer winding, as described in <6> of the static induction electric device. <Part 8> The structure includes an upper support plate positioned between the core and the winding to support the weight of the core, an upper support member that supports the weight of the upper support plate, a fastening member that fastens the upper support plate to the upper support plate, and upper and lower support members that define the height of the upper support member. A static induction electric appliance according to any one of items 1 to 7, having a pressing member directly or indirectly between the upper and lower support members and the winding support plate. <Part 9> The static induction electric device described in <8>, wherein the retaining member is arranged on both the portion on the inner winding and the portion on the outer winding, respectively. <Part 10> The static induction electric device according to <8>, which has a common support plate positioned between the pressing member and the winding support plate, and which spans both the portion of the winding support plate over the inner winding and the portion over the outer winding. <Part 11> The static induction electric device described in <No. 10>, wherein one retaining member is arranged for each common support plate. <Part 12> The static induction electric device described in <Part 8>, wherein the winding is a cylindrical winding structure, and the lead wire of the winding is drawn out from the gap. <Part 13> The static induction electric device described in <No. 10>, wherein the winding support plate is divided into 2 to 8 sections on the inner winding and the outer winding, respectively. <Part 14> The static induction electric device described in <No. 13>, wherein the winding support plate is also arranged on the underside of the winding. <Part 15> The static induction electric device described in <No. 14>, wherein the winding support plate and the common support plate are insulators. <Part 16> The static induction electric device according to <No. 15>, having an inner insulating cylinder inside the inner winding and an outer insulating cylinder outside the outer winding. <Part 17> The static induction electric device described in <No. 16>, wherein the number of divisions is 4. [Explanation of symbols]

[0086] 1: Winding 1A: Outer winding 1B: Inner winding 2: Iron Heart 3: Upper support member 4: Fastening member 5: Iron core regulating member 10: Side support bracket 11: Upper support plate 12: Fastening members 15: Upper and lower support members 30: Inner insulating tube 31:Outer insulation tube 50, 51, 52, 53: Winding support plate 70, 71, 72: Retaining member 80: Common support plate 100, 101: Leader wires 200: Gap

Claims

1. In a static induction electric device having windings and an iron core, The winding has an inner winding and an outer winding, A static induction electric device having a winding support plate that holds both the inner winding and the outer winding.

2. The static induction electric device according to claim 1, wherein the winding support plate has a gap between the inner winding and the outer winding.

3. The static induction electric device according to claim 2, wherein the gap is arc-shaped, or has a curved, elongated shape, or has an R-shaped portion.

4. The static induction electric device according to claim 3, wherein the winding support plate has a shape having a large number of holes or a mesh shape.

5. The static induction electric device according to claim 2, wherein the winding support plate has a portion on the inner winding and a portion on the outer winding, and a portion of the inner winding portion and the outer winding portion are connected.

6. The static induction electric device according to claim 2, wherein the winding support plate has a portion on the inner winding and a portion on the outer winding, and each of the portions on the inner winding and the outer winding is divided into multiple parts.

7. The static induction electric device according to claim 6, wherein the winding support plate has no connecting portion between the portion on the inner winding and the portion on the outer winding.

8. The structure includes an upper support plate positioned between the core and the winding to support the weight of the core, an upper support member that supports the weight of the upper support plate, a fastening member that fastens the upper support plate to the upper support plate, and upper and lower support members that define the height of the upper support member. A static induction electric device according to any one of claims 1 to 7, further comprising a pressing member directly or indirectly between the upper and lower support members and the winding support plate.

9. The static induction electric device according to claim 8, wherein the retaining member is arranged on both the portion on the inner winding and the portion on the outer winding, respectively.

10. The static induction electric device according to claim 8, which has a common support plate disposed between the pressing member and the winding support plate, and which spans both the portion of the winding support plate on the inner winding and the portion on the outer winding.

11. The static induction electric device according to claim 10, wherein one pressing member is provided for each common support plate.

12. The static induction electric device according to claim 8, wherein the winding is a cylindrical winding structure, and the lead wire of the winding is drawn out from the gap.

13. The static induction electric device according to claim 10, wherein the winding support plate is divided into 2 to 8 sections on the inner winding and the outer winding, respectively.

14. The static induction electric device according to claim 13, wherein the winding support plate is also arranged on the underside of the winding.

15. The static induction electric device according to claim 14, wherein the winding support plate and the common support plate are insulators.

16. The static induction electric device according to claim 15, wherein the inner winding has an inner insulating cylinder inside and the outer winding has an outer insulating cylinder outside.

17. The static induction electric device according to claim 16, wherein the number of divisions is four.

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