Oil-filled transformer

Abstract

To provide an oil-filled transformer capable of suppressing increases in size and weight.SOLUTION: An oil-filled transformer 1 includes a core 2, a coil 3 mounted on the core 2, and a side support member 4 supporting the side of the coil 3. The coil 3 is formed with at least a portion of the side facing the side support member 4 bulging outward, and contacts the side support member 4 with a portion of the side.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] An embodiment of the present invention relates to an oil-immersed transformer. [Background technology]

[0002] An oil-immersed transformer includes an iron core and a coil attached to the iron core. The coil of such an oil-immersed transformer must have sufficient mechanical strength to withstand the electromagnetic mechanical force generated during an external short circuit. For example, Patent Document 1 describes a method of holding down the sides of the coil with connecting members fixed to support structures above and below the iron core. Hereinafter, the electromagnetic mechanical force generated during an external short circuit will be referred to as the short-circuit mechanical force, and the members that hold down the sides of the coil will be referred to as support members for convenience. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-54714 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the short-circuit mechanical force is generated inside the coil, and if the distance between the position where the support member is fixed to the support structure and the position where the short-circuit mechanical force actually occurs (i.e., the coil) becomes large, the support member needs to have a certain degree of strength.

[0005] However, if the strength of the support member is improved by adding reinforcing members such as beams, the support member will become larger and heavier, resulting in reduced workability and increased costs. The same applies to ensuring strength by increasing the thickness of the support member. Furthermore, if the support member becomes larger, the tank will also have to become larger, resulting in an increase in the size and weight of the oil-immersed transformer.

[0006] Therefore, an oil-immersed transformer that can suppress increases in size and weight is provided. [Means for solving the problem]

[0007] An oil-filled transformer according to an embodiment comprises an iron core, a coil attached to the iron core, and a side support member that supports the side of the coil, and the coil is formed so that at least a portion of the side facing the side support member bulges outward, and a portion of the side contacts the side support member. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of an oil-immersed transformer according to an embodiment. [Figure 2] Schematic diagram of an example of a coil configuration [Figure 3] FIG. 10 is a diagram illustrating a configuration example of a side support member. [Figure 4] FIG. 10 is a diagram schematically illustrating a contact state between the coil and the side support member. [Figure 5] FIG. 1 is a diagram showing a schematic diagram of a generation mode of a short-circuit mechanical force. [Figure 6] Diagram 1 showing another example of coil configuration [Figure 7] Diagram 2 showing another example of coil configuration [Figure 8] Diagram 3 showing another example of coil configuration DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment will be described with reference to the drawings. As shown in Fig. 1, an oil-immersed transformer 1 of this embodiment includes an iron core 2, a coil 3 attached to the iron core 2, and side support members 4 that support the sides of the coil 3. The iron core 2, the coil 3, and the side support members 4 are housed inside a tank 5, and the inside of the tank 5 is filled with insulating oil (not shown), thereby forming the oil-immersed transformer 1. Although not shown, the oil-immersed transformer 1 is also provided with, for example, a tap changer, a bushing, a conservator, a heat sink, various sensors, a control device, and the like. Hereinafter, the up-down direction in Fig. 1 will be referred to as the up-down direction.

[0010] The iron core 2 is arranged with its upper side supported by an upper support member 6 and its lower side supported by a lower support member 7 fixed to the bottom surface of the tank 5. These upper support member 6 and lower support member 7 correspond to a support structure that fixedly supports the iron core 2. The iron core 2 has three legs 2a, and a coil 3A, a coil 3B, and a coil 3C are attached to each leg 2a. The number of legs 2a shown in FIG. 1 is one example. Although not shown, insulating spacers are provided between the upper end of each coil 3 and the upper support member 6, and between the lower end of each coil 3 and the lower support member 7, to support each coil 3.

[0011] Each coil 3 is formed by winding a sheet-like or rectangular conductor, and as shown in FIG. 2, an inner coil 31 and an outer coil 32 are formed in a generally annular shape and arranged concentrically. The inner coil 31 and the outer coil 32 are arranged concentrically with a so-called inner-outer insulator sandwiched between them. Note that FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1, but hatching has been omitted for ease of viewing. Hereinafter, the up-down direction in FIG. 2 will be referred to as the front-to-rear direction, the length of each coil 3 in the front-to-rear direction will be referred to as the depth (D1), and the length of the coil 3 in the up-to-down direction shown in FIG. 1 will be referred to as the height (H1).

[0012] In the coils 3A and 3C, both the inner coil 31 and the outer coil 32 are formed so that at least a portion of their side surfaces bulges outward. In this embodiment, the side surfaces of the coils 3A and 3C are formed so that they bulge outward in a smooth curved shape overall. Here, in this embodiment, the side surface of the coil 3 corresponds to the surface of the long side of the coil 3 in FIG. 2, that is, the area between the inner circumferential surface of the short side of the outer coil 32. Hereinafter, the length of the side surface in the front-to-rear direction is referred to as the side width (W1). Note that the coils 3A and 3C are formed in the same shape and are attached to the iron core 2 so that the bulging side surfaces are the outermost contours.

[0013] On the other hand, coil 3B is formed in a shape in which the sides are not bulged. Hereinafter, coils with a conventional shape in which the sides are not bulged, such as coil 3B, will be referred to as a straight type for convenience, and coils with bulged sides, such as coils 3A and 3C, will be referred to as an irregular shape for convenience. Furthermore, because coil 3B has a different shape from coils 3A and 3C, coil 3B will be referred to as inner circumferential coil 31B and inner circumferential coil 32B for convenience.

[0014] As shown in Fig. 1, the left side of coil 3A and the right side of coil 3C are supported by side support members 4. These side support members 4 are formed by bending a flat steel plate of a predetermined thickness as shown in Fig. 3. In other words, the side support members 4 have a relatively simple shape and structure.

[0015] Specifically, the side support member 4 has an upper fixing portion 4b at the upper end side in the figure having through holes 4a through which bolts for fixing to the upper support member 6 are passed, a lower fixing portion 4c at the lower end side in the figure having through holes 4a through which bolts for fixing to the lower support member 7 are passed, and a flat support portion 4d that connects the upper fixing portion 4b and the lower fixing portion 4c and supports the side of the coil 3. The upper fixing portion 4b and the lower fixing portion 4c correspond to fixing portions for fixing the side support member 4 to a support structure.

[0016] The side support member 4 is bent at a substantially right angle to the right in the figure at the boundary between the upper fixing portion 4b and the support portion 4d, and at the boundary between the support portion 4d and the lower fixing portion 4c. The bent tip of the side support member 4 is bent at a substantially right angle upward and downward in the figure so as to fit along the end faces of the upper support member 6 and the lower support member 7. Note that the shape of the side support member 4 shown in Figure 3 is one example, and the structure of the fixing portion is not limited to this as long as the support portion 4d is formed in a flat plate shape.

[0017] The side support member 4 has the upper fixing portion 4b fixed to an end of the upper support member 6 and the lower fixing portion 4c fixed to an end of the lower support member 7, so that the support portion 4d is positioned at a predetermined position on the side of the coil. As a result, when the coil 3 is deformed by a short-circuit mechanical force generated during an external short circuit, the side support member 4 can ensure short-circuit strength against mechanical shock by having the support portion 4d suppress the deformation.

[0018] Furthermore, the side support member 4 is formed so that the length (L10) of the support portion 4d in the up-down direction is longer than the height (H1) of the coil 3, and the width (W10) of the support portion 4d in the front-to-rear direction is shorter than the depth (D1) of the coil 3 and shorter than the width (W1) of the side of the coil 3. Therefore, as shown in Fig. 4, the side support member 4 is in contact with the side of the coil 3 over a range (W20) shorter than the width (W10) of the support portion 4d, and supports part of the side of the coil 3 in the front-to-rear direction and supports the side of the coil 3 over the entire area in the height direction.

[0019] Furthermore, if the area of ​​the side surface of the coil 3 that comes into contact with the side support member 4 when no short-circuit mechanical force is generated is defined as the contact surface, the width (W20) of the contact surface, the contact angle (α) that is the angle between the contact surface and the side surface, and the width (W21) of the excess portion other than the contact surface will have values ​​that depend on the shape of the coil 3. However, it is also possible to determine in advance the short-circuit mechanical force expected through actual machine testing or simulation, and set the shape of the side support member 4 so that the width (W20) of the contact surface is narrower than the width (W10) of the support portion 4d even when the short-circuit mechanical force is generated, in other words, so that the contact angle (α) and the width (W21) of the excess portion can be secured.

[0020] Next, the operation of the above-described configuration will be described. As described above, the short-circuit mechanical force is generated inside the coil 3. The side support member 4 is arranged with the upper fixed portion 4b fixed to the upper support member 6 and the lower fixed portion 4c fixed to the lower support member 7, and the side of the side support member 4 is supported by a support portion 4d that is distant from the fixed position. Therefore, the distance between the fixed position of the side support member 4 and the support position that actually supports the coil 3 becomes large, and in order to resist the bending stress applied to the support portion 4d, in other words, to suppress the short-circuit mechanical force, the side support member 4 needs to have a certain degree of strength.

[0021] However, if an attempt is made to improve the strength by adding a reinforcing member such as a beam to the side support member 4, the size and weight of the side support member 4 will increase, resulting in reduced workability and increased costs. The same applies to ensuring strength by increasing the thickness of the side support member 4. Furthermore, if the side support member 4 is made larger, the tank 5 will also have to be made larger accordingly, resulting in an increase in the size and weight of the oil-filled transformer 1.

[0022] Therefore, in this embodiment, the shape of the coil 3 is devised to reduce the bending stress itself applied to the side support member 4. Specifically, the short-circuit mechanical force is generated in the direction toward the surface of the coil 3, as indicated by the outline arrow in Fig. 5. Therefore, in the case of a straight-type coil 3B shown as a comparative example, the short-circuit mechanical force is generated outward (to the left in the figure) over the entire side surface, and all of the outward bending stress is applied to the side support member 4.

[0023] In contrast, in the case of an irregularly shaped coil 3A with bulging sides as shown in the example, the direction of the short-circuit mechanical force changes depending on the position of the side, and therefore the bending stress applied to the side support member 4 is the sum of the outward components of the generated short-circuit mechanical force. In other words, in the case of the irregularly shaped coil 3A, the bending stress applied to the side support member 4 is relatively smaller than in the case of the straight coil 3B.

[0024] Furthermore, because the width (W20) of the contact surface is narrower than the width (W10) of the support portion 4d that actually contacts the coil 3, the total value of the bending stress applied to the side support member 4 is also reduced. In other words, by giving the coil 3 a shape in which the sides bulge outward, the bending stress itself applied to the side support member 4 can be reduced.

[0025] Furthermore, if the bending stress itself applied to the side support member 4 is reduced, it becomes possible to reduce the strength of the side support member 4 that is required to withstand that bending stress. Therefore, it becomes possible to ensure the necessary strength without providing a reinforcing member to the side support member 4 or without increasing the thickness of the side support member 4. Therefore, it is possible to suppress an increase in the size and weight of the side support member 4, and there is no need to increase the size of the tank 5, and it is also possible to suppress an increase in the size and weight of the oil-immersed transformer 1.

[0026] Further effects can be obtained by giving the coil 3 an irregular shape with bulged sides. For example, as shown in Figure 5, if the surface length of the side of the straight coil 3 in a state where no short-circuit mechanical force is generated is L20 and the surface length of the side of the irregular-shaped coil 3 is L21, then the relationship between these surface lengths is L21 > L20.

[0027] When a short-circuit mechanical force occurs, a repulsive force is generated between the inner coil 31 and the outer coil 32 as shown by the black arrow, and the outer coil 32 is pushed outward. However, if the same short-circuit mechanical force is generated, it is thought that the increase in the surface length (ΔL) of each coil 3 will also be the same value.

[0028] Furthermore, if the side surface is pushed outward in accordance with the increase in surface length (ΔL) and its position shifts to the left side of the figure, when comparing the expected displacement amount (ΔX1) when the surface length of the straight coil 3 becomes L20 + ΔL and deforms outward, with the expected displacement amount (ΔX11) when the surface length of the irregularly shaped coil 3 becomes L21 + ΔL and deforms outward, the displacement amount of the irregularly shaped coil 3 will be smaller, as can be determined geometrically.

[0029] In this way, by making the coil 3 irregular in shape, it is possible to relatively suppress the deformation amount of the coil 3 when a short-circuit mechanical force occurs compared to a straight type, and even when the displacement amount is taken into consideration, it does not lead to excessive size increase. Furthermore, by suppressing the deformation amount of the coil 3, it is possible to suppress excessive expansion of the inner-outer periphery insulation and variation in the width of the inner-outer periphery insulation depending on the position, and it is possible to suppress the impact on the performance of the oil-filled transformer 1.

[0030] According to the embodiment described above, the following effects can be obtained. The oil-immersed transformer 1 includes an iron core 2, a coil 3 attached to the iron core 2, and a side support member 4 that supports the side surfaces of the coil 3. At least a portion of the side surface of the coil 3 facing the side support member 4 is formed in a shape that bulges outward, and a portion of the side surface comes into contact with the side support member 4.

[0031] As a result, if a short-circuit mechanical force occurs in the coil 3, the direction of the force is dispersed, and the bending stress acting on the side support member 4 can be alleviated. Therefore, the necessary strength can be ensured while suppressing an increase in the size and weight of the side support member 4. Furthermore, since there is no need to increase the size of the tank 5 that houses the side support member 4, etc., an increase in the size and weight of the oil-filled transformer 1 can also be suppressed.

[0032] Furthermore, the coil 3 is in contact with the side support member 4 over an area narrower than the width of the side support member 4. This reduces the total value of the bending stress applied to the side support member 4, and therefore the bending stress itself applied to the side support member 4 can be reduced.

[0033] Furthermore, the portions of the side support member 4 that support the sides of the coil 3 are formed in a flat plate shape. As described above, the bending stress applied to the side support member 4 is alleviated by the shape of the coil 3, so the necessary strength can be ensured without providing a reinforcing member to the side support member 4 or without increasing the thickness of the side support member 4. Furthermore, since the shape and structure of the side support member 4 can be simplified, manufacturing and assembly work is also facilitated, and manufacturing costs and work costs can also be reduced.

[0034] Furthermore, the coil 3 has a curved contact surface that comes into contact with the side support member 4. In this case, the curved side surface can be formed by winding a conductor, and therefore can be easily manufactured.

[0035] The coil 3 is made up of an inner coil 31 arranged on the inner periphery side and an outer coil 32 arranged on the outer periphery side, which are concentrically arranged, and both the outer coil 32 and the inner coil 31 are formed with their sides bulging outward, which allows for an even gap to be formed between the inner coil 31 and the outer coil 32.

[0036] Furthermore, by making the side surfaces of the coil 3 bulged, even if the coil 3 is pushed outward by the repulsive force generated when a short-circuit mechanical force occurs, the amount of deformation is smaller than in a straight type. Therefore, the strength of the side support member 4 required to suppress deformation can be relatively low, and increases in the size and weight of the side support member 4 can be suppressed. In addition, excessive expansion of the inner-outer periphery insulation and variations in the width of the inner-outer periphery insulation in the circumferential direction can also be suppressed.

[0037] As shown in FIG. 6 as another configuration example 1, the inner circumferential surface of the inner circumferential coil 131 can be configured to bulge outward (to the left in the figure). In other words, by providing a gap (S1) between the inner circumferential coil 131 and the core 2 that bulges outward, and by shaping the outer circumferential coil 132 to match the outer shape of the inner circumferential coil 131, the side surfaces can be configured to bulge outward. A coil 13 configured in this manner can also achieve the various effects described above in the embodiment. Furthermore, the gap (S1) between the inner circumferential coil 131 and the core 2 functions as a flow path for insulating oil, thereby improving cooling performance. Furthermore, since the thickness of the inner circumferential coil 131 is constant, manufacturing is easy. Furthermore, since the gap (S1) allows, for example, structures to be arranged at regular intervals while a conductor is wound, manufacturing is also easy.

[0038] Furthermore, as shown in FIG. 6 as another configuration example 2, one or more inner slits 233 may be provided inside the inner coil 231, i.e., between the wound conductors, as gaps that bulge outward. In this case, since the side surfaces of the inner coil 231 bulge outward, the outer coil 232 may be shaped to conform to the outer shape of the inner coil 231, thereby enabling the side surfaces to bulge outward. A coil 23 having such a configuration can also achieve the various effects described above, similar to those of the embodiment. Furthermore, the inner slits 233 serve as a flow path for insulating oil, thereby improving cooling performance. Furthermore, the inner coil 231 can be easily manufactured because the inner slits 233 can be formed between the conductors by, for example, winding the conductors while arranging structures at regular intervals. Alternatively, one or more inner slits 233 may be provided circumferentially or radially between the conductors of the inner coil 231.

[0039] 7 shows another example configuration 3, in which the inner coil 331 is straight and a gap (S2) that bulges outward is provided between the inner coil 331 and the outer coil 332, so that the side of the outer coil 332 bulges outward. In other words, a configuration can be achieved in which a portion of the inner-outer insulator corresponding to the side is made wider. A coil 33 having such a configuration can also achieve the various effects described above similar to those of the embodiment. Furthermore, the gap (S2) formed between the inner coil 331 and the outer coil 332 functions as a flow path for insulating oil, and the enlargement of this flow path can improve cooling performance.

[0040] As shown in FIG. 7 as another configuration example 4, the inner coil 431 may be straight, and one or more outer slits 433 may be provided inside the outer coil 432, i.e., between the wound conductors, as gaps that bulge outward, thereby forming an outer lateral surface of the outer coil 432. This configuration of the coil 43 can also achieve the same effects as those of the embodiment. Furthermore, the outer slits 433 function as a flow path for insulating oil, thereby improving cooling performance. Furthermore, the outer coil 432 can be easily manufactured because the outer slits 433 can be formed between the conductors by, for example, winding the conductors while arranging structures at regular intervals. Alternatively, one or more outer slits 433 may be provided circumferentially or radially between the conductors of the outer coil 432.

[0041] 8 shows another configuration example 5, in which leg portions 52 of core 2 are shaped to bulge outward, and inner circumferential side coil 531 and outer circumferential side coil 532 are used that match the shapes of leg portions 52, so that the side surfaces of outer circumferential side coil 432 can be shaped to bulge outward. Coil 53 having such a configuration can also achieve the various effects described above similar to those of the embodiment.

[0042] 8 shows a sixth alternative configuration example, in which a portion of the side surface of the coil 63 is bulged out to form a flat surface. In the case of FIG. 8, the contact surface that comes into contact with the side support member 4 is formed flat, and the other portions are formed curved. In this case, the width (W30) of the flat portion that forms the contact surface can be made shorter than the width (W10) of the support portion 4d of the side support member 4, thereby reducing the bending stress applied to the support portion 4d. In this case, the inner coil 631 can be straight, and the side surface of the outer coil 632 can be bulged out.

[0043] The coil 63 having such a configuration can also achieve the various effects described above similar to those of the embodiment. Furthermore, in the above-described embodiment and other configuration examples, the contact surface can be formed flat. Alternatively, the contact surface can be curved and the remaining portions can be bulged outward so that they are flat. That is, a shape with bulging side surfaces includes a shape with an overall curved bulge, a shape with one or more flat portions, a shape with one or more curved portions, and a shape that combines one or more curved portions with one or more flat portions. Shapes with bulging side surfaces also include shapes with partially different inclinations of the flat portions and shapes with partially varying curvatures of the curved portions.

[0044] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied 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 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]

[0045] In the drawings, 1 is an oil-immersed transformer, 2 is an iron core, 3, 3A, 3B, 3C, 13, 23, 33, 43, 53, 63 are coils, 4 is a side support member, 31, 131, 231, 331, 431, 531, 631 are inner coils, 32, 132, 232, 332, 432, 532, 632 are outer coils, 233 is an inner slit (gap between conductors), 433 is an outer slit (gap between conductors), and S2 is a gap (gap between coils).

Claims

1. Iron core and a coil attached to the iron core; a side support member for supporting a side surface of the coil, The coil is an oil-filled transformer in which at least a portion of the side surface facing the side support member is formed in a shape that bulges outward, and a portion of the side surface comes into contact with the side support member.

2. 2. The oil-filled transformer according to claim 1, wherein the side support member has a portion that supports the side surface of the coil and is formed in a flat plate shape.

3. 2. The oil-filled transformer according to claim 1, wherein the coil is in contact with the side support member over an area narrower than the width of the side support member.

4. 2. The oil-immersed transformer according to claim 1, wherein the coil has a contact surface that comes into contact with the side support member and is formed into a curved or flat surface.

5. The coil is configured such that an inner circumferential side coil arranged on the inner circumferential side and an outer circumferential side coil arranged on the outer circumferential side are concentrically arranged, 2. The oil-immersed transformer according to claim 1, wherein at least one of the outer circumferential coil and the inner circumferential coil is formed so that a side surface thereof bulges outward.

6. The coil is configured such that an inner circumferential side coil arranged on the inner circumferential side and an outer circumferential side coil arranged on the outer circumferential side are concentrically arranged, 2. The oil-filled transformer according to claim 1, wherein a gap having an outward bulge is provided between the inner coil and the outer coil, so that the side of the outer coil is formed in an outward bulge shape.

7. 2. The oil-filled transformer according to claim 1, wherein the coil has one or more gaps between the wound conductors, each gap having an outwardly bulging shape, so that the side surfaces of the coil bulge outward.

8. The iron core is formed in a shape that bulges outward, 2. The oil-immersed transformer according to claim 1, wherein the coil is formed along the outer shape of the iron core, so that the side surfaces of the coil bulge outward.

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