Transformer

Abstract

To effectively suppress coil lift-off even with thin coils.SOLUTION: A transformer includes a coil unit configured with an outer coil and an inner coil arranged with a gap inside the outer coil, an upper clamp provided on the upper side of the coil unit, a lower clamp provided on the lower side of the coil unit, which sandwiches the coil unit between itself and the upper clamp, an outer coil retainer provided on the upper clamp, which presses down on the upper surface of the outer coil, and an inner coil retainer provided on the upper clamp to press the top surface of the inner coil in the area including the inside of the upper clamp.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a transformer. [Background technology]

[0002] In a transformer, when a short-circuit current or abnormal current flows through the coil, the low-voltage coil and the high-voltage coil may repel each other, or the low-voltage coil may move upward and become lifted. When this coil lift occurs, the low-voltage coil approaches the high-voltage coil and, in some cases, may even come into contact with it, resulting in the risk of a short circuit. For this reason, conventional transformers sometimes employ a structure that presses down on the top of the coil to prevent a short circuit caused by such coil lift. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-220527 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in transformer design, the coil thickness is sometimes reduced depending on the rated voltage. When the coil thickness is reduced, the contact area between the upper surface of the coil and the member pressing down on the coil from above becomes insufficient, making it difficult to press down the coil stably.

[0005] Therefore, a transformer is provided that can effectively prevent the coil from floating up even if the coil is thin. [Means for solving the problem]

[0006] The transformer according to the embodiment comprises a coil unit having an outer coil and an inner coil arranged inside the outer coil with a gap therebetween, an upper clamp provided above the coil unit, a lower clamp provided below the coil unit and sandwiching the coil unit between the upper clamp and the upper clamp, an outer coil presser provided on the upper clamp and pressing down on the top surface of the outer coil, and an inner coil presser provided on the upper clamp and pressing down on the top surface of the inner coil in an area including the inside of the upper clamp. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view illustrating an example of a transformer according to an embodiment. [Figure 2] FIG. 1 is a front view illustrating an example of a transformer according to an embodiment. [Figure 3] FIG. 1 is a side view illustrating an example of a transformer according to an embodiment. [Figure 4] 3 is a cross-sectional view of an example of a transformer according to an embodiment taken along line X4-X4 in FIG. 2. [Figure 5] 3 is an enlarged view of a portion of a cross section taken along line X5-X5 in FIG. 2 of an example of a transformer according to an embodiment. [Figure 6] 4 is an enlarged view of a portion of a cross section taken along line X6-X6 in FIG. 3 for an example of a transformer according to an embodiment. [Figure 7] 1A and 1B are front and cross-sectional views showing an example of an inner coil retainer according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] A transformer according to an embodiment will be described below with reference to the drawings. While this embodiment will be described using a dry-type three-phase molded transformer as an example, the design concept of this embodiment can also be applied to single-phase transformers and oil-immersed transformers. The term "dry-type" refers to a method of cooling the transformer 10 by using air to dissipate heat. The term "oil-immersed" refers to a method of cooling the coil by immersing it in oil. The transformer 10 of this embodiment is suitable for transformers with a rated capacity of several tens of kVA, a primary rated voltage of several kV, and a secondary rated voltage of several hundred V, but can also be applied to other transformers.

[0009] The transformer 10 of the embodiment includes a coil unit 20 and a housing 30. As shown in FIGS. 1, 2, and 4, the coil unit 20 includes three sets of coils 21 for U, V, and W phases, and an iron core 22. The transformer 10 of the embodiment is a so-called core-type transformer in which each coil 21 is disposed outside the iron core 22, that is, the iron core 22 is disposed inside each coil 21. Note that the transformer 10 may also be a so-called shell-type transformer in which each coil 21 passes inside the iron core 22.

[0010] Each of the three coils 21 has an overall rectangular shape with rounded corners and is formed into a cylindrical shape with its central axis facing up and down. The three coils 21 are aligned in a straight line along a horizontal direction. Each of the three coils 21 includes a primary coil 211 and a secondary coil 212. The primary coil 211 and the secondary coil 212 are formed, for example, by molded coils molded with electrically insulating resin.

[0011] In this embodiment, the primary coil 211 is disposed outside the secondary coil 212. Therefore, the primary coil 211 is the outer coil, and the secondary coil 212 is the inner coil. In this embodiment, the primary coil 211 is on the high-voltage side, and the secondary coil 212 is on the low-voltage side. In addition, in this embodiment, a gap 201 through which air can pass is formed between the primary coil 211 and the secondary coil 212. The primary coil 211 and the secondary coil 212 are cooled by the air flowing through the gap 201. In addition, the coil unit 20 has a primary-side terminal 213 connected to the primary coil 211 of each coil 21, and a secondary-side terminal 214 connected to the secondary coil 212.

[0012] In this embodiment, the side of the transformer 10 where the primary terminal 213 is provided may be referred to as the front side or front side of the transformer 10, and the side where the secondary terminal 214 is provided may be referred to as the back side or rear side of the transformer 10. Also, the direction horizontally perpendicular to the front-to-rear direction may be referred to as the left-to-right direction of the transformer, and both sides of the left-to-right direction may be referred to as side sides of the transformer 10.

[0013] Iron core 22 is made of a magnetic material such as an electromagnetic steel plate. Iron core 22 is generally rectangular with rounded corners and is formed into a cylindrical shape with its central axis oriented horizontally, in this case, in the front-to-rear direction. In other words, the axial direction of the central axis of coil 21 and the axial direction of the central axis of iron core 22 are perpendicular to each other. Iron core 22 is inserted inside three-phase coils 21.

[0014] The housing 30 holds the coil unit 20. As shown in FIGS. 1 to 6 , the housing 30 has an upper clamp 31, a lower clamp 32, a side clamp 33, a base frame 34, a connecting member 35, and a hanging nut 36. The upper clamp 31 is provided above the coil unit 20. The lower clamp 32 is provided below the coil unit 20 and supports the coil unit 20. The upper clamp 31 and the lower clamp 32 hold the coil unit 20 by sandwiching the upper and lower parts therebetween. The upper clamp 31 and the lower clamp 32 are formed by bending a metal plate such as a steel plate.

[0015] The upper clamp 31 is formed in a rectangular shape that is long in the arrangement direction of the three coils 21, i.e., long in the left-right direction, in a plan view, and both edges in the front-to-rear direction are bent downwards. In contrast, the lower clamp 32 has a shape that is upside down as a whole compared to the upper clamp 31. In other words, the lower clamp 32 is formed in a rectangular shape that is long in the arrangement direction of the three coils 21, i.e., long in the left-to-right direction, in a plan view, and both edges in the front-to-rear direction are bent upwards.

[0016] In this embodiment, the upper clamp 31 is configured to have an upper clamp top surface 311, two upper clamp side surfaces 312, and four mounting portions 313. The upper clamp top surface 311 is a horizontally disposed portion of the upper clamp 31, i.e., a portion formed parallel to the top surface of the coil unit 20. The upper clamp side surfaces 312 are portions of the upper clamp 31 bent vertically downward relative to the upper clamp top surface 311. That is, the upper clamp side surfaces 312 are portions extending downward from both edges of the upper clamp top surface 311 in the width direction, i.e., the front-to-rear direction. The mounting portions 313 are provided at both ends of the upper clamp 31 in the longitudinal direction, i.e., the left-to-right direction, and at both ends of the width direction, i.e., the front-to-rear direction. The mounting portions 313 are formed by bending portions of the upper clamp side surfaces 312 opposite the upper clamp top surface 311 horizontally at a right angle toward the outside of the width direction, i.e., the front-to-rear direction, of the upper clamp 31.

[0017] In this embodiment, the lower clamp 32 is configured to have a lower clamp bottom surface portion 321, two lower clamp side surfaces 322, and four mounting portions 323. The lower clamp bottom surface portion 321 is a portion of the lower clamp 32 that is arranged horizontally, i.e., formed parallel to the bottom surface of the coil unit 20. The lower clamp side surfaces 322 are portions of the lower clamp 32 that are bent vertically upward relative to the lower clamp bottom surface portion 321. That is, the lower clamp side surfaces 322 are portions that extend upward from both edges of the lower clamp bottom surface portion 321 in the width direction, i.e., the front-to-rear direction. The mounting portions 323 are provided at both ends of the lower clamp 32 in the longitudinal direction, i.e., the left-to-right direction, and at both ends of the width direction, i.e., the front-to-rear direction. The mounting portions 323 are formed by bending portions of the lower clamp side surfaces 322 opposite the lower clamp bottom surface portion 321 horizontally at a right angle toward the outside of the width direction, i.e., toward the front-to-rear direction, of the lower clamp 32.

[0018] The side clamps 33 shown in Figures 2 to 4 and 6 are formed by bending a metal plate such as a steel plate. The transformer 10 has two side clamps 33. The two side clamps 33 are provided near both ends of the upper clamp 31 and the lower clamp 32 in the longitudinal direction, i.e., the left-right direction, and connect the upper clamp 31 and the lower clamp 32. The two side clamps 33 are fixed to the upper clamp 31 and the lower clamp 32.

[0019] The two side clamps 33 are provided at positions sandwiching the iron core 22. The side clamps 33 are passed between the iron core 22 and the secondary coil 212, which is the inner coil, of both outer coils 21 of the three coils 21. That is, as shown in FIG. 4, the iron core 22 is disposed inside the two side clamps 33. The two side clamps 33 are disposed along the longitudinal direction, i.e., the left-right direction, of the upper clamp 31 and the lower clamp 32. In this embodiment, the side clamps 33 are fixed or welded to the upper clamp 31 via connecting members 35, as shown in FIG. 6.

[0020] The base frame 34 is provided below the lower clamp 32 and supports the housing 30 including the lower clamp 32 and the coil unit 20. The transformer 10 has two base frames 34. The base frames 34 are provided near both longitudinal ends of the lower clamp 32. The base frames 34 are formed by processing a metal plate such as a steel plate. The base frames 34 extend horizontally in a direction perpendicular to the longitudinal direction of the upper clamp 31 and the lower clamp 32, i.e., the direction in which the three coils 21 are arranged.

[0021] The lifting nuts 36 are metal fittings used when transporting the transformer 10, and can be configured, for example, as eye nuts with ring-shaped heads. The transformer 10 is lifted by hooking a transport device onto the lifting nuts 36. The lifting nuts 36 are provided at diagonal positions on both ends of the transformer 10 in the longitudinal direction, and are arranged so that their ring-shaped heads protrude upward from the top surface of the upper clamp 31, for example.

[0022] The transformer 10 further includes an outer coil holder 40 and an inner coil holder 50. The outer coil holder 40 is a member that directly contacts the upper and lower surfaces of the primary coil 211, which is the outer coil of each coil 21. The outer coil holder 40 is provided between the primary coil 211 and the upper clamp 31 and between the primary coil 211 and the lower clamp 32. The outer coil holder 40 is made of, for example, an electrically insulating resin material or rubber material. The outer coil holder 40 is formed in the shape of a small piece, such as a cylindrical, prism, or rectangular plate. Eight outer coil holders 40, for example, are attached to the upper clamp 31. In this case, two or more outer coil holders 40 are provided on the upper surface of each coil 21, for example. Furthermore, four outer coil holders 40 are attached to each lower clamp 32, for example.

[0023] The outer coil presser 40 is provided on each of the upper clamp side surface portion 312 and the lower clamp side surface portion 322. In this case, the outer coil presser 40 is attached to the attachment portion 313 of the upper clamp 31 and the attachment portion 323 of the lower clamp 32. The upper clamp 31 and the lower clamp 32 contact the upper and lower surfaces of the primary coil 211 via the outer coil presser 40, thereby sandwiching and holding the primary coil 211 in the vertical direction while being electrically insulated from the primary coil 211. In this embodiment, as shown in Fig. 4, the outer coil presser 40 presses the upper surface of the primary coil 211 in an area outside the upper clamp 31. Note that in Fig. 4, the upper clamp 31 is indicated by a two-dot chain line.

[0024] The inner coil retainer 50 is a member that directly contacts the upper surface of the secondary coil 212, which is the inner coil of the coil unit 20. The inner coil retainer 50 is provided between the secondary coil 212 and the upper clamp 31. In this case, the upper clamp 31 does not contact the primary coil 211, which is the outer coil.

[0025] The inner coil holders 50 are provided on the upper front and side surfaces of the coil unit 20. When the transformer 10 is a three-phase transformer, the transformer 10 includes five inner coil holders 50. In this case, three of the five inner coil holders 50 correspond to the three secondary coils 212, respectively, and are provided on the upper front surfaces of the respective secondary coils 212. In the following description, the three of the five inner coil holders 50 provided on the upper front surfaces of the secondary coils 212 may be referred to as first inner coil holders 50A. As shown in FIG. 5 , the first inner coil holders 50A are fixed by fastening members such as a bolt 91 and a threaded seat 314. The threaded seat 314 is a member having an internal thread corresponding to the bolt 91, for example, and is fixed by welding to the outer surface of the upper clamp side portion 312, for example.

[0026] 4 and 5, the first inner coil presser 50A presses the upper surface of the secondary coil 212 in a region that includes the inside of the upper clamp 31. That is, the inner coil presser 50A is configured to have an overall L-shaped cross section, as shown in FIG. 5, for example. The first inner coil presser 50A is disposed across the upper clamp side surface portion 312, with the lower end of the L-shape facing toward the inside of the upper clamp 31. Therefore, the first inner coil presser 50A presses the upper surface of the secondary coil 212 in a region that stretches from the inside to the outside of the upper clamp 31.

[0027] The remaining two of the five inner coil holders 50 correspond to the two secondary coils 212 on both sides in the left-right direction and are provided on the upper side surfaces of the secondary coils 212. In the following description, the two of the five inner coil holders 50 corresponding to the two secondary coils 212 on both sides in the left-right direction may be referred to as second inner coil holders 50B. As shown in FIG. 6 , the second inner coil holders 50B are fixed to the side clamps 33 by fastening members such as bolts 92. In this embodiment, for example, nuts 93 corresponding to the bolts 92 are welded to the inner surface of the connecting member 35. The bolts 92 are then threaded into the nuts 93 from the outside of the side clamps 33, passing through the second inner coil holders 50B and the side clamps 33. As a result, the second inner coil holders 50B are fixed to the outer surfaces of the side clamps 33.

[0028] When each inner coil holder 50 is configured to include a metal member, the inner coil holder 50 may be configured such that the metal member is welded to the upper clamp side surface portion 312 or the side clamp 33. In this embodiment, the inner coil holder 50 is provided on the front side and side side of the coil unit 20, but not on the back side.

[0029] In this embodiment, the first inner coil holder 50A and the second inner coil holder 50B are configured to have the same shape. The first inner coil holder 50A and the second inner coil holder 50B are attached in a position that is inverted with respect to the horizontal direction, i.e., the thickness direction of the inner coil holder 50. In other words, the first inner coil holder 50A and the second inner coil holder 50B are configured from a common part with an inverted attachment position.

[0030] As shown in FIG. 7 , the coil presser 50 includes a first member 51 and a second member 52. The first member 51 is fixed in contact with the upper clamp side surface portion 312 or the side clamp 33. The first member 51 is configured not to come into contact with the secondary coil 212. The first member 51 can be made of a resin having high rigidity and electrical insulation, such as engineering plastic. The first member 51 has an L-shaped cross section, with the lower side being thicker than the upper side. As shown in FIG. 7 , the first member 51 has a hole 511 for passing a bolt therethrough. The hole 511 is formed as a so-called elongated hole that is long in the vertical direction. This allows the vertical position of the inner coil presser 50 relative to the upper clamp side surface portion 312 or the side clamp 33 to be adjusted when fixing the inner coil presser 50 to the upper clamp side surface portion 312 or the side clamp 33.

[0031] The second member 52 is a member that directly contacts the upper surface of the secondary coil 212. The second member 52 is provided below the first member 51. In this case, the second member 52 can be fixed to the back surface of the first member 51 by adhesive, screwing, or the like. The second member 52 can be made of a member that is more flexible than the first member 51, for example, an elastic member such as hard rubber. In this case, the height dimension H1 of the first member 51 is larger than the height dimension H2 of the second member 52. Furthermore, the thickness dimension T1 of the first member 51 is larger than the thickness dimension T2 of the second member 52. Furthermore, the width dimension W1 of the first member 51 is larger than the width dimension W2 of the second member 52.

[0032] According to the embodiment described above, the transformer 10 includes a coil unit 20, an upper clamp 31, a lower clamp 32, an outer coil holder 40, and an inner coil holder 50A. The coil unit 20 includes a primary coil 211, which is an outer coil, and a secondary coil 212, which is an inner coil, disposed inside the primary coil 211 with a gap 201 therebetween. The upper clamp 31 is provided above the coil unit 20. The lower clamp 32 is provided below the coil unit 20, and sandwiches the coil unit 20 between the upper clamp 31 and the lower clamp 32.

[0033] The outer coil presser 40 is provided on the upper clamp 31 and presses down the top surface of the outer coil, the primary coil 211. The inner coil presser 50A is provided on the upper clamp 31 and presses down the top surface of the inner coil, the secondary coil 212, in an area including the inside of the upper clamp 31.

[0034] According to this, the outer coil presser 40 presses down the top surface of the primary coil 211, which is the outer coil, and the inner coil presser 50A presses down the top surface of the secondary coil 212, which is the inner coil. The inner coil presser 50A presses down the top surface of the secondary coil 212, which is the inner coil, in an area that includes the inside of the upper clamp 31, so that even if the secondary coil 212 is thin, it can reliably press down the top surface of the secondary coil 212. As a result, even if the secondary coil 212, which is the inner coil, is thin, it is possible to effectively prevent the coil 212 from floating up.

[0035] The inner coil presser 50 has a second member 52, which is an elastic member, at a portion that comes into contact with the secondary coil 212, which is an inner coil. With this, the second member 52, which is an elastic member, comes into contact with the upper surface of the secondary coil 212, and therefore, it is possible to effectively prevent the upper surface of the secondary coil 212 from being scratched. Furthermore, even if the coil 21 thermally expands due to heat during operation, the second member 52 can absorb the thermal expansion of the coil 21 by elastically deforming.

[0036] Furthermore, the inner coil retainer 50 has an L-shaped cross section, which allows the inner coil retainer 50 to press down an area of ​​the upper surface of the secondary coil 212 that includes the inside of the upper clamp 31, with a simple structure.

[0037] The transformer 10 also includes two side clamps 33 and an inner coil holder 50B. The two side clamps 33 are passed between the secondary coil 212, which is an inner coil, and the iron core 22, and connect the upper clamp 31 and the lower clamp 32. The two side clamps 33 are provided in positions that sandwich the iron core 22. The inner coil holder 50B is provided on the side clamps 33. The first inner coil holder 50A provided on the upper clamp 31 and the second inner coil holder 50B provided on the side clamps 33 have the same shape and are attached in an inverted position.

[0038] This allows the first inner coil holder 50A and the second inner coil holder 50B to be configured from the same common part, which reduces the manufacturing and management costs of the parts compared to when the first inner coil holder 50A and the second inner coil holder 50B are made of parts with different shapes, and also makes it possible to avoid the occurrence of incorrect installation of the two.

[0039] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure. [Explanation of symbols]

[0040] 10...transformer, 20...coil unit, 201...gap, 21, 211, 212...coil, 22...iron core, 31...upper clamp, 32...lower clamp, 33...side clamp, 40...outer coil holder, 50...inner coil holder, 50, 50A, 50B...coil holder

Claims

1. a coil unit including an outer coil and an inner coil disposed inside the outer coil with a gap therebetween; an upper clamp provided on an upper side of the coil unit; a lower clamp provided below the coil unit and configured to sandwich the coil unit between the lower clamp and the upper clamp; an outer coil presser provided on the upper clamp and pressing an upper surface of the outer coil; an inner coil presser provided in the upper clamp and configured to press an upper surface of the inner coil in an area including an inside of the upper clamp; A transformer comprising:

2. The inner coil presser has an elastic member at a portion where it comes into contact with the inner coil.

10. The transformer of claim 1.

3. The inner coil holder has an L-shaped cross section.

10. The transformer of claim 1.

4. two side clamps that are passed between the inner coil and the iron core to connect the upper clamp and the lower clamp and are provided at positions that sandwich the iron core; An inner coil holder provided on the side clamp, The inner coil holder provided on the upper clamp and the inner coil holder provided on the side clamp have the same shape and are attached in an inverted position.

4. The transformer according to claim 3.

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