Bushing and electric apparatus

Abstract

To provide a bushing and an electric apparatus which can reduce the size of a porcelain bushing.SOLUTION: A bushing 3 includes: a porcelain bushing 6; a rod-like conductor 5 which extends in a direction along an axial length direction of the porcelain bushing 6, and projects to outside of the porcelain bushing 6 from one end (inside end 6a) in the axial length direction of the porcelain bushing 6; and an insulating cover 7 which covers the rod-like conductor 5 and is different from the porcelain bushing 6. The porcelain bushing 6 and the insulating cover 7 are different from one another, and accordingly the porcelain bushing 6 is short in the axial length direction. Specifically, the size of the porcelain bushing 6 can be reduced.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a bushing and an electrical device. [Background technology]

[0002] Patent Document 1 describes a transformer (electrical equipment) that includes a transformer bushing (bushing). The transformer described in Patent Document 1 includes a transformer body (equipment body) and a case that houses the transformer body. The transformer bushing includes a porcelain tube. The porcelain tube includes a porcelain tube body and an insulating cover (referred to as "body portion" and "mounting portion" in the text). The porcelain tube body is cylindrical and penetrates the wall of the case. In the following description, of both ends of the axial length direction of the porcelain tube body, the end located inside the case will be referred to as the inner end.

[0003] A rod-shaped conductor extending in the axial direction of the porcelain tube body protrudes from the inner end of the porcelain tube body toward the outside of the porcelain tube body. The rod-shaped conductor is electrically connected to the transformer body. The insulating cover is cylindrical and is provided coaxially and integrally with the inner end of the porcelain tube body. The insulating cover surrounds the rod-shaped conductor in a direction along the circumferential direction of the porcelain tube. Since the insulating cover covers the rod-shaped conductor, it is possible to prevent unnecessary other members (especially conductive members) from contacting or coming excessively close to the rod-shaped conductor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-256046 Summary of the Invention [Problem to be solved by the invention]

[0005] In the case of a transformer bushing as described in Patent Document 1, the porcelain tube body and the insulating cover are integral with each other, so the porcelain tube is long in the axial direction. However, Patent Document 1 does not describe any means for shortening the porcelain tube in the axial direction.

[0006] An object of the present disclosure is to provide a bushing and an electrical device that enable miniaturization of a porcelain tube. [Means for solving the problem]

[0007] The bushing of the present disclosure is characterized by comprising a porcelain tube, a rod-shaped conductor extending in a direction along the axial length of the porcelain tube and protruding from one end of the axial length of the porcelain tube toward the outside of the porcelain tube, and an insulating cover covering the rod-shaped conductor and separate from the porcelain tube.

[0008] In the present disclosure, a rod-shaped conductor extending in the axial direction of the porcelain tube protrudes from one end of the porcelain tube in the axial direction toward the outside of the porcelain tube. Since the porcelain bushing and the insulating cover cover the rod-shaped conductor, it is possible to prevent other unnecessary members from contacting or coming excessively close to the rod-shaped conductor. Since the porcelain tube and the insulating cover are separate from each other, the porcelain tube is short in the axial direction. In other words, the porcelain tube can be made compact. This makes it easy to manufacture the porcelain tube. In addition, the porcelain tube can be easily handled when assembling the bushing. Furthermore, the storage space for the porcelain tube before assembling the bushing can be reduced.

[0009] In the bushing according to the present disclosure, the insulating cover includes an attachment portion that is attached to the porcelain tube; The insulator is characterized in that it further comprises a cover body that is supported by the mounting portion and surrounds the rod-shaped conductor in a direction along the circumferential direction of the porcelain tube.

[0010] In the present disclosure, the insulating cover includes an attachment portion and a cover body. The attachment portion is attached to a porcelain tube. The cover body is supported by the mounting portion and surrounds the rod-shaped conductor in a direction along the circumferential direction of the insulator tube. This makes it possible to prevent unnecessary other members from approaching the rod-shaped conductor in a direction intersecting the axial direction of the insulator tube. On the other hand, necessary other members (e.g., conductors connected to the rod-shaped conductor) can approach the rod-shaped conductor in a direction along the axial direction of the insulator tube.

[0011] The bushing according to the present disclosure is characterized in that the cover body is tubular and expands in diameter in the protruding direction of the rod-shaped conductor.

[0012] In the present disclosure, the cover body of the insulating cover is tubular and expands in diameter in the direction in which the rod-shaped conductor protrudes from the porcelain tube. Therefore, the space surrounded by the cover body becomes wider from the base end to the tip end of the rod-shaped conductor. Therefore, it is possible to prevent the cover body from interfering with other members arranged in the space surrounded by the cover body.

[0013] The bushing according to the present disclosure is characterized in that the insulating cover is softer than the porcelain bushing.

[0014] In the present disclosure, since the insulating cover is more flexible than the porcelain tube, when the insulating cover comes into contact with another component, the insulating cover deforms, thereby making it possible to avoid interference with the other component.

[0015] The electrical device disclosed herein comprises an equipment main body, a case that houses the equipment main body, and a bushing, the bushing comprising a porcelain tube that penetrates a wall of the case, a rod-shaped conductor extending in a direction along the axial length of the porcelain tube and protruding from one end of the porcelain tube that is located inside the case toward the outside of the porcelain tube, and an insulating cover that covers the rod-shaped conductor and is separate from the porcelain tube, and the equipment main body and the rod-shaped conductor are electrically connected to each other via an internal conductor housed in the case.

[0016] In the present disclosure, an electric device includes a device body, a case, and a bushing, and the bushing includes a porcelain tube, a rod-shaped conductor, and an insulating cover. The case houses the device body, and the porcelain bushing passes through a wall of the case. In the following description, of both ends of the porcelain bushing in the axial direction, the end located inside the case is referred to as the inner end. A rod-shaped conductor extending in the axial direction of the porcelain tube protrudes from the inner end of the porcelain tube toward the outside of the porcelain tube. The rod-shaped conductor is electrically connected to the device body via an internal conductor housed in the case.

[0017] Since the porcelain bushing and the insulating cover cover the rod-shaped conductor, other members except for the inner conductor can be prevented from contacting or coming excessively close to the rod-shaped conductor. Since the porcelain tube and the insulating cover are separate from each other, the porcelain tube is short in the axial direction. In other words, the porcelain tube can be made compact. This makes it easy to manufacture the porcelain tube. In addition, the porcelain tube can be easily handled when assembling the bushing. Furthermore, the storage space for the porcelain tube before assembling the bushing can be reduced. Effect of the Invention

[0018] According to the bushing and electric device of the present disclosure, the porcelain tube can be made smaller. [Brief description of the drawings]

[0019] [Figure 1] 1 is a block diagram of a main part of an electrical device according to a first embodiment. [Diagram 2] FIG. [Diagram 3] FIG. 11 is a cross-sectional view of a bushing according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, embodiments of the present disclosure will be described.

[0021] Embodiment 1. FIG. 1 is a block diagram of a main part of an electrical device according to a first embodiment. In the figure, reference numeral 1 denotes an electric device, and in this embodiment, the electric device 1 is a switch that opens and closes an electric circuit 21. The electric circuit 21 connects, for example, an electric wire 22 installed on a utility pole (not shown) to a load 23 installed indoors. The electric device 1 is suspended from a support provided on the utility pole. The electric device 1 includes a case 11 and a device body 12 . The case 11 is an airtight case made of metal, for example, and houses a device main body 12 therein.

[0022] The electric device 1 includes N pairs of bushings 3, where N is a natural number. The case 11 accommodates {N×2} inner conductors 4. In the following description, it is assumed that N=1. Each bushing 3 includes a rod-shaped conductor 5. The rod-shaped conductor 5 is made of, for example, metal. One longitudinal end of the rod-shaped conductor 5 is located outside the case 11. The other longitudinal end of the rod-shaped conductor 5 is located inside the case 11. Hereinafter, the end of the rod-shaped conductor 5 located outside the case 11 is referred to as the outer end. Similarly, the end of the rod-shaped conductor 5 located inside the case 11 is referred to as the inner end 5a.

[0023] In the bushing 3 on the left side of the figure, the outer end of the rod-shaped conductor 5 is electrically connected to the electric wire 22, and the inner end 5a of the rod-shaped conductor 5 is electrically connected to the equipment body 12 via the internal conductor 4 on the left side of the figure. In the bushing 3 on the right side of the figure, the outer end of the rod-shaped conductor 5 is electrically connected to the load 23, and the inner end 5a of the rod-shaped conductor 5 is electrically connected to the equipment body 12 via the internal conductor 4 on the right side of the figure. The inner conductor 4 and the rod-shaped conductor 5 each constitute a part of an electric circuit 21 .

[0024] The device body 12 opens and closes the electric circuit 21. The device body 12 has, for example, a vacuum valve provided between the two internal conductors 4 in order to open and close the electric circuit 21. When the vacuum valve of the device body 12 is closed, the rod-shaped conductors 5 of the two bushings 3 are electrically connected to each other via the two internal conductors 4, and the electric circuit 21 is closed. When the vacuum valve of the device body 12 is opened, the electrical connection between the two rod-shaped conductors 5 is cut off, and the electric circuit 21 is opened. A control device (not shown) disposed outside the electric device 1 controls the opening and closing of the vacuum valve of the device body 12 , thereby controlling the opening and closing of the electric circuit 21 by the device body 12 .

[0025] Fig. 2 is a cross-sectional view of the bushing 3. In Fig. 2, a case 11 and a device body 12 are shown in schematic form. The bushing 3 includes a porcelain tube 6 and an insulating cover 7 in addition to the rod-shaped conductor 5. The rod-shaped conductor 5, the porcelain tube 6, and the insulating cover 7 are each separate from one another (separate members). The porcelain tube 6 is made of an insulating material (e.g., porcelain) and has a cylindrical shape. A bushing hole 11b is provided in the wall 11a of the case 11 (see FIG. 1), and the porcelain tube 6 is inserted into the bushing hole 11b to airtightly penetrate the wall 11a of the case 11. One end of the porcelain tube 6 in the axial direction is an inner end 6a located inside the case 11.

[0026] The rod-shaped conductor 5 extends in the axial direction of the porcelain tube 6 and protrudes from the inner end 6a of the porcelain tube 6 toward the outside of the porcelain tube 6. In this embodiment, the rod-shaped conductor 5 penetrates the porcelain tube 6 coaxially, and the inner end 5a of the rod-shaped conductor 5 protrudes from the inner end 6a of the porcelain tube 6. A support portion (not shown) is interposed between the outer peripheral surface of the portion of the rod-shaped conductor 5 located inside the porcelain tube 6 and the inner peripheral surface 6b of the porcelain tube 6. A male thread 51 is provided on the outer peripheral surface of the inner end 5a of the rod-shaped conductor 5. In the following description, it is assumed that the axial length direction of the porcelain tube 6 faces left and right, and the inner end portion 6a of the porcelain tube 6 is the left end portion of the porcelain tube 6. In this case, the inner end portion 5a of the rod-shaped conductor 5 is the left end portion of the rod-shaped conductor 5, and the inner end portion 5a of the rod-shaped conductor 5 protrudes leftward from the inner end portion 6a of the porcelain tube 6.

[0027] The insulating cover 7 is more flexible than the porcelain tube 6 and is made of an insulating material. The insulating cover 7 is made of, for example, synthetic rubber. The insulating cover 7 is configured such that an attachment portion 71 and a cover body 72 are integrally molded. Note that the insulating cover 7 is not limited to being integrally molded, and may be configured such that, for example, a cover body 72 separate from the attachment portion 71 is attached to the attachment portion 71. The insulating cover 7 is cylindrical with a bottom, with the mounting portion 71 as the bottom wall and the cover body 72 as the peripheral wall. The mounting portion 71 is disk-shaped. A through hole through which the inner end 5a of the rod-shaped conductor 5 can be inserted is provided at the center of the mounting portion 71. The cover body 72 is cylindrical and is supported by the mounting portion 71 by coaxially protruding from the peripheral edge of the mounting portion 71.

[0028] The insulating cover 7 is arranged coaxially with the porcelain tube 6 such that the outer surface of the mounting portion 71 contacts the left end surface of the porcelain tube 6 and the inner end portion 6a of the porcelain tube 6 passes through the center position of the mounting portion 71. The cover body 72 surrounds the inner end 5a of the rod-shaped conductor 5 in a direction along the circumferential direction of the porcelain tube 6. In this embodiment, the length from the left end face of the porcelain tube 6 to the left end of the insulating cover 7 is longer than the length from the left end face of the porcelain tube 6 to the left end of the rod-shaped conductor 5, so the inner end 5a of the rod-shaped conductor 5 does not protrude outward from the left end opening of the insulating cover 7. Note that the length from the left end face of the porcelain tube 6 to the left end of the insulating cover 7 may be equal to or shorter than the length from the left end face of the porcelain tube 6 to the left end of the rod-shaped conductor 5.

[0029] The inner conductor 4 includes a conductive wire portion 41 and a terminal portion 42 . The conductor portion 41 is, for example, a flat braided copper wire and has flexibility. The terminal portion 42 is a conductor provided at one end of the conductor portion 41, and is, for example, a copper tube compression terminal. The inner end portion 5a of the rod-shaped conductor 5 can be coaxially inserted into the terminal portion 42. The outer diameter of the terminal portion 42 is smaller than the inner diameter of the attachment portion 71.

[0030] The bushing 3 further comprises a flat washer 31, a nut 32, a spring washer 33, and a nut . The flat washer 31 is harder than the insulating cover 7 and is, for example, a metal disk. The outer diameter of the flat washer 31 is equal to or smaller than the inner diameter of the mounting portion 71. A through hole is provided at the center of the flat washer 31, into which the inner end portion 5a of the rod-shaped conductor 5 can be coaxially inserted. The nuts 32 and 34 are each made of a conductor, for example, metal. The outer diameter of each of the nuts 32 and 34 is smaller than the inner diameter of the mounting portion 71. The female thread of each of the nuts 32 and 34 corresponds to the male thread 51 of the rod-shaped conductor 5. The spring washer 33 has an annular shape. The outer diameter of the spring washer 33 is smaller than the inner diameter of the mounting portion 71.

[0031] The inner end 5a of the rod-shaped conductor 5 passes through the attachment portion 71, the flat washer 31, the nut 32, the spring washer 33, the terminal portion 42 of the inner conductor 4, and the nut 34 in this order from the right side. The female thread of the nut 32 is screwed onto the male thread 51 of the rod-shaped conductor 5, whereby the flat washer 31 and the mounting portion 71 are fastened together to the left end surface of the porcelain tube 6. The flat washer 31 can prevent the nut 32 from sinking into the flexible mounting portion 71. The mounting portion 71 in this embodiment is attached to the porcelain tube 6 by being sandwiched between the flat washer 31 and the left end face of the porcelain tube 6 and tightened with the nut 32, but the present invention is not limited to this. For example, the outer surface of the attachment portion 71 may be bonded to the left end surface of the porcelain tube 6 with an adhesive.

[0032] The female thread of the nut 34 is screwed onto the male thread 51 of the rod-shaped conductor 5, whereby the terminal portion 42 of the inner conductor 4 is fastened between the nuts 32, 34. The spring washer 33 presses the terminal portion 42 against the nut 34, so that the terminal portion 42 (and therefore the inner conductor 4) and the inner end portion 5a of the rod-shaped conductor 5 can be reliably electrically connected via the nut 34. The spring washer 33 also functions to prevent the nuts 32, 34 from loosening. The conductor portion 41 of the inner conductor 4 is pulled out to the left side from the left end opening of the insulating cover 7. The other end of the conductor portion 41 (the end on which the terminal portion 42 is not provided) is electrically connected to the device body 12.

[0033] According to the electric device 1 and bushing 3 described above, the porcelain tube 6 and the insulating cover 7 cover the rod-shaped conductor 5 and a part of the inner conductor 4. Since the insulating cover 7 opens to the left, the inner conductor 4 can be connected to the rod-shaped conductor 5 through the left end opening of the insulating cover 7 without any particular problem. It is possible to prevent other members other than the inner conductor 4 from contacting or coming excessively close to the rod-shaped conductor 5, while suppressing interference of the insulating cover 7 with the inner conductor 4. In addition, since the insulating cover 7 covers a part of the inner conductor 4, the insulation of the inner conductor 4 can also be strengthened. It is preferable that the insulating cover 7 does not come into contact with the internal conductor 4, but it may be in contact if there is no problem with insulation or the like.

[0034] Since the porcelain tube 6 and the insulating cover 7 are separate bodies (not integrally molded), the porcelain tube 6 is short in the axial direction. In other words, the porcelain tube 6 can be made compact. This makes it easy to manufacture the porcelain tube 6. Also, the porcelain tube 6 is easy to handle when assembling the bushing 3. Furthermore, the storage space for the porcelain tube 6 before assembling the bushing 3 can be reduced. Since the insulating cover 7 is flexible, when the insulating cover 7 comes into contact with another component, the insulating cover 7 deforms, thereby preventing interference with the other component. Therefore, there is no need to use, for example, a large case 11 in order to prevent interference between the insulating cover 7 and the other component. Therefore, the size and weight of the electric device 1 can be reduced.

[0035] Generally, porcelain is hard but brittle. Therefore, when a cylindrical porcelain insulating cover is integrated with the porcelain tube 6 in place of the insulating cover 7, it is necessary to thicken the peripheral wall of the porcelain insulating cover to improve the mechanical strength of the porcelain insulating cover. In order to support the insulating cover with a thick peripheral wall, it is necessary to increase the outer diameter of the porcelain tube 6. In this case, the peripheral wall of the porcelain tube 6 becomes thick, and the firing procedure for the porcelain tube 6 becomes complicated. On the other hand, synthetic rubber is more flexible and stronger than porcelain. Therefore, it is not necessary to thicken the peripheral wall of the insulating cover 7. Also, since the porcelain tube 6, which has a thin peripheral wall, can support the insulating cover 7 without any particular problems, the outer diameter of the porcelain tube 6 can be made small. At this time, since the peripheral wall of the porcelain tube 6 is thin, the porcelain tube 6 can be fired in a simple procedure.

[0036] As a result of the above, the bushing 3 can be made even smaller and lighter. Furthermore, the flexible and strong insulating cover 7 is easier to handle than a hard and brittle ceramic insulating cover, so that the workability during assembly of the bushing 3 and the electric device 1 can be improved. The porcelain bushing 6 may be attached to the case 11 after the inner conductor 4 is connected to the rod-shaped conductor 5, or may be attached to the case 11 before the inner conductor 4 is connected to the rod-shaped conductor 5.

[0037] The configuration of the rod-shaped conductor 5 is not limited to the above-mentioned configuration. The insulating cover 7 is not limited to being made of soft synthetic rubber, but may be made of, for example, hard synthetic resin. The insulating cover 7 is not limited to a cylindrical shape with a bottom, and may be, for example, an elliptical cylindrical shape with a bottom or a square cylindrical shape with a bottom. When the insulating cover 7 is a square tubular shape with a bottom, the mounting portion 71 is a rectangular plate, and the cover body 72 is a square tubular shape. The shape of the insulating cover 7 may be any shape that allows it to pass through the bushing hole 11b from the outside of the case 11 and enter the inside of the case 11 when attached to the porcelain tube 6. The insulating cover 7 is not limited to being arranged coaxially with the porcelain tube 6 and the rod-shaped conductor 5, and may be eccentric with respect to them.

[0038] The electric device 1 is not limited to a switch and may be, for example, a transformer. When the electric device 1 is a transformer, the device body 12 is, for example, a transformer body including a coil and a core. The rod-shaped conductor 5 is electrically connected to the coil of the device body 12 via the internal conductor 4.

[0039] Embodiment 2. The electric device 1 and the bushing 3 of the present embodiment are substantially similar to the electric device 1 and the bushing 3 of the first embodiment, except for the configuration of the insulating cover 7. The following will describe the differences from the first embodiment, and other components that are the same as those in the first embodiment will be given the same reference numerals and their description will be omitted.

[0040] FIG. 3 is a cross-sectional view of a bushing 3 according to the second embodiment. The cover body 72 of the present embodiment has a cylindrical shape similar to that of the cover body 72 of the first embodiment. However, the cover body 72 of the present embodiment expands in diameter in the left direction (the direction in which the rod-shaped conductor 5 protrudes from the porcelain tube 6). Therefore, the space surrounded by the cover body 72 becomes wider from the base end to the tip end of the rod-shaped conductor 5. Therefore, it is possible to suppress the cover body 72 from interfering with the internal conductor 4 arranged in the space surrounded by the cover body 72.

[0041] Since the insulating cover 7 can be easily deformed, when attaching the bushing 3 to the case 11 from the outside of the case 11, the insulating cover 7 can be temporarily folded and passed through the bushing hole 11b, and then the insulating cover 7 can be expanded to a predetermined dimension. Therefore, even if the cover body 72 of the insulating cover 7 is a cylindrical shape that expands in diameter, the hole diameter of the bushing hole 11b can be made small, and the porcelain tube 6 can be made smaller.

[0042] The embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is intended to include not only the above-mentioned meaning, but also the meaning equivalent to the claims and all modifications within the scope of the claims. Independent claims and dependent claims described in the claims may be combined with each other in any and all combinations, regardless of the reference format. Furthermore, the claims may be written in a format in which a claim references two or more other claims (multiple claim format), but this is not limited to this format. A multiple claim that references at least one other multiple claim (multiple multiple claim format) may also be written. [Explanation of symbols]

[0043] 1 Electrical equipment; 11 Case; 11a Wall; 12 Equipment body; 3 Bushing; 4 Inner conductor; 5 Rod-shaped conductor; 6 Ceramic tube; 6a Inner end (one end); 7 Insulating cover; 71 Mounting part; 72 Cover body

Claims

1. A porcelain tube and a rod-shaped conductor extending in an axial direction of the porcelain tube and protruding from one end of the porcelain tube in the axial direction toward an outside of the porcelain tube; An insulating cover that covers the rod-shaped conductor and is separate from the porcelain tube. A bushing comprising:

2. The insulating cover is an attachment portion attached to the porcelain tube; a cover body supported by the mounting portion and surrounding the rod-shaped conductor in a circumferential direction of the porcelain tube; The bushing of claim 1 , comprising:

3. 3. The bushing according to claim 2, wherein the cover body is tubular and expands in diameter in a protruding direction of the rod-shaped conductor.

4. 3. The bushing according to claim 1, wherein the insulating cover is softer than the porcelain bushing.

5. The device body, A case for accommodating the device body; Bushing and Equipped with The bushing comprises: a porcelain tube penetrating a wall portion of the case; a rod-shaped conductor extending in an axial direction of the porcelain tube and protruding from one end of the porcelain tube located inside the case toward the outside of the porcelain tube; An insulating cover that covers the rod-shaped conductor and is separate from the porcelain tube. Equipped with An electric device, characterized in that the device body and the rod-shaped conductor are electrically connected to each other via an internal conductor housed in the case.

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