JP2006202666A - Cast insulated conductor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reliable cast insulated conductor, and its manufacturing method, with stable electric characteristics over a long period of time, without fear of leak of air left in a gap of connecting parts at casting. <P>SOLUTION: The cast insulated conductor is provided with a first center conductor 20 used for an electric apparatus, a second center conductor 22 connected to the first center conductor 20, a sealing insulating layer 30 fitted at a connecting part of the first center conductor 20 with the second center conductor 22, and an insulating layer 24 integrally formed by casting around the first center conductor 20 and the second center conductor 22 where the sealing insulating layer 30 is installed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cast insulated conductor cast with an insulating material used for electrical equipment, and more particularly to a cast insulated conductor capable of improving electrical characteristics and a method for manufacturing the cast insulated conductor.

  Conventionally, in electrical equipment such as vacuum valves and main circuit conductors constituting the main circuit of the switchgear, a solid insulation type in which an insulating shell is formed by molding an insulating material such as epoxy resin in order to reduce the overall shape Are known (for example, see Patent Document 1).

  As shown in FIG. 4, the solid insulated switchgear is configured by dividing the inside of a metal box 1 into a power receiving portion 1a on the back side, an opening / closing portion 1b on the middle portion, and a bus bar portion 1c on the front side. .

  The power receiving unit 1a is provided with a cable head 3 to which a power receiving cable 2 is connected. One main circuit end of a current transformer 5 is connected to the cable head 3 via an H-shaped cast insulated conductor 4 cast with an insulating material such as an epoxy resin.

  The opening / closing part 1b is provided with a first disconnector 6 having a pair of contacts cast with an insulating material such as an epoxy resin, and one main circuit end of the first disconnector 6 is current-transformed. It is connected to the other main circuit end of the device 5. The other main circuit end of the first disconnector 6 was cast with a similar insulating material via a U-shaped cast insulated conductor 7 cast with an insulating material such as an epoxy resin. One main circuit end of the circuit breaker 8 having a pair of contacts is connected.

  The busbar portion 1c is provided with a second disconnector 9 having a pair of contacts casted with an insulating material such as an epoxy resin, and one main circuit end of the other is connected to the other main circuit end of the circuit breaker 8. And connected. The other main circuit end of the second disconnector 9 is connected to a bus 10 for connecting to an adjacent panel.

  The first disconnector 6, the breaker 8, and the second disconnector 9 are each provided with an operation mechanism 11 that opens and closes a pair of contacts.

  Here, in the cast insulated conductor 4, as shown in FIG. 5, a first center conductor 20 and a second center conductor 21 are arranged substantially in parallel, and a third center is provided at each intermediate portion. The conductors 22 are arranged, and are connected and fixed in an H shape by bolts 23. An insulating layer 24 is formed around the central conductors 20, 21, 22 so that the end portions are exposed.

  Conventionally, in the formation of the insulating layer 24 having such a complicated shape, a technique is known in which a stress relaxation layer 25 is provided on each of the central conductors 20, 21, and 22 in order to suppress residual stress during casting. (For example, refer to Patent Document 2).

However, although the residual stress of the insulating layer 24 is relieved, for example, air remaining in the gap 26 at the joint surface of the connection portion between the first center conductor 20 and the third center conductor 22 leaks out during casting. The void 27 may be formed in the insulating layer 24. The void 27 is an insulating defect and reduces electrical characteristics such as partial discharge characteristics.
JP 2002-152930 A (page 9, FIG. 1) JP-A-9-69321 (page 3, FIG. 1)

  The conventional cast insulated conductor 4 has a problem that a defective portion such as a void 27 is formed in the insulating layer 24 in the vicinity of the connection portion connecting the central conductors 20, 21, and 22. The voids 27 are those in which partial discharge easily occurs even when the diameter is 0.0 several mm, and the insulation deterioration is advanced. As insulation deterioration progresses, dielectric breakdown eventually occurs.

  For this reason, a highly reliable cast insulated conductor having improved characteristics such as partial discharge characteristics and stable characteristics for a long period of time has been desired.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a cast insulated conductor capable of improving electrical characteristics.

  In order to achieve the above object, the cast insulated conductor of the present invention includes a first central conductor used in an electrical device, a second central conductor connected to the first central conductor, and the first central conductor. A sealing insulating layer provided at a connection portion between the central conductor and the second central conductor, and casting around the first central conductor and the second central conductor provided with the sealing insulating layer And an insulating layer formed integrally.

  According to the present invention, the sealing insulating layer that seals the gap is provided in the connecting portion that connects the central conductors to each other, and the insulating layer that becomes the main insulation is formed around the periphery by casting. Air remaining in the gap between the connecting portions does not leak out, and it can be highly reliable with stable electrical characteristics over a long period of time.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a cast insulated conductor according to Example 1 of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a partially sectional view showing the structure of a cast insulated conductor according to Embodiment 1 of the present invention. FIG. 2 is a process showing a casting procedure of the cast insulated conductor according to Embodiment 1 of the present invention. FIG. In FIG. 1, the same components as those in the prior art are denoted by the same reference numerals. Moreover, since the solid-insulated switchgear has the same configuration as the conventional one, its description is omitted.

  As shown in FIG. 1, the cast insulated conductor 4 includes a first center conductor 20 and a second center conductor 21 that are the main circuit of the electrical equipment, arranged substantially parallel to each other, and at each intermediate portion. A third central conductor 22 is disposed. These central conductors 20, 21, 22 are connected and fixed by bolts 23 and have an H shape. In addition, around these central conductors 20, 21, and 22, the respective end portions are exposed, and a first insulating material such as an epoxy resin is cast to be an integral insulation formed integrally. The layer 24 is provided in an H shape.

  A sealing insulating layer made of a second insulating material such as, for example, an epoxy resin is formed on the entire periphery of the joint surface formed at a substantially right angle at the connection portion between the first central conductor 20 and the third central conductor 22. 30 is provided, and the gap is sealed off. Further, on the surface of the sealing insulating layer 30, for example, a conductive layer 31 coated with a conductive paint is provided at the same potential as at least one of the central conductors 20 (22). Although not shown, a sealing insulating layer 30 and a conductive layer 31 are similarly provided at the connection portion of the second center conductor 21 and the third center conductor 22.

  Next, a method for manufacturing such a cast insulated conductor 4 will be described with reference to FIG.

  First, the center conductors 20, 21, and 22 are assembled in an H shape (st1). This is a conductor assembly process. After assembly, the surfaces of the center conductors 20, 21, and 22 are cleaned, and a liquid second insulating material is applied, for example, by brushing to the entire outer periphery of the joint where the center conductors 20, 21, and 22 are connected ( st2), insulation thickness 0. A sealing insulating layer 30 of several mm to several mm is formed. This is the joint sealing step. In this case, the second insulating material is uniformly applied to the gaps of the joints, and the joints are sealed off. If the center conductors 20, 21, and 22 are heated to several tens of degrees, the viscosity of the second insulating material is lowered and the coating operation is facilitated.

  After that, for example, it is carried into a drying furnace set at 80 ° C., and the second insulating material is dried and cured (st3). This is a sealing insulating layer drying step. After drying, it is taken out from the drying furnace, and the conductive paint is applied by, for example, brushing (st4), and again carried into a drying furnace set at, for example, 80 ° C. and dried (st5). This is the conductive layer drying step.

  Next, the center conductors 20, 21, and 22 in which the sealing insulating layer 30 and the conductive layer 31 are dried are set in a casting mold (st6), and the first insulating material is cast in a vacuum mold. The inside is filled (st7) and cured. When the mold is released after curing (st8), the cast insulated conductor 4 having a predetermined shape and a predetermined insulation thickness of several mm to several tens mm can be obtained. This is the main insulation casting process. In addition, after mold release, you may carry in into a drying furnace again as needed, and an after cure may be performed.

  According to such casting, since the gap between the connecting portions of the center conductors 20, 21, and 22 is sealed off by the sealing insulating layer 30, the air remaining in the connecting portions does not leak out. Further, since the conductive layer 31 has the same potential as the central conductor 20 (21, 22), disturbance of the electric field distribution due to the provision of the sealing insulating layer 30 can be prevented.

  In addition, since the insulating layer 24 is cured after the sealing insulating layer 30 is provided on the central conductors 20, 21, 22 and cured, the thermal expansion coefficient of the central conductors 20, 21, 22 and the insulating layer 24 is increased. Residual stress resulting from the difference can be suppressed. That is, the residual stress of the insulating layer 24 at the time of casting is increased at the connecting portion having a complicated shape, but is suppressed because the sealing insulating layer 30 made of the same kind of insulating material is interposed. Note that it is preferable that the first insulating material and the second insulating material be the same insulating material, because the thermal expansion coefficients of the first insulating material and the second insulating material are the same, and the residual stress in the insulating layer 24 is further reduced.

  According to the cast insulated conductor 4 of the first embodiment, since the connecting portions of the central conductors 20, 21, and 22 are sealed with the sealing insulating layer 30, the air remaining in the gaps between the connecting portions leaks out. Therefore, it is possible to improve the partial discharge characteristics and to have a highly reliable electric characteristic that is stable over a long period of time.

  Next, a cast insulated conductor according to Example 2 of the present invention will be described with reference to FIG. FIG. 3 is a partial cross-sectional view of the structure of the cast insulated conductor according to the second embodiment of the present invention. The difference between Example 2 and Example 1 is the shape of the sealing insulating layer. In FIG. 3, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 3, the curvature of the connecting portion between the first central conductor 20 and the third central conductor 22 of the cast insulated conductor 4 so as to fill the corner of the connecting point formed at a substantially right angle. A sealing insulating layer 40 having a radius R is provided, and the gap is sealed. The sealing insulating layer 40 can be easily formed by placing a second insulating material having a high viscosity. A conductive layer 41 having the same potential as that of at least one of the central conductors 20 (22) is provided on the surface of the sealing insulating layer 40.

  Here, the radius of curvature R of the sealing insulating layer 40 is the same as the radius of the central conductor 20 (22) having the smaller diameter. When the radius of curvature R is equal to or less than ½ of the radius of the center conductor 20 (22), the radius of curvature R is too small and electric field relaxation between the first center conductor 20 and the third center conductor 22 is sufficiently performed. I will not. That is, the electric field distribution formed by the first center conductor 20 and the third center conductor 22 is disturbed. In addition, when the radius of curvature R is twice or more than the radius of the central conductor 20 (22), the electric field is reduced, but the insulating thickness of the insulating layer 24 is reduced, which is not preferable.

  According to the cast insulated conductor 4 of the second embodiment, in addition to the same effects as those of the first embodiment, the electric field in the insulating layer 24 can be relaxed.

  In addition, this invention is not limited to the said Example, In the range which does not deviate from the summary of invention, it can implement in various deformation | transformation. In the above embodiment, the sealing insulating layer 30 (40) is provided at the connection portion of the central conductors 20, 21, and 22. However, by providing a similar sealing insulating layer at the head portion of the bolt 23 as well. The gap between the bolt 23 and the central conductor 20 (21) can be sealed.

  Further, the present invention can be used not only for the H-shaped cast insulated conductor 4 but also for a connection portion of a cast insulated conductor in which the central conductors are connected and fixed to each other, such as a T-shape.

  Further, as a countermeasure against fouling and wetness, it can also be used in a cast insulated conductor in which a ground layer is provided on the surface of the insulating layer 24.

  Furthermore, the conductive layer 31 (41) is provided on the surface of the sealing insulating layer 30 (40). However, at a relatively low rated voltage such as a solid insulated switchgear rated voltage of 6 kV or less, the electric field is Since it is low, the conductive layer 31 (41) can be omitted.

The figure which shows the structure of the cast insulation conductor which concerns on Example 1 of this invention in part cross section. The process figure which shows the casting procedure of the cast insulated conductor which concerns on Example 1 of this invention. The figure which shows the structure of the cast insulation conductor which concerns on Example 2 of this invention partially partially, and shows it. The side view which shows the structure of a solid insulation type switchgear. The figure which shows the structure of the conventional cast insulated conductor in a partial cross section.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Box 1a Power receiving part 1b Opening / closing part 1c Bus line part 2 Power receiving cable 3 Cable head 4, 7 Cast type insulated conductor 5 Current transformer 6 First disconnector 8 Breaker 9 Second disconnector 10 Busbar 11 Operation mechanism 20 First central conductor 21 Second central conductor 22 Third central conductor 23 Bolt 24 Insulating layer 25 Stress relaxation layer 26 Gap 27 Voids 30 and 40 Sealing insulating layers 31 and 41 Conductive layer

Claims (6)

A first central conductor used in electrical equipment;
A second central conductor connected to the first central conductor;
A sealing insulating layer provided at a connection portion between the first central conductor and the second central conductor;
A cast insulated conductor comprising: an insulating layer integrally formed by casting around the first center conductor and the second center conductor provided with the sealing insulating layer.   The cast insulated conductor according to claim 1, wherein a conductive layer is provided on a surface of the sealing insulating layer and has the same potential as at least one central conductor.   2. The sealing insulating layer, wherein the first central conductor and the second central conductor are connected at a substantially right angle, and the connected corner portion is provided with a curvature. 2. The cast insulated conductor according to 2. A conductor assembly process for assembling a plurality of central conductors used in electrical equipment;
A joint sealing step of applying a second insulating material to the connecting portion of the central conductor;
A sealing insulating layer drying step of curing the second insulating material;
A method for producing a cast insulated conductor, comprising: a main insulating casting process in which the center conductor is set in a casting mold and filled with a first insulating material and cured.   5. The cast insulated conductor according to claim 4, further comprising a conductive layer drying step of applying and drying a conductive paint on the surface of the second insulating material after the sealing insulating layer drying step. Manufacturing method.   6. The method for producing a cast insulated conductor according to claim 4, wherein the first insulating material and the second insulating material are the same.

Images