JPS5873916A - Injection molding bushing - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cast bushing, and particularly to an electric field mitigation electrode installed in a cast bushing used in high voltage equipment.

An example of a conventional cast-molded bushing of this type is shown in FIGS. 1 and 1 of the accompanying drawings. That is, in the figure, reference numeral 1 denotes a cast insulator provided covering the outer periphery of the center conductor, and a flange portion /'a is formed in a part of the cast insulator. Reference numeral 3 denotes a cylindrical electric field relaxation electrode arranged surrounding the central conductor, and this electric field relaxation electrode 3 is formed of a metal plate, and is provided with a plurality of punched holes (not shown). One thing is the R-shaped press ring attached to the end of the electric field relaxation electrode J by brazing or soldering, 3 is the required number of pieces embedded in the flank part / a with gold, and 6 is with gold S. This is a connection conductor that electrically connects to the electric field relaxation electrode 3. - In this way, in the conventional cast bushing, since the punched hole is formed in the cylindrical part of the electric field relaxation electrode 3, the cast resin penetrates into the punched hole, causing the casting to fail. The resin and the electric field relaxation electrode 3 are firmly bonded. However, since the electric field is very likely to concentrate at both ends -ζ, it is necessary to form it into an R shape, but since a punched hole is formed in the cylindrical part of the electric field relaxation electrode 3 For example, both ends of the electric field relaxation electrode 3 have an R shape lζ
Even if formed, the electric field will be concentrated at the edges of the punched holes. Therefore, in conventional cast bushings of this type,
The concentration of the electric field was alleviated by adhering and attaching R-shaped press ring bows, which were separately molded into an R-shape, to both ends of the electric field relaxing electrode 3.

Conventional cast bushings are structured like this,
Due to the difference in thermal expansion coefficient between the cast resin and the metal, the electric field relaxation electrode 3 and the R-shaped press ring can be used to prevent the cast insulator from curing and shrinking and expanding and contracting due to temperature changes. The adhesion between the cast insulator L and the electrode J and the R-shaped press ring holder may be broken and peeling may occur, resulting in a gap between the cast insulator L and the electric field relaxing electrode J and the R-shaped press ring trough. Further, the step at the junction between the electric field relaxation electrode 3 and the R-shaped press ring bow also forms a shape in which the electric field tends to concentrate.

Such peeling between the cast insulator l, the electric field relaxation electrode 3 and the R-shaped press ring trough, and the phenomenon of electric field concentration between the electric field relaxation electrode 3 and the R-shaped press ring trough are as follows:
This results in the generation of internal partial discharge (1), which causes deterioration of the insulation of the cast insulator (1), and also has the disadvantage of causing a risk of through-breakage. In addition to this, because electric field relaxation electrodes are mostly manufactured by hand, there are large variations in dimensions.
In addition, productivity is poor, production time is long, and production time is long.
Therefore, it has many disadvantages in terms of production, such as being expensive and expensive.

An object of the present invention is to obtain a cast bushing that eliminates the drawbacks of conventional cast bushings. , which consists of circularly knitting a metal wire into a cylindrical shape and then compressing it, and is characterized by relaxing the electric field due to the voltage applied to the central conductor. It is.

Hereinafter, the present invention will be explained based on FIG. 3 of the accompanying drawings showing one embodiment thereof.

In the figure, reference numeral 10 denotes an electric field relaxation electrode, and the electric field relaxation electrode 10 is made by continuously knitting a metal wire in a circular cylindrical shape around the central conductor so as to be separated from the central conductor. , the intermediate product of this circularly knitted electric field relaxation electrode is compression molded, and whether it has elasticity before compression molding or not.
Or, it is porous but dense.

Note that both ends 10&, 10b of this electric field relaxation electrode 10
is formed in a round shape to prevent concentration of electric field. Note that, other than the above, the configuration is the same as that of the conventional cast-molded bushing.

Since the cast bushing of the present invention is constructed as described above, the cast resin is densely infiltrated into the cylindrical portion of the electric field relaxation electrode 10, so that the electric field relaxation electrode IO and the cast It is in perfect contact with the insulator 1, and does not cause interfacial separation due to curing shrinkage or temperature changes.Also, since both ends are directly molded into an R shape, there is no part where electric field concentration occurs, along with the cylindrical part. Furthermore, there is no need to install an R-shaped press or ring, and this eliminates the formation of clutter due to steps or edges, improves dimensional accuracy, and makes it difficult to deform. For example, by casting this in a vacuum, there is no problem at all. In addition to these effects, Akira Hongo's electric field mitigation electrodes are manufactured mechanically, so productivity is also improved. It can be produced in a short period of time and at a much lower cost than conventional electric field mitigation electrodes.As a result, it is a cast-molded bushing that is superior in terms of electrical performance and manufacturing, and is also resistant to temperature changes. It has the effect of being able to obtain the following.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a conventional cast-molded bushing, and FIG. 2 is a partially enlarged cross-sectional view of the vicinity of the electric field relaxation electrode.・Electrode for electric field relaxation, etc.・R-shaped press ring, S・・
Installation is on the seat, 6... connection conductor, 10%, 1013, both ends of the fist. Agent Ge Shu Shin −

Claims (1)

[Claims] (1) Casting in which an electric field relaxing electrode is arranged around a central conductor and separated from the central conductor, and the central conductor and the electric field relaxing electrode are integrally formed by casting with a casting insulator. In the bushing, the electric field relaxation electrode is
It is constructed by continuously circularly knitting metal into a cylindrical shape and then compression molding it, and is characterized by having a knitted layer that relaxes the electric field caused by the voltage applied to the center conductor. e) A cast bushing according to claim 11j, wherein the electric field relaxing electrode is compression molded in an R-shape at both ends thereof.