JPH0613580Y2 - Cable connection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an improvement of a cable connecting portion.

[Prior Art] The electric field control method for the cable connection portion is roughly classified into a stress cone method and a capacitor cone method.

As shown in FIG. 3, the stress cone type cable connecting portion is formed by winding an insulating paper in a spindle shape around the exposed base side outer periphery of the cable insulator 2 exposed from the end of the cable sheath 1 so as to connect the stress cone 3 to the stress cone 3. After forming, a bell-mouth-shaped auxiliary electrode 4 mainly made of epoxy resin and having a conductive layer on the concave surface is attached to relax the electric field, and these parts are housed in a porcelain tube 5 and the lower metal fitting 6 of the porcelain tube 5 is attached. It is fixed to the cable sheath 1 through the upper portion, and the upper portion of the porcelain insulator 5 is fixed to the conductor drawing rod 8 through the upper metal fitting 7. The conductor pull-out rod 8 is connected to the tip of the cable conductor 9. This type of cable connection has the features that it is easy to assemble and the material cost is low.

As shown in FIG. 4, the cable connecting portion of the condenser cone method is a spindle-shaped winding of insulating paper around the outer periphery of the cable insulator 2 exposed from the tip of the cable sheath 1 over almost the entire length to form the insulating paper layer 10. The cable insulator 2 is formed by embedding the electrodes 11 made of a metal foil in the insulating paper layer 10 in a concentric manner by sequentially shifting the positions in the longitudinal direction and forming concentric backward electrodes between adjacent electrodes. This is a structure in which a condenser cone 12 is provided on the top. In this case, the high potential side end electrode 11A having the smallest outer diameter is electrically connected to the cable conductor 9 via the connection conductor 13 and the conductor lead-out rod 8, and the low potential side end electrode 11B having the largest outer diameter is the conductor. Connected to the cable sheath 1 at 14 and grounded, a cylindrical capacitor is formed between the cable conductor 9 and the electrode 11, between the electrodes 11, and between the electrode 11 and the cable sheath 1, respectively, to share the potential in the cable longitudinal direction. Are equalized.

[Problems to be Solved by the Invention] However, when the potential control is performed by the stress cone 3, there is a drawback that the electric field is concentrated in the lower air of the porcelain tube 5 and an external flashover is likely to occur. There is also a method of making the porcelain bushing 5 thick in order to improve the characteristics, but there is a drawback that the characteristics are not improved in spite of a large increase in cost.

On the other hand, when the electric field is controlled by the condenser cone 12, there is a drawback that manufacturing and material costs are high. Also,
In the case of this method, since the outer diameter of the condenser cone 12 becomes thicker, it is unavoidable to use the thick porcelain insulator 5 and the cost is increased.

For this reason, for example, a stress cone cannot be used at the end of a cable of 132 KV class or higher in the air because of its characteristics, a condenser cone must be used, and a thick porcelain tube 5 must be combined due to space constraints. It was a cause of high cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cable connecting portion which is as inexpensive as a stress cone, is compact, can use a thin porcelain bushing, and has insulation characteristics like a condenser cone.

[Means for Solving the Problems] The structure of the present invention for achieving the above object will be described with reference to FIGS. 1 and 2 corresponding to the embodiments. In a cable connection part in which a capacitor cone 12 is mounted on a cable insulating layer 2 exposed from a portion to relax an electric field, the capacitor cone 12 is mounted on an exposed base side of the cable insulating layer 2, The high potential side end electrode 11A of 12 is insulated from the cable conductor 9, and the high potential side end electrode 11A of the capacitor cone 12 shares a part of the entire potential with the cable conductor 9, The remaining potential is the other electrode 11 of the condenser cone 12.
It is characterized by being shared by.

[Advantage of Invention] Such a cable connecting portion is provided on the high potential side end electrode 11A.
Since the electric potential of some percentage of the whole is shared between the cable conductor 9 and the cable conductor 9 and the rest is shared between the other electrodes 11 of the condenser cone 12, there is no extreme potential concentration and the electric field control capability close to that of the condenser cone system is achieved. Is obtained.

Since the condenser cone 12 used in the present invention is mounted on the exposed base side of the cable insulation layer 2 from the end of the cable sheath 1, it is possible to avoid the electric field concentration in the lower portion of the porcelain tube which is a weak point of the stress cone method, and the conventional condenser cone 12 is used. Since the number of electrodes is smaller than that of
Both the outer diameter and the length can be reduced, and the inner diameter of the porcelain insulator 5 can be reduced.

[Embodiment] The present invention will be described in detail below with reference to an embodiment shown in FIGS. 1 and 2 which is applied to an air cable terminal end portion of an OF cable which is a kind of cable connection portion. The parts corresponding to those in FIGS. 3 and 4 described above are designated by the same reference numerals.

In the cable connecting portion of the present embodiment, the capacitor cone 12 is attached to the outer periphery of the cable insulating layer 2 exposed from the end of the cable sheath 1 on the exposed base side, and the high potential side end electrode 11A of the capacitor cone 12 is A part of the entire potential is shared with the cable conductor 9 at the high potential side end electrode 11A of the capacitor cone 12 which is insulated from the cable conductor 9, and the remaining potential is the other electrode 11 of the capacitor cone 12. Are shared by.

Such a cable connecting portion is fitted with a condenser cone 12, covered with a porcelain insulator 5, sealed at both ends thereof, and then vacuumed to be filled with insulating oil.

In such a cable connecting portion, the high potential side end electrode 11A can be designed to set what percentage of the total potential is used. For example,
If the high potential side end electrode 11A has a potential of 60% and the number of electrodes is 6, if the potential difference between the electrodes is made equal, the potential of the first electrode from the high potential side is 60% 〃 2 〃 50% 〃 3 〃 40% 〃 4 〃 30% 〃 5 〃 20% 〃 6 〃 10% The low-potential-side end electrode 11B is, of course, grounded in the same manner as the ground-side slob of the condenser cone 12. At this time, the remaining 40% of the potential is shared between the high-potential-side end electrode 11A and the cable conductor 9, and the electric lines of force during this period are released above the high-potential-side end electrode 11A, but 60
%, The potential distribution is forcibly determined by the electrode 11, so there is no extreme potential concentration as seen at the end of the cable with the shield cut off, and the electric field control capability close to that of the condenser cone system can be obtained. . Further, the electric field concentration in the lower part of the porcelain tube 5 which is a weak point of the stress cone method is solved by the condenser cone 12, and not only the external flashover characteristic is solved but also the number of electrodes 11 is reduced as compared with the conventional condenser cone method. Condenser cone 12 because it requires less
It has the feature that both the outer diameter and the length are reduced. In particular, since the outer diameter is reduced, the porcelain insulator 5 having a small inner diameter can be used even in the condenser cone system, and the cost can be significantly reduced.

By applying the present invention to the air termination connection part of a 132KVOF cable, the high voltage side end electrode 11A of the condenser cone 12 was designed and shared with a voltage of 60%, and the prototype was manufactured to compare its characteristics with those of the conventional type. went. The insulator 5 has an inner diameter
120mmφ and effective flashover length of 1350mm are used for the conventional stress cone method and the condenser cone method of the present invention.
An inner diameter of 170 mmφ and an effective flashover length of 1,600 mm was used for the conventional condenser cone type. The characteristics comparison of each part is shown in the table below. All destruction was external flash.

From the above table, the characteristics of the condenser cone type cable connection part of the present invention are equivalent to those of the conventional condenser cone type, and the cone size is compact and almost the same as the conventional stress cone size.

When designing the condenser cone 12 in the case of the method of the present invention, the following points should be noted. As shown in FIG. 2, the high-potential-side end electrode 11 of the condenser cone 12 is
Between A and the cable conductor 9, the high potential side end electrode 11
In order to share the potential obtained by subtracting the shared voltage of A from 100%, the cone tip cut should not be perpendicular to the equipotential line and should be tapered as shown by the broken line in Fig. 2 as much as possible to break the surface of oil and oil-impregnated paper. It is necessary to increase the strength. Further, it is possible to reduce the electric field concentration at the tip of the electrode and the electric field on the creeping surface by making the capacitor cone insulating layer thickness t inside the innermost high potential side end electrode 11A sufficiently thick. Further, in order to reduce the concentration of potential at the electrode tip, it is also possible to use a bent electrode as the high-potential side end electrode 11 in which the tip is bent outward and the electrode tip is rounded. However, on the other hand, if the insulating layer thickness t is increased, the condenser cone 12
The outer diameter of the insulator becomes large, and in some cases, the insulator tube 5 has a thin inner diameter.
Therefore, the shared potential of the high potential side end electrode 11A is preferably as large as possible. Sharing potential is 100
Since the total length of the cone becomes longer as it gets closer to%, there is an appropriate sharing potential with sufficient electric field control capability and less stress concentration. When this was obtained by electric field analysis, it was found that when the cable conductor potential was 100% and the ground potential was 0%, it was well-balanced that the high potential side end electrode 11A was shared by 50 to 70%. . In this case, the electric field concentration in the lower part of the porcelain bushing 5 is almost ideally controlled to the same extent as in the conventional condenser cone system, and the controllability in the upper air surface of the porcelain bushing is slightly inferior. In order to improve this, a high-voltage shield such as an epoxy bell mouth 4 is provided in the upper part of the porcelain tube as shown by the broken line in FIG. 1, and the conductive layer of the concave surface is connected to the conductor pull-out rod 8 by the connecting conductor 15. The electric field in the air above the insulator should be relaxed.

In the above-mentioned embodiment, the air termination connection portion of the OF cable is described, but the present invention can be similarly applied to other connection portions and connection portions of the bridge cable.

[Effect of the Invention] As described above, in the cable connecting portion according to the present invention,
A capacitor cone is attached to the exposed base side of the cable insulation layer, the high-potential side end electrode of the capacitor cone is insulated from the cable conductor, and the high-potential side end electrode of the capacitor cone is connected to the cable conductor. Since a part of the entire potential is shared and the remaining potential is shared by the other electrode of the capacitor cone, even if the high potential side end electrode of the capacitor cone is insulated from the cable conductor, It is possible to obtain an electric field control capability close to that of the conventional condenser cone system without extreme concentration of electric potential.

In particular, the capacitor cone used in the present invention is mounted on the exposed base side of the cable insulation layer from the end of the cable sheath, so it is possible to avoid the electric field concentration in the lower part of the insulator tube, which is a weak point of the stress cone method, and compared with the conventional capacitor cone. Since the number of electrodes is reduced, both the outer diameter and the length of the condenser cone can be reduced, and the inner diameter of the porcelain tube can be reduced.

Therefore, according to the present invention, it is possible to use a reduced condenser cone, and therefore, it is possible to control the electric field like a condenser cone with a compact internal insulation like a stress cone, and it is possible to use an insulator tube with a small inner diameter and a short condenser cone. Therefore, the cost of the connecting portion can be reduced, and a cheap connecting portion having excellent characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an embodiment of the cable connecting portion according to the present invention, FIG. 2 is an enlarged view of the tip of the condenser cone of FIG. 1, and FIGS. 3 and 4 are stresses of the conventional cable connecting portion. It is a longitudinal cross-sectional view of a cone type and a condenser cone type. 1 ... Cable sheath, 2 ... Cable insulation layer, 3 ...
Stress cone, 4 ... Epoxy bell mouth, 5 ... Insulator tube, 6 ... Lower fitting, 7 ... Upper fitting, 8 ... Conductor pulling rod, 9 ... Cable conductor, 10 ... Insulating paper layer, 11 ...
Electrode, 11A ... High potential side end electrode, 11B ... Low potential side end electrode, 12 ... Capacitor cone.

Claims (3)

[Scope of utility model registration request] 1. A cable connecting portion in which a capacitor cone is mounted on a cable insulating layer exposed from an end of a cable sheath to relax an electric field, the capacitor cone being mounted on an exposed base side of the cable insulating layer. The high-potential-side end electrode of the capacitor cone is insulated from the cable conductor, and the high-potential-side end electrode of the capacitor cone shares a part of the entire potential with the cable conductor, and the rest. The electric potential of is shared by the other electrode of the condenser cone. 2. When the potential of the cable conductor is 100% and the ground potential is 0%, the potential of the high potential side end electrode is 50%.
The cable connection part according to claim 1, characterized in that the content is set to 70%. 3. The cable connecting portion according to claim 1, wherein the high-potential-side end electrode is a bent electrode having a rounded end with a bent tip.