JP2024053160A - Cable termination structure, ring unit, and method for manufacturing cable termination structure - Google Patents

Abstract

[Problem] To easily manufacture a cable termination connection structure while reducing the outer diameter of a porcelain tube. [Solution] The cable termination connection structure includes a power cable, a condenser cone that is provided so as to surround the outer periphery of the power cable and that reduces the electric field outside the power cable, and a porcelain tube that is erected in the vertical direction and into which the power cable with the condenser cone attached is inserted, the condenser cone has a plurality of ring units that are cylindrical and have an insulating layer that contains insulating rubber and a conductive layer that is provided on the inner or outer periphery of the insulating layer, the plurality of ring units are arranged at different positions from one another in the axial direction of the power cable, and are stacked so that three or more ring units do not overlap in the same cross section perpendicular to the central axis of the power cable. [Selected Figure] Figure 1

Description

The present disclosure relates to a cable termination connection structure, a ring unit, and a method for manufacturing a cable termination connection structure.

A cable termination connection structure (air termination connection part, air termination connection box) is provided to connect a power cable to an overhead transmission line, etc. In a high-voltage cable termination connection structure, a so-called condenser cone may be formed to reduce the electric field on the outside of the power cable that is peeled off in stages (for example, Patent Document 1).

JP 2003-189454 A

The objective of this disclosure is to reduce the outer diameter of the porcelain tube while easily manufacturing the cable termination connection structure.

According to one aspect of the present disclosure,
A power cable;
a condenser cone provided around the outer periphery of the power cable to reduce an electric field on the outside of the power cable;
a porcelain tube that is vertically installed and into which the power cable with the condenser cone attached thereto is inserted;
Equipped with
The condenser cone has a plurality of ring units each having a cylindrical insulating layer containing insulating rubber and a conductive layer provided on an inner periphery or an outer periphery of the insulating layer,
A cable termination connection structure is provided in which the multiple ring units are arranged at different positions from each other in the axial direction of the power cable, and are stacked so that three or more ring units do not overlap within the same cross section perpendicular to the central axis of the power cable.

According to the present disclosure, it is possible to easily manufacture a cable termination connection structure while reducing the outer diameter of the porcelain tube.

FIG. 1 is a schematic side view and a schematic cross-sectional view illustrating a cable termination connection structure according to an embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view showing an enlarged portion of FIG. FIG. 3 is a schematic cross-sectional view of an enlarged portion of a cable termination connection structure according to a first modified example of an embodiment of the present disclosure. FIG. 4 is a schematic cross-sectional view illustrating an enlarged portion of a cable termination connection structure according to a second modified example of an embodiment of the present disclosure. FIG. 5 is a schematic cross-sectional view of an enlarged portion of a cable termination connection structure according to a third modified example of an embodiment of the present disclosure.

[Description of the embodiments of the present disclosure]
<Findings gained by the inventors>
First, the findings of the inventors will be described.

Conventional cable termination connection structures with condenser cones had the following problems:

(i) Condenser cone using oil-impregnated insulating paper (conventional structure described in Patent Document 1)
Conventional capacitor cones are formed by the following process: Oil-impregnated insulating paper impregnated with insulating oil is wrapped around the outer circumference of a power cable without leaving any gaps. While carrying out this process, an electrode made of metal foil is inserted when a predetermined outer diameter is reached. This process is repeated a predetermined number of times. At this time, the electrode is inserted while being shifted in the axial direction of the power cable. Through the above process, capacitors formed by a pair of electrodes sandwiched between insulating paper are arranged in a predetermined distribution along the axial direction of the power cable.

However, in conventional structures using oil-impregnated insulating paper, the formation of the capacitor cone described above requires advanced technology and expertise. This makes on-site work difficult.

In addition, in structures using conventional oil-impregnated insulating paper, the outer diameter of the condenser cone tends to increase depending on the number of times the insulating paper is wrapped around it. This results in a larger outer diameter for the porcelain bushing.

(ii) Condenser cone of Patent Document 1 In the condenser cone of Patent Document 1, a plurality of elements each made of a cylindrical electrode and an insulating material are elastically fitted together while being shifted in the axial direction of the power cable, thereby stacking the elements. This is said to facilitate the assembly work of the condenser cone and to shorten the assembly time.

However, in the condenser cone of Patent Document 1, the peripheral surfaces of two elements adjacent in the radial direction of the power cable are elastically abutted against each other over the entire circumference. As a result, three or more elements overlap in the same cross section perpendicular to the central axis of the power cable. Because of this configuration, the outer diameter of the condenser cone tends to increase depending on the number of elements. As a result, the outer diameter of the porcelain tube is also large.

In addition, in the condenser cone of Patent Document 1, when the porcelain tube becomes longer in accordance with the applied voltage of the power cable, the length of each element must be increased in accordance with the length of the porcelain tube. This increases manufacturing costs.

The inventors conducted extensive research to solve the problems with the above-mentioned structures (i) and (ii), and discovered a new structure that allows the cable termination connection structure to be easily manufactured while reducing the outer diameter of the porcelain tube.

The present invention described below is based on the above findings made by the inventors.

<Embodiments of the present disclosure>
Next, embodiments of the present disclosure will be listed and described.

[1] A cable termination connection structure according to one aspect of the present disclosure includes:
A power cable;
a condenser cone provided around the outer periphery of the power cable to reduce an electric field on the outside of the power cable;
a porcelain tube that is vertically installed and into which the power cable with the condenser cone attached thereto is inserted;
Equipped with
The condenser cone has a plurality of ring units each having a cylindrical insulating layer containing insulating rubber and a conductive layer provided on an inner periphery or an outer periphery of the insulating layer,
The multiple ring units are arranged at different positions in the axial direction of the power cable and are stacked so that three or more ring units do not overlap within the same cross section perpendicular to the central axis of the power cable.
According to this configuration, the cable termination structure can be easily manufactured and the outer diameter of the porcelain bushing can be reduced.

[2] In the cable termination structure according to the above [1],
At least a portion of an inner circumferential surface of each of the plurality of ring units contacts an outer circumferential surface of the power cable at a position other than the position where the inner circumferential surface overlaps with other ring units.
According to this configuration, it is possible to prevent the outer diameter of the condenser cone from becoming unnecessarily large at positions where the condenser is not formed.

[3] In the cable termination connection structure according to the above [1] or [2],
The capacitors formed by the ring units at least partially overlap each other when viewed in the axial direction of the power cable.
According to this configuration, it is possible to stably reduce the outer diameter of the porcelain tube while reducing the electric field outside the power cable.

[4] In the cable termination connection structure according to any one of [1] to [3] above,
Of the plurality of ring units, of two adjacent ring units, the upper part of the ring unit positioned vertically below overlaps the lower part of the ring unit positioned vertically above.
According to this configuration, it is possible to form equipotential lines that radiate from the outer periphery of the power cable.

[5] In the cable termination connection structure according to any one of [1] to [4] above,
The plurality of ring units have the same configuration.
According to this configuration, the condenser cone has a simple structure, and the cable termination connection structure can be easily manufactured.

[6] In the cable termination connection structure according to any one of [1] to [4] above,
The power cable includes a conductor, a cable inner semiconductive layer, a cable insulating layer, a cable outer semiconductive layer, and a cable sheath;
the conductor, the cable-interior semiconductive layer, the cable insulating layer, the cable-exterior semiconductive layer, and the cable sheath are exposed in this order from a tip of the conductor in a reverse direction;
In the condenser cone, the axial length of the power cable, in which two adjacent conductive layers sandwich an insulating layer therebetween, gradually increases from the tip of the power cable toward the tip of the cable outer semiconductive layer.
With this configuration, the capacitance of the capacitor can be gradually increased toward the tip of the cable outer semiconductive layer where a high electric field is likely to occur.

[7] In the cable termination connection structure according to any one of [1] to [4] above,
The power cable includes a conductor, a cable inner semiconductive layer, a cable insulating layer, a cable outer semiconductive layer, and a cable sheath;
the conductor, the cable-interior semiconductive layer, the cable insulating layer, the cable-exterior semiconductive layer, and the cable sheath are exposed in this order from a tip of the conductor in a reverse direction;
In the condenser cone, the thickness of the insulating layer sandwiched between two adjacent conductive layers gradually decreases from the tip of the power cable toward the tip of the cable outer semiconductive layer.
With this configuration, the capacitance of the capacitor can be gradually increased toward the tip of the cable outer semiconductive layer where a high electric field is likely to occur.

[8] In the cable termination connection structure according to any one of [1] to [7] above,
an insulating tube provided on the outer periphery of the power cable at a position vertically below the condenser cone and configured to reduce an electric field on the outer side of the power cable;
an auxiliary conductive portion that covers an outer periphery of the insulating tube and electrically connects a ring unit located at a vertical lower end of the condenser cone to an exposed cable outer semiconductive layer of the power cable so as to reduce an electric field outside the insulating tube;
has.
This configuration makes it possible to reduce the stress of a high electric field on the outside of the insulating cylinder.

[9] A ring unit according to another aspect of the present disclosure includes:
The present invention is used in the condenser cone of the cable termination connection structure according to any one of the above items [1] to [8].
According to this configuration, the cable termination structure can be easily manufactured and the outer diameter of the porcelain bushing can be reduced.

[10] A method for manufacturing a cable termination structure according to another aspect of the present disclosure includes:
Providing a power cable;
providing a condenser cone surrounding an outer periphery of the power cable to reduce an electric field on the outer side of the power cable;
inserting the power cable with the condenser cone attached into a vertically erected porcelain tube;
Equipped with
The step of providing a condenser cone includes:
A step of preparing a plurality of ring units each having a cylindrical insulating layer containing insulating rubber and a conductive layer provided on an inner periphery or an outer periphery of the insulating layer;
arranging the plurality of ring units at different positions in the axial direction of the power cable, and stacking the ring units so that three or more ring units do not overlap within the same cross section perpendicular to the central axis of the power cable;
has.
According to this configuration, the cable termination structure can be easily manufactured and the outer diameter of the porcelain bushing can be reduced.

[Details of the embodiment of the present disclosure]
Next, embodiments of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

<One embodiment of the present disclosure>
(1) Cable Termination Structure A cable termination structure 10 according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG.

Note that the horizontal ratio in Fig. 1 and Fig. 2 is larger than the actual aspect ratio. The left side of Fig. 1 is a side view, and the right side of Fig. 1 is a cross-sectional view. In the right side of Fig. 1 and Fig. 2, the side of the power cable 100 is shown, not the cross section. Also, in Fig. 1 and Fig. 2, hatching of a part of the cross section is omitted. In Fig. 1, a part of the flange portion 210 of the porcelain pipe 200 is omitted by a dashed line.

In the following description, the "axial direction" of the power cable 100 refers to the direction of the central axis of the power cable 100. Additionally, the "radial direction" of the power cable 100 refers to the direction from the central axis of the power cable 100 toward the outer periphery.

Note that the same terminology as for the power cable 100 can also be used for the cylindrical porcelain tube 200, etc.

As shown in Figures 1 and 2, the cable termination connection structure (air termination connection part, air termination connection box, EB-A) 10 of this embodiment is configured to connect a power cable 100 to an overhead transmission line (not shown) or the like. Specifically, the cable termination connection structure 10 includes, for example, a power cable 100, a porcelain tube 200, an upper metal fitting 620, a lower metal fitting 640, an upper shield ring 820, and a lower shield ring 840.

[Power cable]
As shown in Fig. 1 and Fig. 2, the power cable 100 is configured as a solid insulated cable that is a high-voltage power transmission cable. For example, the power cable 100 may be a CV cable (Crosslinked polyethylene insulated PVC sheathed cable, also called an XLPE cable). The power cable 100 may be for AC or DC.

The power cable 100 has, for example, a conductor (cable conductor) 110, a cable inner semiconductive layer (not shown), a cable insulating layer 130, a cable outer semiconductive layer 140, a cable shielding layer (cable metal layer, not shown), and a cable sheath 160, in this order from the central axis of the conductor 110 to the outer periphery.

The power cable 100 is stripped in stages (so-called "step stripping") from the axial tip of the conductor 110 in the opposite direction. That is, the conductor 110, the cable inner semiconductive layer, the cable insulation layer 130, the cable outer semiconductive layer 140, the cable shielding layer, and the cable sheath 160 are exposed in this order from the tip of the conductor 110 in the opposite direction.

[Power cable accessories]
The power cable 100 that has been peeled off in stages has attached thereto, for example, a conductor pull-out rod 610, a condenser cone 30, an insulating tube (rubber unit, stress relief cone, pre-molded insulator, insulating rubber block) 400, an auxiliary conductive part 500, a shielding layer 580, and a metal tube 590.

The conductor pull-out rod 610 is configured so that an overhead power line or the like can be connected to its tip. The exposed tip of the conductor 110 is connected by compression to the base end opposite the tip of the conductor pull-out rod 610. A seal portion (symbol not shown) is provided around the connection between the conductor pull-out rod 610 and the tip of the conductor 110.

The capacitor cone 30, insulating tube 400 and auxiliary conductive portion 500 will be described in detail later.

The shielding layer 580 is provided to surround the outer periphery of the exposed cable outer semiconductive layer 140, and is electrically connected to the cable outer semiconductive layer 140 and the cable shielding layer (not shown). The shielding layer 580 is composed of, for example, a metallic braided wire or a copper mesh tape. This allows the outer area of the exposed cable outer semiconductive layer 140 to be electrically shielded.

The metal tube 590 is arranged to surround the outer periphery of the power cable 100 at a position vertically below the shielding layer 580.

The power cable 100 with the above-mentioned accessories attached is raised vertically and fixed to the top of the porcelain tube 200 described below.

[Ceramic tube]
The porcelain tube 200 is provided so as to surround the outer periphery of the power cable 100, and is configured in a cylindrical shape so as to ensure insulation around the gradually peeled power cable 100. The porcelain tube 200 is made of, for example, ceramic or polymer.

The porcelain pipe 200 is erected vertically and fixed to a stand (not shown) or the like. The porcelain pipe 200 has, for example, a hollow portion, an upper opening, and a lower opening (reference numbers not shown).

The power cable 100, to which the condenser cone 30 and other components are attached, is inserted into the hollow portion of the porcelain tube 200. The power cable 100 is arranged linearly along the central axis of the hollow portion of the porcelain tube 200.

The upper opening of the porcelain tube 200 is opened at the upper end of the hollow portion in the axial direction. On the other hand, the lower opening of the porcelain tube 200 is opened at the lower end opposite the upper end of the hollow portion.

The porcelain tube 200 has a plurality of flanges (folds) 210 that are enlarged in diameter on the outside of the porcelain tube 200. The flanges 210 are arranged at a predetermined interval in the axial direction of the porcelain tube 200. This ensures an insulation distance (creepage distance) between the conductor pull rod 610 and the earth.

The hollow portion of the porcelain tube 200, excluding the power cable 100, is filled with an insulating medium (insulating mixture). In this embodiment, since oil-impregnated insulating paper is not used, it is possible to use insulating gas as well as insulating oil as the insulating medium. By using insulating gas, an oil supply device can be eliminated.

[Upper bracket]
The upper metal fitting 620 is, for example, disk-shaped and configured to close an upper opening at the axial upper end of the porcelain tube 200. The upper metal fitting 620 contacts the axial upper end of the porcelain tube 200 with, for example, an O-ring interposed therebetween. The O-ring seals the gap between the upper metal fitting 620 and the upper end of the porcelain tube 200.

The upper metal fitting 620 is configured to fix the conductor 110. Specifically, the upper metal fitting 620 has, for example, a through hole (reference number not shown) in the center, and the conductor pull-out rod 610 is inserted into the through hole. The conductor pull-out rod 610 is fixed to the upper metal fitting 620 by a specified jig. With this configuration, the conductor 110 is fixed to the upper metal fitting 620 by the conductor pull-out rod 610.

[Upper shield ring]
If necessary, for example, an upper shield ring 820 may be provided around the upper metal fitting 620. This makes it possible to reduce the electric field around the upper metal fitting 620.

[Lower bracket]
The lower metal fitting 640 is configured, for example, in a disk shape, and configured to close a lower opening at the axial lower end of the porcelain tube 200. Like the upper metal fitting 620, the lower metal fitting 640 contacts the axial lower end of the porcelain tube 200 with, for example, an O-ring (not shown) interposed therebetween. The O-ring seals the gap between the lower metal fitting 640 and the lower end of the porcelain tube 200.

The lower metal fitting 640 is arranged, for example, to surround the outer periphery of the power cable 100. Specifically, the lower metal fitting 640 has, for example, an insertion hole (reference number not shown) in the center, and the power cable 100 with the metal tube 590 fitted around the outer periphery of the power cable 100 is inserted into the insertion hole. An O-ring (not shown) is provided on the inner periphery of the insertion hole of the lower metal fitting 640. The O-ring seals the gap between the lower metal fitting 640 and the metal tube 590.

This configuration allows the power cable 100 to expand and contract in the axial direction while keeping the gap between the power cable 100 and the lower metal fitting 640 sealed.

[Lower shield ring]
If necessary, for example, a lower shield ring 840 may be provided around the lower metal fitting 640. This makes it possible to reduce the electric field around the lower metal fitting 640.

(2) Condenser Cone and Its Surrounding Structure The condenser cone 30 and its surrounding structure of this embodiment will be described with reference to FIGS. 1 and 2.

[Condenser cone]
2 , the condenser cone 30 is provided, for example, to surround the outer periphery of the power cable 100 (the exposed cable insulation layer 130). The condenser cone 30 is configured, for example, to reduce the electric field on the outside of the power cable 100.

The condenser cone 30 has, for example, multiple ring units (tube units, rubber rings, rubber tubes) 300.

Each ring unit 300 is, for example, cylindrical (ring-shaped) and is elastically fitted around the outer periphery of the power cable 100. The ring unit 300 has, for example, an insulating layer 320 and a conductive layer 340.

The insulating layer 320 is, for example, cylindrical and contains insulating rubber. The rubber constituting the insulating layer 320 is, for example, silicone rubber or ethylene propylene rubber (EP rubber). The insulating layer 320 of this embodiment does not require impregnation with insulating oil.

The conductive layer 340 is, for example, conductive or semiconductive, and is provided on the inner or outer periphery of the insulating layer 320. In this embodiment, the conductive layer 340 is provided on the outer periphery of the insulating layer 320. This makes it possible to necessarily interpose the insulating layer 320 between adjacent conductive layers 340. As a result, it is possible to suppress short circuits between adjacent conductive layers 340.

The conductive layers 340 are provided at a predetermined distance from each of the upper and lower axial ends of the ring unit 300. This ensures an insulation distance (creepage distance, interface length) along the outer surface of the ring unit 300 between adjacent conductive layers 340. This prevents the insulation strength of the ring unit 300 in the creepage direction from becoming excessively lower than the insulation strength in the thickness direction of the ring unit 300. As a result, the condenser cone 30 can function stably.

The conductive layer 340 includes, for example, conductive or semi-conductive rubber, and is molded integrally with the insulating layer 320. The base rubber constituting the conductive layer 340 is the same as the rubber of the insulating layer 320.

The conductive layer 340 may, for example, contain a conductive or semiconductive paint and be applied to the inner or outer periphery of the insulating layer 320. When the conductive layer 340 contains paint, the ring unit 300 can be easily manufactured by applying the conductive layer 340 to the outer periphery of the insulating layer 320.

In this embodiment, the multiple ring units 300 are arranged, for example, at different positions from each other in the axial direction of the power cable 100. The multiple ring units 300 are stacked in order, for example, along the axial direction of the power cable 100.

Specifically, for example, the first ring unit 300a, the second ring unit 300b, and the third ring unit 300c are arranged in this order at a predetermined pitch in a direction away from the region close to the tip of the power cable 100. A portion of the inner circumferential surface of the second ring unit 300b overlaps with a portion of the outer circumferential surface of the first ring unit 300a and elastically abuts against the outer circumferential surface. A portion of the inner circumferential surface of the third ring unit 300c overlaps with a portion of the outer circumferential surface of the second ring unit 300b and elastically abuts against the outer circumferential surface.

In the first ring unit 300a and the second ring unit 300b, the conductive layer 340a of the first ring unit 300a and the conductive layer 340b of the second ring unit 300b are arranged with the insulating layer 320b of the second ring unit 300b in between. The first ring unit 300a and the second ring unit 300b arranged in this manner form a single capacitor.

Capacitors are formed in the second ring unit 300b and the third ring unit 300c in the same manner as described above.

In this way, multiple capacitors can be formed in the condenser cone 30 at predetermined intervals along the axial direction of the power cable 100. This allows the equipotential lines on the outside of the power cable 100 to be evenly distributed.

In this embodiment, the multiple ring units 300 are stacked such that, for example, three or more ring units 300 do not overlap within the same cross section perpendicular to the central axis of the power cable 100. For example, within the same cross section perpendicular to the central axis of the power cable 100, only the first ring unit 300a and the second ring unit 300b are stacked, and the third ring unit 300c, etc. are not stacked.

In this embodiment, at least a portion of the inner circumferential surface of each of the multiple ring units 300 contacts the outer circumferential surface of the power cable 100 at a position other than where it overlaps with the other ring units 300. For example, the inner circumferential surface of the second ring unit 300b contacts the outer circumferential surface of the power cable 100 at a position other than where it overlaps with the first ring unit 300a, without overlapping with the other ring units 300.

In this embodiment, the multiple capacitors formed by the multiple ring units 300 at least partially overlap each other when viewed in the axial direction of the power cable 100. In other words, at least a portion of each of the multiple capacitors is located at the same diameter with respect to the central axis of the power cable 100. For example, the capacitors of the first ring unit 300a and the second ring unit 300b and the capacitors of the second ring unit 300b and the third ring unit 300c overlap when viewed in the axial direction of the power cable 100. Note that the stacking surfaces of the first ring unit 300a and the second ring unit 300b and the stacking surfaces of the second ring unit 300b and the third ring unit 300c may form the same cylindrical surface.

The above-mentioned configuration allows the outer diameter of the condenser cone 30 to be reduced.

In this embodiment, among the multiple ring units 300, the upper part of the ring unit 300 located vertically below overlaps the lower part of the ring unit 300 located vertically above among two adjacent ring units 300. For example, the upper part of the second ring unit 300b overlaps the lower part of the first ring unit 300a. This makes it possible to form equipotential lines that radiate from the outer periphery of the power cable 100.

In this embodiment, the multiple ring units 300 have the same configuration. For example, the multiple ring units 300 contain the same material, have the same shape and size, and have the same insulating layer 320 and conductive layer 340. This can reduce manufacturing costs.

In this embodiment, the multiple ring units 300 are evenly arranged (arranged at equal pitch) along the axial direction of the power cable 100. The conductive layer 340 of the topmost ring unit 300 is electrically connected to the conductor pull-out rod 610. With this configuration, the equipotential lines formed along the conductive layer 340 can be evenly distributed (spaced apart) along the axial direction of the power cable 100.

[Insulating tube]
2, the insulating tube 400 is provided in a cylindrical shape so as to surround the outer periphery of the power cable 100 within the hollow portion of the porcelain tube 200. The insulating tube 400 is configured to reduce the electric field around the power cable 100 (particularly around the tip of the cable outer semiconductive layer 140) that is peeled off in stages.

Specifically, the insulating tube 400 has, for example, an insulating section 420 and a semiconductive section 440. These are integrally molded into a cylindrical shape. The insulating section 420 contains, for example, insulating rubber. Meanwhile, the semiconductive section 440 contains, for example, semiconductive rubber. The semiconductive section 440 has a cone shape and has an inner diameter that gradually widens from the lower end to the upper end of the insulating tube 400 in the axial direction. In other words, the semiconductive section 440 forms a so-called stress cone.

In the cable termination connection structure 10, the insulating portion 420 is arranged so as to contact the outer peripheral surface of the exposed cable insulating layer 130. The semiconductive portion 440 is arranged so as to contact the outer peripheral surface of the exposed cable outer semiconductive layer 140. With this configuration, the cone-shaped semiconductive portion 440 can evenly distribute equipotential lines around the exposed cable outer semiconductive layer 140, where a relatively high electric field is generated, thereby suppressing electric field concentration.

[Auxiliary conductive part]
The auxiliary conductive part 500 is provided, for example, so as to cover the outer periphery of the insulating tube 400. The auxiliary conductive part 500 electrically connects the ring unit 300 located at the vertical lower end of the condenser cone 30 and the cable outer semiconductive layer 140 exposed in the power cable 100, so as to reduce the electric field outside the insulating tube 400, for example.

In this embodiment, the auxiliary conductive portion 500 has, for example, a plurality of auxiliary ring units 510. The auxiliary ring unit 510 has, for example, a configuration similar to that of the ring unit 300 of the condenser cone 30. That is, the auxiliary ring unit 510 has an insulating layer 520 and a conductive layer 540.

The upper part of the auxiliary ring unit 510 overlaps the lower part of the ring unit 300 located at the vertical lower end of the condenser cone 30. In two adjacent auxiliary ring units 510, the upper part of the auxiliary ring unit 510 located vertically lower overlaps the lower part of the auxiliary ring unit 510 located vertically upper. The conductive layer 540 of the auxiliary ring unit 510 located at the vertical lower end of the auxiliary conductive portion 500 is connected to the shielding layer 580 described above.

This configuration can reduce the stress of the high electric field on the outside of the insulating tube 400.

(3) Manufacturing method of cable termination structure (cable termination method)
Next, a method for manufacturing the cable termination structure according to this embodiment will be described.

The manufacturing method of the cable termination connection structure 10 of this embodiment includes, for example, a preparation process S10, a lower metal fitting arrangement process S20, an insulating tube arrangement process S30, a capacitor cone formation process S40, an auxiliary conductive part formation process S50, a conductor pull rod connection process S60, an insertion process S70 into the porcelain tube, an upper metal fitting arrangement process S80, and an insulating medium filling process S90.

(S10: Preparation process)
First, a stand for mounting the cable termination connection structure 10 of this embodiment is installed.

Next, prepare the power cable 100 to be terminated. The power cable 100 is erected vertically from a stand. Specifically, scaffolding is set up around the stand. Once the scaffolding is set up, the power cable 100 is erected vertically. At this time, a bridge is made between the supports of the scaffolding using a single-tube pipe or the like, and the power cable 100 is fixed to the bridge and maintained in this state.

Next, the power cable 100 is gradually stripped in the axial direction from the tip of the conductor 110 to expose the conductor 110, the cable insulating layer 130, and the cable outer semiconductive layer 140 in that order.

After the power cable 100 has been peeled off in stages, the shielding layer 580 and metal tube 590 are positioned to surround the outer circumference of the exposed cable outer semiconductive layer 140.

(S20: Lower metal fitting arrangement process)
Next, the lower metal fitting 640 is disposed so as to surround the outer periphery of the power cable 100. Specifically, an O-ring is disposed on the inner circumferential surface of the insertion hole of the lower metal fitting 640, and the power cable 100 with the metal tube 590 fitted therein is inserted into the insertion hole of the lower metal fitting 640.

(S30: Insulating tube arrangement process)
After the shielding layer 580 and the lower metal fitting 640 are attached to the power cable 100 , the insulating tube 400 is fitted onto the outer periphery of the power cable 100 , and the insulating tube 400 is disposed near the tip of the cable outer semiconductive layer 140 .

(S40: Condenser cone forming process)
After the insulating tube 400 is placed, the condenser cone 30 for reducing the electric field on the outside of the power cable 100 is provided so as to surround the outer periphery of the power cable 100 .

The condenser cone forming process S4 in this embodiment includes, for example, a ring unit preparation process S42 and a lamination process S44.

(S42: Ring unit preparation step)
A plurality of ring units 300 each having a cylindrical insulating layer 320 and a conductive layer 340 provided on the inner or outer periphery of the insulating layer 320 are prepared in advance.

(S44: Lamination process)
After preparing the ring units 300, the multiple ring units 300 are arranged at different positions in the axial direction of the power cable 100. At this time, the multiple ring units 300 are stacked in the same cross section perpendicular to the central axis of the power cable 100 such that three or more ring units 300 do not overlap.

(S50: Auxiliary conductive portion forming process)
After the condenser cone 30 is formed, the outer periphery of the insulating tube 400 is covered with the auxiliary conductive part 500. At this time, the ring unit 300 located at the vertical lower end of the condenser cone 30 and the cable outer semiconductive layer 140 exposed in the power cable 100 are electrically connected by the auxiliary conductive part 500 so as to reduce the electric field outside the insulating tube 400.

(S60: Conductor lead rod connecting process)
Furthermore, the axial tip of the conductor 110 is connected by compression to the base end of the conductor pull-out rod 610. The conductor pull-out rod 610 and the conductive layer 340 of the uppermost ring unit 300 are electrically connected.

(S70: Insertion into porcelain tube process)
Next, the power cable 100 with the condenser cone 30 and other components attached thereto is inserted into the hollow portion of the porcelain tube 200, and the porcelain tube 200 is set upright in the vertical direction.

Once the porcelain pipe 200 is erected, the lower opening of the porcelain pipe 200 is closed with the lower metal fitting 640, and the porcelain pipe 200 is fixed to the stand.

(S80: Upper metal fitting arrangement process)
When the inserting step S70 into the porcelain tube is completed, the conductor 110 is fixed to the upper metal fitting 620 and the upper opening of the porcelain tube 200 is closed by the upper metal fitting 620.

(S90: Insulating medium filling process)
Next, the hollow portion of the porcelain tube 200 excluding the power cable 100 is filled with an insulating medium.

This completes the manufacture of the cable termination connection structure 10 of this embodiment.

(4) Summary of the Present Invention According to the present invention, one or more of the following advantages can be obtained.

(a) In this embodiment, the condenser cone 30 is composed of a plurality of ring units 300 each having a cylindrical insulating layer 320 containing insulating rubber and a conductive layer 340 provided on the inner or outer periphery of the insulating layer 320. As a result, the condenser cone 30 can be easily formed by stacking a plurality of ring units 300 along the axial direction of the power cable 100. In other words, the work can be easily performed on site without requiring advanced technology and expertise.

In this way, in this embodiment, it is possible to easily and stably manufacture a cable termination connection structure 10 having a condenser cone 30.

(b) In this embodiment, the multiple ring units 300 are arranged at different positions in the axial direction of the power cable 100. The multiple ring units 300 are stacked so that three or more ring units 300 do not overlap within the same cross section perpendicular to the central axis of the power cable 100. This allows the radial thickness of the condenser cone 30 to be the thickness of only two ring units 300. In other words, the outer diameter of the condenser cone 30 can be reduced. As a result, it is possible to reduce the outer diameter of the porcelain tube 200 while easily manufacturing the cable termination connection structure 10.

(c) In this embodiment, by adjusting the number of ring units 300, the overall axial length of the condenser cone 30 can be adjusted, and the number of capacitors in the condenser cone 30 can be adjusted as desired. This allows the configuration of this embodiment to be easily and stably applied to cable termination connection structures 10 with high voltage classes and long overall lengths of the porcelain tube 200.

(d) In this embodiment, at least a portion of the inner circumferential surface of each of the multiple ring units 300 contacts the outer periphery of the power cable 100 at a position other than the position where it overlaps with the other ring units 300. This makes it possible to prevent the outer diameter of the condenser cone 30 from becoming unnecessarily large at a position where a capacitor is not formed. As a result, it becomes possible to stably reduce the outer diameter of the porcelain tube 200.

(e) In this embodiment, the multiple capacitors formed by the multiple ring units 300 at least partially overlap each other when viewed in the axial direction of the power cable 100. This makes it possible to distribute the multiple capacitors at a predetermined interval along the axial direction of the power cable 100 while suppressing excessive spread of the capacitor distribution in the radial direction of the power cable 100. As a result, it becomes possible to stably reduce the outer diameter of the porcelain tube 200 while mitigating the electric field on the outside of the power cable 100.

(f) In this embodiment, among the multiple ring units 300, the upper part of the ring unit 300 located vertically below overlaps the lower part of the ring unit 300 located vertically above in two adjacent ring units 300. This allows the conductive layer 340 of each ring unit 300 to be positioned so that it gradually moves away from a position close to the outer circumferential surface of the power cable 100 as it approaches the tip of the power cable 100. As a result, equipotential lines that radiate out from the outer periphery of the power cable 100 can be formed.

(g) In this embodiment, the multiple ring units 300 have the same configuration. This allows the condenser cone 30 to have a simple structure, and the cable termination connection structure 10 to be easily manufactured.

Furthermore, multiple ring units 300 can be formed using the same mold. This reduces the manufacturing cost of the cable termination connection structure 10.

(h) In this embodiment, the auxiliary conductive portion 500 is provided to cover the outer periphery of the insulating tube 400. The auxiliary conductive portion 500 electrically connects the ring unit 300 located at the vertical lower end of the condenser cone 30 to the cable outer semiconductive layer 140 exposed in the power cable 100 so as to reduce the electric field outside the insulating tube 400.

Here, a high electric field is likely to be generated at the tip of the cable external semiconductive layer 140. Therefore, a high electric field is also likely to be generated outside the insulating tube 400 that is provided to surround the tip of the cable external semiconductive layer 140.

In this embodiment, the auxiliary conductive portion 500 is provided to cover the outer periphery of the insulating tube 400 as described above, thereby reducing the stress of the high electric field on the outside of the insulating tube 400. This improves the safety of the cable termination connection structure 10.

(i) In this embodiment, the auxiliary conductive portion 500 has a plurality of auxiliary ring units 510. The auxiliary ring units 510 have a configuration similar to that of the ring unit 300 of the condenser cone 30.

Here, if the entire outer circumferential surface of the insulating tube 400 is covered with a semiconductive or conductive layer as the auxiliary conductive portion 500, the electric field relaxation on the outside of the insulating tube 400 is hindered. As a result, the electric field may become high in the area near the tip of the insulating tube 400.

In contrast, in this embodiment, the auxiliary conductive part 500 has an auxiliary ring unit 510 similar to the ring unit 300, which can reduce the stress of the high electric field on the outside of the insulating tube 400.

(5) Modifications of an embodiment The above-described embodiment can be modified as necessary as in the following modifications. Only elements different from the above-described embodiment will be described below, and elements substantially the same as those described in the above-described embodiment will be denoted by the same reference numerals and description thereof will be omitted.

<Modification 1>
As shown in FIG. 3, in the first modification, the conductive layer 340 is provided, for example, on the inner periphery of the insulating layer 320 .

In the first modification, the conductive layer 340 contains, for example, conductive or semiconductive rubber. This makes it easier to set the conductive layer 340 in the center of the mold. As a result, it is easy to manufacture the ring unit 300 in which the conductive layer 340 is formed on the inner circumference of the insulating layer 320.

In the first ring unit 300a and the second ring unit 300b, the conductive layer 340a of the first ring unit 300a and the conductive layer 340b of the second ring unit 300b are arranged with the insulating layer 320a of the first ring unit 300a in between. This arrangement forms a single capacitor.

In variant 1, the conductive layer 340 is provided, for example, at a predetermined distance from each of the upper and lower ends of the ring unit 300 in the axial direction. This makes it possible to prevent the conductive layer 340 from coming into contact with the conductive layer 340 of another overlapping ring unit 300. In addition, as described above, it is possible to ensure an insulation distance (creepage distance, interface length) along the outer surface of the ring unit 300 between adjacent conductive layers 340. As a result, a capacitor can be reliably formed between two adjacent ring units 300.

According to the first modification, the same effect as the above embodiment can be obtained even in a configuration in which the conductive layer 340 is provided on the inner circumference of the insulating layer 320.

<Modification 2>
The cable termination connection structure 10 of the second modified example will be described with reference to Fig. 4. In Fig. 4, parts other than the condenser cone 30 are omitted, and the upper side of Fig. 4 is the area close to the tip of the power cable 100. Fig. 5 described later is similar to Fig. 4.

As shown in FIG. 4, in the second modification, in the condenser cone 30, the axial length of the power cable 100 in which two adjacent conductive layers 340 are overlapped with an insulating layer 320 in between (also called the wrap length of the conductive layers 340) gradually increases from the tip of the power cable 100 toward the tip of the cable outer semiconductive layer 140.

In this modified example, for example, the length of each ring unit 300 gradually increases from the tip of the power cable 100 toward the tip of the cable outer semiconductive layer 140. This allows the wrap length of the conductive layer 340 to gradually increase toward the tip of the cable outer semiconductive layer 140.

Even if the ring units 300 themselves all have the same configuration, the overlap length of two adjacent ring units 300 may be changed to gradually increase the wrap length of the conductive layer 340 toward the tip of the cable outer semiconductive layer 140.

According to the second modification, the wrap length of the conductive layer 340 is gradually increased toward the tip of the cable external semiconductive layer 140, so that the area of the capacitor is gradually increased toward the tip of the cable external semiconductive layer 140 where a high electric field is likely to occur (the equipotential lines are likely to become dense), and the capacitance of the capacitor is gradually increased. This allows the electric field to be alleviated according to the strength of the electric field, which changes depending on the axial position of the power cable 100.

<Modification 3>
A cable termination structure 10 according to a third modified example will be described with reference to FIG.

As shown in FIG. 5, in the third variant, in the condenser cone 30, the thickness of the insulating layer 320 sandwiched between two adjacent conductive layers 340 (hereinafter also referred to simply as the insulating thickness) gradually becomes thinner from the tip of the power cable 100 toward the tip of the cable outer semiconductive layer 140.

In this modified example, for example, the thickness of each ring unit 300 itself gradually becomes thinner from the tip of the power cable 100 toward the tip of the cable outer semiconductive layer 140. This allows the insulation thickness to be gradually thinner toward the tip of the cable outer semiconductive layer 140.

Even if the ring units 300 themselves all have the same thickness, the insulation thickness may be gradually thinned toward the tip of the cable outer semiconductive layer 140 by varying the thickness of a spacer containing insulating rubber inserted between two overlapping ring units 300.

According to the third modification, by gradually thinning the insulation thickness toward the tip of the cable external semiconductive layer 140, the insulation thickness of the capacitor can be gradually thinned (the distance between the electrodes can be shortened) toward the tip of the cable external semiconductive layer 140 where a high electric field is likely to occur, and the capacitance of the capacitor can be gradually increased. This allows the electric field to be alleviated according to the strength of the electric field, which changes depending on the axial position of the power cable 100.

<Other embodiments of the present disclosure>
Although the embodiments of the present disclosure have been specifically described above, the present disclosure is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit and scope of the present disclosure.

In the above embodiment, a case has been described in which the upper part of the ring unit 300 located vertically below overlaps the lower part of the ring unit 300 located vertically above, but the present disclosure is not limited to this case. The lower part of the ring unit 300 located vertically above may also overlap the upper part of the ring unit 300 located vertically below. However, the above embodiment allows for smoother formation of equipotential lines.

<Additional Notes>
The following additional aspects of the present disclosure.

(Appendix 1)
A power cable;
a condenser cone provided around the outer periphery of the power cable to reduce an electric field on the outside of the power cable;
a porcelain tube that is vertically installed and into which the power cable with the condenser cone attached thereto is inserted;
Equipped with
The condenser cone has a plurality of ring units each having a cylindrical insulating layer containing insulating rubber and a conductive layer provided on an inner periphery or an outer periphery of the insulating layer,
The multiple ring units are arranged at different positions in the axial direction of the power cable, and are stacked so that three or more ring units do not overlap within the same cross section perpendicular to the central axis of the power cable.

(Appendix 2)
2. The cable termination connection structure according to claim 1, wherein at least a portion of an inner circumferential surface of each of the plurality of ring units is in contact with an outer circumferential surface of the power cable at a position other than the position where the inner circumferential surface overlaps with other ring units.

(Appendix 3)
3. The cable termination connection structure according to claim 1, wherein the capacitors formed by the ring units at least partially overlap each other when viewed in the axial direction of the power cable.

(Appendix 4)
A cable termination connection structure described in any one of Appendix 1 to Appendix 3, wherein, among the multiple ring units, in two adjacent ring units, the upper part of the ring unit located vertically below overlaps the lower part of the ring unit located vertically above.

(Appendix 5)
The cable termination connection structure according to any one of claims 1 to 4, wherein the plurality of ring units have the same configuration.

(Appendix 6)
The cable termination structure according to claim 1, wherein the plurality of ring units are evenly arranged along an axial direction of the power cable.

(Appendix 7)
The power cable includes a conductor, a cable inner semiconductive layer, a cable insulating layer, a cable outer semiconductive layer, and a cable sheath;
the conductor, the cable-interior semiconductive layer, the cable insulating layer, the cable-exterior semiconductive layer, and the cable sheath are exposed in this order from a tip of the conductor in a reverse direction;
The cable termination connection structure according to any one of Supplementary Note 1 to Supplementary Note 4, wherein in the condenser cone, an axial length of the power cable in which two adjacent conductive layers sandwiching an insulating layer are overlapped is gradually increased from the tip of the power cable toward the tip of the cable outer semiconductive layer.

(Appendix 8)
The power cable includes a conductor, a cable inner semiconductive layer, a cable insulating layer, a cable outer semiconductive layer, and a cable sheath;
the conductor, the cable-interior semiconductive layer, the cable insulating layer, the cable-exterior semiconductive layer, and the cable sheath are exposed in this order from a tip of the conductor in a reverse direction;
5. The cable termination connection structure according to claim 1, wherein in the condenser cone, a thickness of an insulating layer sandwiched between two adjacent conductive layers gradually becomes thinner from the tip of the power cable toward the tip of the cable outer semiconductive layer.

(Appendix 9)
an insulating tube provided on the outer periphery of the power cable at a position vertically below the condenser cone and configured to reduce an electric field on the outer side of the power cable;
an auxiliary conductive portion that covers an outer periphery of the insulating tube and electrically connects a ring unit located at a vertical lower end of the condenser cone to an exposed cable outer semiconductive layer of the power cable so as to reduce an electric field outside the insulating tube;
9. The cable termination structure according to claim 1, further comprising:

(Appendix 10)
The cable termination connection structure described in Appendix 9, wherein the auxiliary conductive portion has an auxiliary ring unit having a configuration similar to that of the ring unit.

(Appendix 11)
A ring unit for use in the condenser cone of the cable termination connection structure according to any one of appendix 1 and appendix 8.

(Appendix 12)
Providing a power cable;
providing a condenser cone surrounding an outer periphery of the power cable to reduce an electric field on the outer side of the power cable;
inserting the power cable with the condenser cone attached into a vertically erected porcelain tube;
Equipped with
The step of providing a condenser cone includes:
A step of preparing a plurality of ring units each having a cylindrical insulating layer containing insulating rubber and a conductive layer provided on an inner periphery or an outer periphery of the insulating layer;
arranging the plurality of ring units at different positions in the axial direction of the power cable, and stacking the ring units so that three or more ring units do not overlap within the same cross section perpendicular to the central axis of the power cable;
A method for manufacturing a cable termination structure comprising:

10 Cable termination connection structure 30 Condenser cone 100 Power cable 110 Conductor 130 Cable insulating layer 140 Cable outer semiconductive layer 160 Cable sheath 200 Ceramic tube 210 Flange portion 300 Ring unit 300a First ring unit 300b Second ring unit 300c Third ring unit 320, 320a to 320c Insulating layer 340, 340a to 340c Conductive layer 400 Insulating tube 420 Insulating portion 440 Semiconductive portion 500 Auxiliary conductive portion 510 Auxiliary ring unit 520 Insulating layer 540 Conductive layer 580 Shielding layer 590 Metal tube 610 Conductor lead rod 620 Upper metal fitting 640 Lower metal fitting 820 Upper shield ring 840 Lower shield ring

Claims (10)

A power cable;
a condenser cone provided around the outer periphery of the power cable to reduce an electric field on the outside of the power cable;
a porcelain tube that is vertically installed and into which the power cable with the condenser cone attached thereto is inserted;
Equipped with
The condenser cone has a plurality of ring units each having a cylindrical insulating layer containing insulating rubber and a conductive layer provided on an inner periphery or an outer periphery of the insulating layer,
The multiple ring units are arranged at different positions in the axial direction of the power cable, and are stacked so that three or more ring units do not overlap within the same cross section perpendicular to the central axis of the power cable. The cable termination connection structure according to claim 1 , wherein at least a portion of an inner circumferential surface of each of the plurality of ring units contacts an outer circumferential surface of the power cable at a position other than a position where the inner circumferential surface overlaps with other ring units. 3. The cable termination connection structure according to claim 1, wherein the capacitors formed by the ring units at least partially overlap each other when viewed in the axial direction of the power cable. The cable termination connection structure described in claim 1 or claim 2, wherein, among the plurality of ring units, in two adjacent ring units, the upper part of the ring unit located vertically below overlaps the lower part of the ring unit located vertically above. The cable termination connection structure according to claim 1 or 2, wherein the plurality of ring units have the same configuration. The power cable includes a conductor, a cable inner semiconductive layer, a cable insulating layer, a cable outer semiconductive layer, and a cable sheath;
the conductor, the cable-interior semiconductive layer, the cable insulating layer, the cable-exterior semiconductive layer, and the cable sheath are exposed in this order from a tip of the conductor in a reverse direction;
3. The cable termination connection structure according to claim 1, wherein the axial length of the power cable in the condenser cone, in which two adjacent conductive layers sandwiching an insulating layer therebetween, gradually increases from the tip of the power cable toward the tip of the cable outer semiconductive layer. The power cable includes a conductor, a cable inner semiconductive layer, a cable insulating layer, a cable outer semiconductive layer, and a cable sheath;
the conductor, the cable-interior semiconductive layer, the cable insulating layer, the cable-exterior semiconductive layer, and the cable sheath are exposed in this order from a tip of the conductor in a reverse direction;
3. The cable termination connection structure according to claim 1, wherein in the condenser cone, a thickness of an insulating layer sandwiched between two adjacent conductive layers gradually decreases from the tip of the power cable toward the tip of the cable outer semiconductive layer. an insulating tube provided on the outer periphery of the power cable at a position vertically below the condenser cone and configured to reduce an electric field on the outer side of the power cable;
an auxiliary conductive portion that covers an outer periphery of the insulating tube and electrically connects a ring unit located at a vertical lower end of the condenser cone to an exposed cable outer semiconductive layer of the power cable so as to reduce an electric field outside the insulating tube;
The cable termination structure according to claim 1 or 2, comprising: A ring unit used in the condenser cone of the cable termination connection structure according to claim 1 or 2. Providing a power cable;
providing a condenser cone surrounding an outer periphery of the power cable to reduce an electric field on the outer side of the power cable;
inserting the power cable with the condenser cone attached into a vertically erected porcelain tube;
Equipped with
The step of providing a condenser cone includes:
A step of preparing a plurality of ring units each having a cylindrical insulating layer containing insulating rubber and a conductive layer provided on an inner periphery or an outer periphery of the insulating layer;
arranging the plurality of ring units at different positions in the axial direction of the power cable, and stacking the ring units so that three or more ring units do not overlap within the same cross section perpendicular to the central axis of the power cable;
A method for manufacturing a cable termination structure comprising:

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