KR101830030B1 - Jointing power cable system using joint box and joint box for power cable - Google Patents

Abstract

The present invention relates to a DC power cable intermediate connection system which can facilitate the impregnation of insulation oil in a high viscosity DC power cable and the flow of the insulation oil in the intermediate connection box, and to an intermediate connection box for a DC power cable. The DC power cable intermediate connection system of the present invention comprises a pair of DC power cables having a conductor, an inner semi-conductive layer, a cable insulation layer, and an outer semi-conductive layer; and an intermediate connection box connecting the pair of DC power cables to each other. The pair of DC power cables is provided such that each end of the conductor, the inner semi-conductive layer, the cable insulation layer, and the outer semi-conductive layer, which are sequentially exposed, are opposite to each other.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an intermediate connection system for a DC power cable intermediate connection system and a DC power cable,

The present invention relates to an intermediate connection box for a DC power cable and a power cable connection system using the same.

Generally, a power cable is used to power a desired location through the ground, ground, or seabed using a power-supplying conductor.

The power cables are connected by a joint box at intervals of several hundred meters or tens of kilometers, and the ends of the power cables are connected to the wires by a termination connection box. In the case of connecting the power cable in the intermediate connection box or the termination connection box, the conductor is first connected in a state where the insulation layer of the cable is exposed, and the reinforcing insulation layer is formed by inserting the insulation paper impregnated in the insulation oil on the insulation layer surface. In this case, the insulating paper is supported while applying the insulating oil in the course of winding the insulating paper, that is, between the insulating paper, and then the outer semiconductive layer, the metallic sheath and / or the conventional layer are restored.

There are OF cables and MI cables in the cable in which the insulating layer is formed with insulating paper impregnated with insulating oil. The OF cable is impregnated with insulating paper using a relatively low-viscosity insulating oil. Since the oil must be pressurized to keep the hydraulic pressure at a certain level, the extension length is limited. On the other hand, the MI cable impregnates insulating paper using a relatively high-viscosity insulating oil, so there is a merit that the length of the extension is long since there is no need to maintain the hydraulic pressure because the flow of the insulating oil is small in the insulating paper.

However, it is not easy to impregnate insulating paper with high-viscosity insulating oil. Especially, it is easy to pressurize insulating oil in a cable connection box in which a pair of cables are connected to each other by using a connection box after manufacturing cables It is difficult to impregnate with insulating oil. Especially, since the insulating oil needs to be injected and impregnated into the copper pipe fixedly connected to the cable sleeve, it is difficult to pressurize.

In addition, if the insulation oil flow inside the connection box is not smooth when the insulation oil shrinks / expands due to the temperature change at the time of energizing the cable, there is a problem that the connection box internal pressure is locally increased.

It is an object of the present invention to provide a DC power cable intermediate connection system and an intermediate connection box for a DC power cable in which insulation oil is easily impregnated in a high viscosity DC power cable and the flow of insulating oil in the intermediate connection box is easy.

A DC power cable intermediate connection system according to an embodiment of the present invention includes a pair of DC power cables having a conductor, an inner semiconductive layer, a cable insulation layer, and an outer semiconductive layer, and a pair of DC power cables In the DC power cable intermediate connection system including the intermediate connection box, the pair of DC power cables are provided such that the respective ends of the conductor, the inner semiconductive layer, the cable insulating layer and the outer semiconductive layer, which are sequentially exposed, And the intermediate connection box includes: a conductor connection part for electrically connecting the conductors of the pair of cables to each other; And a first reinforcing insulating layer having an insulating paper wound so as to surround the conductor connecting portion, the exposed inner semiconductive layer and the cable insulating layer to form an outer diameter of the cable insulating layer and having inclined surfaces at both ends in the longitudinal direction, A reinforcing insulation layer and a cable insulation layer surrounding the cable insulation layer and having a width in the cable longitudinal direction and a width in the radial direction of the cable, A reinforcing insulating layer including a second reinforcing insulating layer having a decreasing slope portion; A connection box outer semiconductive layer formed along the outer surface of the slope portion of the second reinforcing insulating layer and having a slope shape by itself and made of a semiconductive material; A metal shielding layer formed on the semi-conductive layer outside the connection box; A copper pipe surrounding the reinforcing insulation layer and a portion of the power cable and including an insulating oil therein; And a spacer for maintaining a gap between the copper tube and the metal shielding layer, wherein the metal shielding layer is perforated so that the insulating oil in the copper tube can move to the reinforcing insulating layer through the hole of the metal shielding layer .

In the present invention, the metal shield layer may be formed by forming a perforated metal plate on the straight portion of the second reinforcing insulating layer, and winding the metal wire on the slope portion of the second reinforcing insulating layer.

In the present invention, the spacer may include: a through hole having an inside diameter larger than an outside diameter of the second reinforcing insulating layer; And a concave portion facing the through hole on the outer side thereof; And the insulating oil in the copper pipe can flow in the longitudinal direction of the intermediate connection box through the recess.

In the present invention, it is preferable to further include a protective layer formed on the metal shield layer, wherein the protective layer protects the metal shield layer when the spacer is fitted on the second reinforcing insulating layer through the through hole .

In the present invention, the protective layer may be made of PPLP or kraft paper.

In the present invention, the connection semiconductive outer layer may be formed so as to surround the slope portion and the straight portion of the second reinforcing insulating layer.

In the present invention, both ends of the connection semispherical semiconductive layer, the metal shielding layer, and the protective layer, which are sequentially formed on the second reinforcing insulating layer, may be peeled off.

In the present invention, an electric field relaxation portion may be provided at a portion where both ends of the connection semiconductive semiconductive layer, the metal shielding layer, and the protection layer are separated.

In the present invention, the electric field relaxation portion can be formed by winding a half-conductive wrinkle.

In the present invention, both ends of the connection semiconductors outer semiconductive layer, the metal shielding layer, and the protection layer sequentially formed on the second reinforcing insulation layer may be tapered in the radial direction of the second reinforcing insulation layer .

An intermediate connection case for a DC power cable according to an embodiment of the present invention includes a conductor, an inner semiconductive layer, a cable insulation layer, and an outer semiconductive layer, and at the end, the conductor, the inner semiconductive layer, An intermediate connection box for connecting a pair of DC power cables sequentially exposed to each other, the intermediate connection box comprising: a conductor connection part for electrically connecting the conductors of the pair of cables to each other; And a first reinforcing insulating layer having an insulating paper wound so as to surround the conductor connecting portion, the exposed inner semiconductive layer and the cable insulating layer to form an outer diameter of the cable insulating layer and having inclined surfaces at both ends in the longitudinal direction, A reinforcing insulation layer and a cable insulation layer surrounding the cable insulation layer and having a width in the cable longitudinal direction and a width in the radial direction of the cable, A reinforcing insulating layer including a second reinforcing insulating layer having a decreasing slope portion; A connection box outer semiconductive layer formed along the outer surface of the slope portion of the second reinforcing insulating layer and having a slope shape by itself and made of a semiconductive material; A metal shielding layer formed on the semi-conductive layer outside the connection box; A copper pipe surrounding the reinforcing insulation layer and a portion of the power cable and including an insulating oil therein; And a spacer for maintaining a gap between the copper tube and the metal shielding layer, wherein the metal shielding layer is perforated so that the insulating oil in the copper tube can move to the reinforcing insulating layer through the hole of the metal shielding layer .

In the present invention, the metal shield layer may be formed by forming a perforated metal plate on the straight portion of the second reinforcing insulating layer, and winding the metal wire on the slope portion of the second reinforcing insulating layer.

In the present invention, the spacer may include: a through hole having an inside diameter larger than an outside diameter of the second reinforcing insulating layer; And a concave portion facing the through hole on the outer side thereof; And the insulating oil in the copper pipe can flow in the longitudinal direction of the intermediate connection box through the recess.

In the present invention, it is preferable to further include a protective layer formed on the metal shield layer, wherein the protective layer protects the metal shield layer when the spacer is fitted on the second reinforcing insulating layer through the through hole .

In the present invention, the protective layer may be made of PPLP or kraft paper.

In the present invention, the connection semiconductive outer layer may be formed so as to surround the slope portion and the straight portion of the second reinforcing insulating layer.

In the present invention, both ends of the connection semispherical semiconductive layer, the metal shielding layer, and the protective layer, which are sequentially formed on the second reinforcing insulating layer, may be peeled off.

In the present invention, an electric field relaxation portion may be provided at a portion where both ends of the connection semiconductive semiconductive layer, the metal shielding layer, and the protection layer are separated.

In the present invention, the electric field relaxation portion can be formed by winding a half-conductive wrinkle.

In the present invention, both ends of the connection semiconductors outer semiconductive layer, the metal shielding layer, and the protection layer sequentially formed on the second reinforcing insulation layer may be tapered in the radial direction of the second reinforcing insulation layer .

According to one embodiment of the present invention, the impregnation of the dielectric oil in the high viscosity DC power cable and the flow of the dielectric oil in the intermediate junction box are easy.

1 is a perspective view showing an internal configuration of a power cable.
2 is a partial cutaway view schematically showing a cable connected by an intermediate connection box;
FIG. 3 is an enlarged view of FIG. 2C.
4 is a cross-sectional view showing a conductor crimping sleeve before crimping.
Fig. 5 is a cross-sectional view showing a conductor compression sleeve after compression. Fig.
6 is a cross-sectional view showing the first reinforcing insulating layer and the second reinforcing insulating layer of the intermediate connection box shown in FIG. 2 in more detail.
7 is an enlarged cross-sectional view of part I of Fig.
8 is a cross-sectional view taken along line II-II 'of FIG.
9 is an enlarged view of the portion III in Fig.
Figs. 10-14 are cross-sectional views of various embodiments illustrating a crimp sleeve after crimping. Fig.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals designate like elements throughout the specification.

Generally, a DC power cable is connected by an intermediate connection box at intervals of several hundred meters to several kilometers, and a terminal of the DC power cable is connected to a working line by terminating connection. Hereinafter, the construction of the dielectric-oil-impregnated power cable will be described first, and the connection process of the connection box will be described.

1 is a partially cutaway perspective view showing an internal configuration of an ultra-high voltage power cable.

1, a power cable 100 includes a conductor 11, an inner semiconductive layer 12, a cable insulation layer 14, and an outer semiconductive layer 16, And the cable core portion 10 for preventing electric current from leaking in the cable radial direction.

The conductor 11 serves as a passage through which a current flows to transmit electric power and is made of a material having excellent conductivity and strength and flexibility suitable for cable manufacturing and use such as copper or aluminum ≪ / RTI >

1, the conductor 11 has a circular central strand 11A and a rectangular strand 11C composed of a square strand 11B stranded to surround the circular central strand 11A May be a rectangular conductor having an entirely circular cross section, and as another example, it may be a circular compression conductor in which a plurality of circular element wires are twisted and compressed in a circular shape. The rectangular conductor has an advantage that the outer diameter of the cable can be reduced because the dot rate is relatively higher than that of the circular compressed conductor.

Since the conductor 11 is formed by twisting a plurality of elemental wires, the surface of the conductor 11 may not be smooth and the electric field may be uneven, and corona discharge is likely to occur partially. In addition, when a gap is formed between the surface of the conductor 11 and the cable insulation layer 14 described later, the insulation performance may be deteriorated.

In order to solve the above-mentioned problems, an inner semiconductive layer 12 may be formed outside the conductor 11. The inner semiconductive layer 12 may have semiconducting properties by adding conductive particles such as carbon black, carbon nanotube, carbon nanoplate, or graphite to the insulating material.

The inner semiconductive layer 12 functions to stabilize the insulation performance by preventing a sudden change in the electric field between the conductor 11 and the cable insulation layer 14 described later. In addition, by suppressing the uneven distribution of electric charge on the conductor surface, it is possible to make the electric field uniform and prevent the gap between the conductor 11 and the cable insulation layer 14 from being formed, thereby suppressing the corona discharge and dielectric breakdown do.

The cable insulation layer 14 is provided on the outer side of the inner semiconductive layer 12 to electrically isolate the cable insulation layer 14 from the outside so that a current flowing along the conductor 11 does not leak to the outside.

The cable insulation layer 14 may be formed of insulating paper impregnated with insulating oil. That is, the cable insulation layer 14 may be formed by winding up insulation paper in multiple layers so as to surround the inner semiconductive layer 12 and impregnating the insulation oil after the cable core is formed. As the insulating oil is absorbed by the insulating paper, the insulating property of the cable insulating layer 14 can be improved.

The insulating oil is filled in gaps between the voids inside the insulating paper and the gap formed between the layers formed by winding the insulating paper to improve the insulating property and reduce the frictional force between the insulating paper at the time of bending the cable to improve the bending property of the cable. Although the kind of the insulating oil is not particularly limited, it should be in contact with copper or aluminum constituting the conductor 11 and not be oxidized by heat. It is preferable that the insulating paper be impregnated at an impregnation temperature, for example, It is preferable to use a medium-viscosity insulating oil having a sufficiently low viscosity and a kinematic viscosity at 60 DEG C of 10 to 500 centistokes or a high-viscosity insulating oil having a kinematic viscosity at 60 DEG C of 500 centistokes or more.

In the case of using a low-viscosity insulating oil having a relatively low viscosity, it is necessary to pressurize the insulating oil using a lubricating device or the like in order to keep the insulating paper impregnated with the insulating oil and prevent the gap from being generated in the cable insulating layer due to the flow of the insulating oil There is a need. However, when medium viscosity or high viscosity insulating oil is used, the flow of insulating oil is small, so there is no need for an oil supply device for pressurizing the insulating oil, or the number of required oil supply facilities can be reduced, thereby extending the cable extension length. For example, the insulating oil may be at least one insulating oil selected from the group consisting of naphthenic insulating oil, polystyrene insulating oil, mineral oil, alkylbenzene, polybutene-based synthetic oil, heavy alkaline,

The insulating paper may be a kraft paper in which kraft pulp is used as a raw material and an organic electrolyte in the pulp is removed, or a composite insulating paper in which a kraft paper is adhered to one side or both sides of a plastic film. The plastic film has a resistivity higher than that of the kraft paper adhered to one side or both sides thereof, so that even if bubbles are generated in the kraft paper due to the flow of the insulating oil during the impregnation process or cable operation, the voltage distributed to the bubbles can be relaxed, A polyolefin resin such as polypropylene or polybutylene, a tetrafluoroethylene-hexafluoropropylene copolymer, an ethylene-tetrafluoroethylene copolymer, an ethylene-tetrafluoroethylene copolymer, And a polypropylene homopolymer resin which is excellent in heat resistance.

Specifically, the cable insulation layer 14 can be formed by winding up a kraft and impregnating the insulation oil. In this case, the insulating oil may flow in the direction of the cable load, and the gap may be generated. On the other hand, when the composite insulating paper is wound and impregnated with the insulating oil to form the cable insulating layer 14, the thermoplastic resin such as the polypropylene resin is not impregnated with the insulating oil, and the impregnation temperature at the time of cable production, Thermal expansion is caused by operating temperature. When the thermoplastic resin thermally expands, a surface pressure is applied to the laminated kraft paper, thereby narrowing the passage of the insulating oil. Therefore, the flow of the insulating oil due to the gravity or the shrinkage / expansion of the insulating oil according to the temperature can be suppressed. In addition, the composite insulating paper has an advantage of being able to reduce the outer diameter of the cable because the dielectric insulating strength is higher than that of the craft paper.

On the other hand, when the power cable is energized, heat is generated in the conductor serving as a passage through which the current flows, and the temperature gradually decreases from the inside toward the outside in the cable radial direction, Occurs. Therefore, the insulation oil of the cable insulation layer, that is, the cable insulation layer formed on the inner semiconductive layer 12, which belongs to the conductor directly above the section, moves to the outside due to low viscosity and thermal expansion, The viscosity of the insulating oil is increased and it does not return to the original state, so that voids may be generated in the portion of the cable insulation layer in the region directly above the conductor.

In addition, a high electric field acts on the cable insulation layer, that is, the cable insulation layer formed in the direction of the outer semiconductive layer 16, which belongs to the section under the metal sheath where the electric field gradually increases due to the temperature difference. The conductor straight section and the metal sheath lower section have a high possibility of occurrence of voids and can act as an insulation weak portion which is a starting point of partial discharge and dielectric breakdown as a region where a high electric field acts in accordance with a temperature change in the cable.

In order to solve the above-described problems, only a kraft may be used as an insulating paper in the area of the cable insulation layer 14 including the insulation weak portion. That is, the cable insulation layer 14 is divided into the first cable insulation layer, the second cable insulation layer, and the third cable insulation layer in the direction of the outer semiconductive layer 16 described later from the inner semiconductive layer 12, Only the kraft may be used for the cable insulation layer and / or the third cable insulation layer, and the composite insulation paper may be used for the second cable insulation layer.

In this case, a difference in resistivity occurs between the second cable insulating layer on which the composite insulating paper is wound and the first cable insulating layer and / or the third cable insulating layer on which the kraft paper is wound, and the cable insulation layer The first cable insulation layer and / or the third cable insulation layer of the second insulation layer 14 has a relatively low resistivity and functions to alleviate an electric field shared among the insulation fragile portions. Specifically, a high electric field acts on the second cable insulating layer on which the composite insulating paper having a high resistivity is wound due to the resistive electric field distribution characteristic of the DC cable in which the electric field is distributed according to the resistivity, and the first cable insulating layer and / A relatively low electric field acts on the conductor straight section and / or the metal sheath lower section included in the insulation layer, so that the electric field acting on the insulation weak portion is relaxed and the insulation performance can be stabilized.

In addition, the cable insulation layer 14 may form the third cable insulation layer to be thicker than the first cable insulation layer. In the case of forming a metallic sheath 22 described later on the outside of the cable insulation layer 14 or restoring the metallic sheath 22 after connecting two power cables exposed sequentially from the inside of the cable core portion The second cable insulation layer may be formed to have a larger thickness than the first cable insulation layer so that the second cable insulation layer 14 may be deformed, It is preferable to protect the plastic film from heat. In this case, the thickness of the first cable insulation layer can be selected in consideration of the impulse surge voltage required for the power cable and the like.

The outer semiconductive layer 16 may be provided outside the cable insulation layer 14. The outer semiconductive layer 16 is formed of a material having semiconducting properties by adding conductive particles such as carbon black, carbon nanotube, carbon nanoplate, graphite and the like to an insulating material such as an inner semiconductive layer, Uneven charge distribution between the layer 14 and the metal sheath 22 described later is suppressed to stabilize the insulation performance. In addition, the outer semiconductive layer 16 functions to smooth the surface of the cable insulation layer 14 in the cable so as to prevent corona discharge by alleviating electric field concentration, and to physically protect the cable insulation layer 14 Can be performed. The outer semiconductive layer 16 may further include a metalized paper. The metalized sheet may be formed by laminating an aluminum foil on a kraft paper, and a plurality of perforations may be present to facilitate impregnation of the cable insulating layer 14 with insulating oil.

The cable core portion 10 may further include a water absorbing portion 21 for preventing water from penetrating into the cable. The moisture absorbing portion can be formed between the stranded strands of the conductor 11 and / or the outside of the conductor 11. The water absorbing portion can absorb the moisture penetrated into the cable at a high speed, Tape, a coating layer or a film including a super absorbent polymer (SAP) so as to prevent moisture from penetrating in the longitudinal direction of the cable. In addition, the water absorbing part may have a semiconductive property to prevent a sudden change in the electric field.

A cable protecting portion 20 is provided outside the cable core portion 10 and a power cable installed in the seabed may further include a cable covering portion 30. The cable protector and cable protector protects the core from various environmental factors such as moisture penetration, mechanical trauma, and corrosion which may affect the power transmission performance of the cable.

The cable protection portion 20 includes a metal sheath 22 and a polymer sheath 24 to protect the cable from an accident current, an external force or other external environmental factors.

The metallic sheath 22 may be formed so as to surround the core portion 10. In particular, when the power cable is installed in an environment such as a seabed, the cable core portion 10 may be sealed to prevent foreign matter such as moisture from entering the cable core portion 10, The melted metal is extruded outside the cable core portion 10 so as to have a continuous outer surface having no seams, so that the order performance can be improved. Lead or aluminum is used as the above metal. In the case of a power cable installed on the seabed, it is preferable to use lead having excellent corrosion resistance against seawater. To compensate for mechanical properties, It is more preferable to use a lead alloy. The metal sheath 22 serves as a passage through which a fault current flows when a ground fault or a short circuit occurs in the ground at a power cable end, protects the cable from external impacts, and prevents an electric field from being discharged to the outside of the cable .

The metal sheath 22 may be coated with a corrosion inhibiting compound such as a blown asphalt or the like in order to further improve the corrosion resistance, water repellency and the like of the cable and improve the adhesive strength with the polymer sheath 24 .

In addition, a copper wire-directing tape or a moisture absorbing layer 21 may be additionally provided between the metal sheath 22 and the cable core portion 10. The copper wire direct tape is composed of a copper wire and a nonwoven tape and acts to smooth electrical contact between the outer semiconductive layer 16 and the metal sheath 22. The moisture absorbing layer absorbs moisture penetrating the cable A tape, a coating layer or a film including a super absorbent polymer (SAP) excellent in the ability to maintain the absorbent state at a high speed and to prevent moisture from penetrating in the cable longitudinal direction It plays a role. The copper wire-directing tape and the water-absorbing layer preferably have a semiconducting property in order to prevent a sudden change in the electric field, and may include a copper wire in the water-absorbing layer so as to be capable of both conducting and absorbing water.

The polymer sheath 24 is formed outside the metal sheath 22 to improve the corrosion resistance and water repellency of the cable and to protect the cable from mechanical damage and other external environmental factors such as heat and ultraviolet rays . The polymer sheath 24 may be formed of a resin such as polyvinyl chloride (PVC), polyethylene or the like. In the case of a power cable installed in the seabed, it is preferable to use a polyethylene resin having excellent water repellency. In the environment, polyvinyl chloride resin is preferably used.

The power cable 100 includes a metal reinforcing layer 26 made of a steel cap or the like galvanized on the inner side or the outer side of the polymer sheath so that the metal sheath 22 expands due to expansion of the insulating oil . The upper and / or lower portions of the metal reinforcing layer 26 may be provided with a bedding layer (not shown) made of a semiconductive nonwoven tape or the like to buffer an external force applied to the power cable, and may be made of polyvinyl chloride or polyethylene It is possible to further improve the corrosion resistance, water resistance and the like of the power cable, and further protect the cable from other external environmental factors such as mechanical trauma and heat and ultraviolet rays.

In addition, the power cable installed on the seabed may be easily damaged by an anchor or the like of a ship, and may be damaged by a bending force due to currents or waves, a frictional force with the sea floor, etc. Therefore, (30) may be additionally provided.

The cable sheathing may include an armor layer 34 and a covering layer 38. The armor layer 34 may be composed of at least one layer made of steel, zinc-plated steel, copper, brass, bronze, etc., And performance as well as additional protection from external forces.

Polypropylene yarn or the like is formed in one or more layers on the upper and / or lower portions of the armor layer 34 to protect the cable, and the serving layer 34 formed at the outermost portion is formed of a color Can be made of two or more different materials to ensure the visibility of the cable installed at the seabed.

2 is a partial cutaway view schematically showing a cable connected by an intermediate connection box; 1 is a partial cut-away view schematically showing a state in which DC power cables 100A and 100B having the configuration shown in Fig. 1 are connected to each other by an intermediate connection box 200. Fig. FIG. 3 is an enlarged view of FIG. 2C.

Referring to FIGS. 2 and 3, first, a pair of DC power cables 100A and 100B are connected to the DC power cables 100A and 100B in a state in which the cable insulating layers 14A and 14B and the conductors 11A and 11B are exposed. The conductor connecting portions can be formed by electrically connecting the respective ends of the conductors 11A and 11B. The conductor connection portion serves as a current path through the electrically conductive conductors 11A and 11B, through which the power can be transmitted. The conductor connecting portions are formed by pressing and welding the conductors 11A and 11B with the conductor crimping sleeve 1P and electrically connecting the conductors 11A and 11B to each other.

The cable insulation layer 14A may be composed of the first cable insulation layer 14A1, the second cable insulation layer 14A2, and the third cable insulation layer 14A3 as described above. The cable insulation layer 14A can be pen-sled to have a multi-stage structure. As an example, as shown in FIGS. 2 and 6, the cable insulation layer 14A may be configured to have a multi-stage structure of a first pen sling end 14a1, a second pen sling end 14a2, and a third pen sling end 14a3. Can be pen sling. The first pen sling end 14a1 is made up of a part of the inner semiconductive layer 12, the first cable insulating layer 14A1 and the second cable insulating layer 14A2, And the third pen sling end 14a3 may be formed of a part of the second cable insulating layer 14A2 and the third cable insulating layer 14A3. This will be described later together with the reinforcing insulating layer.

A counterflow leakage preventing portion PC for preventing the copper powder generated from the conductors 11A and 11B from flowing out may be positioned between the conductor crimping sleeve 1P and the conductors 11A and 11B.

When a pair of cables, for example, a DC power cable, is connected by an intermediate junction, the conductor in the cable is heated as the current flows through the cable, so that the viscosity of the dielectric oil in the cable decreases, . ≪ / RTI > The copper moving in the gravity direction flows out to the reinforcing insulating layer, and there is a problem that insulation breakdown occurs in the copper powder flowing out to the reinforcing insulating layer.

According to one embodiment of the present invention, the counterpart leakage preventing portion PC is provided between the conductor crimping sleeve 1P and the conductors 11A and 11B and / or between the innermost layer 2101A of the first reinforcing insulating layer 2101 It is possible to prevent the copper generated from the conductors 11A and 11B from flowing out to the reinforcing insulating layer 210 by being disposed between the conductors 11A and 11B.

The counterflow leakage preventing portion PC includes a first electric field smoothing layer 12 located on the conductor 11A exposed between the first pen sling end 14a1 of the cable 100A and the conductor crimping sleeve 1P And a copper flow-out prevention plate 211 disposed between the conductor compression sleeve 1P and the conductor 11A.

The first electric field uniforming layer 12 may be disposed between the conductor compression sleeve and the conductor, and between the reinforcing insulation layer and the conductor. That is, the first electric field smoothing layer 12 can extend not only between the first cable insulation layer 14A1 and the conductor compression sleeve 1P, but also extends between the conductor compression sleeve 1P and the conductor 11A.

The first electric field uniforming layer 12 may be formed, for example, by extending the inner semiconductive layer of the cable 100A. That is, the first electric field uniforming layer 12 is removed as the inner semi-conductive layer itself of the cable 100A together with the first cable insulating layer 14A1 without being removed and leaving a predetermined length, The conductor 11A is exposed.

The first electric field smoothing layer 12 may be formed by inserting at least one insulating paper on the conductor 11A, but the first two sheets of paper may be formed in a gap region after the first two sheets are formed.

Specifically, the first electric field uniforming layer 12 has a plurality of semi-conductive layers (not shown) so as to overlap the innermost layer adjacent to the conductors 11A and 11B of the DC power cables 100A and 100B in the longitudinal direction of the cable, The tape may be formed by transversely winding the semi-conductive tape, which is a kind of insulating paper, in the longitudinal direction of the DC power cables 100A and 100B.

As another example, the first electric field uniforming layer 12 may be formed on the conductors 11A and 11B of the direct current power cables 100A and 100B with the innermost layer adjacent to the conductors of the direct current power cables 100A and 100B. A plurality of carbon paper, which is a semiconductive tape, is laid across the length of the cable in the longitudinal direction of the DC power cables 100A and 100B, (Carbon paper), which is a kind of insulating paper, is horizontally spaced apart in the longitudinal direction of the DC power cables 100A and 100B.

Since the first electric field uniforming layer 12 is formed in a gap region after the air gap, the air gap of a plurality of insulating paper sheets (carbon paper) is minimized, and thus the flow of the same amount can be primarily prevented. Further, since a plurality of sheets of insulating paper (carbon paper) are allowed to pass through the gap, and the gap is inspected, the bending characteristics can be improved.

The first electric field smoothing layer 12 can be removed from the first cable insulating layer 14A1 to expose the inner semiconductive layer of the exposed cable 100A and extend between the conductor crimping sleeve 1P and the conductor 11A . That is, one end of the first electric field smoothing layer 12 may be positioned between the conductor compression sleeve 1P and the conductor 11A.

The first electric field uniforming layer 12 is formed at a position where the corrugated acid (1 Pa 'in FIG. 5) on the inner side of the conductor crimp sleeve 1P formed by the pressing of the conductor crimp sleeve 1P, And may extend to one end of the sleeve 1P. As another example, as shown in FIG. 5, the first electric field uniforming layer 12 may extend to the immediately before the highest ridge T in the corrugated acid (1 Pa 'in FIG. 5). By extending in this way, a sufficient current path can be ensured between the conductor 11A of the cable and the conductor crimping sleeve 1Pa. As another example, as shown in FIG. 6, the first electric field uniforming layer 12 may extend beyond the highest ridge T in the corrugated acid (1 Pa 'in FIG. 5). This will be described later.

The foul spill preventing plate 211 can be disposed between the conductor crimping sleeve 1P and the conductor 11A. That is, the counterflow leakage preventing plate 211 is disposed so as to correspond to the inside of the conductor crimping sleeve 1P and may not exceed the conductor crimping sleeve 1P. As another example, as shown in Figs. 9 and 10, the spill preventing plate 211 " can extend beyond both ends of the conductor crimping sleeve 1P as well as between the conductor crimping sleeve 1P and the conductor 11A .

The copper leakage preventing plate 211 may be formed of a metal material having a structure that is dense enough to prevent the copper from permeating, and may preferably be formed of a metal material capable of withstanding a force acting upon pressing of the pressing sleeve. The copper leakage preventing plate 211 may be made of copper, aluminum, a copper alloy, or an aluminum alloy so as to correspond to the material of the conductors 11A and 11B of the cables 100A and 100B.

The copper leakage preventing plate 211 may be formed by wrapping a part of the first electric field uniforming layer 12 and the conductor 11A with a copper tape and attaching or brazing an end portion of the copper tape which is in contact with each other. When both ends of the copper tape are soldered to form the copper portion leakage prevention plate 211, it is preferable that the connection portion of the solder is smoothly processed so that no edge is generated.

The outflow route of the copper foil generated in the conductor 11A formed so as to enclose the cable conductor 11A by the tangs between the conductor crimping sleeve 1P and the conductor 11A is minimized So that the fingers can be blocked by the fingertip leakage preventing plate 211.

One end of the copper spill preventing plate 211 which faces the end of the cable conductor 11A is pressed against the crimp trough 1Pb 'beyond the crimp mountain 1Pa' formed on the inner side by pressing the conductor crimping sleeve 1P It can be pressed against the conductor crimp sleeve 1P by extending from the adjacent position a1 to the first cable insulating layer 14A1. For example, as shown in FIG. 5, the flow dividing plate 211 preferably extends beyond the ridge T, which is the highest point in the ridge 1Pa '.

The other end a2 of the copper flow-out prevention plate 211 that faces the first cable insulation layer 14A1 of the cable may protrude from the conductor compression sleeve 1P and may not act as an edge.

Referring to FIGS. 4 and 5, the arrangement of the first field equalization layer 12 and the counterflow leakage prevention plate 211 will be described below.

4 and 5 are cross-sectional views showing a state in which a pair of conductors 11A and 11B are electrically connected to each other by a conductor crimping sleeve. 4 is a cross-sectional view showing a conductor crimping sleeve before crimping, and Fig. 5 is a cross-sectional view showing a crimp sleeve after crimping.

4, when the pair of conductors 11A and 11B are electrically connected, the respective ends of the pair of conductors 11A and 11B are fitted in the conductor accommodating portion of the conductor compression sleeve 1P , The outer surface of the conductor crimping sleeve is pressed by the crimping device to grip the pair of conductors to firmly support the connection state as shown in FIG. 5, and after the crimping, the outer surface of the conductor crimping sleeve is uniformly polished, .

5, the conductor compression sleeve 1P includes at least two protrusions 1Pa protruding from the outer surface, at least one recess 1Pb formed between the protrusions 1Pa, As shown in FIG. 5, the area where the protrusion 1Pa is formed is pressed by the compression device and protruded to the inside of the conductor compression sleeve 1P to form a corrugated acid 1Pa ' And the outer surface of the conductor crimping sleeve 1P, which is uneven due to the pressing, can be flattened to prevent the electric field concentration on the outer surface of the conductor crimping sleeve, the corona discharge, and the like.

The first electric field uniforming layer 12 extends in the direction toward the conductor compression sleeve 1P from the inner semiconductive layer of the cable 100A as described above and one end of the first electric field uniformizing layer 12 is sandwiched between the conductor compression sleeve 1P and the conductor 11A The other end portion of the cable 100A facing the first cable insulating layer 14A1 does not protrude from the conductor crimping sleeve 1P and one end portion of the cable 100A facing the end portion of the conductor 11A As shown in FIG.

As shown in Fig. 5, by pressing the conductor crimping sleeve 1P, a corrugated acid 1Pa 'is formed on the inner surface of the conductor crimp sleeve 1P, and the first electric field uniforming layer 12 is formed of the corrugated acid 5A and 5B) extends to a point just before the highest ridge T in FIG. 5 and extends to a point beyond the ridge T which is the highest point in the ridge 1Pa ' .

Figs. 10 to 14 are views showing various modifications of the first electric field smoothing layer and the coarse leakage preventing plate.

10, the first electric field smoothing layer 121 extends from the inner semiconductive layer of the cable 100A in the direction toward the conductor compression sleeve 1P, and one end of the first electric field uniformization layer 121 is connected to the conductor compression sleeve 1P and the conductor 11A. And the other end portion of the cable 100A which faces the first cable insulating layer 14A1 is not protruded from the conductor crimping sleeve 1P and is disposed between the end portions of the conductors 11A The portion can be extended to a predetermined length.

As shown in Fig. 10, by pressing the conductor crimping sleeve 1P, a corrugate acid 1Pa 'is formed on the inner surface of the conductor crimp sleeve 1P, and the first field uniforming layer 121 is formed of the corrugated acid 1Pa '), and the equipotential leakage preventing plate 211 can extend beyond the ridge T, which is the highest point in the ridge 1Pa'.

11, the first electric field leveling layer 122 extends from the inner semiconductive layer of the cable 100A in the direction toward the conductor compression sleeve 1P, and one end of the first electric field uniformization layer 122 is connected to the conductor compression sleeve 1P and the conductor 11A. And the copper flow-out prevention plate 211 'may be disposed over the entire surface between the conductor compression sleeve 1P and the conductor 11A. 5 and 6, a single flow leakage preventing plate 211 is disposed between the conductor 11A and the conductor crimping sleeve 1P and another one between the conductor 11B and the conductor crimping sleeve 1P In the embodiment shown in FIG. 11, one flow dividing prevention plate 211 'is disposed between the conductor crimping sleeve 1P and the conductors 11A and 11B. The end portion of the cable flow-out prevention plate 211 'facing the first cable insulation layer 14B1 of the cable 100A and the end portion of the cable 100A facing the first cable insulation layer 14A1 are electrically connected Can be disposed between the conductor crimping sleeve 1P and the conductors 11A and 11B without protruding from the sleeve 1P.

As shown in Fig. 11, by pressing the conductor crimping sleeve 1P, a corrugate acid 1Pa 'is formed on the inner side of the conductor crimp sleeve 1P, and the first field uniforming layer 122 is formed of the corrugated acid 1 Pa ') beyond the highest ridge (T).

12, the first electric field smoothing layer 123 extends from the inner semiconductive layer of the cable 100A in the direction toward the conductor compression sleeve 1P, and one end of the first electric field smoothing layer 123 contacts the conductor compression sleeve 1P and the conductor 11A. And the copper flow-out prevention plate 211 'may be disposed over the entire surface between the conductor compression sleeve 1P and the conductor 11A. 5 and 10, one flow-out prevention plate 211 is disposed between the conductor 11A and the conductor crimp sleeve 1P and another one between the conductor 11B and the conductor crimp sleeve 1P In the embodiment shown in FIG. 12, a single flow leakage preventing plate 211 'is disposed between the conductor crimping sleeve 1P and the conductors 11A and 11B. The end portion of the cable flow-out prevention plate 211 'facing the first cable insulation layer 14B1 of the cable 100A and the end portion of the cable 100A facing the first cable insulation layer 14A1 are electrically connected Can be disposed between the conductor crimping sleeve 1P and the conductors 11A and 11B without protruding from the sleeve 1P.

As shown in Fig. 8, by pressing the conductor crimping sleeve 1P, a corrugate acid 1Pa 'is formed on the inner surface of the conductor crimp sleeve 1P, and the first field uniforming layer 123 is formed of the corrugated acid 1Pa ') without extending beyond the highest ridge (T).

13, the first electric field smoothing layer 124 extends from the inner semiconductive layer of the cable 100A in the direction toward the conductor compression sleeve 1P, and one end thereof is connected to the conductor compression sleeve 1P and the conductor 11A. The other end portion of the cable 100A which faces the first cable insulating layer 14A1 protrudes from the conductor crimping sleeve 1P and extends from the end portion of the conductor 11A A part of the flow blocking plate 211 "may be disposed between the conductor crimping sleeve 1P and the conductors 11A, 11B while the other portion may be a conductor crimping sleeve (not shown) 1P and extend toward the cable insulation layer 14A.

As shown in Fig. 13, by pressing the conductor crimping sleeve 1P, a corrugate acid 1Pa 'is formed on the inner surface of the conductor crimp sleeve 1P, and the first field uniforming layer 124 is formed of the corrugated acid 1Pa '), and the equipotential leakage preventing plate 211 can extend beyond the ridge T, which is the highest point in the ridge 1Pa'. The other part of the flow blocking preventing plate 211 " and the first electric field equalizing layer 124 may overlap with each other in a region beyond the conductor crimping sleeve 1P.

14, the first electric field smoothing layer 125 extends from the inner semiconductive layer of the cable 100A in the direction toward the conductor compression sleeve 1P, and one end thereof is connected to the conductor compression sleeve 1P and the conductor 11A. The other end portion of the cable 100A which faces the first cable insulating layer 14A1 protrudes from the conductor crimping sleeve 1P and extends from the end portion of the conductor 11A A part of the flow blocking plate 211 "may be disposed between the conductor crimping sleeve 1P and the conductors 11A, 11B while the other portion may be a conductor crimping sleeve (not shown) 1P and extend toward the cable insulation layer 14A.

As shown in Fig. 10, by pressing the conductor crimping sleeve 1P, a corrugate acid 1Pa 'is formed on the inner surface of the conductor crimp sleeve 1P, and the first field uniforming layer 124 is formed by the corrugated acid 1 Pa '), and the peaks leakage preventing plate 211 can extend beyond the ridge T, which is the highest point of the pebble mountain 1Pa'. In addition, the first electric field equalizing layer 125 and the other part of the first flow blocking plate 211 " may overlap with each other in the region beyond the conductor crimping sleeve 1P.

Referring to FIG. 3, the counterflow leakage preventing portion PC includes a first electric field equalization layer 12, a first flow blocking layer 211 surrounding the first electric field uniforming layer 12, a second electric field smoothing layer 211 surrounding the conductor compression sleeve 1P, And a pressing layer 213 wound on the second electric field uniforming layer 212. The first and second electric field uniforming layers 212,

The second electric field smoothing layer 212 is formed by wrapping the carbon creep paper so as to surround the first electric field uniforming layer 12, the flow blocking plate 211 and the conductor compression sleeve 1P, It is possible to additionally prevent the copper from flowing out by strongly adhering the layer 12, the copper leakage preventing plate 211, and the conductor compression sleeve 1P. In other words, it is difficult to maintain a high degree of smoothness while pressing the surface of the conductor crimping sleeve 1P. The second electric field smoothing layer 212 can uniform the electric field on the outer circumferential surface of the conductor crimp sleeve 1P by covering the outer circumferential surface of the finished conductor crimp sleeve 1P and making the surface even.

In addition, the second electric field uniforming layer 212 can press the first electric field uniforming layer 212 and the coarse leakage preventing plate 211.

The second electric field smoothing layer 212 may, for example, bond the carbon creep paper in a wraparound manner. That is, the second electric field uniforming layer 212 can be formed by directing the carbon creep paper to overlap in the longitudinal direction of the cable.

The second electric field smoothing layer 212 may be made of carbon paper as another example. It is preferable that the second electric field homogenizing layer 212 is made of corrugated carbon paper considering the step at both ends of the conductor crimp sleeve 1P.

Since the second electric field uniforming layer 212 is semi-conductive, it is possible to prevent a sudden electric field change between the conductor crimping sleeve 1P and the reinforcing insulating layer 210 from occurring.

A pressing layer 213 may be wound on the second field uniforming layer 212. The pressing layer 213 is formed to closely contact the first electric field uniforming layer 12, the flow blocking plate 211, the conductor pressing sleeve 1P and the second electric field uniforming layer 212 to each other to prevent .

The pressing layer 213 is preferably deposited on the second field uniforming layer 212 in a gap in consideration of bending characteristics. That is, the pressing layer 213 can be formed by horizontally stacking the kraft paper in the longitudinal direction of the cable as an example.

The pressing layer 213 can be wound with an insulating paper in order to alleviate the electric field on the conductor crimping sleeve 1P in which a high electric field is applied when the cable is energized.

The pressing layer 213 may have a volume resistance lower than that of the reinforcing insulating layer 2110 by 10 ² or more.

6 is a cross-sectional view showing the first reinforcing insulating layer and the second reinforcing insulating layer of the intermediate connection box shown in FIG. 2 in more detail.

6, the respective conductors of the DC power cables 100A and 100B are crimped and connected to the conductor crimping sleeve 1P to form the copper leakage preventing portion PC and then the conductors 11A and 11B The reinforcing insulating layer 210 covering at least a part of the cable insulating layers 14A1, 14A2, and 14A3 including the connection portions of the cable insulating layers 14A1, 14A2, and 14A3.

The reinforcing insulating layer 210 may include a first reinforcing insulating layer 2101 and a second reinforcing insulating layer 2102. The first reinforcing insulating layer 2101 is formed up to the outer diameter of the third insulating layer 14A3 of the cable 100A and the innermost layer 2101A, the first intermediate layer 2101B, and the second intermediate layer 2101B of the reinforcing insulating layer 210 2101C). The second reinforcing insulating layer 2102 may be formed on the first reinforcing insulating layer 2101. That is, the second reinforcing insulating layer 2102 may be laminated in the radial direction of the first reinforcing insulating layer 2101. The second reinforcing insulating layer 2102 may be the outermost layer 2101D of the reinforcing insulating layer 210.

2 and 6, the first reinforcing insulating layer 2101 may be formed by restoring to the outer diameter of the cable insulating layer 14A on the conductor compression sleeve 1P. The first reinforcing insulating layer 2101 has slopes at both ends so as to have a shape corresponding to the ends of the pen slings ends 14a1, 14a2 and 14a3 of the cable insulation layer 14A exposed to have a slope shape By winding an insulating paper.

The first reinforcing insulating layer 2101 has an inclined surface at both ends and is in contact with each of the pen slings 14a1, 14a2 and 14a3 of the cable insulating layer 14A. The first reinforcing insulating layer 2101 has both end portions of the first reinforcing insulating layer 2101 A sufficient interface length can be secured compared with the case where each of the pen slings 14a1, 14a2 and 14a3 of the cable insulation layer 14A contacts vertically without a slope. As the interface length between the first reinforcing insulating layer 2101 and the cable insulating layer 14A increases, the surface electric field characteristics between the first reinforcing insulating layer 2101 and the cable insulating layer 14A can be improved.

Therefore, as shown in FIGS. 2 and 6, the interfacial length between the first reinforcing insulating layer 2101 and the cable insulating layer 14A is increased by pen-slitting the cable insulating layer 14A in multiple steps and forming an inclined surface at the end portion thereof . Furthermore, by reducing the angle of the inclined surfaces of the respective ends of the cable insulating layer 14A, the interface length between the first reinforcing insulating layer 2101 and the cable insulating layer 14A can be further increased. The increase of the interfacial length can further improve the surface electric field characteristics between the first reinforcing insulating layer 2101 and the cable insulating layer 14A.

It is not possible to configure the length of the intermediate connection box on the customer's demand, specification, or manufacturing cost for a long time without limitation. As described above, according to the present invention, it is possible to reduce the angle of the inclined surface where the first reinforcing insulating layer 2101 and the cable insulating layer 14A contact with each other within a predetermined intermediate connecting box length without increasing the length of the intermediate connecting box, By increasing the interface length between the layer 2101 and the cable insulating layer 14A, it is possible to maintain a constant surface electric field level without increasing the overall length of the intermediate connection box. Thus, the length of the intermediate connection box can be kept shorter while maintaining a constant level of ground surface electric field, thereby reducing the manufacturing cost of the intermediate connection box.

The second reinforcing insulating layer 2102 may be made of a composite insulating paper having excellent dielectric strength as compared with insulating paper. As an example, the second reinforcing insulating layer 2102 may be made of PPLP, which is a type of composite insulating paper. In this case, the electric field concentrated on the insulating layer 14 and the first reinforcing insulating layer 2101 of the cable 100 having a relatively high temperature during the operation of the cable 100 is referred to as the second reinforcing insulating layer 211, So that the insulation performance of the intermediate connection box 200 can be enhanced.

The second reinforcing insulating layer 2102 which is the outermost layer 2101D of the reinforcing insulating layer 210 may be composed of a straight portion 210A and a slope portion 210B.

The straight portion 210A is formed on the first reinforcing insulating layer 2101 formed to the outer diameter of the cable insulating layer 14A on the conductor crimping sleeve 1P and is configured to be parallel to the longitudinal direction of the cable 100A . The slope portion 210B may be formed so that the width of the slope portion 210B in the longitudinal direction of the cable 100A is narrower at both ends of the straight portion 210A.

The connection box outer semiconductive layer 230 formed by restoring the outer semiconductive layer 16 of the cable 14A is formed along the outer surface of the slope portion 210B of the second reinforcing insulating layer 2102, May be formed to cover the linear portion 210A of the insulating layer 2102. [ The connection semiconductors outer semiconductive layer 230 formed on the outer surface of the slope portion 210B has a slope shape as a whole and the equipotential lines extending from the cable insulation layer 14A to the intermediate connection box 200 are formed in a slope shape Can be distributed according to the geometric shape of the connection semiconductors external semiconductive layer (230). That is, it is possible to control the electric field distribution according to the slope shape of the connection semiconductive layer 230.

The first reinforcing insulating layer 2101 and the second reinforcing insulating layer 2102 may be formed of a plurality of insulating ground layers 212L as shown in FIG. The insulating paper layer 212L is formed by winding insulating paper in a radial direction of the intermediate connection box 210, and each insulating paper layer 212L is not continuous with the wrapping insulating paper. That is, the insulating paper constituting the insulating layer 212L of the same layer is formed of continuous insulating paper, but the insulating paper layer 212L of the other layer is not continuous with the insulating paper. In other words, the insulation layer 212L refers to a radial layer of the intermediate connection box 200 that is not continuous in its longitudinal direction with insulating paper having a certain width and length.

The first reinforcing insulating layer 2101 and the second reinforcing insulating layer 2102 are insulated by using an insulating paper roll wound with insulating paper having a predetermined length. When all of the insulating paper having the predetermined length is wound, Is repeated to form a plurality of insulating ground layers 212L. Since the reinforcing insulating layer 210 can be formed using insulating paper having different widths / lengths for each insulating layer 212L, the size of the first reinforcing insulating layer 2101 and the size of the second reinforcing insulating layer 2102 And can be configured in various forms. Particularly, the slope portion 210B at both ends of the second reinforcing insulating layer 2102 can be formed such that the inclination of the slope portion 210B gradually increases toward the ends of the cable conductors 11A and 11B. That is, since insulating paper having different widths and lengths is used for each insulating layer 212L, the slope of the slope portion 210B can be precisely controlled.

The reinforcing insulating layer 210 may be formed of insulating paper and / or composite insulating paper. The innermost layer 2101A of the reinforcing insulating layer 210 may be formed of insulating paper. The outermost layer 2101D may be a composite insulating paper Lt; / RTI >

Hereinafter, the present invention will be described in detail. 2, between the conductor crimping sleeve 1P and the first cable insulating layer 14A1 located at the innermost side of the cable insulating layer 14A of the cable 100A, Can remain. The remaining space between the compression sleeve (1P) and the first pen sling end (14a1) located at the innermost side of the cable insulation layer (14) can be covered with insulating paper. The insulating paper may be a kraft paper.

In this case, the outermost surface of the innermost layer 2101A made of insulating paper of the reinforcing insulating layer 210 is located at a substantially equal distance from the outermost surface of the first pen sling end 14a1 and the longitudinal center axis of the cable .

The outer surface of the compression sleeve 1P may be surrounded by a semi-conductive tape so as to make the electric field distribution uniform. At this time, when the outer surface of the semi-conductive tape is positioned at a distance from the longitudinal center axis of the cable, from the outer surface of the first pen sling end (14a1) located at the innermost side of the insulating layer (14A) of the cable, The outermost surface of the innermost layer 2101A of the layer 210 may be formed to be located at substantially the same distance from the longitudinal center axis of the cable.

If the outer surface of the innermost layer 2101A made of insulating paper of the reinforcing insulating layer 210 and the first pen sling end 14a1 positioned at the innermost one of the multi-end structures of the cable insulating layer 14A is the length If the step is not formed at substantially the same distance from the directional center axis, the portion where the step is generated acts as an electric field weakening point, so that the electric field may be concentrated and cause dielectric breakdown.

The outermost layer 2101D of the reinforcing insulating layer 210 is formed at an outer diameter of the exposed cable insulation layer 14A of the cable 100. [ Since the exposed conductor 11A of the cable is connected by the compression sleeve 1P, not only the height of the conductor section is increased by the thickness of the compression sleeve 1P but also a relatively large amount of heat is generated in the conduction of the cable. Since the reinforcing insulating layer 210 is formed by winding a plurality of insulating sheets or composite insulating sheets and is relatively vulnerable to insulation, the outermost layer 2101D of the reinforcing insulating layer 210 is formed to have an outer diameter of the cable insulating layer 14A It is necessary to reinforce the insulation performance.

The outermost layer 2101D of the reinforcing insulating layer 210 is composed of a composite insulating paper having an excellent dielectric strength as compared with an insulating paper. In this case, at the time of operating the cable 100, the insulation layer 14 of the cable 100 having a relatively high temperature and the regions 210A to 210C (not shown) located inside the outermost layer 2101D of the reinforcing insulation layer 210 May be dispersed in the outermost layer 2101D of the reinforcing insulating layer 210. [

Intermediate layers 210B and 210C made of a composite insulation layer may be provided between the innermost layer 2101A and the outermost layer 2101D of the reinforcing insulating layer 210. [ The intermediate layer of the reinforcing insulating layer 210 may include a first intermediate layer 2101B and a second intermediate layer 2101C sequentially from the inner side to the outer side between the innermost layer 2101A and the outermost layer 2101D .

The innermost layer 2101A of the reinforcing insulating layer 210 is made of insulating paper and the first intermediate layer 2101B, the second intermediate layer 2101C, and the outermost layer 2101D of the reinforcing insulating layer 210, Can be made of composite insulating paper.

That is, when the innermost layer 2101A of the reinforcing insulating layer 210 is an insulating layer and the first intermediate layer 2101B and the second intermediate layer 2101C are composite insulating paper, the electric field is distributed according to the resistivity The electric field is applied to the first intermediate layer 2101B and the second intermediate layer 2101C which are formed of composite insulating paper having a relatively higher resistivity than the kraft paper as the insulating paper of the innermost layer 2101A according to the resistive electric field distribution characteristic of the DC power cable It is widely distributed. Accordingly, the relatively high temperature in the operation of the cable causes the contraction / expansion of the insulating oil to be relatively actively generated, so that there is a high possibility that bubbles are generated, and the electric field to be distributed to the innermost layer 2101A, So that the insulation performance of the intermediate connection box can be stabilized.

In addition, since the remaining regions 210B to 210D except for the innermost layer 2101A of the reinforcing insulating layer 210 are all covered with the composite insulating paper, the productivity is improved, productivity can be improved remarkably, and the defective ratio can be further reduced .

Meanwhile, in another embodiment, the reinforcing insulating layer 210 may include a first intermediate layer 2101B made of composite insulating paper and a second intermediate layer 2101C made of insulating paper.

The first intermediate layer 2101B and the second intermediate layer 210C provided between the innermost layer 2101A and the outermost layer 2101D of the reinforcing insulating layer 210 may have a second pen sling end 14a2 and a second inter- And may be disposed at the same distance from the center of the third pen slings end 14a3 and the cable 100A.

In this case, since the innermost layer 2101A of the reinforcing insulating layer 210 is composed of an insulating ground layer and the first intermediate layer 2101B is composed of composite insulating paper, the resistive electric field of the direct current power cable, A large amount of electric field is distributed to the first intermediate layer 2101B formed of a composite insulating paper having a relatively higher resistivity than the kraft paper of the innermost layer 2101A of the reinforcing insulating layer 210 according to the distribution characteristics. Therefore, the electric field is distributed to the innermost layer 2101A of the reinforcing insulating layer, which is relatively vulnerable to insulation due to a high possibility of bubbling due to relatively high temperature during the operation of the cable and contraction / expansion of the insulating oil. So that it is possible to stabilize the insulation performance.

The connection box outer semiconductive layer 230 may be formed on the outer surface of the slope portion 210B of the second reinforcing insulating layer 2102 and on the straight portion 210A. The connection box outer semiconducting layer 230 can be energized with the outer semiconductive layer 16 or the metal sheath layer 22 of the cable 100.

A metal shielding layer 260 may be formed on the connection box outer semiconductive layer 230. That is, the connection box outer semiconductive layer 230 is disposed between the second reinforcing insulating layer 2102 and the metal shielding layer 260, and the cable insulating layers 14A and 14B, the reinforcing insulating layer 210, It is possible to prevent an abrupt change in the electric field between the second reinforcing insulating layer 2102 and the metal shielding layer 260 because the second reinforcing insulating layer 2102 has a lower volume resistivity than the layer 220. [ The second reinforcing insulating layer 2102 and the metal shielding layer 260 can be smoothly energized.

The connection box outer semiconductive layer 231 disposed on the straight portion 210A of the second reinforcing insulating layer 2102 may be formed so as to surround the straight portion 210A of the second reinforcing insulating layer 2102, For example, carbon black having semi-conductive properties can be formed by extrusion.

The connection box outer semiconductive layer 232 disposed on the slope portion 210B of the second reinforcing insulating layer 2102 is formed by restoring the cable semiconductive layer 16 along the outer surface of the slope portion 210B. The connection box outer semiconductive layer 232 is formed in a slope shape corresponding to the outer surface of the slope portion 210B so that an equipotential line continuing from the cable insulation layer 14A to the intermediate connection box 200 is connected to the outer side The electric field can be controlled so as to be distributed according to the geometrical shape of the semiconductive layer 232.

The metal shielding layer 260 may be formed on the connection semiconductive outer layer 230. The metal shielding layer 260 is formed on the connection port outer semiconducting layer 231 formed on the straight portion 210A of the second reinforcing insulating layer 2102 and the second reinforcing insulating layer 2102 is formed on the connection port outer semiconducting layer 231, May also be formed on the junction box outer semiconducting layer 232 formed on the slope portion 210B of the junction box. The metal shielding layer 260 may be energized with the metal sheath layer 22 of the electromagnetic wave shielding and cable to serve as a fault current path.

The metal shielding layer 260 formed on the straight portion 210A of the second reinforcing insulating layer 2102 may be formed by attaching a metal plate. The metal plate is perforated so that the insulating oil can pass through the metal plate to impregnate the insulating paper of the reinforcing insulating layer 210.

The metal shielding layer 260 formed on the slope portion 210B of the second reinforcing insulating layer 2102 may be formed of a metal wire such as a metal wire or a metal strip. Since the metal shielding layer 260 is formed of the metal wire and the metal shielding layer 260 can be easily formed along the slope of the slope portion 210B and the insulating oil can move between the metal wires, It is easy.

The passivation layer 270 may be disposed between the metal shield layer 260 and the spacer 250. The protective layer 270 may be formed by winding a PPLP or kraft paper on the metal shielding layer 260.

The protective layer 270 can prevent the metal shield layer 260 from being damaged by the spacer 250. Specifically, the spacer 250 has a disk shape having a through hole therein, and is fitted outside the reinforcing insulating layer 210. A scratch is generated on the surface of the metal shielding layer 260 formed on the reinforcing insulating layer 210 when the spacer 250 is fitted to the reinforcing insulating layer 210 or a load is applied to the spacer 250, The metal shielding layer 260 may be pressed to cause an edge portion. The protective layer 270 is formed between the spacer 250 and the metal layer so as to prevent the metal shield layer 260 from being damaged by the spacer 250 and to prevent damage to the surface, Concentration can be prevented.

The spacers 250 may be fitted outside the reinforcing insulating layer 210 through the through holes to maintain a gap between the copper pipes 240 and the reinforcing insulating layer 210. Particularly, as shown in FIG. 9, the spacer 250 may have a through hole in its inside and a plurality of recesses may be formed on the outer side in a radial direction. The insulating oil in the copper pipe 240 passes through the concave portion. That is, the insulating oil injected into the copper pipe 240 when the insulating oil is impregnated can smoothly move in the longitudinal direction of the intermediate connection box 200 through the recesses. If there is no insulating oil passage such as the recess 251, the spacer 250 can be moved when insulated oil is injected. In order to prevent the movement of the spacer 250, metal wires are additionally wound on both sides of the spacer 250 .

The spacer 250 may be formed of aluminum.

A metal shielding layer 260 and a protective layer 270 sequentially formed on the linear portion 210A of the second reinforcing insulating layer 2102 as shown in FIG. Both end portions may have inclined surfaces. That is, both ends may have a tapered shape in the radial direction of the second reinforcing insulating layer 2102. As an example, the inclined surfaces may be formed in a manner that the amount of the connection semiconductive outer semiconductive layer 230, the metal shielding layer 260, and the protective layer 270 sequentially stacked on the straight portion 210A of the second reinforcing insulating layer 2102 And may be formed by removing the end portions.

By forming the inclined surfaces at the end portions of the connection semiconductors outer semiconductive layer 230, the metal shielding layer 260, and the protective layer 270 formed on the straight portion 210A, it is possible to prevent the edges at the end portions from being formed , Thereby preventing the electric field concentration due to edge formation.

Particularly, when the inclined end portion is adjacent to the slope portion 210B of the reinforcing insulating layer 210, the electric field relieving portion 281 may be formed in a region where the inclined surface and the outer surface of the passivation layer 270 meet have. The electric field relieving portion 281 may be formed by winding a semiconductive wrinkle paper 281 on a region where the inclined surface and the outer surface of the protective layer 270 meet. Since the electric field relaxation unit 281 surrounds the edge formed in the region where the inclined surface meets the outer surface of the passivation layer 270, it is possible to prevent the electric field from being concentrated due to the edge formation.

8, when a slope is generated between the sloped end portion and the connection hermetic outer semiconductive layer 230 formed in the slope portion 210B of the reinforcing insulating layer 210, the slope portion 210B The half-conductive wrinkle paper 282 can be further wound on the outer semiconductive layer 230 on the outer semiconductive layer 230 so that the level difference can be minimized. Thus, the edge portion is not formed, and the electric field can be prevented from concentrating along the edge portion.

The protective copper tube 240 is then covered. The protective copper pipe 240 protects the inside of the connection box from the outside and is energized with the metal sheath 22 of the cable 100 to serve as a path for the fault current.

As described above, according to one embodiment of the present invention, by forming the perforated metal shielding layer 260 on the second reinforcing insulating layer 2102, the insulating oil moves in the gravity direction to form the perforated metal shielding layer 260 And an insulating oil passage is provided in the spacer 250 so that the insulating oil can smoothly flow in the longitudinal direction of the intermediate connection box. Accordingly, when the insulation oil shrinks or expands due to a change in temperature when the cable is energized, it is possible to prevent the insulation oil from flowing smoothly inside the intermediate connection box and locally increasing the internal pressure of the intermediate connection box.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments.

The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: Cable
11: Conductor
12: inner semiconductive layer
14: Insulating layer
16: outer semiconductive layer
200: Medium connection
210: reinforced insulation layer
230: Outer sheath layer

Claims (20)

1. A direct current power cable intermediate connection system comprising a pair of direct current power cables each having a conductor, an inner semiconductive layer, a cable insulation layer and an outer semiconductive layer, and an intermediate connection box connecting the pair of direct power cables to each other,
Wherein the pair of DC power cables are provided such that the respective ends of the conductor, the inner semiconductive layer, the cable insulating layer, and the outer semiconductive layer, which are sequentially exposed,
The intermediate junction box includes:
A conductor connecting portion for electrically connecting the conductors of the pair of cables to each other; And
A first reinforcing insulating layer having an insulating paper wound around the conductor connecting portion, the exposed inner semiconductive layer and the cable insulating layer to form an outer diameter of the cable insulating layer and having inclined surfaces at both ends in the longitudinal direction; A reinforcing insulation layer and a cable insulation layer surrounding the cable insulation layer and having a width in the cable longitudinal direction and a width in the radial direction of the cable, A reinforcing insulating layer including a second reinforcing insulating layer having a slope portion formed therein;
A connection box outer semiconductive layer formed along the outer surface of the slope portion of the second reinforcing insulating layer and having a slope shape by itself and made of a semiconductive material;
A metal shielding layer formed on the semi-conductive layer outside the connection box;
A copper pipe surrounding the reinforcing insulation layer and a portion of the power cable and including an insulating oil therein; And
And a spacer for maintaining a gap between the copper tube and the metal shielding layer,
The metal shielding layer is perforated so that the insulating oil in the copper tube can move to the reinforcing insulating layer through the penetration of the metal shielding layer,
The spacer
A through hole having an inside diameter larger than an outside diameter of the second reinforcing insulating layer; And
A concave portion facing the through-hole; / RTI >
And the insulating oil in the copper pipe can flow in the longitudinal direction of the intermediate connection box through the recessed portion. The method according to claim 1,
Wherein the metal shield layer
A perforated metal plate is formed on the linear portion of the second reinforcing insulating layer,
And a metal wire is wound on the slope portion of the second reinforcing insulating layer. delete The method according to claim 1,
And a protective layer formed on the metal shield layer,
Wherein the protective layer protects the metal shielding layer when the spacer is fitted on the second reinforcing insulating layer through the through hole. 5. The method of claim 4,
Wherein the protective layer comprises PPLP or kraft paper. The method according to claim 1,
Wherein the connection box outer semiconductive layer is formed so as to surround a slope portion and a straight portion of the second reinforcing insulation layer. The method according to claim 1 or 4,
And the both ends of the connection half-shell outer semiconductive layer, the metal shielding layer, and the protection layer, which are sequentially formed on the second reinforcing insulating layer, are tapered in the radial direction of the second reinforcing insulating layer. Intermediate access system. The method according to claim 1 or 4,
Shielding layer and the protection layer, which are sequentially formed on the second reinforcing insulating layer, are peeled off from both ends of the connection-side outer semiconductive layer, the metal shielding layer, and the protection layer. 9. The method of claim 8,
And the electric field mitigating portion is provided at a portion where both ends of the outer semiconductive layer, the metal shielding layer, and the protection layer are separated from each other. 10. The method of claim 9,
Wherein the electric field mitigation portion is formed by winding a half-conductive wrinkle paper. A DC power cable for connecting a pair of DC power cables having a conductor, an inner semiconductive layer, a cable insulation layer and an outer semiconductive layer, the conductor, the inner semiconductive layer, the cable insulating layer and the outer semiconductive layer sequentially exposed at an end thereof, In an intermediate connection case for a power cable,
A conductor connecting portion for electrically connecting the conductors of the pair of cables to each other; And
A first reinforcing insulating layer having an insulating paper wound around the conductor connecting portion, the exposed inner semiconductive layer and the cable insulating layer to form an outer diameter of the cable insulating layer and having inclined surfaces at both ends in the longitudinal direction; A reinforcing insulation layer and a cable insulation layer surrounding the cable insulation layer and having a width in the cable longitudinal direction and a width in the radial direction of the cable, A reinforcing insulating layer including a second reinforcing insulating layer having a slope portion formed therein;
A connection box outer semiconductive layer formed along the outer surface of the slope portion of the second reinforcing insulating layer and having a slope shape by itself and made of a semiconductive material;
A metal shielding layer formed on the semi-conductive layer outside the connection box;
A copper pipe surrounding the reinforcing insulation layer and a portion of the power cable and including an insulating oil therein; And
And a spacer for maintaining a gap between the copper tube and the metal shielding layer,
The metal shielding layer is perforated so that the insulating oil in the copper tube can move to the reinforcing insulating layer through the penetration of the metal shielding layer,
The spacer
A through hole having an inside diameter larger than an outside diameter of the second reinforcing insulating layer; And
A concave portion facing the through-hole; / RTI >
And the insulating oil in the copper pipe can flow in the longitudinal direction of the intermediate connection box through the recessed portion. 12. The method of claim 11,
Wherein the metal shield layer
A perforated metal plate is formed on the linear portion of the second reinforcing insulating layer,
And a metal wire is wound on the slope portion of the second reinforcing insulating layer. delete 12. The method of claim 11,
And a protective layer formed on the metal shield layer,
Wherein the protective layer protects the metal shielding layer when the spacer is fitted on the second reinforcing insulating layer through the through hole. 15. The method of claim 14,
Wherein the protective layer comprises PPLP or kraft paper. 12. The method of claim 11,
Wherein the connection box outer semiconductive layer is formed so as to surround a slope portion and a straight portion of the second reinforcing insulation layer. 15. The method according to claim 11 or 14,
And the both ends of the connection half-shell outer semiconductive layer, the metal shielding layer, and the protection layer, which are sequentially formed on the second reinforcing insulating layer, are tapered in the radial direction of the second reinforcing insulating layer. Medium connection box. 15. The method according to claim 11 or 14,
Wherein the connection terminal outer semiconductive layer, the metal shielding layer, and the protection layer, which are sequentially formed on the second reinforcing insulating layer, are peeled off. 19. The method of claim 18,
An intermediate layer for the direct current power cable, and an electric field relieving portion at the both ends of the outer semiconductive layer, the metal shield layer and the protective layer. 20. The method of claim 19,
Wherein the electric field relaxation portion is formed by winding a half-conductive wrinkle paper.

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