WO2018182075A1

WO2018182075A1 - Power cable

Info

Publication number: WO2018182075A1
Application number: PCT/KR2017/003583
Authority: WO
Inventors: 고경로
Original assignee: 엘에스전선 주식회사
Priority date: 2017-03-30
Filing date: 2017-03-31
Publication date: 2018-10-04

Abstract

The present invention relates to a power cable, particularly, an ultra-high voltage underground or submarine cable for long-distance direct current transmission. Specifically, the present invention relates to a power cable in which an insulating layer has high dielectric strength, and an electric field applied from the insulating layer to a metal sheath is uniformly and effectively relieved and, particularly, a return circuit of a fault current is effectively ensured when a grounding or short-circuit accident of the cable occurs, thereby enabling safety to be promoted, insulating oil is impregnated well during manufacturing process, and problems such as damage of metalized paper are removed during cable manufacturing.

Description

Power cable

The present invention relates to power cables, in particular ultra high voltage underground or submarine cables for long distance direct current transmission. Specifically, the present invention has a high insulation strength of the insulating layer itself, the electric field applied from the insulating layer to the metal sheath is effectively alleviated uniformly, in particular, the return of the fault current is effectively ensured in the event of a ground fault or short circuit of the cable The present invention relates to a power cable which can achieve safety and has no problem such as breakage of metallized paper when the cable is manufactured, while impregnating the insulating oil in the manufacturing process.

As an insulating layer, a power cable using a polymer insulator such as crosslinked polyethylene (XLPE) is used.However, due to a problem of forming a space charge in a DC high electric field, an ultra-high voltage DC power transmission cable is impregnated with insulating oil in a cross winding insulating paper so as to surround a conductor. Paper-insulated cables having an insulating layer are used.

The ground insulation cable includes an OF (Oil Filled) cable for circulating low viscosity insulation oil, a Mass Impregnated Non Draining (MIND) cable impregnated with high viscosity insulation oil, and the OF cable has a limitation in the transmission length of hydraulic pressure for circulation of the insulation oil. It is not suitable for long distance transmission cables, and in particular, there is a problem that it is difficult to install insulating oil circulation facilities on the seabed, which is not suitable for submarine cables.

Therefore, MIND cable is commonly used for long distance direct current transmission or subsea high voltage cable.

Figure 1 schematically shows the longitudinal cross-sectional structure of a conventional MIND cable.

As shown in FIG. 1, a conventional MIND cable includes a conductor 10, an inner semiconducting layer 20 surrounding the conductor 10, an insulating layer 30 surrounding the inner semiconducting layer 20, and the insulation. An outer semiconducting layer 40 surrounding the layer 30, a metal sheath layer 50 surrounding the outer semiconducting layer 40, a cable protection layer 60 surrounding the metal sheath layer 50, and the like. can do.

The insulating layer 30 is formed by impregnating the insulating paper wrapped in a plurality of layers in the insulating oil, the insulating paper is used, for example, kraft paper (Kraft paper), or a thermoplastic such as kraft paper and polypropylene (Polypropylene) resin Semi-synthetic paper laminated with resin can be used, or kraft paper and semi-synthetic paper can be used simultaneously. In addition, the inner semiconducting layer 20 and the outer semiconducting layer 40 are formed by transversely winding semi-conductive paper such as carbon paper treated with carbon black on insulating paper.

In particular, the outer semiconducting layer 40 may be secured with the metal sheath layer 50 between the metal sheath layer 50 so that the return of the fault current is effectively secured in the event of a ground fault or a short circuit of the cable. The metallization layer 42 may be further included for smooth electrical contact.

Specifically, the outer semiconducting layer 40 is a metallized paper in which metal foils 42b such as aluminum tape, aluminum foil, copper foil, etc. are laminated on the lower layer 41 and the kraft paper 42a, which are transversely wound into a plurality of layers. The metallization paper layer 42 transversely winding 42A may be included.

However, the outer semiconducting layer 40 structurally contacts the kraft paper 42a introduced to reinforce the insufficient tensile strength of the metallized paper 42A and the semiconductor cell of the lower layer 41, so that the kraft The electrical resistance between the semiconductor cell of the lower layer 41 and the metal sheath layer 50 is not smooth due to the insulation resistance of the paper 42a, resulting in nonuniformity between the insulating layer 30 and the metal sheath layer 50. An electric field distribution may be formed to lower the dielectric strength of the insulating layer 30.

Furthermore, in case of a cable break or other cause, as a result, in case of a ground fault or a short circuit accident, the return of the fault current may not be effectively ensured, which may cause a safety problem.

In addition, in the manufacturing process of the MIND cable, there is a process of impregnating the insulating oil in the insulating layer, and in general, the insulating oil is kraft paper, which is an insulating paper well penetrated, there is no difficulty in impregnation, but the metal foil forming the metallized paper does not transmit, In order to make the insulating oil impregnated by making a hole in the insulation oil, the impregnating passage of the insulating oil is made. Especially in the MIND cable, high viscosity oil is used as the insulating oil. If the perforation is too large, it may cause a problem of not giving a constant sheet tension when the paper roll is rolled.

Therefore, the insulation strength of the insulation layer is high, and the electric field applied from the insulation layer to the metal sheath is uniformly and effectively alleviated, and in particular, the return of fault current is effectively ensured in the event of a ground fault or a short circuit of the cable, thereby promoting safety. In the manufacturing process, while the impregnation of the insulating oil is good, there is an urgent need for a power cable without problems such as breakage of metallized paper during cable manufacturing.

SUMMARY OF THE INVENTION An object of the present invention is to provide a power cable having a high insulation strength of an insulation layer and which can effectively relax an electric field applied from the insulation layer to the metal sheath.

In addition, an object of the present invention is to provide a power cable capable of effectively ensuring the return of the fault current in the event of a ground fault or a short circuit of the cable.

In addition, it is an object of the present invention to provide a power cable that is well impregnated with insulating oil in the manufacturing process and does not cause problems such as breakage of metallized paper during cable manufacturing.

In order to solve the above problems, the present invention,

Conductor; An inner semiconducting layer surrounding the conductor; An insulating layer surrounding the inner semiconducting layer and impregnated with insulating oil; An outer semiconducting layer surrounding the insulating layer; A metal sheath layer surrounding the outer semiconducting layer; And a cable protection layer surrounding the metal sheath layer, wherein the outer semiconducting layer comprises a lower layer formed by a transverse winding of a semi-conductive paper and an upper layer formed by the void of a metallization paper and a semiconductor cell on the lower layer. Includes, wherein the metallized paper is a metal foil laminated on the base paper, to provide a power cable.

Here, the semiconductor battery includes carbon paper treated with carbon black on an insulating paper, and the base paper includes kraft paper or semi-conductive paper, and the metal foil is aluminum tape, copper tape, It provides a power cable, characterized in that it comprises one or more kinds of aluminum foil and copper foil.

In addition, the lower layer includes one or more layers formed by the transverse winding of the semiconducting battery, and when transversely winding the semiconducting battery, it is transversely wound with a constant gap so that the semiconducting cells of the same layer do not overlap. Provide a power cable.

And an overlap ratio of 20 to 80%, wherein the semiconductor battery overlaps on the metal paper based on the total width of the metal paper when the metallization paper and the semiconductor battery are in the upper layer. To provide a power cable.

Further, the metallized paper provides a power cable, characterized in that a plurality of perforations through which the insulating oil can pass.

Here, the area ratio of the entire perforations included therein per unit area of the metallized paper is 4 to 15%, it provides a power cable.

In addition, between the upper layer and the metal sheath layer, a non-woven fabric is further provided, characterized in that it further comprises a copper wire direct fabric in which copper wire is a copper wire directly inserted.

Meanwhile, the insulating layer includes an inner insulating layer, an intermediate insulating layer, and an outer insulating layer, and the inner insulating layer and the outer insulating layer are each formed of kraft paper impregnated with insulating oil, and the middle insulating layer Silver is formed of a semi-synthetic paper impregnated with an insulating oil, the semi-synthetic paper comprises a plastic film and kraft paper laminated on at least one side of the plastic film, the resistivity of the inner insulating layer and the outer insulating layer is less than the resistivity of the intermediate insulating layer It is characterized by providing a power cable.

Here, based on the total thickness of the insulating layer, the thickness of the inner insulating layer is 1 to 10%, the thickness of the intermediate insulating layer is 75% or more, the thickness of the outer insulating layer is 5 to 15%. A power cable is provided.

In addition, there is provided a power cable, characterized in that the thickness of the outer insulation layer is larger than the thickness of the inner insulation layer.

On the other hand, the insulating oil provides a power cable, characterized in that the high viscosity insulating oil having a kinematic viscosity of 60 ℃ or more than 500 centistokes (Cst).

In addition, the cable protection layer, characterized in that it comprises an inner sheath, a bedding layer, a metal reinforcing layer and an outer sheath, provides a power cable.

And, the cable protective layer further provides a power cable, characterized in that it further comprises an outer wire and the outer serving layer.

The power cable according to the present invention has a high dielectric strength of its own by precisely designing the structure of the insulating layer and uniform electric field distribution between the insulating layer and the metal sheath layer by smooth electrical contact between the outer semiconducting layer and the metal sheath layer. It shows an excellent effect that can form.

In addition, the power cable according to the present invention by precisely designing the structure of the outer semiconducting layer by the smooth electrical contact between the outer semiconducting layer and the metal sheath layer effectively ensures the return of the fault current in the event of a ground fault or short circuit of the cable to ensure safety It shows an excellent effect that can be planned.

1 schematically illustrates a longitudinal cross section of a conventional MIND cable.

Figure 2 shows schematically a cross section of a power cable according to the invention.

3 is a schematic cross-sectional view of the power cable of FIG. 2.

4 is a graph schematically illustrating a process in which an electric field is relaxed in an insulating layer of a power cable according to the present invention.

FIG. 5 schematically illustrates a cross-sectional structure of a semi-synthetic paper forming an intermediate insulating layer of the power cable shown in FIG.

FIG. 6 is an enlarged view of a metal foil applied to the metallized paper of the outer semiconducting layer in FIG. 3.

Hereinafter, preferred embodiments of the present invention will be described in detail. However, the invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosure may be made thorough and complete, and to fully convey the spirit of the present invention to those skilled in the art. Like numbers refer to like elements throughout.

2 and 3 schematically show the cross-sectional and longitudinal cross-sectional structures of one embodiment of a power cable according to the invention, respectively.

As shown in FIGS. 2 and 3, the power cable according to the present invention includes a conductor 100, an inner semiconducting layer 200 surrounding the conductor 100, and an insulating layer surrounding the inner semiconducting layer 200 ( 300, an outer semiconducting layer 400 surrounding the insulating layer 300, a metal sheath layer 500 surrounding the outer semiconducting layer 400, and a cable protection layer surrounding the metal sheath layer 500 ( 600) and the like.

The conductor 100 is a movement path for electric current for transmission, and has high electrical conductivity to minimize power loss, and has high purity copper (Cu), aluminum (Al), etc. having appropriate strength and flexibility required for use as a conductor of a cable. In particular, it may be made of a linkage line having a high elongation and a high conductivity. In addition, the cross-sectional area of the conductor 100 may be different depending on the amount of power transmission, the use of the cable.

Preferably, the conductor 100 may be composed of a circular compression conductor compressed by placing a flat element wire in multiple layers on a flat conductor or a circular center line composed of multiple flat angle wires on a circular center line. In addition, the conductor 100 made of a flat conductor formed by a so-called keystone method has a high area ratio of the conductors, so that the outer diameter of the cable can be reduced, and the cross-sectional area of each element wire can be formed to be large. It is economical because it can reduce the number.

The inner semiconducting layer 200 suppresses uneven electric field lines or conductor surface electric field distribution on the surface of the conductor 100, mitigates electric field distribution of cable internal insulation, and gaps between the conductor 100 and the insulating layer 300. It removes the electric field applied to the circuit and suppresses partial discharge and insulation breakdown at the part.

The inner semiconducting layer 200 may be formed of a semi-conductive paper such as a film formed from a polymer composite material in which conductive material such as carbon black or carbon black coated with conductive material such as carbon black is coated on insulating paper. It may be formed by, the thickness of the inner semiconducting layer 200 may be about 0.2 to 3.0 mm.

The insulating layer 300 is formed by wrapping the insulating paper in a plurality of layers, and the insulating paper is, for example, using a kraft paper or a semi-synthetic paper in which a thermoplastic resin such as kraft paper and a polypropylene resin is laminated. Can be used.

According to a preferred embodiment of the present invention, the insulating layer 300 includes an inner insulating layer 310, an intermediate insulating layer 320 and an outer insulating layer 330, the inner insulating layer 310 and the outer The insulating layer 330 is made of a material having a lower resistivity than the intermediate insulating layer 320, whereby the inner insulating layer 310 and the outer insulating layer 330 are each connected to the conductor 100 when the cable is operated. To suppress the application of a high electric field formed by applying a direct current above the conductor 100 or directly below the metal sheath layer 500, and further suppress the deterioration of the intermediate insulating layer 320 It works for.

4 is a graph schematically illustrating a process in which an electric field is relaxed in an insulating layer of a power cable according to the present invention. As shown in FIG. 4, a direct current (DC) electric field is relaxed in the inner insulation layer 310 and the outer insulation layer 330 having a relatively low resistivity, thereby directly above the conductor 100 and directly below the metal sheath layer 500. In addition to effectively suppressing the application of a high electric field generated in a conventional DC cable, in the case of an impulse, an internal insulation layer is controlled while controlling the maximum impulse electric field applied to the intermediate insulation layer 320 to 100 kV / mm or less. Since the high impulse electric field applied is reduced to suppress the deterioration of the internal insulating layer 310, the deterioration of the intermediate insulating layer 320 can also be suppressed. Here, the impulse electric field means an electric field applied to the cable when an impulse voltage is applied to the cable.

Therefore, as shown in FIG. 4, the maximum impulse electric field value of the internal insulation layer is designed to be smaller than the maximum impulse electric field value of the intermediate insulation layer so that the high electric field does not act directly on the conductor or directly under the sheath. The maximum impulse electric field applied to 320 is an inner electric field of the intermediate insulating layer 320, and the inner electric field is controlled to an allowable impulse electric field of the intermediate insulating layer 320, for example, 100 kV / mm or less. Deterioration of the insulating layer 320 can be suppressed.

Therefore, the high electric field is suppressed from being applied to the inner insulation layer 310 and the outer insulation layer 330, particularly a cable connection member vulnerable to an electric field, and further, the performance with the intermediate insulation layer 320 can be minimized. It is possible to suppress the deterioration and to suppress the decrease in the dielectric strength and other physical properties of the insulating layer 300, resulting in a compact cable with a higher impulse withstand voltage than the cable. Shortening can be suppressed.

According to an embodiment of the present invention, the inner insulating layer 310 and the outer insulating layer 330 may be formed by transversely kraft paper made of kraft pulp and impregnated with an insulating oil, respectively. The insulating layer 310 and the outer insulating layer 330 may have a lower resistivity and a higher dielectric constant than the intermediate insulating layer 320. The kraft paper can be prepared by washing the kraft pulp with deionized water in order to remove the organic electrolyte in the kraft pulp to obtain good dielectric loss tangent and permittivity.

The intermediate insulating layer 320 may be formed by transversely winding a semi-synthetic paper having kraft paper laminated on either or both of the top and bottom surfaces of the plastic film and impregnating insulating oil. The intermediate insulating layer 320 formed as described above has a higher resistivity, lower dielectric constant, higher DC breakdown voltage, and impulse breakdown voltage than the inner insulation layer 310 and the outer insulation layer 330 because it includes a plastic film. Due to the high resistivity of the intermediate insulating layer 320, it is possible to reduce the outer diameter of the cable by direct current and by impulse by low dielectric constant.

In the semi-synthetic paper forming the intermediate insulating layer 320, the plastic film prevents the insulating oil impregnated in the insulating layer 300 from moving toward the outer semiconductive layer 400 due to heat generation during operation of the cable. The production of deoiled voids due to the movement of the insulating oil can be suppressed, and as a result, electric field concentration and insulation breakdown by the deoiled voids can be suppressed. Here, the plastic film may be made of a polyolefin resin such as polyethylene, polypropylene, polybutylene, fluorine resin such as tetrafluoroethylene-hexafluoro polypropylene copolymer, ethylene-tetrafluoroethylene copolymer, Preferably it may be made of a polypropylene homopolymer resin excellent in heat resistance.

In addition, the semi-synthetic paper may be 40 to 70% of the total thickness of the plastic film. When the thickness of the plastic film is less than 40% of the total thickness of the semi-synthetic paper, the resistivity of the intermediate insulating layer 320 may be insufficient to increase the outer diameter of the cable, whereas when the thickness of the plastic film is greater than 70%, the manufacture of the semi-synthetic paper is remarkably difficult. It can be expensive and expensive.

The inner insulating layer 310 may have a thickness of 1 to 10% of the total thickness of the insulating layer 300, and the outer insulating layer 330 may have a thickness of 5 to 15% of the total thickness of the insulating layer 300. The intermediate insulating layer 320 may have a thickness of 75% or more of the total thickness of the insulating layer 300. As a result, the maximum impulse electric field value of the inner insulation layer 310 may be lower than the maximum impulse electric field value of the intermediate insulation layer 320. If the thickness of the inner insulation layer is increased more than necessary, the maximum impulse electric field value of the intermediate insulation layer 310 becomes larger than the allowable maximum impulse electric field value, and in order to alleviate this, the cable outer diameter is increased. Done. In addition, the outer insulating layer 330 preferably has a sufficient thickness than the inner insulating layer, which will be described later.

In addition, in the present invention, the internal insulation layer 310 and the external insulation layer 330 having a small resistivity are provided to prevent the direct current high electric field from being applied directly above the conductor 100 and directly below the metal sheath layer 500. In addition, by designing the thickness of the intermediate insulating layer 320 with high resistivity to 75% or more, it is possible to reduce the cable outer diameter.

As such, the inner insulation layer 310, the intermediate insulation layer 320, and the outer insulation layer 330 constituting the insulation layer 300 each have the precisely controlled thickness, so that the insulation layer ( 300 may have a desired dielectric strength while minimizing the outer diameter of the cable. In addition, the DC and impulse electric field applied to the insulating layer 300 can be designed most efficiently, and a high electric field of DC and impulse is applied directly above the conductor 100 and directly below the metal sheath layer 500. It can suppress that, especially the insulation strength of the cable connection member which is weak to an electric field, and the fall of other physical properties can be avoided.

Preferably, the thickness of the outer insulating layer 330 is greater than the thickness of the inner insulating layer 310, for example, in a cable of 500 kV DC, the thickness of the inner insulating layer 310 is 0.1 to 2.0 mm. The thickness of the outer insulating layer 330 may be 1.0 to 3.0 mm, and the thickness of the intermediate insulating layer 320 may be 15 to 25 mm.

Since the heat generated during soft connection for the cable connection according to the present invention is applied to the insulating layer 300 to melt the plastic film of the semi-synthetic paper forming the intermediate insulating layer 320, the plastic from the heat In order to protect the film, it is necessary to sufficiently secure the thickness of the outer insulating layer 330, and it is preferable to be formed thicker than the thickness of the inner insulating layer 310, the thickness of the outer insulating layer 330 It may be 1.5 to 30 times the thickness of the internal insulating layer 310.

In addition, the thickness of the sheet of semi-synthetic paper forming the intermediate insulating layer 320 is 70 to 200 ㎛, the thickness of the kraft paper forming the inner and outer insulating

layers

310, 320 may be 50 to 200 ㎛.

The thickness of the kraft paper forming the inner and outer insulating

layers

310 and 320 is greater than that of the kraft paper constituting the semi-synthetic paper.

If the thickness of the kraft paper forming the inner and outer insulating layers (310,320) is too thin, the strength is insufficient and can be damaged during the transverse winding and the number of the transverse windings to form the insulating layer of the desired thickness increases the productivity of the cable On the other hand, if the thickness of the kraft paper is excessively thick, the total volume of the gap between the kraft papers forming the main passage of the insulating oil in the transverse winding of the kraft paper is reduced, which may take a long time when the insulating oil is impregnated and the amount of the insulating oil impregnated. This may be lowered and thus it may be difficult to achieve the desired dielectric strength.

Since the insulating oil impregnated in the insulating layer 300 uses a high viscosity insulating oil having a relatively high viscosity, unlike the insulating oil used in the conventional OF cable, it is generally not circulated at room temperature and its movement is very slow. The insulating oil may perform a lubrication role to facilitate the movement of the insulating paper when the cable is bent, as well as the function of implementing the desired dielectric strength of the insulating layer 300.

The insulating oil is not particularly limited, but should not be oxidized by heat in contact with the copper and aluminum constituting the conductor 100, and an impregnation temperature, for example, 100 ° C., may be used to facilitate the impregnation of the insulating layer 300. While the viscosity should be sufficiently low above, the cable should have a sufficiently high viscosity so as not to flow down at the operating temperature of the cable, for example, 60-90 ° C. For example, a kinematic viscosity of 60 ° C is 500 centistokes (cSt High viscosity insulating oil, in particular naphthenic insulating oil, polystyrene insulating oil, mineral oil, at least one insulating oil selected from the group consisting of alkyl benzene, polybutene-based synthetic oil, heavy alkylate and the like.

However, the present invention is not limited thereto, and it is also possible to use a medium viscosity insulating oil having a lower viscosity than the high viscosity insulating oil, for example, an insulating oil having a kinematic viscosity of 10 to 500 centistokes (cSt) at 60 ° C.

In the process of impregnating the insulating layer 300 with the insulating oil, the kraft paper constituting the inner insulating layer 310, the intermediate insulating layer 320 and the outer insulating layer 330 are formed to a desired thickness, respectively And semi-wound each of the semi-synthetic papers, and vacuum-dried to remove residual moisture of the insulating layer 300, and thereafter tank the insulating oil heated to an impregnation temperature, for example, 100 to 120 ° C. under a high pressure environment. It may be carried out by impregnating the insulating oil into the insulating layer 300 for a predetermined time under the condition, and then gradually cooling.

The outer semiconducting layer 400 suppresses non-uniform electric field distribution between the insulating layer 300 and the metal sheath layer 500, mitigates electric field distribution, and removes the insulating layer from the various types of metal sheath layer 500. 300) to physically protect.

The outer semiconducting layer 400 may be formed by a transverse winding of a semi-conductive paper such as carbon paper treated with conductive carbon black on insulating paper, for example, a gap winding, that is, a transverse winding in the same layer. The gaps are formed between the semiconducting cells that are traversed with a constant gap so that the cells do not overlap each other, and the gaps formed in an arbitrary layer are formed when there are a plurality of layers in which the semiconducting cells are traversed. It may be formed by the side wound so as to be covered by a semiconductor cell constituting the upper layer and the lower layer of the optional layer, the thickness of the outer semiconducting layer 400 may be about 0.1 to 3.0 mm. When the semiconductor cell is a gap winding, the insulating oil can be easily moved through the gap, thereby shortening the impregnation time of the cable to further improve the production yield.

In particular, as shown in FIG. 3, when the outer semiconducting layer 400 transverses the semiconductor cell, the metallization paper 421 and the semiconductor cell 422 are preferably formed on the lower layer 410 formed by the gap winding. It may further include an upper layer 420 which is formed to be rolled together so that the metal sheet 421 and the semiconductor cell 422 overlap with a predetermined portion, and the upper layer 420 is formed of the metal sheath. Contact with layer 500.

Here, the metallized paper 421 may have a structure in which a metal foil 421b such as aluminum tape, copper tape, aluminum foil, copper foil, etc. is laminated on the base paper 421a, and the base paper 421a is carbon paper. It may be the same semiconductor cell, kraft paper and the like. In addition, a plurality of perforations 421c may be present in the metallized paper 421 so that the insulating oil can easily penetrate the metal paper 421.

In the case where the insulating paper is used as the kraft paper as the base paper 421a of the metallized paper, the outer semiconducting layer 400 has the structure described above so that the semiconductor cell of the lower layer 410 is a peninsula of the upper layer 420. The battery 422 smoothly and electrically contacts the metal foil 421b of the metallization paper 421, thereby smoothly contacting the outer semiconducting layer 400 and the metal sheath layer 500. As a result, in the event of a ground fault or a short circuit of the cable, the return of the fault current can be effectively ensured, and safety can be achieved, and a uniform electric field distribution can be formed between the insulating layer 300 and the metal sheath layer 500. have.

Specifically, when the metallization paper 421 and the semiconductor battery 422 are wound in the upper layer 420, the widths of the metallization paper and the semiconductor battery are generally the same width, but the width of the metallization paper 421 An overlap rate, which is a rate at which the semiconductor battery 422 overlaps the metallized paper 421 based on the entire width, may be 20 to 80%. Here, the pitch when the metallized paper and the semiconductor battery overlap and are rolled up is equal to the size of the width of the metallized paper or within +2 mm. This is because two layers should be formed evenly by the air space. If the space pitch is smaller than the width of the metal paper, three or four layers may be formed, resulting in a thickness deviation, and the space pitch of the metal paper is +2 mm wide. If it becomes larger, there is a one-layer part, which also causes a thickness variation, so that the electrical contact between the metal sheath and the metallization layer is not made uniform, and thus the electric field distribution is not uniform, which may lower the dielectric strength.

In this case, when the overlap rate is less than 20%, when the cable repeats the bending and the bending, the overlapped portions of the overlapped metallization paper 421 and the semiconductor battery 422 are small, and thus the overlapped portion of the cable may be overlapped. When the cable is unfolded after the overlap of the parts is released, the overlapped parts are not overlapped again but collide with each other to be crushed or torn. In addition, the above problems may occur even when the overlap ratio is greater than 80%. In addition to the above problems, the area ratio of the metalized paper and the carbon paper, which appears as an appearance after the side winding, is less than 20% of the metalized paper and the area of the carbon paper. The ratio exceeds 80%, and the purpose of smooth electrical contact between the carbon paper and the metal sheath, which is the original purpose of the metallized paper, cannot be achieved.

As shown in FIG. 6, the metallized paper 421 may include a plurality of perforations 421c to pass the insulating oil. Here, the ratio (perforation area ratio) of the entire area of the plurality of perforations 421c included therein per unit area of the metallization paper 421 may be about 4 to 15%, and when the area ratio is less than about 4%, While the impregnation may not be smooth, the production yield of the cable may be lowered, whereas when the yield is greater than about 15%, the tensile strength of the metallization paper 421 is greatly reduced, so that the metallization paper 421 for forming the upper layer 420 is formed. When the winding of the metallization paper 421 may be broken.

In addition, three or more perforations 421c formed on the metallization paper 421 may be arranged in one column in the width direction of the metallization paper 421, and a plurality of perforations 421c are arranged in a zigzag pattern in each row. The horizontal length S ₁ between the adjacent perforations 421c in the longitudinal direction of the metallization paper 421 and the length S ₂ between the adjacent perforations 421c in the one column are each independently. About 2 to 5 mm.

Here, when the length s ₁ , s ₂ between the perforations 421c is less than 2 mm, the metallized paper 421 may be broken when the metallized paper 421 is rolled at a corresponding portion, whereas the metallized paper 421 may be broken. If the perforation area ratio is low, the impregnation of the insulating oil may not be smooth.

In addition, the shape of the perforation 421c is not particularly limited, and may be, for example, circular, elliptical, square, rectangular, and the like, and are circular in terms of ease of impregnation of insulating oil and securing tensile strength of the metallized paper 421. Preferably, the equivalent diameter d of the perforations 421c may be about 0.9 to 1.1 mm. Here, the circular conversion diameter means a diameter of a circle having the same area as the perforation 421c when the shape of the perforation 421c is not circular.

If the circular conversion diameter (d) of the perforation (421c) is less than 0.9 mm, the impregnation of the insulating oil may not be smooth, whereas if more than 1.1 mm, the tensile strength of the metallization paper 421 is greatly reduced to the upper layer 420 When the metallization paper 421 is wound up to form the metallization paper 421 may be broken. The metallized paper 421 may have a tensile strength of 9.1 kg / 15 mm or more due to the above-described structure and the arrangement, number, and diameter of the perforations 421c included in the metallized paper 421.

The outer semiconducting layer 400 may further include a copper wire direct fabric (not shown) between the upper layer 420 and the metal sheath layer 500. The copper wire direct fabric is a structure in which 2 to 8 strands of copper wire are directly inserted into a nonwoven fabric, and a semiconductor cell, a metal paper, and the like wound up to form the outer semiconducting layer 400 are not released while performing an impregnation process. It functions to bind them firmly so as to maintain a structure and to prevent tearing or scratching from external force, and further, the outer semiconducting layer 400 and the metal sheath layer 500 are formed by the copper wire. It is possible to perform the function of smooth electrical contact.

The metal sheath layer 500 prevents leakage of insulating oil from the inside of the cable and prevents an electric field from going out of the cable to obtain an electrostatic shielding effect, and causes a ground fault or a short circuit of the cable through grounding at one end of the cable. When generated, it acts as a return of the fault current to promote safety, protects the cable from shocks, pressures, etc. outside the cable, and improves the cable's orderability and flame retardancy.

The metal sheath layer 500 may be formed by, for example, a soft sheath made of pure lead or lead alloy. As the metal sheath layer 500, the soft sheath has a relatively low electric resistance, which serves as a large current collector, and can further improve cable ordering, mechanical strength, and fatigue characteristics when formed as a seamless type. have.

In addition, the soft psi is a surface of the anti-corrosion compound, for example, in order to further improve the corrosion resistance, water resistance of the cable and the adhesion between the metal sheath layer 500 and the cable protection layer 600, Blown asphalt, or the like.

The cable protection layer 600 includes, for example, a metal reinforcement layer 630 and an outer sheath 650, and further includes an inner sheath 610 and

bedding layers

620 and 640 disposed above and below the metal reinforcement layer 630. It can be included as. Here, the inner sheath 610 improves the corrosion resistance, the degree of ordering of the cable, and performs a function of protecting the cable from mechanical trauma, heat, fire, ultraviolet rays, insects or animals. The inner sheath 610 is not particularly limited, but may be made of polyethylene having excellent cold resistance, oil resistance, chemical resistance, and the like, or polyvinyl chloride having excellent chemical resistance, flame resistance, and the like.

The metal reinforcement layer 630 may be formed of a galvanized steel tape, a stainless steel tape, etc. to perform a function of protecting a cable from mechanical shock and to prevent corrosion, and the galvanized steel tape may have an anti-corrosion compound on its surface. Can be applied. In addition, the bedding layers 620 and 640 disposed above and below the metal reinforcing layer 630 may perform a function of alleviating impact, pressure, and the like from the outside, and may be formed by, for example, a nonwoven tape.

The outer sheath 650 has substantially the same functions and characteristics as the inner sheath 610, and fires in submarine tunnels, land tunnel sections, etc. are used in the region because they are dangerous factors that greatly affect the safety of personnel or facilities. The outer sheath of the cable is applied to polyvinyl chloride excellent in flame retardant properties, the cable outer sheath of the pipe section can be applied to polyethylene with excellent mechanical strength and cold resistance.

In addition, although not shown here, the metal sheath 500 may be provided with a metal reinforcing layer 630 immediately omitted, and a bedding layer may be provided inside and outside the metal reinforcing layer 630 as necessary. have. That is, the metal sheath layer may be formed to be provided with a bedding layer, a metal reinforcing layer, a bedding layer and an outer sheath sequentially. In this case, since the metal reinforcement layer 630 allows deformation of the metal sheath 500, but suppresses the change in the outer circumference, it is preferable in view of the fatigue characteristics of the metal sheath 500, and the cable insulation layer in the metal sheath 500 during cable energization. Increasing the hydraulic pressure of (300) and, on the contrary, compensates for the lowering of the hydraulic pressure due to shrinkage of the insulating oil due to the temperature drop when the cable is turned off, and the hydraulic pressure is rapidly increased as in the inner semiconducting layer 200 in the high hydraulic pressure portion. It is desirable to have the effect of replenishing the oil by moving the oil to the down portion.

In addition, when the cable is a submarine cable, the cable protection layer 600 may further include, for example, an outer serving layer 670 made of an iron sheath 660 and polypropylene yarn. The outer wire sheath 660, the outer serving layer 670 may perform a function of additionally protecting the cable from the sea current, reefs and the like.

Although the present specification has been described with reference to preferred embodiments of the invention, those skilled in the art may variously modify and change the invention without departing from the spirit and scope of the invention as set forth in the claims set forth below. Could be done. Therefore, it should be seen that all modifications included in the technical scope of the present invention are basically included in the scope of the claims of the present invention.

Claims

Conductor;

An inner semiconducting layer surrounding the conductor;

An insulating layer surrounding the inner semiconducting layer and impregnated with insulating oil;

An outer semiconducting layer surrounding the insulating layer;

A metal sheath layer surrounding the outer semiconducting layer; And

A cable protective layer surrounding the metal sheath layer;

The outer semiconducting layer includes a lower layer formed by a transverse winding of a semi-conductive paper and an upper layer formed by a void of a metallized paper and a semiconducting battery on the lower layer.

The metallized paper is a power cable, characterized in that the metal foil is laminated on the base paper.
The method of claim 1,

The semiconductor cell includes carbon paper treated with carbon black on insulating paper,

The base paper includes kraft paper or semi-conductive paper,

The metal foil is characterized in that it comprises at least one selected from the group consisting of aluminum tape, copper tape, aluminum foil and copper foil, power cable.
The method according to claim 1 or 2,

The lower layer includes one or more layers formed by the transverse winding of the semiconductor cell,

A power cable, characterized in that it is wound with a constant gap so that the semiconductor cells of the same layer do not overlap when the semiconductor battery is rolled up.
The method according to claim 1 or 2,

When the metallization paper and the semiconductor battery in the upper layer, characterized in that the overlap rate is 20 to 80%, the ratio of the semiconductor battery is overlapped on the metallization paper based on the total width of the metallization paper, Power cable.
The method according to claim 1 or 2,

The metallized paper is characterized in that it comprises a plurality of perforations through which the insulating oil can pass, power cable.
The method of claim 5,

The ratio of the area occupied by the entire plurality of perforations included therein per unit area of the metallized paper is 4 to 15%, the power cable.
The method according to claim 1 or 2,

And a copper wire direct fabric in which copper wire, which is a copper wire, is directly inserted into the nonwoven fabric between the upper layer and the metal sheath layer.
The method according to claim 1 or 2,

The insulating layer includes an inner insulating layer, an intermediate insulating layer and an outer insulating layer,

The inner insulating layer and the outer insulating layer are each formed of kraft paper impregnated with insulating oil, and the intermediate insulating layer is formed of a semi-synthetic paper impregnated with insulating oil, and the semi-synthetic paper is at least one of a plastic film and the plastic film. Including kraft paper laminated on one side,

And the resistivity of the inner insulation layer and the outer insulation layer is smaller than that of the intermediate insulation layer.
The method of claim 8,

Based on the total thickness of the insulating layer, the thickness of the inner insulating layer is 1 to 10%, the thickness of the intermediate insulating layer is 75% or more, the thickness of the outer insulating layer is characterized in that 5 to 15%. Power cable.
The method of claim 9,

And the thickness of the outer insulation layer is greater than the thickness of the inner insulation layer.
The method of claim 8,

The insulating oil is a high-viscosity insulating oil having a kinematic viscosity of 60 ℃ or more 500 centistokes (Cst), power cable.
The method according to claim 1 or 2,

Wherein said cable protection layer comprises an inner sheath, a bedding layer, a metal reinforcement layer and an outer sheath.
The method of claim 12,

The cable protective layer is characterized in that it further comprises a wire sheath and an outer serving layer, power cable.