KR101818879B1 - Power cable - Google Patents

Abstract

The present invention relates to a power cable, and more particularly, to an ultra high voltage underground or submarine cable for long distance direct current transmission. Specifically, the present invention relates to the power cable in which the dielectric strength of an insulating layer is high, the electric field applied to the insulating layer is effectively reduced, and especially partial discharge, dielectric breakdown, etc. due to an electric field concentrated on an oil-free void is effectively suppressed by suppressing the oil-free void where insulating oil does not exist from being formed in the insulating layer. Therefore, the lifetime of the power cable can be extended.

Description

Power cable {Power cable}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power cable, in particular, an ultra-high voltage submarine or submarine cable for long distance direct current transmission. More particularly, the present invention relates to a method for manufacturing a semiconductor device, which has a high dielectric strength of the insulating layer itself, effectively alleviates an electric field applied to the insulating layer, and particularly prevents the occurrence of defective voids, The dielectric breakdown and the like caused by the electric field concentrated on the power cable.

A power cable using a polymer insulator such as crosslinked polyethylene (XLPE) is used as an insulating layer. However, since a space charge is formed in a direct current high-voltage system, an ultra-high voltage DC transmission cable is impregnated with insulation oil Insulated cable having an insulating layer is used.

An OF (Oil Filled) cable for circulating a low-viscosity insulating oil, a MIND (Mass Impregnated Non-Draining) cable impregnated with a high viscosity or a medium viscosity oil, and the like, It is not suitable for long-distance transmission cable because there is a limit in length. Especially, it is not suitable for submarine cable because there is a problem that it is difficult to install an oil circulation facility at the seabed.

Therefore, MIND cables are often used for long distance direct current transmission or submarine ultra high voltage cables.

Such a MIND cable is formed by wrapping a plurality of layers of insulating paper such as a semi-synthetic paper in which a thermoplastic resin such as kraft paper, kraft paper and polypropylene resin are laminated in forming an insulating layer, and the inner semiconductive layer The outer semiconductive layer may be formed by wrapping a semiconductive battery such as carbon black paper in a plurality of layers, and the semiconductive paper or semiconductive battery is impregnated with insulating oil.

However, in the conventional MIND cable, insulation oil that forms an insulation layer and a semiconductive layer by heat generation of a conductor during its operation, insulation oil impregnated in a semiconductive battery, and insulation oil filled in a gap generated when the insulation paper and semiconductive battery are wound The insulating fluid impregnated in the insulating layer is moved to the inner and outer sides of the insulating layer. When the heating of the conductor is stopped and the internal temperature of the cable starts to decrease when the energization is stopped, There is a problem that a plurality of deaerated voids are formed in the insulating layer without insulating oil and a partial discharge is generated by an electric field concentrated on the deaerated openings and insulation breakdown occurs .

Therefore, the insulating layer has a high dielectric strength, and the electric field applied to the insulating layer is effectively mitigated. In particular, it is possible to suppress the occurrence of defective voids that do not exist in the insulating layer, A power cable capable of prolonging the life span by effectively suppressing partial discharge and dielectric breakdown by the power cable is in desperate need.

An object of the present invention is to provide a power cable which has a high dielectric strength of an insulating layer itself and can effectively alleviate an electric field applied to the insulating layer to prolong its service life.

Further, the present invention is effective in suppressing generation of deaeration voids that do not have insulating oil in the insulating layer due to shrinkage of insulating oil in a low-temperature environment or during energization off, effectively preventing partial discharge and dielectric breakdown by an electric field concentrated on the voids And to provide a power cable which can be suppressed.

In order to solve the above problems,

Conductor; An inner semiconductive layer surrounding the conductor; An insulating layer surrounding the inner semiconductive layer and impregnated with insulating oil; An outer semiconductive layer surrounding the insulating layer; A metal sheath layer surrounding the outer semiconductive layer; And a cable protective layer surrounding the metal sheath layer, wherein the insulating layer is formed by being transversely oriented and impregnated with insulating oil, and the inner semiconductive layer includes a lower layer stacked on the conductor and an upper layer stacked on the lower layer Wherein the lower layer is formed by a metal sheet or a metallic tape made of a metal material on which a semiconductive battery is laminated on a metal foil, and the upper layer is formed by a transverse winding of a semiconductive battery.

Here, the lower layer is formed by being transversely wrapped by a wrapping paper which is made so that the metalized paper or the metal tape which is in a horizontal direction overlaps with a certain portion of each other.

Further, the present invention provides a power cable characterized in that the overlap ratio, which is a ratio of widths overlapping with the width of the metal paper or the metal tape which is traversed by the wrapping paper, is 20 to 80%.

Wherein the lower layer is formed by being traversed by a gaps that are divergent with a certain gap so that the metalized paper or the metal tape that is to be rolled does not overlap with each other in the same layer do.

Wherein a width of the gap is 5 to 15% of a width of the metal paper or the metal tape which is traversed by the gap.

Further, the metal foil or the metal tape includes copper or aluminum and is cured.

The present invention also provides a power cable, wherein the semiconductive battery comprises carbon paper coated with carbon black on insulating paper.

The lower layer is formed by horizontally laying one to four metal sheets or metal tapes, and the upper layer is formed by horizontally winding four to eight semiconductive batteries, and the total thickness of the inner semiconductive layer is about 0.2 to 3.0 mm And a power cable.

The outer semiconductive layer includes a lower layer formed by the transverse direction of the semiconductive battery, and an upper layer formed by the semi-conducting battery and the metal paper alternately and horizontally.

Wherein the outer semiconductive layer further comprises a top layer by a copper wire web into which at least one copper wire is inserted into the nonwoven fabric.

Meanwhile, the insulating layer is formed by sequentially laminating 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 a kraft paper impregnated with insulating oil, Wherein the insulating layer is formed of a semi-synthetic paper impregnated with insulating oil, and the semi-synthetic paper comprises a plastic film and a kraft paper laminated on at least one surface of the plastic film, and 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 external insulating layer is 5 to 15%, the resistivity of the internal insulating layer and the external insulating layer is smaller than the resistivity of the intermediate insulating layer And a power cable.

The thickness of the inner insulating layer is 0.1 to 2.0 mm, the thickness of the outer insulating layer is 0.1 to 3.0 mm, and the thickness of the intermediate insulating layer is 15 to 25 mm .

Further, the dielectric oil has a kinetic viscosity at 60 DEG C of 5 centistokes (cSt) or more.

INDUSTRIAL APPLICABILITY The electric power cable according to the present invention exhibits an excellent effect that the dielectric strength is improved by the insulation layer and the semiconductive layer having a specific structure, and the electric field applied to the insulation layer is effectively mitigated, thereby extending the service life of the cable.

Further, the power cable according to the present invention is characterized in that, due to the specific structure of the inner semiconductive layer, the insulating oil in the insulating layer expands when the cable is energized and moves to a gap between the conductors, thereby suppressing the generation of deaerating voids in the insulating layer, It exhibits an excellent effect of effectively suppressing partial discharge and dielectric breakdown caused by an electric field concentrated in the deaerating void.

1 schematically shows a cross-sectional structure of an embodiment of a power cable according to the present invention.
2 schematically shows a longitudinal section of the power cable shown in Fig.
FIG. 3 is a graph schematically illustrating a process of reducing an electric field inside an insulation layer of a power cable according to the present invention.
4 schematically shows a cross-sectional structure of a semi-conductive paper forming an intermediate insulating layer in the power cable shown in FIG. 1;

Hereinafter, preferred embodiments of the present invention will be described in detail. 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 this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Like reference numerals designate like elements throughout the specification.

Figs. 1 and 2 schematically show a cross section and a longitudinal sectional structure of an embodiment of a power cable according to the present invention, respectively.

1 and 2, a power cable according to the present invention includes a conductor 100, an inner semiconductive layer 200 surrounding the conductor 100, an insulating layer (not shown) surrounding the inner semiconductive layer 200 A metal sheath layer 500 surrounding the outer semiconductive layer 400 and a cable protective layer 500 surrounding the metal sheath layer 500. The outer semiconductive layer 400 surrounds the insulating layer 300, 600), and the like.

The conductor 100 is a high-purity copper (Cu), aluminum (Al), or the like having high conductivity and excellent strength and flexibility required for use as a conductor of a cable so as to minimize power loss, , And can be made of an interconnection 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 transmission amount of the cable, the use, and the like.

Preferably, the conductor 100 may be formed of a rectangular conductor formed by laying square wire strands on a circular center line, or a circular compression conductor formed by stacking a plurality of circular wires on a circular center line and then compressing the conductor. The conductors 100 formed of a square conductor formed by a so-called keystone method have a high percentage of conductors and can reduce the outer diameter of the cable. In addition, since the cross-sectional area of each element wire can be greatly increased, It is economical to reduce. In addition, since there is less void in the conductor 100 and the weight of the dielectric oil contained in the conductor 100 can be reduced, it is effective.

The inner semiconductive layer 200 can suppress the electric field disturbance and the electric field concentration by the surface irregularity of the conductor 100 and prevent the electric field from being concentrated at the interface between the inner semiconductive layer 200 and the insulating layer 300, And performs a function of suppressing partial discharge, dielectric breakdown, and the like caused by an electric field concentrated on the substrate.

As shown in FIG. 2, the inner semiconductive layer 200 may include a lower layer 210, 210 'stacked on a conductor and an upper layer 220, 220' stacked on the lower layer 210, 210 '. The lower layers 210 and 210 'may be formed of a metal sheet 211 in which a semi-conductive paper 211b is stacked on a metal foil 211a made of an electrically conductive metal material such as copper or aluminum or an electrically conductive (Hereinafter, referred to as' metalized paper 211 'or the like) made of a metal material, and the upper layers 220 and 220' may be formed by the transverse direction of the semiconductive battery.

Here, the semiconductive battery included in the lower layers 210 and 210 'and the upper layers 220 and 220' may be formed of carbon paper coated with a conductive material such as carbon black or a film formed of a polymer composite material in which a conductive material such as carbon black is dispersed And the metal foil 211a or the metal tape may be cured so that the tensile strength of the metal foil 211a or the metal tape may be increased by the conventional binder.

The power cable according to the present invention can be applied to the structure of the semiconductive layer 200 and more particularly to the structure of the insulating oil 300 between the conductor 100 and the insulating layer 300 through the semiconductive layer 200, The viscosity of the insulating oil impregnated in the insulating layer 300 is lowered and the fluidity is increased due to the temperature rise during the conduction of the cable so that the viscosity of the insulating oil impregnated in the conductor 100 through the semiconductive layer 200 It is possible to effectively suppress the generation of the deaerating cavity in which the insulating oil is not present in the insulating layer 300 due to the contraction of the insulating oil impregnated in the insulating layer 300 due to the temperature drop, As a result, it is possible to suppress the occurrence of dielectric breakdown due to the partial discharge from the depleted voids as a result thereof, and at the same time, negative pressure is generated in the insulation layer 300 W is effective to suppress the deformation of the structure that the insulating layer (300).

2 (A), the lower layer 210 has a predetermined gap so that the metalized paper 211 and the like, which are horizontally overlapped, do not overlap with each other in the same layer 2, the lower layer 210 'may be wrapped with a wrapping paper such that the metalized paper 211 or the like, which is rolled up so as to overlap each other at certain portions, As shown in FIG.

Here, the gaps are traversed such that a predetermined gap is formed between the metal sheets 211 and the like, and the gaps are formed on the metal sheets 211 by a new metal sheet 211 or the like It means that the trailing edge is covered with the new metallized sheet 211 or the like at the same time and at the same time a gap is also formed between the new metallized sheet 211 or the like and is continuously traversed in a repeated manner.

In view of blocking the movement of the insulating oil through the semiconductive layer 200, the rap sheet is more advantageous than the gaps, the productivity of the cable is improved by improving the efficiency of the transverse winding, and the metal sheet, The gaps may be advantageous in comparison with the above-mentioned rappels from the viewpoint of preventing breakage due to collision or structural change.

It is preferable that the metal foil 211a is disposed toward the conductor 100 when the metal foil 211 is ganged or wrapped and if the metal foil 211 is gapped, The gap between the metal sheets 211 and the like may be 5 to 15% of the width of the metal sheet 211 or the like. When the metal sheets 211 are wrapped, The overlap ratio can be about 20 to 80%.

If the gap is less than 5%, the metalized paper 211 and the like which are in the same layer may collide with each other on the inside of the bending radius when the cable is bent. If the gap is more than 15% The metalized paper sheet 211 and the like, which are transversely bent at the bending radius at the time of bending, are separated from the layer through a gap between the metalized paper 211 and the like, The metalized paper 211 or the like can not be returned to the original layer and may be damaged or changed in structure.

On the other hand, when the overlap ratio is less than about 20% or more than about 80%, when the cable repeats bending and flexing, the overlapping portion of the metalizing paper 211 or the like, And can not return to the original layer and may be damaged or changed in structure.

In the inner semiconductive layer 200, the lower layers 210 and 210 'are formed to have one to four sheets of metal paper 211 and the like, and the upper layers 220 and 220' may be formed to have four to eight semi- And the total thickness of the inner semiconductive layer 200 may be about 0.2 to 3.0 mm.

The insulating layer 300 is formed by wrapping insulating paper in a plurality of layers. As the insulating paper, for example, a kraft paper is used, or a semi-synthetic paper laminated with a thermoplastic resin such as a kraft paper and a polypropylene resin 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 insulating layer 330 is made of a material having a lower resistivity than the intermediate insulating layer 320 so that the inner insulating layer 310 and the outer insulating layer 330 are electrically connected to the conductor 100 To suppress the application of a high electric field to the conductor 100 directly under the metal sheath layer 500 or to suppress the deterioration of the intermediate insulating layer 320. In addition, .

FIG. 3 is a graph schematically illustrating a process of reducing an electric field inside an insulation layer of a power cable according to the present invention. 3, the direct current (DC) electric field is relaxed in the inner insulating layer 310 and the outer insulating layer 330, which are relatively low in resistivity, so that the electric field is formed directly on the conductor 100 and directly below the metal sheath layer 500 It is possible to effectively suppress the application of a high electric field generated in the DC cable and also to control the maximum impulse electric field applied to the intermediate insulation layer 320 to 100 kV / Deterioration of the internal insulating layer 310 is suppressed by lowering the applied high impulse electric field, so that deterioration of the intermediate insulating layer 320 can also be suppressed. Here, the impulse voltage refers to an electric field applied to the cable when an impulse voltage is applied to the cable.

Therefore, as shown in FIG. 3, by designing the maximum impulse electric field value of the inner insulating layer 310 to be smaller than the maximum impulse electric field value of the intermediate insulating layer 320, the high electric field is prevented from acting directly on the conductor, , The maximum impulse electric field applied to the intermediate insulating layer 320 is an inner electric field of the intermediate insulating layer 320 and the inner electric field is a maximum impulse electric field of the middle insulating layer 320, for example, 100 kV / mm The deterioration of the intermediate insulating layer 320 can be suppressed.

Therefore, it is possible to suppress the application of a high electric field to the inner insulating layer 310 and the outer insulating layer 330, particularly, to the cable connecting member which is vulnerable to an electric field, and further to maximize the performance of the intermediate insulating layer 320 As a result, the entire insulating layer 300 can be made compact, its deterioration can be suppressed, and the dielectric strength and other physical properties of the insulating layer 300 can be prevented from being lowered. As a result, It is possible not only to use the cable but also to suppress the shortening of the life of the cable.

According to an embodiment of the present invention, the inner insulating layer 310 and the outer insulating layer 330 may be formed by horizontally inserting a kraft paper made of kraft pulp and impregnating insulating oil, 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 may be prepared by removing the organic electrolyte in the kraft pulp and washing the kraft pulp with deionized water to obtain excellent dielectric tangent and dielectric constant.

The intermediate insulating layer 320 may be formed by horizontally inserting a semifinished paper in which kraft paper is laminated on the front, back, or both sides of a plastic film and impregnating insulating oil. Since the intermediate insulating layer 320 thus formed has a plastic film, it has a high resistivity, a low dielectric constant, a high DC dielectric strength and an impulse breakdown voltage as compared with the inner insulating layer 310 and the outer insulating layer 330, The DC electric field is concentrated on the intermediate insulating layer 320 which is stronger than the electric field strength in the DC by the high resistivity of the intermediate insulating layer 320 and the impulse electric field is applied to the intermediate insulating layer 320 which is strong against the impulse electric field The insulating layer 300 as a whole can be made compact, and as a result, the outer diameter of the cable can be reduced.

The plastic film in the semi-conductive paper sheet forming the intermediate insulating layer 320 expands due to heat generation during operation of the cable to increase the oil resistance, so that the insulating oil impregnated in the insulating layer 300 is transferred to the outer semiconductive layer 400 , Thereby suppressing the generation of the deoiling void due to the movement of the insulating oil, and consequently, the field concentration and the insulation breakdown due to the deoiling void can be suppressed. Here, the plastic film may be made of a fluororesin such as a polyolefin resin such as polyethylene, polypropylene or polybutylene, a tetrafluoroethylene-hexafluoropropylene copolymer or an ethylene-tetrafluoroethylene copolymer, Preferably a polypropylene homopolymer resin having excellent heat resistance.

Also, the semi-synthetic paper may have a thickness of 40 to 70% of the total thickness of the plastic film. If the thickness of the plastic film is less than 40% of the total thickness of the semisynthetic paper, the resistivity of the intermediate insulating layer 320 may be insufficient to increase the outer diameter of the cable, while if it exceeds 70% And the impregnation may become difficult due to the shortage of the circulating oil of the insulating oil, which may be 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 1 to 15% And the intermediate insulating layer 320 may have a thickness of 75% or more of the total thickness of the insulating layer 300. [ Accordingly, the maximum impulse electric field of the inner insulating layer 310 may be lower than the maximum impulse electric field of the intermediate insulating layer 320. If the thickness of the inner insulating layer is increased more than necessary, the maximum impulse electric field value of the intermediate insulating layer 310 becomes larger than the permissible maximum impulse electric field value. In order to alleviate the problem, . It is preferable that the thickness of the outer insulating layer 330 is sufficiently larger than that of the inner insulating layer, which will be described later.

In the present invention, by providing the inner insulating layer 310 and the outer insulating layer 330 having a low resistivity, it is possible to suppress the direct current high electric field from being applied directly to the conductor 100 and directly below the metallic sheath layer 500 However, by designing the thickness of the intermediate insulating layer 320 having a high resistivity to 75% or more, it becomes possible to reduce the cable outer diameter while maintaining sufficient dielectric strength.

The inner insulating layer 310, the intermediate insulating layer 320, and the outer insulating layer 330, which constitute the insulating layer 300, respectively have the precisely controlled thickness, 300) can have a desired dielectric strength while the outer diameter of the cable can be minimized. The direct current and the impulse electric field applied to the insulating layer 300 can be designed most effectively on the adielectric system and a high electric current of the direct current and the impulse can be directly applied to the conductor 100 and directly to the metal sheath layer 500 So that it is possible to apply a designing means capable of raising the dielectric strength of the cable connecting member, which is particularly vulnerable to an electric field, to a sufficient height.

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 inner insulating layer 310 may have a thickness of 0.1 to 2.0 mm , The thickness of the external insulating layer 330 may be 0.1 to 3.0 mm, and the thickness of the intermediate insulating layer 320 may be 15 to 25 mm.

The heat generated during the connection of the plug for connection of the cable 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, It is desirable to secure a sufficient thickness of the outer insulating layer 330 to protect the film and it is preferable that the thickness of the outer insulating layer 330 is thicker than the thickness of the inner insulating layer 310, The thickness of the inner insulating layer 310 is preferably 1 to 30 times the thickness of the inner insulating layer 310.

The thickness of the sheet of semi-synthetic paper forming the intermediate insulating layer 320 is 70 to 200 mu m and the thickness of the kraft paper forming the inner and outer insulating layers 310 and 330 may be 50 to 150 mu m. The thickness of the kraft paper forming the inner and outer insulating layers 310 and 330 may be greater than the thickness of the kraft paper constituting the semifinished paper.

If the thickness of the kraft paper forming the inner and outer insulating layers 310 and 330 is excessively thin, mechanical strength may be insufficient due to insufficient strength, so that the number of the horizontal portions for forming the insulating layer of the desired thickness increases, The total volume of the gap between the kraft paper constituting the main passage of the insulating oil during the transverse winding of the kraft paper may be reduced to take a long time for impregnating the insulating oil and the content of the insulating oil impregnated may be reduced, May be difficult to implement.

Since the insulating oil impregnated in the insulating layer 300 is fixed without being circulated in the longitudinal direction of the cable like the low viscosity insulating oil used in the conventional OF cable, the insulating oil having a relatively high viscosity is used. The insulating oil may perform not only an intended dielectric strength of the insulating layer 300 but also a lubricating function to facilitate movement of the insulating paper when the cable is bent.

The insulating oil is not particularly limited, but a high-viscosity insulating oil having a kinematic viscosity of 5 to 500 centistokes (cSt) at 60 DEG C may be used, or a high viscosity insulating oil having a kinematic viscosity at 500 DEG C of 500 centistokes (cSt) or more may be used . For example, at least one insulating oil selected from the group consisting of naphthenic insulating oil, polystyrene insulating oil, mineral oil, alkylbenzene or polybutene synthetic oil, heavy alkylate, and the like can be synthesized and used.

The step of impregnating the insulating layer 300 with the insulating oil may include a step of forming the inner insulating layer 310, the intermediate insulating layer 320, and the outer insulating layer 330, respectively, And the semi-synthetic paper are each transversely wound a plurality of times, vacuum-dried to remove residual moisture in the insulating layer 300, and thereafter the insulating oil is heated in a high-pressure environment at a high-temperature impregnation temperature of, for example, 100 to 120 ° C Injecting the insulating oil into the tank, impregnating the insulating oil into the insulating layer 300 for a predetermined time under the condition, and then slowly cooling the insulating layer.

The outer semiconductive layer 400 may be formed by controlling the nonuniform electric field distribution between the insulating layer 300 and the metal sheath layer 500 and reducing the electric field distribution, 300) to be physically protected.

The outer semiconductive layer 400 may be formed by, for example, a transverse region of a semi-conductive paper such as a carbon paper in which a conductive carbon black is applied to insulating paper, An upper layer in which the lower layer and the semiconductive battery and the metalized paper are formed in a gapped or coaxial manner.

Also, when the semiconductive battery and the metalized paper are allowed to be in the upper layer, the metalized paper and the semiconductive battery may be alternately allowed to overlap by a certain amount, for example, about 20 to 80% overlap.

Here, the metalized paper may have a structure in which a metal foil such as an aluminum tape or an aluminum foil is laminated on a base paper such as kraft paper or carbon paper, and the metal foil is easily permeated into a semiconductive battery, insulating paper, So that the semiconductive battery of the lower layer is brought into electrical contact with the metal foil of the metalized paper through the semiconductive battery of the upper layer. As a result, the outer semiconductive layer (400) and the outer semiconductive layer A uniform electrical field distribution can be formed between the insulating layer 300 and the metal sheath layer 500 by allowing the metal sheath layer 500 to smoothly come into electrical contact.

In addition, the outer semiconductive layer 400 may further include a copper wire layer (not shown) between the outer semiconductive layer 400 and the metal sheath layer 500. The copper wire fabric has a structure in which 2 to 8 strands of copper wire are directly connected to the nonwoven fabric, and the copper wires function to smoothly make the outer semiconductive layer 400 and the metal sheath layer 500 electrically in contact with each other, Metal sheets or the like wound to form the outer semiconductive layer 400 can be unfolded and firmly tied to each other so that the structure described above can be maintained. It is possible to prevent damage such as tearing of the metal paper or the like in accordance with the movement of the metal sheath layer 500 during bending.

The metallic sheath layer 500 prevents the insulating oil from leaking to the outside of the cable and fixes the voltage applied to the cable during the DC transmission between the conductor 100 and the metallic sheath layer 500, It functions as a return path of a fault current in case of a cable ground fault or a short circuit to protect the cable from external shock or pressure, and improves the water resistance and flame retardancy of the cable.

The metal sheath layer 500 may be formed, for example, by a soft contact made of pure alloy or lead alloy. The soft solder as the metal sheath layer (500) has a relatively low electrical resistance and also functions as a current-carrying high current. Further, when formed into a seamless type, the cable watertightness, mechanical strength and fatigue characteristics of the cable can be further improved have.

In addition, the softface may be formed of a corrosion-inhibiting compound, for example, a metal or a metal oxide, in order to further improve the corrosion resistance, water-repellency, etc. of the cable and improve the adhesion between the metal sheath layer 500 and the cable- Blown asphalt or the like.

The cable protection layer 600 includes a metal reinforcing layer 630 and an outer sheath 650 and includes an inner sheath 610 and bedding layers 620 and 640 disposed above and below the metal reinforcing layer 630 As shown in FIG. Here, the inner sheath 610 improves the corrosion resistance, water repellency and the like of the cable, and functions to protect the cable from mechanical trauma, heat, fire, ultraviolet rays, insects and animals. The inner sheath 610 is not particularly limited, but may be made of polyethylene having excellent cold resistance, oil resistance, chemical resistance, etc., or polyvinyl chloride having excellent chemical resistance and flame retardancy.

The metal reinforcing layer 630 may be formed of a galvanized steel tape, a stainless steel tape, or the like to protect the cable from mechanical impact and to prevent corrosion, and the galvanized steel tape may have a corrosion- Can be applied. In addition, the bedding layers 620 and 640 disposed above and below the metal reinforcing layer 630 perform a function of alleviating external impact, pressure, and the like, and may be formed of, for example, a nonwoven tape.

The metal reinforcing layer 630 may be provided directly on the metal sheath layer 500 or through bedding layers 620 and 640. In this case, expansion strain of the metallic sheath layer 500 due to high temperature expansion of the insulating oil in the metal reinforcing layer 630 is suppressed to improve the mechanical reliability of the cable, and at the same time, the insulating layer 300 in the metallic sheath layer 500 There is an effect of enhancing the dielectric strength by converting the portions of the semiconductive layers 200 and 400 into effervescent.

Since the outer sheath 650 has substantially the same function and characteristics as the inner sheath 610 and the fire in the submarine tunnel and the land tunnel section is a risk factor that greatly affects manpower or facility safety, The outer sheath of the cable is made of polyvinyl chloride, which has excellent flame retardant properties, and the cable outer sheath of the duct section is made of polyethylene having excellent mechanical strength and cold resistance.

Although not shown, a metal reinforcing layer 630 may be provided immediately after the inner sheath 610 is omitted on the metal sheath 500. A bedding layer may be provided on the inner side and the outer side of the metal reinforcing layer 630, have. That is, the metal sheath layer may be formed to have a bedding layer, a metal reinforcing layer, a bedding layer, and an outer sheath sequentially outward from the metal sheath layer. In this case, because the metal reinforcing layer 630 restricts the deformation of the metal sheath 500 and suppresses changes in the outer circumference, it is preferable for the fatigue characteristics of the metal sheath 500, It is possible to compensate for the lowering of the hydraulic pressure caused by the contraction of the insulating oil due to the temperature lowering when the cable energization is turned off and conversely the hydraulic pressure of the inner semiconductive layer 300 is suddenly increased It is preferable to transfer the oil to the descending portion by replenishing with oil.

In addition, when the cable is a submarine cable, the cable protection layer 600 may further include, for example, a wire shield 660 and an outer shield layer 670 made of polypropylene yarn or the like. The iron wire sheath 660, the outer surfacing layer 670, and the like may further function to protect the cable from the sea current, the reef, and the like.

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. . It is therefore to be understood that the modified embodiments are included in the technical scope of the present invention if they basically include elements of the claims of the present invention.

100: conductor 200: inner semiconductive layer
300: insulating layer 400: outer semiconductive layer
500: metal sheath layer 600: cable protective layer

Claims (13)

Conductor;
An inner semiconductive layer surrounding the conductor;
An insulating layer surrounding the inner semiconductive layer and impregnated with insulating oil;
An outer semiconductive layer surrounding the insulating layer;
A metal sheath layer surrounding the outer semiconductive layer; And
And a cable protective layer surrounding the metal sheath layer,
Wherein the insulating layer is formed by transversely insulating paper and impregnated with insulating oil,
Wherein the inner semiconductive layer includes a lower layer stacked on the conductor and an upper layer stacked on the lower layer, wherein the lower layer is formed by a metal tape or metal tape having a metal foil laminated on a metal foil, Wherein the power cable is formed by a transverse section of a semiconductive battery. The method according to claim 1,
Characterized in that the lower layer is formed by being transversely wrapped by a wrapping paper which is made so that the metalized paper or the metal tape which is in the horizontal direction overlaps with a certain portion of the metal tape. 3. The method of claim 2,
Characterized in that the overlap ratio, which is a ratio of the overlap width of the metal paper or the metal tape to the width of the metal paper or the metal tape which is crossed by the wrap paper, is 20 to 80%. The method according to claim 1,
Wherein the lower layer is formed by being traversed by a gaps that are diverted with a certain gap so that the metalized paper or the metal tape that is to be rolled does not overlap with each other in the same layer. 5. The method of claim 4,
Characterized in that the width of the gap is 5 to 15% of the width of the metalized paper or metal tape which is traversed by the gap. 6. The method according to any one of claims 1 to 5,
Wherein the metal foil or the metal tape comprises copper or aluminum and is cured. 6. The method according to any one of claims 1 to 5,
Characterized in that said semiconductive battery comprises carbon paper coated with carbon black on insulating paper. 6. The method according to any one of claims 1 to 5,
Wherein the lower layer is formed by horizontally laying one to four metal sheets or four metal tapes, and the upper layer is formed with four to eight sheets of the semicircular batteries horizontally, and the total thickness of the inner semiconductive layer is 0.2 to 3.0 mm Power cable. 6. The method according to any one of claims 1 to 5,
Wherein the outer semiconductive layer comprises a lower layer formed by the transverse direction of the semiconductive battery and an upper layer formed by the semiconductive sheet and the metal paper alternately transversely with each other. 10. The method of claim 9,
Characterized in that said outer semiconductive layer further comprises a top layer by a copper wire web into which at least one copper wire is inserted into the nonwoven fabric. 6. The method according to any one of claims 1 to 5,
Wherein the insulating layer is formed by sequentially laminating an inner insulating layer, an intermediate insulating layer, and an outer insulating layer,
Wherein the inner insulating layer and the outer insulating layer are each formed of a kraft paper impregnated with insulating oil, the intermediate insulating layer is formed of a semi-
Wherein the semi-synthetic paper comprises a plastic film and a kraft paper laminated on at least one side of the plastic film,
Wherein 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% based on the total thickness of the insulating layer,
And the resistivity of the inner insulating layer and the outer insulating layer is smaller than the resistivity of the intermediate insulating layer. 12. The method of claim 11,
Wherein the thickness of the inner insulating layer is 0.1 to 2.0 mm, the thickness of the outer insulating layer is 0.1 to 3.0 mm, and the thickness of the intermediate insulating layer is 15 to 25 mm. 6. The method according to any one of claims 1 to 5,
Wherein the dielectric oil has a kinematic viscosity at 60 占 폚 of 5 centistokes (cSt) or more.

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