KR20190029990A - Power cable - Google Patents

Abstract

The present invention relates to a power cable and, more specifically, to an ultra-high voltage underground or submarine cable for long distance direct current transmission. Specifically, the present invention relates to a power cable that has insulation layer itself having a high dielectric strength, effectively relaxes an electric field applied to the insulating layer, especially reduces production time so that production yield can be improved, and can maintain a uniform dielectric strength throughout the insulating layer even when the temperature in the insulating layer is lowered in a low-temperature environment or in the stop of energization.

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 specifically, the present invention is characterized in that the insulating layer itself has a high dielectric strength, the electric field applied to the insulating layer is effectively relaxed, the production time is shortened and the production yield can be improved, To a power cable capable of maintaining a uniform dielectric strength throughout the insulating layer even when the temperature inside the insulating layer is lowered.

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.

This MIND cable is formed by wrapping insulating paper in a plurality of layers when impregnating an insulating layer and impregnating the insulating paper with insulating oil. In order to uniformly impregnate insulating oil in the insulating layer, impregnation with insulation oil is required for a long time. There is a problem that the production yield is lowered.

As the insulating paper, for example, kraft paper may be used, or a semi-synthetic paper laminated with a thermoplastic resin such as kraft paper and polypropylene resin may be used.

In the case of a cable in which a kraft cable is wound and impregnated with an insulating oil, the cable is radially inward due to heat generation due to a line loss caused by a current flowing through the cable conductor (during energization) That is, toward the outer semiconductive layer outside the insulating layer.

Therefore, the viscosity of the insulating oil in the insulating layer portion at the higher temperature, that is, the inner semiconductive layer side, is lowered and thermally expanded to move to the insulating layer on the outer semiconductive layer side. However, when the temperature is lowered, the viscosity of the moving insulating oil increases, So that deaeration voids due to heat shrinkage of the insulating oil can be formed in the insulating layer portion on the inner side in the radial direction, that is, on the inner semiconductive layer side.

In addition, the insulating oil impregnated by the heat generated by the heat loss due to the current loss due to the current flowing through the cable conductor during the operation of the cable (when energized) is low in viscosity and thermally expanded, so that the cable portion, And when the temperature is lowered, the viscosity of the moved insulating oil is increased, and the viscosity of the moved insulating oil does not return to the original state, so that an oil-deficient void due to heat shrinkage of the insulating oil can be formed.

Since there is no insulating oil in the deaerated voids, the electric field is concentrated, and partial discharge and insulation breakdown may occur from this point, and the lifetime of the cable may be shortened.

However, in the case of forming the insulating layer with the semisynthetic paper, the thermoplastic resin such as polypropylene resin which is not impregnated with the oil during the operation of the cable thermally expands, so that the flow of the insulating oil can be suppressed. In the polypropylene resin, It is possible to alleviate the voltage to which the deaerated voids are generated.

In addition, since the insulating oil does not move in the polypropylene resin, it is possible to suppress the flow of the insulating oil in the cable diameter direction due to gravity, and the polypropylene resin The thermal expansion causes the surface pressure to be applied to the kraft paper, so that the flow of the insulating oil can be further suppressed.

However, even when the MIND cable is used as an underground cable or submarine cable of an extreme fat and is installed under a low temperature environment, the insulation oil impregnated in the insulation layer, semiconductive layer, etc., A plurality of deaerated voids can be generated in the insulating layer or the like and the temperature of the insulating layer or the like is raised by the heat generated by the conductor during operation of the cable and the deaerated air is removed, Problems such as partial discharge, dielectric breakdown, etc. may be caused by an electric field concentrated in the voids.

Therefore, the insulating layer itself has a high dielectric strength, and the electric field applied to the insulating layer is effectively relaxed. Particularly, the production time can be shortened and the production yield can be improved. The temperature in the insulating layer There is a strong demand for a power cable capable of maintaining a uniform dielectric strength throughout the insulating layer even when it is deteriorated.

An object of the present invention is to provide an ultra-high voltage power cable in which the insulation resistance of the insulation layer is high and the electric field applied to the insulation layer is effectively mitigated to extend the service life.

It is another object of the present invention to provide an ultra-high voltage power cable that can be manufactured at a significantly shorter production time than a conventional MIND cable, thereby improving the production yield of the cable.

Further, it is an object of the present invention to provide an ultra high-voltage direct current power cable capable of maintaining a uniform dielectric strength throughout the insulating layer in a low-temperature environment or in the stop of energization, despite the temperature drop in the insulating layer.

In order to solve the above problems,

Conductor; An inner semiconductive layer surrounding the conductor; An insulating layer surrounding the inner semiconductive layer; An outer semiconductive layer surrounding the insulating layer; A metal sheath layer surrounding the outer semiconductive layer; And a cable protective layer surrounding the metallic sheath layer, wherein the insulating layer is formed by inserting the insulating paper in a transversal direction and filling insulating gas inside the insulated insulating paper or between the insulating paper or both.

Wherein the insulated gas comprises sulfur hexafluoride (SF ₆ ) gas, nitrogen (N ₂ ) gas, or both.

In addition, the insulating paper comprises a porous structure or comprises at least one through hole penetrating in the thickness direction.

Further, the conductor includes an injection tube through which the insulating gas can be injected, and at least one insulated gas outlet connected to the injection tube and capable of discharging the injected insulated gas to the outside of the conductor. do.

The insulating layer is formed by sequentially laminating an inner insulating layer, an intermediate insulating layer, and an outer insulating layer. The inner insulating layer and the outer insulating layer are formed by winding a kraft paper horizontally, Wherein the intermediate insulating layer comprises a plastic film and a kraft paper laminated on at least one side of the plastic film, the semi-conductive paper being formed by being transversely oriented and filled with insulating gas.

Wherein the plastic film comprises a porous structure or comprises at least one through hole penetrating in the thickness direction.

In addition, the kraft or the semi-synthetic paper or both of them are made to be sideways by a gap, and the gap is sideways so that a constant gap is formed between the kraft paper or the semi-synthetic paper, On the upper side of the kraft paper or the semi-fabric paper is covered by the new kraft paper or the semifinished paper when the new kraft paper or semifinished paper is sideways, and at the same time, a gap is formed between the new kraft paper or the semi- The power cable is continuously repeated.

The intermediate insulation layer is divided into at least two layers depending on the size of the width of the semi-synthetic paper constituting the intermediate insulation layer. A layer located on the side of the conductor is referred to as a lower layer and a layer located on the outer side of the lower layer is referred to as an upper layer , The width of the semi-synthetic paper forming the upper layer is larger than the width of the semi-synthetic paper forming the lower layer, and the width of the gap between the semi-synthetic paper formed by the gap of the semi-synthetic paper is 5 to 15% Wherein the power cable is a cable.

The present invention also provides a power cable characterized in that the width of the semi-synthetic paper constituting the intermediate insulation layer adjacent to the inner insulation layer is equal to the width of the semi-synthetic paper constituting the inner insulation layer adjacent thereto.

The inner semiconductive layer is formed by winding a semiconductive battery horizontally into a gap and filled with an insulating gas. The outer semiconductive layer is formed by winding a semi-conductive paper horizontally to a gap and filling an insulating gas, And an upper layer which is formed by filling the insulated gas with a bottom layer formed by filling the insulated gas with the gap being crossed with the lower layer formed by inserting the insulating gas.

Furthermore, a power cable is provided, wherein the resistivity of the inner insulating layer and the outer insulating layer is smaller than that of the intermediate insulating layer.

And the thickness of the outer insulating layer is larger than the thickness of the inner insulating layer.

Meanwhile, the cable protection layer includes an inner sheath, a bedding layer, a metal reinforcing layer, and an outer sheath.

Wherein the cable protection layer further comprises a wire sheath and an outer sheath layer.

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

In addition, the power cable of the present invention has an excellent effect that the production time of the cable can be shortened and the yield of the cable can be greatly improved by filling the insulation layer with insulating gas instead of impregnating the insulation oil.

Further, even when the temperature of the insulating layer is lowered in a low-temperature environment or in a stop state, the power cable of the present invention ensures a uniform dielectric strength throughout the insulating layer due to stable thermal characteristics of the insulating gas, It exhibits an excellent effect of effectively suppressing partial discharge and dielectric breakdown due to field concentration.

1 schematically shows a cross-section of a power cable according to the invention.
Figure 2 schematically shows a longitudinal section of the power cable of Figure 2;
Figure 3 schematically illustrates a configuration of one embodiment of a conductor of the power cable shown in Figure 1;
FIG. 4 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.
5 schematically shows a cross-sectional structure of a semi-synthetic paper forming the intermediate insulating layer in the power cable shown in FIG.

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.

Figure 3 schematically illustrates a configuration of one embodiment of a conductor of the power cable shown in Figure 1;

3, the conductor 100 includes an injection tube 110 for injecting the insulating gas into the insulating layer 300 to fill the insulating gas, and an injection tube 110 connected to the injection tube 110 And one or more insulating gas outlets 120 capable of discharging the injected insulated gas out of the conductor 100 may be included. Thus, after inserting the cable, insulated gas is injected through the injection tube 110 of the conductor 100 at the end of the cable and the injected insulated gas is discharged through the insulated gas outlet 120, The insulating layer 300 is rapidly and uniformly charged through the semiconductor layer 200 so that a uniform dielectric strength can be ensured throughout the insulating layer 300.

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.

The inner semiconductive layer 200 may be formed of, for example, semi-conductive paper such as 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 thickness of the inner semiconductive layer 200 may be about 0.2 to 3.0 mm. Here, the semiconductive battery may have a plurality of through-holes which include a porous structure or penetrate in the thickness direction in order to retain permeability capable of permeating insulating gas and retain such permeability.

The insulating layer 300 may be formed by wrapping the insulating paper in a plurality of layers and filling the gap between the insulating paper and / or the insulating paper with an insulating gas. Since the power cable according to the present invention can quickly and uniformly inject the insulating gas into the insulating layer 300 from the end of the cable after completion of the cable installation, the insulative paper forming the insulating layer in the conventional MIND cable is impregnated with insulating oil It is possible to solve the problem that takes a long time in the process, and the cable production yield can be greatly improved.

The insulating paper may include a porous structure or may include at least one through hole penetrating the insulating paper in the thickness direction, and the insulating paper may include, for example, A Kraft paper 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. 4 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, 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 not only to effectively suppress the application of a high electric field generated in the DC cable but also to control the maximum impulse electric field applied to the intermediate insulating layer 320 to 100 kV / The deterioration of the intermediate insulating layer 320 can be suppressed because deterioration of the internal insulating layer 310 is suppressed by lowering the high impulse electric field applied to the intermediate insulating layer 310. [ Here, the impulse voltage refers to an electric field applied to the cable when an impulse voltage is applied to the cable.

Therefore, it is possible to suppress application of a high electric field to the inner insulating layer 310 and the outer insulating layer 330, particularly to a cable connecting member which is vulnerable to an electric field, and further to reduce the performance of the intermediate insulating layer 320 It is possible to suppress deterioration of the insulating layer 300 and to prevent deterioration of dielectric strength and other physical properties of the insulating layer 300. As a result, it is possible to provide a compact cable having an impulse withstand voltage higher than that of the cable, The 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 horizontally inserting a kraft paper made of kraft pulp and filling insulating gas, The inner 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.

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

5, the intermediate insulation layer 320 is formed by transversely inserting the synthetic paper laminated with the kraft paper 322 and 323 on the upper surface, the lower surface, or both of the plastic film 321 and the inside of the synthetic paper, And filling the gap between the pores with insulating gas. The intermediate insulating layer 320 thus formed has a higher resistivity, lower dielectric constant, higher DC breakdown voltage, and impulse breakdown voltage than the inner insulating layer 310 and the outer insulating layer 330, It is possible to reduce the outer diameter of the cable impulsively by a low dielectric constant in a direct current by the high resistivity of the intermediate insulating layer 320. [

Here, the plastic film 321 is made of a fluororesin such as a polyolefin resin such as polyethylene, polypropylene or polybutylene, a tetrafluoroethylene-hexafluoropropylene copolymer, or an ethylene-tetrafluoroethylene copolymer And preferably a polypropylene homopolymer resin having excellent heat resistance.

The plastic film 321 may include a porous structure so that the insulating gas can pass through the plastic film 321 so that the insulating gas can be quickly and uniformly filled in the insulating layer 300. Alternatively, One or more through holes 321a penetrating the film 321 in the thickness direction of the film 321 may be included.

The maximum impulse electric field value of the inner insulating layer 310 may be lower than the maximum impulse electric field value of the intermediate insulating layer 320. If the thickness of the inner insulating layer 310 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. To alleviate this, the cable outer diameter is increased A problem occurs.

It is preferable that the thickness of the outer insulating layer 330 is sufficiently thicker than that of the inner insulating layer 310. 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, And may be 1 to 30 times the thickness of the inner insulating layer 310.

The insulating gas filled in the insulating paper 300 forming the insulating layer 300 and the insulating paper between the insulating paper 300 can be quickly and uniformly discharged from the end of the cable after the completion of the cable unlike the insulating oil impregnated with the insulating paper forming the insulating layer of the conventional MIND cable The cable according to the present invention can greatly shorten the manufacturing time and consequently the cable production yield can be greatly improved.

Further, the conventional MIND cable having the insulating layer formed by the transversal area of the insulating paper impregnated with the insulating oil has a problem in that, when the temperature of the insulating layer is lowered in the low temperature environment or when the insulating layer stops flowing, A large number of voids are generated and an electric field is concentrated on the defoaming voids, thereby causing a partial discharge of the insulating layer and dielectric breakdown. In contrast, the cable according to the present invention may have a problem in that, The conventional problems as described above can be solved by applying an insulating gas having stable thermal characteristics and minimizing a volume change according to the temperature.

The insulating gas may preferably include sulfur hexafluoride (SF ₆ ) gas, nitrogen (N ₂ ) gas, and the like. The sulfur hexafluoride (SF ₆ ) gas and the nitrogen (N ₂ ) gas are colorless, odorless, harmless, and nonflammable gases having excellent thermal stability. They have excellent dielectric strength, fast recovery of insulation, The arc is stable. Since the sulfur hexafluoride (SF ₆ ) gas and the nitrogen (N ₂ ) gas have a high thermal conductivity, the heat transmitted from the conductor 100 when the conductor 100 generates heat by the energization of the conductor 100 is effectively transferred to the insulating layer 300 So that the deterioration of the insulating layer 300 is effectively suppressed, so that the life of the cable can be further extended. Further, in terms of environment friendliness, nitrogen (N ₂ ) gas may be preferable to sulfur hexafluoride (SF ₆ ) gas.

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 of a semi-conductive paper such as carbon paper or the like coated with a conductive carbon black on insulating paper, And an upper layer which is formed so as to be coaxial with the lower layer of the semiconductor battery and the metal paper, that is, the metal paper and the semiconductor battery are overlapped with each other by a certain amount, for example, about 40 to 60% The thickness of the outer semiconductive layer 400 may be about 0.1 to 3.0 mm, and the thickness of the semiconductive layer 400 forming the semiconductive layer 400 may be about 1 to 4 and the thickness of the outer semiconductive layer 400 may be about 0.1 to 3.0 mm.

The metalized paper may have a structure in which a metal foil such as aluminum tape or aluminum foil is laminated on a base paper such as kraft paper or carbon paper so that the semiconductive battery of the lower layer is wound on the metal foil As a result, the external semiconductive layer 400 and the metallic sheath layer 500 are brought into electrical contact with each other smoothly. Thus, when a cable is shorted or short-circuited, a return current of a fault current is effectively secured And a uniform electric field distribution can be formed between the insulating layer 300 and the metal sheath layer 500.

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-wound cloth has a structure in which 2 to 8 strands of copper wire are directly connected to the nonwoven fabric so that the semiconductive wire wound around the outer semiconductive layer 400 to form the metal semiconductive layer 400 is not loosened, And the function of smoothly bringing the outer semiconductive layer 400 and the metal sheath layer 500 into electrical contact with each other by the copper wire can be performed.

Particularly, in the power cable of the present invention, the semiconductive battery forming the inner semiconductive layer 200, the kraft paper forming the inner insulating layer 310 and the outer insulating layer 330 of the insulating layer 300, A semiconductive battery or the like for forming the intermediate semiconductive layer 400 (hereinafter referred to as a " semiconductive battery ") or the like, which forms the intermediate insulating layer 320, And the gap is covered by the new semiconductive battery or the like when a new semiconductive battery or the like is laid on the upper side of the semiconductive battery or the like and at the same time a gap it is possible to make the gaps to be diagonally formed such that gaps are formed continuously.

Thus, since the insulating gas can be easily moved through the gap, uniform filling of the insulating layer 300 can be achieved when filling the insulating layer 300 and the charging time can be shortened, thereby improving the productivity of the cable.

Also, the semiconductive battery or the like is slid to the left or right through an open space of a gap formed on the left and right sides thereof, so that the structure can be stably maintained without colliding with another adjacent semiconductive battery or the like even when the cable is bent. Therefore, in order for the semiconductor battery or the like to slide stably without colliding with each other, the width of the gap must be secured in proportion to the width of the semiconductive battery or the like. For example, gap may be about 5 to 15% of the width of the semiconductor battery or the like.

When the width of the gap is less than 5% of the width of the semiconductive battery or the like, the semiconductor battery may collide with the semiconductor battery when the cable is bent. If the width of the gap is more than 15% A semiconducting cell or the like may protrude through a gap of the upper or lower layer thereof to break the semiconductive battery or the structure of the layer.

On the other hand, in the insulating layer 300, only the insulating gas having a lower resistance than the insulating paper forming the insulating layer 300 exists in the gap formed between the insulating paper such as the kraft paper or the semi- an electric field is concentrated on the gap, and partial discharge and insulation breakdown are generated from the electric field, thereby shortening the service life of the cable.

Therefore, the present invention precisely controls the width of the insulating paper such as kraft paper, semi-finished paper or the like and the width of the gap to form the insulating layer 300, thereby securing a high dielectric strength of the insulating layer 300 At the same time, productivity and flexibility of the cable in conflict with each other can be improved at the same time.

Specifically, the intermediate insulating layer 320 formed by the lateral side of the semi-synthetic paper in the insulating layer 300 is divided into at least two layers depending on the width of the semi-synthetic paper, and the layer located on the side of the conductor is referred to as a lower layer 320a ), The width of the semi-synthetic paper forming the upper layer 320b may be larger than the width of the semi-formed paper forming the lower layer 320a.

That is, when the cable is energized, the width of the insulation paper forming the lower layer 320a, which is the closest to the conductor 100 and is applied with a relatively strong electric field, is narrowed, so that only insulation gas having a relatively low resistance is present The lower layer 320a is disposed on the inner side of the cable. Therefore, the bending radius of the lower layer 320a is small when the cable is bent, so that the lower layer 320a Is designed to be relatively narrow, it is possible to avoid that the insulating paper collides with each other and is broken or the structure is changed.

Since the upper layer 320b is disposed farther from the conductor 100 than the lower layer 320a, a relatively weak electric field is applied when the cable is energized, so that the width of the gap in which only insulated gas having a relatively low resistance exists As the width of the gap included in the upper layer 320a increases, it is possible to control the width of the insulating paper to be wider, so that the upper layer 320a The productivity of the cable can be improved and the insulation paper can be prevented from being collided with the upper layer 320a having a large bending radius at the bending of the cable and being damaged or changing the structure .

Here, the upper layer 320b and the lower layer 320a adjacent to each other may have a width of the semi-synthetic paper forming the upper layer 320b of 105 to 125% of the width of the semi-formed paper forming the lower layer 320a.

The gap between the insulating sheets forming the lower layer 320a is about 1.5 to 2.5 mm, the gap between the insulating sheets forming the upper layer 320b is about 2.1 to 2.7 mm, and between the insulating sheets forming the additional upper layer The gap may be about 2.3 to 3.0 mm.

Particularly, the width of the semi-synthetic paper forming the intermediate insulating layer 320 adjacent to the internal insulating layer 310 may be the same as the width of the semi-synthetic paper constituting the internal insulating layer 310 adjacent thereto. This is because the electric field distribution is unstable due to the suddenly changing electric field at the point where the inner insulating layer 310 made of kraft paper is converted into the intermediate insulating layer 320 made of semi-synthetic paper, and partial discharge and insulation breakdown It is because.

The width of the kraft paper forming the inner insulating layer 310 and the width of the semiconductive battery forming the inner semiconductive layer 200 may be independently 20-30 mm and the outer insulating layer 330 The width of the kraft paper to be formed and the width of the semiconductive battery and the metallized paper forming the outer semiconductive layer 400 may be 27 to 34 mm, respectively, and the width of the copper wire, which may be additionally included in the outer semiconductive layer 400, The gap between the kraft paper and the semiconductive battery included in each side may be about 5 to 15 times as large as the width of the kraft paper, %. ≪ / RTI >

The semiconductive battery or the like forming the inner semiconductive layer 200 to the outer semiconductive layer 400 forming the power cable according to the present invention is alternately changed in the transverse direction every predetermined number of times so that the structure of the cable is stabilized and the bending property is improved And the appearance can be uniformly produced.

Here, the insulating layer 300 alternately includes a S-direction transverse winding layer made of a plurality of layer winding materials wound in the S direction and a Z-direction winding winding layer made of a plurality of winding layers wound in the Z direction, 0.0 > 320 < / RTI > may include two or more S direction transverse sheath layers or Z direction transverse sheath layers.

In the intermediate insulating layer 320, the S-direction transverse winding layer or the semi-insulating sheet constituting the Z-direction transverse winding layer may have the same width in one S-direction transverse winding layer or the same single Z-direction transverse winding layer.

Particularly, in the insulating layer 300, the difference in the sum of the total number of layers wound in the S-direction transverse winding layer and the total number of winding layers wound in the Z-direction transverse winding layer is determined based on the total sum of the number of winding layers wound in the S- It may not exceed ± 10%. Thus, it is possible to prevent the insulating layer 300 from being twisted after filling the insulating layer 300 with the insulating gas.

Specifically, the semiconductive battery forming the inner semiconductive layer 200 is traversed in the S direction, and the kraft paper forming the inner insulating layer 310 is traversed in the Z direction. Particularly, the uppermost layer of the intermediate insulating layer 320 A predetermined number of semiprons belonging to the outer insulating layer 330 can be cooperated with a predetermined number of kraft paper sheets belonging to the lowest layer of the outer insulating layer 330 so that the structure of the cable is more stable and a uniform electric field can be obtained by the additional electric field buffer have.

The metal sheath layer 500 prevents the insulating gas from leaking to the outside of the cable and prevents the electric field from escaping to the outside of the cable so as to obtain an electrostatic shielding effect. The grounding or shorting of the cable It functions as a return path of fault current in the event of an accident to ensure safety, protects the cable from impacts and pressures on the outside of the cable, and improves the water repellency 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.

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 air pressure due to the contraction of the insulating gas due to the temperature lowering when the cable energization is turned off and conversely, It is preferable that the insulating gas is moved and replenished by the air pressure difference.

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 (14)

Conductor;
An inner semiconductive layer surrounding the conductor;
An insulating layer surrounding the inner semiconductive layer;
An outer semiconductive layer surrounding the insulating layer;
A metal sheath layer surrounding the outer semiconductive layer; And
And a cable protection layer surrounding the metal sheath layer,
Wherein the insulating layer is formed by inserting an insulating paper sheet and filling insulating paper in a space between the insulator paper and the insulating paper or both. The method according to claim 1,
The insulating gas is sulfur hexafluoride (SF ₆₎ gas or nitrogen (N ₂₎ gas or the power cable, characterized in that it comprises both. 3. The method according to claim 1 or 2,
Characterized in that said insulating paper comprises at least one through-hole comprising a porous structure or penetrating in the thickness direction. 3. The method according to claim 1 or 2,
Wherein the conductor includes an injection tube into which the insulating gas can be injected and at least one insulated gas outlet connected to the injection tube and capable of discharging injected insulated gas out of the conductor. 3. The method according to claim 1 or 2,
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 formed by horizontally laying a kraft paper and filling insulating gas,
Wherein the intermediate insulating layer is formed by inserting a plastic film and a kraft paper laminated on at least one side of the plastic film, and the insulated gas is charged. 6. The method of claim 5,
Characterized in that the plastic film comprises at least one through-hole containing a porous structure or penetrating in the thickness direction. 6. The method of claim 5,
The kraft or the semi-synthetic paper or both of them are crossed by a gap,
Wherein the gap is transversal so that a constant gap is formed between the kraft paper or the semifinished paper and the gap is formed when the new kraft paper or the semi- Characterized in that it continues to be rolled over so that a gap is also formed between the new kraft paper or semifinished paper while being covered by the paper or semifinished paper. 8. The method of claim 7,
The intermediate insulation layer is divided into at least two layers depending on the width of the semi-synthetic paper constituting the intermediate insulation layer. The layer located on the side of the conductor is referred to as a lower layer and the layer located on the outer side of the lower layer is referred to as an upper layer , The width of the semi-synthetic paper forming the upper layer is larger than the width of the semi-synthetic paper forming the lower layer,
And the width of the gap between the semi-synthetic papers formed by the gap of the semi-synthetic papers is 5 to 15% of the width of the semi-synthetic papers. 9. The method of claim 8,
Wherein the width of the semi-synthetic paper constituting the intermediate insulation layer adjacent to the inner insulation layer is equal to the width of the semi-synthetic paper constituting the inner insulation layer adjacent thereto. 8. The method of claim 7,
The inner semiconductive layer is formed by winding a semiconductive battery horizontally to a gap and filled with an insulating gas. The outer semiconductive layer is formed by winding a semi-conductive paper horizontally to a gap and filled with an insulating gas, And an upper layer which is formed by filling the insulated gas with a bottom layer formed by being filled with insulating gas, and a bottom layer formed by filling the insulated gas with the semi-conducting battery and the metal paper together. 6. The method of claim 5,
And the resistivity of the inner insulating layer and the outer insulating layer is smaller than the resistivity of the intermediate insulating layer. 6. The method of claim 5,
Wherein the thickness of the outer insulating layer is greater than the thickness of the inner insulating layer. 3. The method according to claim 1 or 2,
Wherein the cable protective layer comprises an inner sheath, a bedding layer, a metal reinforcement layer and an outer sheath. 14. The method of claim 13,
Wherein the cable protective layer further comprises a wire sheath and an outer sheath layer.

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