KR102202692B1 - Extra high voltage cable - Google Patents

Abstract

The present invention relates to an ultra-high voltage cable. Specifically, the present invention relates to an ultra-high voltage cable having a watertight layer that is lighter than a conventional ultra-high voltage cable, has excellent corrosion resistance, and maintains interlayer adhesion even with external physical impacts and temperature changes, thereby effectively suppressing peeling.

Description

Extra high voltage cable

The present invention relates to an ultra-high voltage cable. Specifically, the present invention relates to an ultra-high voltage cable having a watertight layer that is lighter than a conventional ultra-high voltage cable, has excellent corrosion resistance, and maintains interlayer adhesion even with external physical impacts and temperature changes, thereby effectively suppressing peeling.

Ultra-high voltage cables such as submarine cables generally include a watertight layer that suppresses the penetration of moisture from the outside.

1 schematically shows a cross-sectional structure of a power cable disclosed in US Patent Publication No. 4,472,597. As shown in Figure 1, the conventional power cable is a conductor (1), an inner semiconducting layer (2), an insulating layer (3), an outer semiconducting layer (4), a metal shielding layer (5), a conductive tape layer (8) , The watertight layer 7 and the outer jacket 6 may have a structure including these configurations in the order.

Here, when an aluminum laminated tape coated with polyethylene on both sides of an aluminum foil is used as the watertight layer 7, the aluminum foil is susceptible to corrosion and is caused by moisture passing through the outer jacket 6. Damage can shorten the life of the cable.

Meanwhile, FIG. 2 schematically shows a cross-sectional structure of a power cable disclosed in US Patent Publication No. 4,501,928. As shown in Figure 2, the conventional power cable is a conductor (1'), an inner semiconducting layer (2'), an insulating layer (3'), an outer semiconducting layer (4'), a metal shielding layer (5'), The conductive tape 6', the watertight layer 7', and the outer jacket 8'may have a structure including these configurations in that order.

Here, when a lead laminated tape coated with polyethylene, polyvinyl chloride, etc. on both sides of a lead foil as the watertight layer 7'is used, the lead foil is heavy and the light weight of the cable is reduced. I can.

In addition, the watertight layers 7 and 7 ′ applied to conventional power cables have insufficient adhesion to the outer jackets 6 and 8 ′, and thus the watertight layers 7 and 7 ′ due to external physical shocks and temperature changes. There is a problem that the outer jackets 6 and 8'are peeled from each other.

Accordingly, there is an urgent need for an ultra-high voltage cable having a watertight layer that is lighter than the conventional ultra-high voltage cable, improves corrosion resistance, and maintains interlayer adhesion even with external physical impacts and temperature changes, thereby effectively suppressing peeling.

An object of the present invention is to provide an ultra-high voltage cable that is lighter than the conventional ultra-high voltage cable.

In addition, an object of the present invention is to provide an ultra-high voltage cable having a watertight layer in which corrosion resistance is improved and interlayer adhesion is maintained even with external physical impacts and temperature changes, so that peeling is effectively suppressed.

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

A central conductor, an inner semiconducting layer surrounding the central conductor, an insulating layer surrounding the inner semiconducting layer, an outer semiconducting layer surrounding the insulating layer, a metal shielding layer surrounding the outer semiconducting layer, a watertight layer surrounding the metal shielding layer, the In the ultra-high voltage cable comprising an adhesive layer surrounding the watertight layer, and an outer jacket surrounding the adhesive layer, the watertight layer is formed on a copper tape and the copper tape, and includes an adhesive auxiliary layer comprising a random copolymer resin of olefin and polar monomer It provides an ultra-high voltage cable, characterized in that.

Here, the polar monomer is a vinyl ester monomer of vinyl acetate or vinyl versatate, a vinyl-unsaturated carboxylic acid monomer of methacrylic acid, acrylic acid, maleic acid or itaconic acid, an acrylic monomer of (meth)acrylate or alkyl (meth)acrylate It provides an ultra-high voltage cable, characterized in that.

In addition, the random copolymer resin of the olefin and the polar monomer is characterized in that ethylene acrylic acid (EAA), ethylene vinyl acetate (EVA) or ethylene butyl acrylate (EBA), it provides an ultra-high voltage cable.

Here, the content of the polar monomer is 5 to 20% by weight, based on the total weight of the random copolymer resin, it provides an ultra-high voltage cable.

Further, the copper tape has a thickness of 0.1 to 0.2 mm, and the adhesive auxiliary layer has a thickness of 0.05 to 0.09 mm, providing an ultra-high voltage cable.

On the other hand, the outer jacket is made of high-density polyethylene (HDPE), it provides an ultra-high voltage cable, characterized in that the thickness is 6.5 to 7.5 mm.

In addition, the metal shielding layer includes a first semiconducting tape rolled horizontally on the outer semiconducting layer, a metal layer disposed on the first semiconducting tape and including a plurality of copper neutral wires, and a second semiconducting tape rolled horizontally on the metal layer. It characterized in that it comprises, it provides an ultra-high voltage cable.

In addition, the insulating layer provides an ultra-high voltage cable, characterized in that made of crosslinked polyethylene (XLPE).

Further, the watertight layer provides an ultra-high voltage cable, characterized in that both ends of the watertight layer overlap each other, and the lower and upper surfaces of the watertight layer in the overlapping region are bonded by a hot melt adhesive.

Here, the hot melt adhesive provides an ultra-high voltage cable, characterized in that made of a polyamide resin.

In addition, the hot melt adhesive provides an ultra-high voltage cable, characterized in that it has a creep resistance temperature and a softening temperature of 90°C or higher.

On the other hand, it provides an ultra-high voltage cable, characterized in that the inner semiconducting layer, the insulating layer and the outer semiconducting layer are made of the same base resin.

The ultra-high voltage cable according to the present invention includes a watertight layer made of a lightweight material, thereby exhibiting an excellent effect of being lightweight compared to the conventional ultra-high voltage cable.

The ultra-high voltage cable according to the present invention exhibits an excellent effect of suppressing corrosion of the watertight layer by including a watertight layer made of a material having excellent corrosion resistance.

The ultra-high voltage cable according to the present invention effectively suppresses the peeling of the watertight layer even with external physical shocks and temperature changes by improving the adhesion between the watertight layer and the outer jacket. Show.

1 schematically shows a cross-sectional structure of an embodiment of a conventional power cable.
FIG. 2 schematically shows a cross-sectional structure of another embodiment of a conventional power cable.
3 is a cross-sectional view schematically showing a cross-sectional structure of an embodiment of an ultra-high voltage cable according to the present invention.
4 is a longitudinal sectional view schematically showing a cross-sectional structure of an embodiment of an ultra-high voltage cable according to the present invention.
5 schematically shows the cross-sectional structure of the watertight layer 80 in the ultra-high voltage cable according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art. The same reference numbers throughout the specification denote the same elements.

3 and 4 schematically show a cross-sectional structure of an embodiment of an ultra-high voltage cable according to the present invention. 3 and 4, the ultra-high voltage cable according to the present invention includes a central conductor 10, an inner semiconducting layer 20 surrounding the central conductor 10, and an insulating layer surrounding the inner semiconducting layer 20 ( 30), the outer semiconducting layer 40 surrounding the insulating layer 30, the outer semiconducting layer 40, and a first semiconducting tape 50, a metal layer 60, and a second semiconducting tape 70 A configured metal shielding layer, a watertight layer 80 surrounding the metal shielding layer, an adhesive layer 90 bonding the watertight layer 80 and the outer jacket 100, and an outer jacket 100 may be included.

The center conductor 10 may be formed of a single wire made of copper, aluminum, preferably copper or a stranded wire in which a plurality of conductors are combined, and the diameter of the center conductor 10, the diameter of the wires constituting the stranded wire, etc. The included standard may be different depending on the transmission voltage and use of the power cable including the same, and may be appropriately selected by a person skilled in the art. For example, when the ultra-high voltage cable according to the present invention is used for a purpose requiring installation, flexibility, etc., such as a submarine cable, the center conductor 10 is preferably made of a stranded wire having superior flexibility rather than a single wire.

The inner semiconducting layer 20 is disposed between the central conductor 10 and the insulating layer 30 to eliminate an air layer that causes interlayer lifting of the central conductor 10 and the insulating layer 30, and It performs functions such as relieving the concentration of phosphorus electric field. On the other hand, the outer semiconducting layer 40 performs a function of applying an equal electric field to the insulating layer 30, mitigating local electric field concentration, and protecting the cable insulating layer from the outside.

Typically, the inner semiconducting layer 20 and the outer semiconducting layer 40 are formed by extrusion of a semiconducting composition in which conductive particles such as carbon black, carbon nanotube, carbon nanoplate, graphite are dispersed in a base resin, The base resin is an olefin resin of the same series as the base resin of the insulating composition forming the insulating layer 30 for interlayer adhesion between the semiconducting layers 20 and 40 and the insulating layer 30, for example, olefin It is preferable to use a copolymer resin of an acrylic monomer, in particular, ethylene butyl acrylate (EBA), ethylene ethyl acrylate (EEA), or the like.

The thickness of the inner and outer semiconducting layers 20 and 40 may be different depending on the transmission voltage of the cable, for example, in the case of a 345kV ultra-high voltage cable, the thickness of the inner semiconducting layer 20 is 1.6 to 1.8 mm. The thickness of the outer semiconducting layer 40 may be 1.02 to 2.54 mm.

The insulating layer 30 may be, for example, a polyolefin resin such as polyethylene or polypropylene as a base resin, and preferably may be formed by extrusion of an insulating composition containing a polyethylene resin.

The polyethylene resin may be ultra low density polyethylene (ULDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), or a combination thereof. In addition, the polyethylene resin may be a homopolymer, a random or block copolymer of an α-olefin such as ethylene and propylene, 1-butene, 1-pentene, 1-hexene, and 1-octene, or a combination thereof.

In addition, since the insulating composition forming the insulating layer 30 includes a crosslinking agent, the insulating layer 30 is a crosslinked polyolefin (XLPO), preferably a crosslinked polyethylene (XLPE) by a separate crosslinking process during or after extrusion. ) Can be made. In addition, the insulating composition may further contain other additives such as an antioxidant, an extrusion enhancer, and a crosslinking aid.

The crosslinking agent is a silane-based crosslinking agent, or dicumyl peroxide, benzoyl peroxide, lauryl peroxide, t-butyl cumyl peroxide, di(t-butyl peroxy isopropyl) benzene, 2,5 according to the crosslinking method of the polyolefin. It may be an organic peroxide-based crosslinking agent such as -dimethyl-2,5-di(t-butyl peroxy)hexane and di-t-butyl peroxide. Here, the crosslinking agent may be included in an amount of 1 to 5 parts by weight based on 100 parts by weight of the base resin.

The thickness of the insulating layer 30 may vary depending on the transmission voltage of the power cable. For example, in the case of a 345kV ultra-high voltage cable, the thickness of the insulating layer 30 may be 27.45 to 34.55 mm.

In the metal shielding layer, the first semiconducting tape 40 is rolled horizontally under the metal layer 50 formed by a plurality of neutral wires made of metal, preferably copper, and the second semiconducting tape 60 is rolled horizontally thereon. It can be formed and serves to protect the cable under harsh environmental conditions such as the seabed.

The first semiconducting tape 40 performs buffering for suppressing deformation of the insulating layer 30 due to the load of the metal layer 50, and the second semiconducting tape 60 is applied to the metal layer 50 ) Bind. In addition, the first and second semiconducting tapes 40 and 60 may be wet and swollen tapes, and in this case, they may perform a water-blocking function in parallel. The thickness of the first and second semiconducting tapes 40 may be, for example, about 200 to 1,000 μm.

The thickness of the metal layer 50 forming the metal shielding layer may be, for example, about 2.2 to 2.4 mm, and the thickness of the first and second semiconducting tapes 40 and 60 may be, for example, about 0.85 to 0.95 May be mm.

5 schematically shows a cross-sectional structure of the watertight layer 80 in the ultra-high voltage cable according to the present invention. As shown in FIG. 5, the watertight layer 80 may include a metal, preferably a copper tape 81 and an adhesive auxiliary layer 82. The watertight layer 80 serves to suppress the penetration of moisture penetrating through the outer jacket 100 into the insulating layer 30.

The thickness of the copper tape 81 may be, for example, about 0.1 to 0.25 mm, and the thickness of the adhesive auxiliary layer 82 may be, for example, about 0.05 to 0.09 mm. The adhesive auxiliary layer 82 should be formed as thin as possible to avoid negative effects on the electrical properties of the cable.

In the watertight layer, the copper tape 81 has an advantage in that it has excellent corrosion resistance compared to the conventional aluminum foil layer and is lighter than that of the conventional lead foil layer. An auxiliary adhesive layer 82 is formed on the copper tape 81. Since adhesion between the copper tape 81 and the adhesive layer 90 is not easy, an adhesive auxiliary layer 82 made of a resin that is easily adhered to the adhesive layer 90 is laminated on the copper tape 81 ( lamination).

A method of laminating the adhesive auxiliary layer 82 is not particularly limited, and for example, a method such as deposition, electro deposition, or extrusion may be used. The adhesive auxiliary layer 82 has a function of maintaining close adhesion between the watertight layer 80 and the outer jacket 100 even under severe conditions in which an impact is applied from the outside of the cable or the temperature rapidly changes, and the copper tape ( 81) has a function of inhibiting corrosion.

The adhesive auxiliary layer 82 may be formed of an adhesive comprising an acrylic resin, an olefin resin, preferably a random copolymer resin of an olefin and a polar monomer as a base resin. The adhesive auxiliary layer 82 may be formed by a general coating process such as spraying, impregnation, and extrusion.

Here, the polar monomers include vinyl ester monomers such as vinyl acetate and vinyl versatate; Vinyl-unsaturated carboxylic acid monomers such as methacrylic acid, acrylic acid, maleic acid, and itaconic acid; Acrylic monomers such as (meth)acrylate and alkyl (meth)acrylate, or a combination thereof may be included, and the content of the polar monomer is 5 to 20% by weight, preferably 5, based on the total weight of the resin. To 15% by weight.

Preferably, the base resin of the adhesive forming the adhesive auxiliary layer 82 may be ethylene acrylic acid (EAA), ethylene vinyl acetate (EVA), ethylene butyl acrylate (EBA), or the like.

As shown in FIG. 4, both ends of the watertight layer 80 may be overlapped to realize more excellent watertight properties, and in the overlapping region, the lower and upper surfaces of the watertight layer 80 are hot melt ( It can be tightly bonded by hot melt) adhesive. The hot melt adhesive is a hot melt adhesive that exhibits adhesive strength while cooling and solidifying within a few seconds after coating and compression in a liquid state at high temperature using 100% thermoplastic resin without using any water or solvent.

Compared with other solvent-type adhesives or water dispersion-type adhesives, the hot melt adhesive does not require a drying process, has a small working space, and has a high adhesion speed. In addition, the material of the hot melt adhesive may be, for example, polyurethane, polyamide, polyester, ethylene vinyl acetate, rubber, and the like, and in general, it may further include a wax, an adhesive, a plasticizer, a filler, an antioxidant, and the like.

The hot melt is preferably made of a polyamide series having a creep resistance temperature and a softening temperature of 90° C. or higher for use in a power cable, for example, from Henkel. The commercially available Q8740 or Q6239 can be purchased and used.

The adhesive layer 90 performs a function of bonding the watertight layer 80 to the outer jacket 100. The adhesive layer 90 is a resin of the same series as the resin forming the watertight layer 80 and the outer jacket 100 for close adhesion with the watertight layer 80 and the outer jacket 100, for example. For example, an α-olefin resin, preferably a copolymer resin of an α-olefin and an acrylic monomer, more preferably a random copolymer resin of ethylene and acrylic acid, a polyethylene copolymer resin in which ethylene, acrylic acid and butyl acrylate are randomly copolymerized, etc. I can. The thickness of the adhesive layer 90 may be, for example, 0.5 to 2 mm.

The outer jacket 100 may include polyethylene, polyvinyl chloride, polyurethane, etc., and in order to maintain close adhesion with the adhesive layer 90, a resin of the same series as the resin constituting the adhesive layer 90, For example, it is preferably made of polyethylene resin, and since it is a layer disposed on the outermost side of the cable, in consideration of mechanical strength, it is more preferable that it is made of high-density polyethylene resin.

When an impact is applied to the cable from the outside, the outer jacket 100 preferably has a thickness of, for example, 6 to 8 mm in order to absorb the impact and maintain close adhesion with the adhesive layer 90.

As described above, the ultra-high voltage cable according to the present invention has a base layer of the watertight layer made of copper tape that is lighter than conventional lead and has excellent corrosion resistance compared to conventional aluminum, so that it is lighter than conventional ultra-high voltage cables and has excellent corrosion resistance. An adhesive auxiliary layer forming a watertight layer, an adhesive layer that bonds the watertight layer to the outer jacket, the thickness of the outer jacket and a specific resin constituting the thickness of the outer jacket, the interlayer constituting the cable even with external physical impact and temperature change It shows an excellent effect of keeping the adhesion tight.

[Example]

1. Manufacturing example

Sample sheets of Examples and Comparative Examples consisting of layers and thicknesses as shown in Table 1 below through a hot press operation under conditions of a press temperature of 160°C (10 minutes), a cooling temperature of 40°C (10 minutes), and a pressure of 4,800 kg/m2 Were prepared respectively. The unit of the thickness of the layer listed in Table 1 below is mm.

Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Cu
tape 0.215 0.16 0.127 0.127 0.127 0.132 0.132 0.132 adhesion
Auxiliary layer 0.055 - - - - - - - Adhesive layer 0.5 0.5 2 0.5 2 2 0.5 2 Out
jacket 6 3 6 6 3 6 6 3

-Cu tape (manufacturer: Korea-Ilecom)

-Adhesion auxiliary layer: ethylene/acrylic acid random copolymer resin (EAA)

-Adhesive layer: ethylene/acrylic acid random copolymer resin adhesive (manufacturer: Bassell; product name: Lucalen A2920M)

-Outer jacket: high density polyethylene

2. Evaluation of peeling

In accordance with the IEC 61901 standard specified in AEIC CG-13, it was evaluated whether or not the layers were peeled off when imparting impact or impact + high temperature corrosion. Specifically, the sample sheet according to each of the Examples and Comparative Examples prepared in the above Preparation Example has an impact corresponding to a weight of 5 kg at a point 1 m in height from this, and whether or not interlayer peeling is determined after being applied to three different points. As described above, some samples were subjected to high-temperature corrosion conditions in an oven at 80° C. for one week after the impact was applied as described above, and then it was confirmed whether or not interlayer peeling was performed. The results are as shown in Table 2 below.

Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Evaluation 1 Good Bad Bad Bad Bad Bad Bad Bad Evaluation 2 Good Bad Bad Bad Bad Bad Bad Bad

-Evaluation 1: Evaluation of peeling after impact is applied

-Evaluation 2: Evaluation of peeling after imparting impact and high temperature corrosion

As shown in Table 2, the sample sheet of the embodiment according to the present invention maintains interlayer adhesion even under external physical impact and rapid temperature change by the appropriate thickness of the constituent layers and the adhesive auxiliary layer laminated on the copper (cu) tape. Thus, delamination was not observed, whereas delamination was observed in all of the sample sheets according to the comparative example due to interlayer adhesion failure.

Although the present specification has been described with reference to preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention within the scope not departing from the spirit and scope of the present invention described in the claims described below. You will be able to do it. Therefore, if the modified implementation basically includes the elements of the claims of the present invention, it should be seen that all are included in the technical scope of the present invention.

10: conductor 20: inner semiconducting layer
30: insulating layer 40: outer semiconducting layer
50,70: semiconductive tape 60: metal layer
80: watertight layer 90: adhesive layer
100: outer jacket

Claims (12)

A central conductor, an inner semiconducting layer surrounding the central conductor, an insulating layer surrounding the inner semiconducting layer, an outer semiconducting layer surrounding the insulating layer, a metal shielding layer surrounding the outer semiconducting layer, a watertight layer surrounding the metal shielding layer, the In the ultra-high voltage cable comprising an adhesive layer surrounding the watertight layer, and an outer jacket surrounding the adhesive layer,
The watertight layer includes a copper tape and an adhesive auxiliary layer formed on the copper tape and comprising a random copolymer resin of an olefin and a polar monomer,
The content of the polar monomer is 5 to 20% by weight, based on the total weight of the random copolymer resin,
The adhesive layer comprises a copolymer resin of an α-olefin and an acrylic monomer,
The outer jacket includes high density polyethylene (HDPE),
The adhesive layer and the outer jacket contain the same series of resin,
Both ends of the watertight layer are overlapped with each other, and a lower surface and an upper surface of the watertight layer in the overlapping region are bonded by a hot melt adhesive. The method of claim 1,
The polar monomer is a vinyl ester monomer of vinyl acetate or vinyl versatate, a vinyl-unsaturated carboxylic acid monomer of methacrylic acid, acrylic acid, maleic acid or itaconic acid, an acrylic monomer of (meth)acrylate or alkyl (meth)acrylate. Characterized by the ultra-high voltage cable. The method of claim 2,
The random copolymer resin of the olefin and the polar monomer is characterized in that ethylene acrylic acid (EAA), ethylene vinyl acetate (EVA), or ethylene butyl acrylate (EBA), ultra-high pressure cable. delete The method according to any one of claims 1 to 3,
The copper tape has a thickness of 0.1 to 0.2 mm, and the adhesive auxiliary layer has a thickness of 0.05 to 0.09 mm. The method according to any one of claims 1 to 3,
The outer jacket is characterized in that the thickness is 6.5 to 7.5 mm, ultra-high voltage cable. The method according to any one of claims 1 to 3,
The metal shielding layer includes a first semiconducting tape rolled horizontally on the outer semiconducting layer, a metal layer disposed on the first semiconducting tape and including a plurality of copper neutral wires, and a second semiconducting tape rolled horizontally on the metal layer. It characterized in that, ultra-high voltage cable. delete delete The method of claim 1,
The hot melt adhesive is characterized in that made of a polyamide resin, ultra-high voltage cable. The method of claim 1,
The hot melt adhesive is characterized in that it has a creep resistance temperature and a softening temperature of 90° C. or higher. The method according to any one of claims 1 to 3,
An ultra-high voltage cable, characterized in that the inner semiconducting layer, the insulating layer, and the outer semiconducting layer are made of a base resin of the same series.

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