JPS6210899Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a rubber or plastic insulated underwater cable, particularly a lightweight and flexible underwater cable that has excellent water-shielding properties against water seepage inside the conductor and/or water seepage outside the cable. be.

Generally, high-voltage rubber or plastic insulated underwater cables have an internal semiconductive layer 2 and an insulating layer 3 made of polyethylene, cross-linked polyethylene, ethylene propylene rubber, butyl rubber, etc. on the outer periphery of a conductor 1, as shown in Figure 1. , a type in which an external semiconducting layer 4 is provided on the insulating layer 3, or an external semiconducting layer 4
It has a basic structure in which a shielding layer 5 made of copper tape or the like and a protective sheath 6 made of metal such as lead are sequentially provided on top. If moisture intrudes into the cable from the cable terminal or/and the cable outer periphery for some reason during installation or use of such underwater cables, so-called water trees will occur in the insulating layer and each semiconducting layer, and the insulation performance of the cable will deteriorate. This not only deteriorates the performance of the cable, but also deteriorates the various characteristics of the cable, causing accidents.

Therefore, undersea cables used for submarine cables and the like use lead in their protective sheaths to completely prevent moisture from entering from the outside. However, even in such cables, during manufacturing, storage, cable pulling work, etc., moisture can enter through the conductor from the cable end or cable connection, causing damage to the internal semiconducting layer and even the insulating layer from the conductor side. It is known that water trees occur due to water intrusion.

Conventionally, in order to solve this problem, a mixture of low molecular weight polyethylene, microcrystalline wax, polybutene petrolactam, etc., or a mixture of polyvinyl chloride, natural rubber, butyl rubber, etc. and a softening agent was used between the conductor strands. A means is provided to fill the conductor with water and make the conductor watertight. However, conductor filling mixtures generally have strong thixotropic properties, and therefore, when the wires are twisted, the mixture is troweled under high temperature heating or press-fitted under high pressure, so that the mixture is deposited around the wire twisting machine. Not only do they scatter, significantly deteriorating the working environment, but also the wire twisting process that involves such filling operations has the drawback of significantly reducing the wire twisting speed and reducing cable manufacturing efficiency.

In view of this, and as a result of various studies, the present invention has developed a lightweight and flexible rubber/plastic insulated underwater cable that has excellent water-blocking properties against water seepage inside the conductor and/or water seepage outside the cable. An underwater cable in which an inner semiconducting layer and an insulating layer are sequentially provided on the outer periphery of a conductor, and only an outer semiconducting layer or an outer semiconducting layer and a protective sheath are sequentially provided on the insulating layer,
The conductor is covered with a laminated tape of metal tape and semiconductive plastic tape between the conductor and the internal semiconductive layer to form an internal water-blocking layer, and the insulating layer and the external semiconductive layer or the external semiconductive layer and a protective sheath are formed. In between, the insulating layer or the outer semiconductive layer is covered with a laminated tape of a metal tape and a semiconductive plastic tape to form an outer water-blocking layer.

This will be explained in detail using the drawings.

Figure 2 shows an example of the underwater cable of the present invention, in which 1 is a conductor, 2 is an internal semiconducting layer, and 3 is a conductor.
is an insulating layer made of polyethylene, crosslinked polyethylene, ethylene propylene rubber, or butyl rubber, etc.; 4 is an external semiconducting layer; 6 is a protective sheath; 7 is an internal water-blocking layer; 8 is an external water-blocking layer; An internal water-shielding layer 7 is formed thereon, an internal semi-conducting layer 2 and an insulating layer 3 are sequentially provided thereon, an external water-shielding layer 8 is formed on the insulating layer 3, and an external semi-conducting layer 4 is formed thereon. Alternatively, as shown in the figure, an outer semiconducting layer 4 and a protective sheath 5 are sequentially provided, or, although not shown in the figure, an outer semiconducting layer is provided on an insulating layer and an external A protective sheath is provided by forming a water-blocking layer.

The internal water-shielding layer 7 is formed by vertically covering the outer peripheral surface of the conductor 1 with a laminated tape of a metal tape 7a and a semiconductive plastic tape 7b and fusing the joints, and the external water-shielding layer 8 is formed using a metal tape. The outer peripheral surface of the insulating layer 3 or the outer semiconducting layer 4 is covered vertically with a laminated tape consisting of a semiconductive plastic tape 8a and a semiconductive plastic tape 8b, and the bonded portion is fused.

The laminated tape that forms the internal and external water-blocking layers is a metal tape made of copper, lead, aluminum, etc., with semiconductive plastic tape laminated on both sides or one side, and in particular, semiconductive plastic tape is laminated on one side of the metal tape. When forming an internal water-shielding layer on a conductor using tape, place the metal surface on the conductor side, and when forming an external water-shielding layer on an insulating layer, place the semi-conducting layer on the insulating layer side. It is desirable to measure the electric field relaxation of the cable insulation by placing the plastic side facing up.

Low as a semiconductive plastic tape,
Medium, high density polyethylene, polypropylene, polybutene-1, polymethylpentene, ethylene propylene copolymer, ionomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate-
The base material is a rubber or plastic material such as chlorinated polyethylene, chlorosulfonated polyethylene, isoprene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber, etc., and an appropriate amount of carbon black is mixed into it to form a tape. Alternatively, a fibrous base material coated with a conductive mixture may be used. There are no particular restrictions on the carbon black used, but for example,
The product name: KETSUCHEN BLACK EC (manufactured by Akzo Corporation) can be used in the semiconductive plastic tape of the present invention with good results because high conductivity can be obtained by adding a small amount.

The underwater cable of the present invention has the above-mentioned structure, and the internal water-shielding layer acts effectively against water seepage inside the conductor, prevents deterioration of the internal semiconducting layer and insulating layer, and external water-shielding against water seepage outside the cable. The layers work effectively,
Deterioration of the insulator layer can be prevented. The underwater cable of the present invention shown in Fig. 2 has an external water-blocking layer between the insulating layer and the external semiconducting layer, and a protective sheath on the outermost layer, but even if the protective sheath is omitted,
The same effect can be obtained.

Furthermore, if an external water-blocking layer is formed on the external semiconductive layer and a protective sheath is provided thereon, deterioration of the external semiconductive layer can be prevented. Further, since the metal tape is covered vertically with semiconductive plastic tape laminated on both sides and the plastic parts are heated to thermally fuse the plastic layers together, the water-shielding property is further improved.

Examples of the underwater cable of the present invention will be described below.

Example (1) In a 6KV, 1 x 250mm ² CV underwater cable, a 20μ thick copper tape is laminated with a 50μ thick semiconductive polyethylene tape on one side on the conductor, and the semiconductive polyethylene side is an insulator. The layer side is vertically spliced and wrapped, and the lap part is heat-sealed to form an internal water-blocking layer, and an internal conductive layer, a crosslinked polyethylene insulator layer, and an external conductive layer are sequentially provided on top of that, and a thick One side of a 50μ thick copper tape is covered with a 100μ thick semiconductive polyethylene tape laminated vertically, the lap part is heat fused to form an external water barrier layer, and a vinyl sheath is placed on top of that. Extrusion coated.

Example (2) In a 6KV, 1×250mm ² CV underwater cable, a laminated tape similar to Example (1) was wrapped vertically on the conductor to form an internal water-shielding layer, and an internal conductive layer was placed on top of that. and an insulator layer are sequentially provided, and on top of that, a tape made by laminating 100μ thick semiconductive polyethylene tape on both sides of a 50μ thick copper tape is attached vertically to form an external water shielding layer. A conductive layer was extrusion coated.

Example (2) In a 6KV, 1×250mm ² CV underwater cable, internal shielding was done by covering the conductor with a tape made by laminating 50μ thick semiconductive polyethylene tape on both sides of a 30μ thick copper tape. Form a water layer, then sequentially form an inner conductive layer, an insulator layer, and an outer conductive layer on it, and laminate a 100 μ thick semiconductive polyethylene tape on one side of a 50 μ thick lead tape on the outer conductive layer. The obtained tape was attached vertically with the semiconductive polyethylene side facing the outer conductive layer to form an outer water-blocking layer, and a shielding metal protective sheath was provided on top of the tape.

Comparative Example In each of the above Examples, cables without an inner water-shielding layer and an outer water-shielding layer were manufactured.

For these cables, we applied a 15KV voltage under conditions of water immersion inside the conductor and water immersion outside the cable (temperature 80℃), and conducted a water immersion charging experiment for 6 months. We measured water content and observed water trees. As a result, the AC characteristics and moisture content in the insulator layer of the underwater cables of the present invention in Examples (1), (2), and (3) were the same as the original (AC 150KV or more, moisture content 0.01% or less), and the water content was the same as the original. There were no trees either. On the other hand, in each cable of Comparative Example (1), the AC characteristics were reduced to 30% of the original, the moisture content in the insulator layer was about an order of magnitude higher, and many water trees were observed.

As described above, the underwater cable of the present invention has extremely excellent water-blocking properties against water seepage inside the conductor and water seepage outside the cable, and is extremely effective in practice.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a conventional cable, and FIG. 2 is a sectional view showing an example of the cable of the present invention. DESCRIPTION OF SYMBOLS 1... Conductor, 2... Inner semiconducting layer, 3... Insulator layer, 4... Outer semiconducting layer, 5... Shielding layer, 6...
...Protective sheath, 7... Internal water-blocking layer, 8... External water-blocking layer.

Claims (1)

[Scope of utility model registration request] In an underwater cable in which an inner semiconducting layer and an insulating layer are sequentially provided on the outer periphery of a conductor, and only an outer semiconducting layer or an outer semiconducting layer and a protective sheath are sequentially provided on the insulating layer, there is a layer between the conductor and the inner semiconducting layer. A laminated tape of metal tape and semiconductive plastic tape forms an internal water-shielding layer that covers the conductor, and a metal tape and semiconductive plastic tape is used between the insulating layer and the external semiconductive layer or between the external semiconductive layer and the protective sheath. 1. A rubber/plastic insulated underwater cable, characterized in that an outer water-shielding layer is formed by covering an insulating layer or an outer semiconducting layer with a laminated tape with a rubber/plastic plastic tape.