JPH0520210U - Impermeable power cable - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a water-impervious power cable capable of preventing fatigue and breakage of a metal water-impervious layer due to a long heat cycle by an economical and simple means. [Structure] An inner semiconductive layer 13, an insulator layer 14, and an outer semiconductive layer 15 are sequentially arranged on a conductor 12. On the outside of the outer semiconductive layer 15, a 100 μm thick conductive resin layer 17 is laminated on one side of a 9 μm thick copper foil 16 and a 5 μm thick tin-coated water-blocking tape is applied on the other side. After covering vertically so that the conductive resin layer 17 is on the side of the outer semiconductive layer 15, the outer semiconductive layer 15, the metal impermeable layer 18, and the portion where the impermeable tape are overlapped are heat-sealed. The metal water blocking layer 18 is arranged. On the peripheral surface of the metal water-impervious layer 18, 16 copper wires 19 having a diameter of 1.2 mm are SZ-twisted and arranged to form a metal shield layer. A protective sheath layer (20) is arranged by extruding and covering vinyl chloride on the peripheral surface of the metal water-impervious layer (18) including the copper wire (19).

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a water-impervious power cable.

[0002]

[Prior Art]

 Generally, a rubber or plastic power cable has an inner semiconducting layer 32, an insulator layer 33, an outer semiconducting layer 34, a metal shielding layer 35 made of a copper tape, on a conductor 31, as illustrated in FIG. And a protective sheath layer 36 made of a soft vinyl chloride resin composition or the like in this order. Of these, the conductor 31, the inner semiconductive layer 32, the insulator layer 33, and the outer semiconductive layer 34 are usually referred to as a cable core portion.

In the power cable 30 having such a configuration, it is important to prevent water from penetrating from the external environment of the cable into the inside of the cable core portion, which causes deterioration of the electrical characteristics of the power cable. In order to prevent such moisture from entering the inside of the cable, the inventors of the present invention firstly attached a laminated tape, in which a metal tape and a conductive resin were sequentially laminated, to the outside of the cable core, to make it conductive. We have proposed a water-impervious power cable on the core that has a water-impervious layer integrated with an external semiconducting layer by vertically adhering a conductive resin so that it is on the side of the cable core, and then heat-sealing it (Actual Kosho) In such a water shield type power cable on a core, since the water shield layer and the cable core portion are integrated, water intrusion may occur between the water shield layer and the cable core portion. Almost no water runs.

[0004]

[Problems to be solved by the device]

 However, in a water-impervious power cable, the energized state and the extinguished state are frequently repeated when actually used. Therefore, in the energized state, the temperature of the entire cable rises, and in the deenergized state, the temperature of the entire cable falls, and the heat cycle is continuously repeated. As a result, each layer that makes up the power cable repeats expansion and contraction according to such heat cycles, and fatigue accumulates, especially in the impermeable layer, and in the worst case damage such as cracks in the impermeable layer. Is more likely to occur and is a cause of significantly shortening the product life of water-impervious power cables. In addition, if the water-impervious power cable on the core is used for a long time in a submerged condition, water may pass through the protective sheath from the outside and penetrate into the water-impervious layer. In this case, the copper tape of the metal shielding layer is prone to corrosion and discoloration from the edges, and if a bending load (vent) is repeatedly applied to the cable in this state, there is a problem that the copper tape is buckled or broken.

The present invention has been made in view of the above point, and almost no fatigue occurs in each layer of the cable even by a heat cycle for a long period of time, and the metal shielding layer is formed by the intrusion of water from the outside. The present invention provides a water-impervious power cable that has excellent vent resistance even when it is slightly corroded or discolored, and can prevent damage to the water-impervious layer by economical and simple means.

[0006]

[Means for Solving the Problems]

 According to the present invention, a conductive resin is laminated on one side of a copper foil on the outside of a cable core portion in which an inner semiconductive layer, an insulating layer, and an outer semiconductive layer are sequentially arranged on a conductor. A metal impermeable layer formed by arranging the laminate so that the conductive resin is on the side of the cable core; a metal shielding layer made of copper wire arranged outside the metal impermeable layer; A water-impervious power cable comprising a protective sheath layer disposed on the outside.

In the water-impervious power cable of the present invention, the thickness of the copper foil is preferably 0.025 mm or less. This is because when the thickness of the copper foil exceeds 0.025 mm, wrinkles tend to occur on the copper foil when the cable core section repeatedly expands and contracts, and when it exceeds this thickness, the cable repeats. This is because when a vent is added, the copper foil is likely to buckle, and in particular, the thickness of the copper foil is preferably in the range of 0.007 to 0.020 mm. Further, as a copper foil to be used, oxygen-free acid is preferable because it is excellent in flexibility and elongation.

The conductive resin laminated on one side of the copper foil includes low, medium and high density polyethylene, polypropylene, polybutene-1, polymethylpentene, ethylene propylene copolymer, ionomer, ethylene-ethyl acrylate copolymer. Polymer, ethylene-vinyl acetate-vinyl chloride graft copolymer, ethylene-acrylic acid copolymer, chlorinated polyethylene, chlorosulfonated polyethylene, polyvinyl chloride, and other plastics, isoprene rubber, chloroprene rubber, acrylonitrile-butadiene It is possible to use a mixture of rubber such as rubber and styrene-butadiene rubber with conductive carbon black as appropriate. The conductive resin preferably has a volume resistivity of 10 ⁵ Ωcm or less.

The other surface of the copper foil on which the conductive resin is not laminated is preferably tin-plated or solder-plated in order to prevent the copper foil surface from being corroded or discolored.

[0010]

[Action]

 According to the water-impervious power cable of the present invention, the copper foil is used as the water-impervious metal for preventing the intrusion of moisture from the outside. Since copper foil has excellent fatigue resistance, it is difficult for the copper foil to be damaged when the cable repeatedly expands and contracts due to heat cycles. Also, since copper wire is used as the shielding metal, it is less likely to be damaged when the cable repeatedly expands and contracts, and when the cable is repeatedly subjected to bending load (vent), the copper tape will not buckle or bend. It is unlikely to break, and there is less risk of damaging the copper foil at the edges like copper tape. Furthermore, since the copper foil and the copper wire are made of the same material, a potential difference between them is unlikely to occur, and there is less risk of an undesired phenomenon such as discharge between the two when a surge enters the cable. ..

Further, since the conductive resin is disposed between the cable core portion and the copper foil, electrical conduction can be obtained from the conductor to the metal shielding layer.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an explanatory view showing an example of the water-impervious power cable of the present invention.

Reference numeral 11 in the figure denotes a cable core portion used for a 35 kV 1/0 AWG, XLPE cable, in which an inner semiconductive layer 13, an insulator layer 14, and an outer semiconductive layer 15 are sequentially arranged on a conductor 12. It is a thing.

On the other hand, a conductive resin layer 17 is laminated on one side of the copper foil 16 and a water blocking tape having a tin plating of 5 μm in thickness on the other side is prepared. This water-impervious tape was vertically placed on the outer side of the outer semiconductive layer 15 so that the conductive resin layer 17 was on the outer semiconductive layer 15 side. The metal impermeable layer 18 is arranged by heat-sealing the portions. In this case, for the conductive resin layer 17, a resin having a good compatibility with the outer semiconductive layer 15 is selected, and the outer semiconductive layer 15 is vertically aligned and covered, and thereafter, both are melted. It is preferable that they are integrated with each other. After this, 16 copper wires 19 having a diameter of 1.2 mm are SZ-twisted and arranged on the peripheral surface of the metal water shield layer 18, and the metal shield layer is arranged. Further, a protective sheath layer 20 is arranged by extruding and covering vinyl chloride on the peripheral surface of the metal water-impervious layer 18 including the copper wire 19.

Examples 1 and 2 Next, in the water-impervious power cable 10 having such a structure, as the metal water-impervious layer, the water-impervious layer having the structure shown in the first and second columns of Table 1 is used. The cables of Examples 1 and 2 using the respective tapes were manufactured. The prototype cables of Examples 1 and 2 were subjected to (1) heat cycle durability test and (2) cable vent test as follows.

(1) Heat Cycle Durability Test First, each cable was cut into a length of 3 m, both ends were fixed in a state of being bent to a diameter 20 times the outer diameter of the cable, and then a current was intermittently applied to the conductor 12. Was conducted, and the heat cycle in which the temperature of the conductor 12 was 130 ° C. and 40 ° C. as one cycle was repeated 50 times and 100 times. Then, each cable was disassembled and the state of the copper foil 16 was evaluated. The results are shown in Table 2.

(2) Cable Vent Test Each cable is placed along a vent plate having a diameter 10 times the outer diameter of the cable, and a bending load of 10 reciprocations is applied. Then, each cable is disassembled, and a metal shielding layer and a metal shielding layer are provided. The state of the water layer 18 was evaluated. The results are also shown in Table 2.

In Table 1, conductive PET means a resin layer obtained by blending conductive carbon black with polyolefin terephthalate (PET), and conductive EEA means a heat-adhesive ethylene ethyl acrylate copolymer. (EEA) shows a mixture of conductive carbon black (manufactured by Nippon Yunika Co., Ltd., trade name GA-004BK). The conductive adhesive layer is a mixture of an adhesive polyolefin resin and conductive carbon black. Show things.

Comparative Examples 1 and 2 The same configurations as in Examples 1 and 2 except that, as the metal water blocking layer 18, water blocking tapes having the configurations shown in columns 3 and 4 of Table 1 were used. The water-impervious power cables of Comparative Examples 1 and 2 were manufactured as prototypes. The cables of Comparative Examples 1 and 2 were subjected to the same heat cycle durability test and cable vent test as in Examples 1 and 2. The results are shown in Table 2.

Comparative Examples 3 to 4 Examples 1 to 1 except that as the metal shielding layer, a copper tape having a thickness of 0.1 mm was wound on the peripheral surface of the metal water shielding layer 18 instead of the copper wire 19. The water-impervious power cables of Comparative Examples 3 and 4 having the same configuration as that of No. 2 were prototyped. The cables of Comparative Examples 3 to 4 were subjected to the same heat cycle durability test and cable vent test as in Examples 1 and 2. The results are shown in Table 2.

[0022]

[Table 1]

[0023]

[Table 2]

As is clear from Table 2, in the trial cables of Examples 1 and 2, no damage to the copper foil was observed in any of the trial cables even after 100 heat cycles.

Further, after the repeated bending load was applied, the metal shielding layer was good in that the copper wire 19 had some pitch disturbance. No damage or breakage was observed in the copper foil as well as in the metal impermeable layer.

On the other hand, in the prototype cable of Comparative Example 1 in which the lead foil was used instead of the copper foil, the lead foil was cracked after 50 heat cycles. In the prototype cable of Comparative Example 2 in which the aluminum foil was used instead of the copper foil, the lead foil had wrinkles after 50 heat cycles, and the lead foil had cracks after 100 heat cycles. On the other hand, when repeated bending loads were applied, in the prototype cables of Comparative Examples 1 and 2, the metal shielding layer was good in that the copper wire 19 constituting it had some pitch disturbance, but it was good. In the metal water-impervious layer, breakage due to scratches was observed on the lead foil (Comparative Example 1) and the aluminum foil (Comparative Example 2).

In each of the prototype cables of Comparative Examples 3 and 4 using the copper tape as the metal shielding layer, it was confirmed that the edge of the copper tape causes damage to the copper foil. On the other hand, when a repeated bending load was applied, in the trial cables of Comparative Examples 3 and 4, the metal shielding layer caused buckling of the copper tape, and some breakage was observed at the edge of the copper tape. In addition, in the metal water-impervious layer, breakage and damage were observed in the plastic layer of the water-impermeable tape in response to buckling of the copper tape and breakage at the edges.

[0028]

[Effect of the device]

 As described above, according to the water-impervious power cable of the present invention, it is possible to prevent fatigue and breakage of the metal water-impervious layer due to a long heat cycle by an economical and simple means. As a result, it has remarkable effects such as prolonging the product life of the water-impervious power cable.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a water-impervious power cable of the present invention.

FIG. 2 is an explanatory diagram showing a conventional power cable.

[Explanation of symbols]

10 ... Water-impervious power cable, 11 ... Cable core part, 1
2 ... Conductor, 13 ... Internal semiconductive layer, 14 ... Insulator layer, 15
... external semiconductive layer, 16 ... copper foil, 17 ... conductive resin layer, 1
8 ... Metal impermeable layer, 19 ... Copper wire, 20 ... Protective sheath layer.

Claims (1)

[Scope of utility model registration request] 1. A conductive resin is laminated on one side of a copper foil on the outside of a cable core portion in which an inner semiconductive layer, an insulator layer, and an outer semiconductive layer are sequentially arranged on a conductor. And a metal shielding layer composed of a copper wire disposed outside the metal shielding layer, and a metal shielding layer formed by arranging the laminated body so that the conductive resin is on the cable core side. A water-impervious power cable comprising a protective sheath layer disposed on the outside of the.