JPH11288626A - Rubber/plastic insulated power cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber/plastic insulated power cable which can carry a sufficient ground current, while avoiding the breaking of an impervious shield layer when the cable is bent. SOLUTION: A laminate tape 5 serving as an impervious shield layer is longitudinally put on cable corps 1-4 and a plastic sheath 6 is provided thereon. The laminate tape 5 is formed by integrally stacking an adhesive layer, an aluminum layer with a thickness of 150 μm or more, and at least one copper layer with a thickness of 30 μm or less. The laminate tape 5 has the copper layer oriented to the inner periphery of a cable, and the overlap of side edges, the laminate tape, and the plastic sheath are bonded together via the adhesive layer. The use of the aluminum layer in the laminate tape results in flexibility such that the laminate layer is not broken even when the cable is bent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to rubber having a rubber / plastic insulator such as EP rubber or crosslinked polyethylene.
The present invention relates to a plastic insulated power cable.

[0002]

2. Description of the Related Art FIG. 6 is a cross-sectional view of a rubber and plastic insulated power cable having a conventional water-blocking structure. A cable core is composed of a conductor 21, an inner semiconductive layer 22, an insulator 23 such as cross-linked polyethylene, and an outer semiconductive layer 24 in order from the inner circumference, and a metal tape such as a copper tape is wound thereon to form a shielding layer. twenty five
Are formed. On the shielding layer 25, a lead laminated tape 26 in which a lead foil, a plastic tape such as a polyester (PET) tape or the like, and an adhesive layer are compounded is applied vertically with the lead foil inside, and furthermore, such as PVC or the like A plastic sheath 27 is extrusion coated. The overlapping portion of the side edge of the lead laminated tape 26 and the space between the lead laminated tape 26 and the plastic sheath 27 are bonded via an adhesive layer.

[0003] However, in this conventional water-impervious cable, a metal layer (lead laminate tape 26) is provided as a water-impervious layer separately from the shield layer, so that the cost is greatly increased. Therefore, as a technique for solving this problem, there has been proposed a cable in which a water-blocking layer also serves as a shielding layer (Japanese Patent Laid-Open No. 6-309948). Although it is necessary to use a metal laminate tape for the water-blocking / shielding layer, it is conceivable to use copper, which has been widely used as a shielding layer, as the metal. FIG. 7 shows the cable configuration.

[0004] In this example, a copper laminated tape 30 is longitudinally attached to a cable core similar to that shown in Fig. 6, and a plastic sheath 27 made of polyvinyl chloride (PVC) is extruded and coated thereon. This copper laminated tape 30 has a thickness of 2
A tape in which a 50 μm copper layer 31, a plastic tape layer 32, and an adhesive layer 33 are combined (FIG. 7B), with the copper layer 31 on the inner side, the plastic tape layer 32 in the middle, and the adhesive layer 33 on the outer side. It is arranged. The copper layer 31 has both a function as a shielding layer and a function as a water shielding layer.

[0005]

On the other hand, when considering a cable that can be used in a 22 kv system (resistance grounding system), the copper layer used for the copper laminated tape is required to carry a ground fault current.
0 μm or more is required. However, since the thickness of the copper layer in the above-mentioned copper laminate tape is 50 μm or less, it may not be able to function as a shielding layer depending on the use conditions. That is, the copper layer having a thickness of more than 50 μm lacks flexibility, and may be wrinkled or torn in the copper laminate tape due to bending or ironing when laying the cable,
It is difficult to make the copper layer thicker than this. Therefore, there is a problem that the current carrying capacity of the ground fault current is insufficient.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by forming a water-shielding layer and a shielding layer with a material more flexible than a copper laminated tape, and solves the above-mentioned problems inherent in a power cable. An object of the present invention is to provide a rubber-plastic insulated power cable having the same water-tightness as a conventional water-proof cable after being filled.

[0007] The feature is that in a rubber-plastic insulated power cable in which a plastic sheath is provided on a cable core in which a laminate tape is vertically attached, the laminate tape is composed of an adhesive layer and an aluminum layer having a thickness of 150 µm or more. This laminated tape is formed by laminating at least one copper layer having a thickness of 30 μm or less, and the copper tape is directed to the inner periphery, and an overlapping portion of a side edge and an adhesive layer are provided between the laminated tape and the plastic sheath. That they are glued together.

In the rubber-plastic insulated power cable of the present invention, a laminated tape having a more flexible aluminum layer is used in place of the copper laminated tape 30 in FIG.
The aluminum laminate tape serves both as a water-shielding layer and a shielding layer.

In order to use an aluminum layer as a water / shielding layer, a thickness of 150 μm or more is required to supply a ground fault current. By using a laminate tape having such an aluminum layer, it is possible to suppress the laminate tape from being torn or peeled due to bending or ironing when laying a cable.

However, since aluminum is used, an oxide film is formed on the surface of the aluminum layer. When the oxide film is formed,
An increase in electrical resistance due to the oxide film is seen on the aluminum surface,
It is not preferable as a shielding layer. Therefore, as a method for preventing the formation of an oxide film on the aluminum layer, a thin copper layer is combined by vapor deposition, plating, or other methods. That is, a copper layer may be combined on one side of the aluminum layer, or a copper layer may be combined on both sides of the aluminum layer. As a result, it is possible to prevent an increase in electrical resistance due to the generation of an oxide film while maintaining the same flexibility as the aluminum layer alone. The thickness of this copper layer is 30 μm or less. If it is 30 μm or less, the flexibility of the aluminum layer is not affected. Actually, a laminate tape was prepared with a copper layer having a thickness of 0.1 μm, and a cable was trial-produced using the laminate tape, and it was confirmed that there was no problem in bending the cable.

An adhesive layer is provided on one side of the "copper layer / aluminum layer" or "copper layer / aluminum layer / copper layer" metal tape, and the copper layer side is on the inner peripheral side (external semiconductive layer side). And adhere to the outer sheath with an adhesive.

With the above construction, the step of winding the lead laminated tape separately from the shielding layer as in the conventional water-impervious cable is not required, so that not only the productivity is greatly improved, but also the shielding metal tape is improved. The material cost of a considerable part can be greatly reduced, and the same high reliability as that of the conventional impermeable cable can be obtained.

[0013]

Embodiments of the present invention will be described below. FIG. 1 is a cross-sectional view of a specific example of a rubber / plastic insulated power cable of the present invention, and FIG. 2 is a cross-sectional view of a laminate tape used in the present invention. As shown in FIG. 1, this cable has a laminated tape layer 5 and a plastic such as PVC on a cable core having an inner semiconductive layer 2, an insulator 3 such as cross-linked polyethylene, and an outer semiconductive layer 4 provided on a conductor 1. The sheath 6 is provided sequentially.

As shown in FIG. 2A, the laminated tape layer 5 has a copper layer 8 (soft copper foil) having a thickness of 30 μm or less on one side of an aluminum layer 7 having a thickness of 150 μm or more. Has a structure in which an adhesive layer 9 is laminated and integrated on the other surface. Further, as shown in FIG. 2B, a configuration in which a copper layer 8 is laminated on both surfaces of the aluminum layer 7 and an adhesive layer 9 is laminated on the surface of one copper layer 8 may be adopted.

Such a laminated tape is vertically attached on the cable core so that the copper layer 8 is on the inside. The adhesive layer 9 is formed between the overlapping portion of the side edges of the laminate tape layer 5 and the space between the laminate tape layer 5 and the plastic sheath 6 by utilizing the heat generated when the plastic sheath 6 is extruded.
(FIG. 1).

Here, if the aluminum layer 7 is smooth in the above-mentioned laminated tape 5, irregular and local stress is applied to the aluminum layer 7 due to bending of the cable during manufacturing and laying of the cable, and wrinkles and breakage occur. May occur. In order to prevent this, as shown in FIG. 3, the laminating tape 5 is subjected to regular corrugation in advance in the longitudinal direction (wave valley lines and crest lines are orthogonal to the longitudinal direction). The stress is evenly distributed to each part of the laminate tape 5 to prevent wrinkles and breakage. In the figure, the shape and size of the wave are desirably in a range of a mountain height h = 1 to 5 times the thickness of the aluminum layer 7 and a pitch P of the wave = 2 to 10 times the thickness of the aluminum layer 7. If it is smaller than this range, wrinkles are likely to be generated even at portions other than the wave portion.

The corrugating process may be performed at the stage of manufacturing the laminated tape, or may be performed online in the step of covering the plastic sheath.

Further, in order to increase the effect of corrugating the laminate tape 5, the cable core and the laminate tape 5 are used.
A lubrication layer may be provided between them. Thereby, the friction between the cable core and the laminate tape when the cable is bent is reduced, the local stress applied to the laminate tape 5 is further reduced, and wrinkles and cuts are less likely to occur. The friction coefficient of the lubricating layer is suitably μ = 0.6 or less, and the material and the means for forming the material are not particularly limited, but a sufficient effect can be obtained by applying silicone oil.

The same effect can be obtained by embossing the laminated tape 5 as shown in FIG. 4 instead of the corrugation described above. The shape of the emboss 10 is not particularly limited,
The height h 'and the interval P' of the emboss 10 are 1 'to 5 times the thickness of the aluminum layer 7 as in the case of corrugation, and the interval P' is 2 to 10 times the thickness of the aluminum layer 7. desirable.

When a so-called single-core stranded cable is formed by twisting at least two or more wires of the power cable of the present invention,
The twisting pitch is preferably 15 to 40 times the core diameter.
If the pitch is less than 15 times, wrinkling or breakage of the laminated tape tends to occur due to twist and bending applied to the cable at the time of twisting, and if it exceeds 40 times, twisting will be broken when laying the cable and handling will be poor Become.

In the above-described single-core stranded cable, if a soft copper wire or a soft copper stranded wire is arranged as a ground wire 16 at the center of the twist of the cable 15 of the present invention as shown in FIG. Since the current at the time of short-circuit or short-circuit can be bypassed through the ground wire 16, it can be used for a resistance grounding cable line having a large ground fault or short-circuit current. in this case,
The ground wire 16 and the aluminum layer of the laminate tape of the cable 15 are connected by a cable connection box 17 as shown in FIG. The ground wire 16 may be provided with a coating layer such as PVC for corrosion protection.

In the above structure, if the volume resistivity of the plastic sheath of the cable is set to 10 ⁵ Ω-cm or less, a ground fault and a short-circuit current flow directly to the ground wire through the sheath. There is no need to connect the ground wire and the soft copper foil in the box.

[0023]

As described above, in the rubber / plastic insulated power cable of the present invention, a laminate tape having a flexible aluminum layer has both a function as a shielding layer and a function as a water shielding layer. is there. This laminate tape can secure a sufficient cross-sectional area (thickness) for supplying a ground fault current due to the flexibility of the aluminum layer, and does not break even when bent at the time of laying. In addition, by laminating a copper layer on an aluminum layer, the problem of an increase in electric resistance due to an oxide film can be solved. Therefore, there is no need to wind a metal tape to be a water-shielding layer separately from the shielding layer as in the conventional cable, which not only greatly improves the manufacturability, but also significantly increases the material cost of the portion corresponding to the shielding metal tape. Can be reduced to Moreover, high reliability equivalent to that of a conventional water-impervious cable can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a cable of the present invention.

FIGS. 2A and 2B are cross-sectional views of a laminate tape used for the cable of the present invention, in which FIG.
The case of a layer is shown.

FIG. 3 is an explanatory view of a laminated tape subjected to a corrugating process.

FIG. 4 is an explanatory diagram of a laminated tape subjected to emboss processing.

FIG. 5A is a structural diagram of an example of a single-core stranded cable using the cable of the present invention, and FIG. 5B is an explanatory diagram of an example of ground wire connection.

FIG. 6 is a cross-sectional view of a conventional rubber-plastic insulated power cable having a water-blocking structure.

FIG. 7A is a cross-sectional view of a conventional rubber / plastic insulated power cable using a copper laminated tape serving as a water-shielding / shielding layer, and FIG. 7B is a cross-sectional view of the copper laminated tape.

[Explanation of symbols]

1,21 conductor 2,22 inner semiconductive layer 3,23 insulator 4,24 outer semiconductive layer 5 laminate tape (layer) 6,27 plastic sheath 7 aluminum layer 8 copper layer 9 adhesive layer 10 emboss 15 cable 16 ground Wire 17 junction box
25 Shielding layer 26 Lead laminate tape 30 Copper laminate tape 31
Copper layer 32 Plastic tape layer 33 Adhesive layer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuto Mizunami 1-3-1 Shimaya, Konohana-ku, Osaka Sumitomo Electric Industries, Ltd. Osaka Works

Claims (1)

[Claims] 1. A rubber / plastic insulated power cable in which a laminate tape is longitudinally attached to a cable core and a plastic sheath is provided, wherein the laminate tape has an adhesive layer, an aluminum layer having a thickness of 150 μm or more, and a thickness of 30 μm. In the following, at least one copper layer is integrally laminated, and the laminated tape is configured such that the copper layer is directed to the inner periphery, and the overlapping portion of the side edge and the adhesive between the laminated tape and the plastic sheath are provided via an adhesive layer. Rubber / plastic insulated power cable characterized in that it is adhered by bonding.