JP3212251B2 - Power cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber or plastic insulated power cable, and more particularly, to a power cable having a waterproof tape.
Between the external semiconductive layer of the metal and the metal corrugated sheath
Regarding power cables .

[0002]

2. Description of the Related Art Generally, corrugated metal sheaths are used in rubber and plastic insulated power cables having a voltage of 30 kV or more in foreign countries. This power cable is, for example, as shown in FIG.
Inner semiconductive layer 12, rubber or plastic, especially insulator layer 13 made of crosslinked polyethylene, outer semiconductive layer 1
4, a semiconductive cushion layer 15, a copper wire woven fabric tape 16, a corrugated metal shielding layer 18 made of aluminum or stainless steel, and an anticorrosion layer 19 in this order. The cable is provided with a gap of about 1 mm in advance between the copper wire woven fabric tape 16 and the corrugated metal shielding layer 18 in consideration of the expansion of the insulator at the time of energization. About 4 in layer 18
A valley-like gap 17 having a depth of 10 to 10 mm is provided.

[0003] The metal armored power cable of this structure is often laid directly underground, especially in foreign countries. Therefore, for example, at the time of road construction, the corrugated metal shielding layer may be partially damaged by a shovel car, a crane or the like. In this case, the surrounding water penetrates into the cable, the water runs long distances along the cable and becomes electrically dangerous, and the long-distance power cable must be replaced. , Very expensive.

[0004] As described above, since the corrugated metal armored cable has an extremely large gap in comparison with a normal cable, it is very difficult to prevent water from entering.

[0005] In order to solve this problem, various proposals have hitherto been made.

For example, (1) A water-swellable tape is used as a semiconductive cushion layer by winding a water-swellable tape a plurality of times along the spiral groove pitch of the tape and the corrugated metal layer. The method of rotation is 3-8
No. 2517 and Japanese Patent Laid-Open No. 3-182008.

(2) A water-swellable tape wound a plurality of times as a semiconductive cushion layer and a braid density of 50%
The following weaving braid can be used.
No. 6,086,045.

(3) Japanese Patent Application Laid-Open No. 4-160709 discloses a method in which an extruded cushion layer is eccentrically applied on the outer semiconductive layer in advance and the valley of the corrugated metal sheath is cut into the cushion layer. ing.

(4) A water-swellable semiconductive layer is provided as a semiconductive cushion layer, and a water-absorbing and swelling spherical body or a water-absorbing and swelling member is inserted into the space between the valleys of the corrugated metal sheath. Bulletin, Japanese Utility Model Application No. 5-65013
No. 6,086,045.

(5) Japanese Laid-Open Utility Model Publication No. 6-45217 discloses that a water-tight dam portion made of a highly elastic rubber or plastic is intermittently provided in the longitudinal direction between a corrugated metal exterior layer and a core. .

(6) An annular corrugated metal exterior layer is provided on a water-absorbing swelling layer provided on an external semiconductive layer such that a valley thereof is in contact with or separated from the water-absorbing swelling layer. It is disclosed in JP-A-6-168630.

(7) An external semiconductive layer, a water-absorbing swelling layer, and a corrugated metal sheath are sequentially provided, and the corrugated metal sheath is recessed linearly or spirally along a longitudinal direction by groove processing. No. 2,111,152.

[0013]

However, each of these water intrusion prevention means has a defect.

In the means (1), when the water-swellable string is insulative and used in combination with the copper wire woven fabric tape, the electrical contact between the corrugated metal sheath and the water-swellable semiconductive layer is not complete. It is electrically unstable, and it is mechanically difficult to perfectly match the water-swellable string to the groove pitch of the corrugate. It is uneconomical because it requires extra.

Means (2) is that it is very difficult for the underlying water-swellable tape to swell to the valley of the metal corrugate through the interwoven braid, so that the water swelling tape runs over a short distance. It cannot be prevented.

The means (3) requires a special die in the extruder, and requires a special device to extrude the cushion layer while rotating the conductor or the die. It is difficult to corrugate the metal while penetrating to the depth of the water, and the cushion layer made by adding water-swellable polymer powder to elastic rubber or plastic has an extremely slow swelling speed even when it comes in contact with water and runs only over long distances. Cannot prevent water.

In the means (4), a water-absorbing and swellable spherical body or member must be inserted in a corrugated metal sheath of a completed cable in a later step, and it is difficult to insert uniformly, and even if water enters, They can be swept away by water pressure to considerable distances.

In the means (5), it is necessary to provide a dam in an additional step after winding the copper wire woven fabric tape, and the dam needs to be provided with a height depending on the place, and furthermore, the height of the dam and the height of the corrugate are matched. And it is almost impossible to implement them mechanically.

The means (6) requires special provision of an annular corrugation forming apparatus for forming an annular corrugated metal sheath, which makes it impossible to use an existing spiral corrugator, is inefficient in production, and requires equipment costs. They are also very expensive and uneconomical.

In the means (7), it is necessary to further process the cable subjected to the corrugated metal exterior processing by a groove processing machine, which is economically disadvantageous.

The problem to be solved by the present invention is to solve the above-mentioned various problems in the prior art, and it is possible to use ordinary cable manufacturing equipment and to effectively prevent water running of a corrugated metal sheath. Power cable
To provide a bull .

[0022]

SUMMARY OF THE INVENTION The present invention relates to a metal corrugated power cable, in which a water-absorbing semiconductive rubber composition is impregnated or impregnated on both surfaces of a substrate made of a woven fabric in which several copper wires are woven in the length direction. A tape that has been applied, and the copper wire is exposed on the surface while the composition is not applied, and a semiconductive rubber composition is applied on one surface of a substrate made of a thick woven fabric, and on the other surface. A water-absorbing semiconductive rubber composition is applied, and a tape on which a low-weight nonwoven fabric cover is attached on a coating layer of the water-absorbing semiconductive rubber composition is applied to a power cable with the water absorbing surface facing outward . It is characterized in that it is spirally wound between the outer semiconductive layer and the metal corrugated casing.

[0023]

In the present invention, the metal having the structure shown in FIG.
The above-mentioned tape is placed on the outer semiconductive layer of the corrugated armored cable.
By winding the loops together , water running in the corrugated metal exterior groove and the gap can be more reliably prevented.

In addition, since all tapes are wound together with the water absorbing surface facing outward between the outer semiconductive layer and the corrugated metal sheath, if the metal sheath is damaged and water enters the cable, Both tapes simultaneously absorb water and swell.

In particular, those having a low-weight nonwoven fabric cover on the water-absorbing swelling layer act as swelling dams,
Since the outflow of the swollen gel is prevented, almost all of the swollen gel is not swept away by the water pressure, so that the effect of preventing water running is sufficiently exhibited, and water running can be prevented over a short distance.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION As the copper wire woven fabric tape base material used for the water-absorbing semiconductive copper wire woven fabric tape of the present invention, all of those used in conventional power cables as shown in FIG. Can be used.

As the material, polyester, nylon, cotton, rayon, polynosic, high-strength viscose rayon, vinylon and the like can be used alone or in combination. In particular, since there is a possibility that a high temperature of 200 ° C. or more may be applied to the tape at the time of melt extrusion / welding and corrugating of the metal exterior, the cotton, rayon, polynosic, and high heat do not shrink in the vertical and horizontal directions at these high temperatures. Particularly preferred are viscose rayon and vinylon.

The yarn thickness of these fibers is generally 10 to
The thickness of the copper wire which is 100th and is woven in the length direction of the base material is preferably larger than the above-mentioned yarn. If the copper wire is thinner than the base thread, the copper wire does not make good contact with the metal corrugated sheath even when wound on a cable, and the conductive layer, that is,
This is because it cannot serve as a metal shielding layer.

The number of copper wires to be driven is three or more per tape width, and the number is determined by the electric capacity of the power cable. As the copper wire, either a single wire consisting of one wire or a stranded wire consisting of several wires can be used, and simple copper or tin-plated copper wire can also be used.

The yarns and copper wires of the various fibers mentioned above are woven with a desired tape width by a usual plain weaving method. It is woven with the tape width in order to prevent yarn fraying.

However, in the case of the present invention, since the water-absorbing semiconductive rubber composition is applied to the copper wire woven fabric tape, even if the woven tape is woven in a wide width, thread fraying does not occur after slitting.

It is desirable that the tensile strength at 5% elongation in the vertical direction of the substrate is as high as possible. If the tensile strength at 5% elongation is extremely low, the width of the tape becomes narrow at the time of applying or impregnating the water-absorbing semiconductive rubber composition and at the time of winding around the cable.

The thick fabric which can be used for the water-absorbing semiconductive fabric tape of the present invention preferably has a thickness of 0.3 to 1.5 mm. When the thickness is less than 0.3 mm, there is no cushioning effect and it cannot serve as a cushion layer, and when the thickness is 1.5 mm or more, it is expensive and economically disadvantageous.
As the material of the yarn, polyester, nylon, cotton, rayon, polynosic, high-strength viscose rayon, vinylon, etc. can be used alone or in combination, but for the above-mentioned reasons, cotton, rayon, polynosic, high-strength viscose which does not shrink at high temperatures. Rayon, vinylon and the like are particularly preferred. These fibers generally have a thickness of 5 to 20 yarns, or may be used by twisting several yarns. Generally, the weaving method is plain weaving.

The low-weight nonwoven fabric cover to be laminated on the water-absorbing semiconductive rubber composition of the water-absorbing semiconductive woven tape of the present invention is preferably made of a polyester having excellent heat resistance in terms of material, and has a weight of 8 to 15 g / m2. ² , and a long-fiber nonwoven fabric produced by a melt blow method or a spun bond method is preferable. This low-weight nonwoven fabric cover has inter-fiber gaps, so-called “meski”, and the degree of the “meski” is suitably such that only 10% or less of the water-absorbent resin powder used in the water-absorbent semiconductive rubber composition passes. This is because, if the degree of the mesquite is too large, even if it swells in contact with the water that has penetrated into the cable, a gel dam that has swollen and absorbed water cannot be formed, and the effect of preventing water running is significantly impaired.

The water-absorbing semiconductive rubber composition of the present invention comprises a synthetic rubber binder, a conductive substance, a water-absorbing resin powder, a processing aid, a metal corrosion inhibitor, a softener, a tackifier, a lubricant, A rubber compound composed of a vulcanizing agent, a vulcanization aid, a filler, an antioxidant and the like is dissolved and dispersed in an organic solvent.

The synthetic rubber binder used in the water-absorbing semiconductive rubber composition has a function of adhering the water-absorbing resin powder and the conductive substance to the above-mentioned woven fabric substrate, and is made of an acrylic resin, butyl rubber, polyisobutylene. Rubbers, ethylene / propylene rubbers, acrylic rubbers and the like that do not contain halogen atoms are preferred and can be used alone or in combination. When using a binder containing a halogen atom,
This is because, for example, hydrochloric acid or the like is generated during long-term use to corrode the metal in the cable.

The conductive substance used in the water-absorbing semiconductive rubber composition is preferably conductive carbon black, graphite, metal powder, short carbon fiber, etc., and can be used alone or in combination of two or more. The amount of the conductive substance is preferably from 10 to 500 parts by weight based on 100 parts by weight of the synthetic rubber binder. If the amount is less than 10 parts by weight, sufficient semiconductivity cannot be obtained, and if it is more than 500 parts by weight, a problem of falling off occurs.

The water-absorbing resin powder used for the water-absorbing semiconductive rubber composition is a synthetic resin which does not dissolve in water even when it comes into contact with water, has a water absorbing capacity of 10 to several thousand times its own weight, and contains microorganisms. Any 100% synthetic product that does not decompose can be used. For example, acrylate-based crosslinked products, saponified vinyl acetate / acrylate copolymers, polyvinyl alcohol / maleic anhydride reactants, isobutylene / maleates Crosslinked copolymers, acrylates / acrylamide copolymers, acrylic acid / polyvinyl alcohol copolymers, modified polyethylene oxide, etc. are preferred,
They can be used alone or in combination of two or more. The particle size of the water-absorbent resin powder is desirably 150 μm or less. Fifteen
In the case of 0 μm or more, impregnation or application is difficult,
In addition, when the tape is pressed down locally as in the case of a corrugated metal sheath, the tape cannot be locally absorbed and swelled.

In addition to producing a water-absorbing semiconductive woven tape by impregnating or applying a water-absorbing semiconductive rubber composition to a base cloth as in the present invention, it also has a large particle size, for example, 200 to 400 μm.
m and a thermoplastic resin powder are spread over the semiconductive nonwoven fabric of the base material, and after heating, a production method of laminating a low weight nonwoven fabric cover is also considered. Since the particle size of the conductive resin powder is too large and there are countless spaces, even if it comes into contact with water locally, water permeates the whole and cannot swell locally, which is not suitable for this use.

The amount of the water-absorbent resin is 100
20 to 1000 parts by weight per part by weight is suitable. 2
If the amount is less than 0 parts by weight, the effect of preventing water running is not exhibited, and
If the amount is more than the weight part, there is a problem that the water-absorbing resin powder and the conductive substance fall off the base material.

The water-absorbing semiconductive rubber composition comprises a binder,
In addition to the conductive substance and the water-absorbing resin powder, well-known processing aids, metal corrosion inhibitors, softening agents, tackifiers in some cases,
It also contains lubricants, vulcanizing agents, vulcanizing aids, fillers, anti-aging agents and the like. In particular, since the water-absorbing semiconductive woven tape of the present invention is always in contact with the copper wire and the corrugated metal sheath, in order to prevent metal corrosion due to the water-absorbing resin, a metal corrosion inhibitor, for example, disclosed in JP-A-4-94013. 1, which is described
It is particularly desirable to add 2,3-benzotriazole or a derivative thereof. The above-mentioned materials are used in the usual addition amounts well known in the rubber industry.

The semiconductive rubber composition used for the thick water-absorbing semiconductive tape of the present invention is obtained by removing the water-absorbing resin powder from the above-described water-absorbing semiconductive rubber. Since this composition does not contain a water-absorbing resin powder, the metal corrosion inhibitor is not required.

The materials of the above two compositions are kneaded using a Banbury mixer or an open roll, and are put together as a rubber compound.

The water-absorbing semiconductive rubber composition or the compound of the semiconductive rubber composition comprising the above-mentioned materials is dissolved and dispersed in an organic solvent for impregnating or coating a copper wire woven fabric or a thick woven fabric. As the organic solvent, those which do not dissolve the base material, the conductive substance and the water-absorbing resin powder, and can dissolve the binder can be used, for example, toluene, xylene, benzene, methyl ethyl ketone, acetone, hexane, methyl Isobutyl ketone, ethyl acetate,
Dioxane, tetrahydrofuran, cyclohexanone,
General-purpose solvents such as alcohols are used alone or as a mixture.

The solution of the water-absorbing semiconductive rubber composition and the semiconductive rubber composition compound dissolved and dispersed in an organic solvent by using a dissolver is mixed with a copper wire woven fabric and a thick material using a well-known coating method. Impregnated or applied to the fabric,
The solvent is volatilized by hot air heating, applied to each fabric,
Optionally vulcanized.

In the case of the water-absorbing semiconductive copper wire woven fabric tape of the present invention, the copper wire woven fabric is immersed (impregnated) in the compound solution of the water-absorbing semiconductive rubber composition and passed between two mangle rolls. The excess solution is squeezed and the solvent is volatilized by hot-air drying. After drying, the solution is passed between two doctor blades to scrape off the composition adhering to the copper wire, thereby exposing the copper wire to the surface of the base material. If the copper wire remains covered with the composition, even if the tape comes into contact with the corrugated metal sheath, the copper wire will come in contact with the composition. The charge accumulated during use cannot be sufficiently released from the metal sheath.

The thick water-absorbing semiconductive tape of the present invention is obtained by impregnating or applying the above semiconductive rubber composition compound solution to a thick woven base material and applying the solution on one side to evaporate the solvent by heating with hot air. It is manufactured by applying a conductive semiconductive rubber composition compound solution to one side, bonding a low-weight nonwoven fabric cover in a wet state, so-called wet lamination, and then evaporating the solvent by heating with hot air.

In the case of both the water-absorbing semiconductive fabrics of the present invention,
As a function, semi-conductivity other than general strength, elongation and taping characteristics, for example, thickness or length direction volume resistivity and water absorption height are very important. The volume resistivity is measured according to the test method described in JCS No. 311A “Testing method of cloth tape for electric wire” issued by the Japan Electric Wire & Cable Makers Association.

The water-absorbing semiconductive fabrics of the present invention include:
A volume resistivity in the thickness direction of × 10 ⁶ or less and a water absorption height of 1.5 times or more of the gap size to prevent water running in the cable are required. If the volume resistivity is 1 × 10 ⁶ or more, the required electric shielding effect cannot be obtained, and the water absorption height is 1.
If it is less than 5 times, a sufficient water running prevention effect cannot be obtained.

[0051]

FIG . 1 shows a first tape (a water-absorbing semiconductive copper wire woven tape having a copper wire exposed) forming a wound tape wound layer 16 in the cable shown in FIG.
Flop) is a perspective view of a 10. FIG. 2 shows a section viewed from the length direction of the exposed copper wire.

In FIGS. 1 and 2, the woven fabric is made of a woven fabric in which a cotton thread 1a is woven by plain weaving in the length direction and the width direction, and three or more copper wires 2a are woven in the length direction. Are filled with the water-absorbing semiconductive rubber composition 3a containing the water-absorbing resin powder except for the exposed portion of the copper wire 2a.

In order to produce this tape, a solvent solution of a water-absorbing semiconductive rubber composition is first prepared. From 100 parts by weight of polyisoprene rubber (binder), 50 parts by weight of conductive carbon black (conductive substance), 5 parts by weight of paraffin wax (lubricant), 3 parts by weight of antioxidant, and 3 parts by weight of stearic acid (processing aid) Is kneaded with a Banbury mixer, and the volume resistivity in the thickness direction is 3.0 × 10 ² Ω ·
cm of compound was obtained. This compound is cut into chips by a rubber cutting cutter, taken into a container, added with 500 parts by weight of toluene (organic solvent), allowed to stand for 24 hours, stirred and mixed using a stirrer, dispersed and dissolved, 200 parts by weight of AQUALIC CA-H3R (water-absorbent resin powder) and 5 parts by weight of 1,2,3-benzotriazole (metal corrosion inhibitor) manufactured by Catalyst Co., Ltd. are added, and the mixture is sufficiently stirred to absorb the water-absorbing semiconductive material. A rubber composition solvent solution was obtained.

Next, one copper wire having a diameter of 0.29 mm was used for every eight 20-count polynosic yarns in the vertical direction, and a 20-count 2-twist polynosic yarn was used in the horizontal direction. Included length: Polynosic yarn 72 / inch and copper wire 8 / inch, horizontal: 16 polynosic yarn /
A 60 mm wide plain woven copper wire woven fabric tape is impregnated with the solvent solution of the water-absorbing semiconductive rubber composition, and the solvent is volatilized in a dryer at 100 ° C. to give a dry adhesion amount of 65 g / m ² . A water-absorbing semiconductive copper wire woven fabric tape was obtained. This tape has a thickness of 0.50 mm, a unit mass of 430 g / m ² , and a volume resistivity in the thickness direction of 3.3 × 10Ω.
Cm.

[0055]

[Manufacture of the second tape] FIG. 3 shows the cable shown in FIG.
The second tape forming the wound tape winding phase 5
FIG. 2 is a cross-sectional view of a loop (a water absorbing semiconductive thick woven tape) 20.

In this figure, a plain woven fabric substrate 1b in which the length direction and the width direction are made of cotton fiber yarn is coated on one side with a semiconductive rubber composition 2b, and the other side is made of a water-absorbing resin powder. It is coated with a conductive semiconductive rubber composition 3b, and a low-weight nonwoven fabric cover 4b is bonded thereon.
Since the cover 4b is attached to the water-absorbing semiconductive rubber composition 3b in a wet state, the cover 4b firmly adheres to the composition. The cover 4b prevents the surface from sticking when the tape absorbs moisture and prevents the water-absorbing resin powder from falling off.
It also prevents the gel that has swollen by water from flowing out.

This tape is prepared by applying and drying a solvent solution of a semiconductive rubber composition on one side of a thick woven fabric substrate, applying a solvent solution of a water-absorbing semiconductive rubber composition on the other side, and then wet the tape. And then dried and obtained.

In order to manufacture this tape, first, a semiconductive rubber composition solvent solution is prepared. Butyl rubber 100
Parts by weight, 15 parts by weight of process oil (softening agent), 3 parts by weight of stearic acid (processing aid), petrolatum (softening agent)
4 parts by weight, 5 parts by weight of zinc oxide (filler) and 90 parts by weight of conductive carbon black (conductive substance) are kneaded with a Banbury mixer, and a semiconductive rubber having a volume resistivity of 2.5 × 10 ² Ω · cm. A composition was obtained. This composition is cut into chips by a rubber cutter, taken into a container, and toluene (organic solvent) 5
Then, the mixture was left for 24 hours, stirred with a stirrer and dispersed and dissolved to obtain a semiconductive rubber composition solution.

Next, a solvent solution of the water-absorbing semiconductive rubber composition is prepared. 80 parts by weight of ethylene / propylene rubber, 20 parts by weight of polyisobutylene rubber, 50 parts by weight of conductive carbon black, 5 parts by weight of paraffin wax (lubricant), 3 parts by weight of stearic acid, and 3 parts by weight of an antioxidant are kneaded with a Banbury mixer. , Volume resistivity 2.3 × 10 ² Ω · cm
Was obtained. This composition was cut into chips using a rubber cutter, placed in a container, added with 500 parts by weight of toluene, allowed to stand for 24 hours, stirred and dispersed and dissolved. 200 parts by weight of Alilic CA-H3R and 5 parts by weight of 1,2,3-benzotriazole were added thereto and sufficiently stirred to obtain a solvent solution of a water-absorbing semiconductive rubber composition.

Finally, using a twisted cotton yarn of 20th count in the vertical direction and a twisted cotton yarn of 10th count in the weft direction, the unit mass is 33 g / inch and 31 weft / inch in unit mass 200 g. / M ² and a 0.5 mm thick plain woven thick woven fabric 1b.

The solvent solution of the above semiconductive rubber composition was applied to one side of the thick fabric 1b and dried (dry adhesion amount: 40 g /
m ^2), the above water-absorbing semiconductive rubber composition solvent solution <br/> applied to the other surface (dry coverage 150g / m ^2), immediately spunbonded nonwoven polyester fabric thereon (basis weight 12 g / m
² ) was laminated (wet lamination) and dried to obtain a water-absorbing semiconductive thick woven tape.

This tape has a thickness of 0.60 mm, a unit mass of 400 g / m ² and a volume resistivity of 8.8 × 10 ⁴ Ω · c.
m.

Production of the first tape and production of the second tape
In each of FIGS. 1, 2 and 3, the fiber gaps of the woven fabric shown as 1a and 1b are densely filled with the water-absorbing semiconductive rubber composition 3a, 3b or the semiconductive rubber composition 2b. In each case, it has uniform volume resistivity and water absorption height. In addition, since the water absorption and swelling is 1.5 times or more of the gap of the corrugated metal exterior, a large valley of the corrugated metal exterior is filled with the swelling gel, which is effective in preventing water running over a short distance.

[0064]

Embodiment 1 Production of the above-mentioned first tape and second tape
With the two tapes obtained by abutting on each other, the water absorption surface is
And spirally wound to obtain a composite tape.

Comparative Example 1 FIG . 1 is a perspective view of a first water-absorbing semiconductive copper wire woven
A tape was produced by the same method except that the water-absorbing resin and the metal corrosion inhibitor were removed from the tape obtained in the production of the first tape, which was Group 10 .

COMPARATIVE EXAMPLE 2 A water-absorbing semiconductive thick woven tape 20, which is a second tape shown in a sectional view in FIG. 3, is obtained by manufacturing a second tape.
Do not attach the low-weight nonwoven fabric cover from the tape
Others produced the tape in a similar manner.

[0067] In a state abutting both tape obtained in Comparative Example 3 Comparative Example 1 and Comparative Example 2
The composite tape was manufactured by spirally winding the tape with the water absorbing surface facing outward .

[0068] of the first tape of the production and the second tape
The tapes obtained in Production and Comparative Examples 1 and 2 were subjected to the following conductivity test and water absorption height test, and the tapes obtained in Example 1 of the present invention and Comparative Example 3 were subjected to the following water stop test.

<Conductivity Test> The production of the first tape and the second tape between the two circular metal electrodes were performed .
And the tapes obtained in Comparative Examples 1 and 2
The resistance of each tape was measured using a resistance meter under a load of 0 g / cm ^{2, and} the volume resistivity in the thickness direction was calculated.

[0070] <water height test> Take a circular test piece S with a diameter of 78mm from a first tape manufacturing and second tape tapes obtained in Production and Comparative Examples 1 and 2, the diameter of the specimen S 78mm Between the circular tissue papers P1 and P2, with the water absorption surface facing upward, and placed in the bottom of the lower cup A having an inner diameter of 80 mm of the test apparatus shown in FIG. The distributed top lid B (mass 97 g) is placed on it, and a dial gauge (gauge pressure: 100 g) C is set on the top lid B. Then, perform zero adjustment of dial gauge C,
Distilled water was poured onto the upper lid B, and the moving distance of the dial gauge was read 10 minutes after the water injection, and this moving distance was defined as the water absorption height.

<Water stop test> An example was carried out on a linear rod having an outer diameter of 79 mm and a length of 3.5 m.
Absorb water with both tapes obtained in Comparative Example 1 and Comparative Example 3
Spirally wound with the surface facing outward, and
mm, 101 mm in outer diameter, 5 mm in maximum valley (gap), 3.5 m in length, inserted into an aluminum corrugate with a length of 3.5 m , and tap water is always maintained at a water head pressure of 1 m in a plastic tube with an inner diameter of 12 mm attached at a height of 1 m at the center. While the tap water was flowing out from both ends or one end of the aluminum corrugate. When the tap water does not flow out from both ends or one end, it is left for 24 hours while maintaining the water head pressure of 1 m at normal temperature. Next, the tap water remaining between the aluminum corrugate and the tape winding rod is heated by winding a band heater while maintaining the head pressure of 1 m, and a heat cycle of 70 ° C. × 8 hours ← → normal temperature × 16 hours. It was applied ten times, disassembled, and the running distance was measured.

Table 1 shows the test results.

[0073]

[Table 1] From this result, it can be seen that the wrapped tape of the present invention has an excellent water running prevention effect. In particular, it has been found that a water-absorbing semiconductive thick woven tape having a cover and a water-absorbing semiconductive copper wire woven textile tape spirally wound in a butt state have an excellent water running preventing effect.

In addition, each of the tapes was 1.0 × 10 ⁶ Ω.
-It has a volume resistivity of not more than cm, and when used for a power cable, shows a shielding effect similar to that of a conventional tape.

In the corrugated metal armored power cable having the structure shown in FIG. 5, a water-absorbing semiconductive thick film of the present invention is provided on a core composed of a conductor 11, an inner semiconductive layer 12, an insulator 13 and an outer semiconductive layer 14 in this order. A woven tape and a water-absorbing semiconductive copper wire woven textile tape are spirally wound in a butt winding with the water-absorbing surface facing outward. Alternatively, a thick water-absorbent semiconductive tape may be spirally wound on the core by abutting, and a water-absorbent semiconductive copper wire woven tape may be spirally wound with a gap. When the cushioning property of the water-absorbing semiconductive thick woven tape is insufficient, a semiconductive cushion tape may be wound on a core as before, and both tapes of the present invention may be wound thereon.

[0076]

【The invention's effect】

(1) Rubber with corrugated metal sheath of conventional structure
By winding a water-absorbing semiconductive thick woven tape having a cover and a water-absorbing semiconductive copper wire woven fabric tape of the present invention on a core of a plastic insulated power cable together, even if water enters the cable, it can be short-distance. Water can be reliably stopped, and it is very economical in terms of cable maintenance.

(2) The water-absorbing semiconductive copper wire woven fabric tape of the present invention has an effect of preventing water running because the copper wire is exposed on the surface similarly to the conventional copper wire woven fabric tape. Nevertheless, it exhibits the same excellent shielding effect as the conventional one.

(3) The use of the two types of water-absorbing semiconductive woven fabric tapes of the present invention makes it possible to manufacture a power cable having a metal corrugated sheath with conventional equipment without the need for a specially expensive device, and is economically advantageous. It is.

[Brief description of the drawings]

[1] first tape to be used in power cable of the invention
It is a perspective view of a loop.

FIG. 2 shows a cross section of the first tape shown in FIG.

[Figure 3] a second tape to be used in power cable of the invention
It is sectional drawing of a loop .

FIG. 4 shows a first cable used in the power cable of the present invention.
The outline of the test device for measuring the water absorption height of the tape and the second tape is shown.

FIG. 5 shows a longitudinal section through a power cable using a corrugated metal sheath.

[Explanation of symbols]

1a, 1b plain woven fabric 2a copper wire 2b semiconductive rubber composition 3a, 3b water absorbing semiconductive rubber composition 4b low weight nonwoven fabric cover 10 water absorbing semiconductive copper wire weaving tape 11 conductor 12
Internal semiconductive layer 13 Insulator layer 14 External semiconductive layer 15 Semiconductive cushion layer 16
Copper wire woven fabric tape wound layer 17 Valley-like gap 18 Corrugated metal shielding layer 19 Corrosion protection layer
20 Water absorbing semiconductive thick woven tape

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01B 7/282 H01B 9/02

Claims (1)

(57) [Claims] 1. A metal corrugated power cable, wherein a water-absorbing semiconductive rubber composition is impregnated or coated on both surfaces of a base material made of a woven fabric in which several copper wires are woven in the length direction, and Tapes whose wires are exposed on the surface in the uncoated state of the composition, a semiconductive rubber composition is applied to one surface of a substrate made of a thick woven fabric, and a water-absorbing semiconductive rubber composition is applied to the other surface. A tape, which is coated and has a low-weight nonwoven fabric cover adhered on a coating layer of the water-absorbing semiconductive rubber composition, is provided with an outer semiconductive layer of a power cable and a metal corrugated sheath with the water absorbing surface facing outward. Screw between
A power cable characterized by being spirally wound.