JPH10223071A - Manufacture of cross-linked polyethylene insulation power cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing efficiently cross-linked polyethylene insulation power cable which enables a circular shape to be well maintained on the premise of a fan-shaped conductor which enables an outer diameter to be lessened. SOLUTION: Three strands of fan-shaped cross-linked polyethylene insulation power cable 1, wherein a fan-shaped conductor having no preshape is coated by extruding cross-linked polyethylene thereon and further a plastic sheath as a coating is applied thereto by extrusion, are stranded together so as to be finished into a circular cross-section shape and thereafter are annealed with the said stranded circular shape left as it is. When there is a case where the shape is deformed after stranding before annealing because rigidity of an insulating material is strong, the stranded shape is prevented from being deformed by a binder tape 2 for binding at the time of stranding. An adhesive agent or a thermosetting resin, in place of the binder tape 2, may be applied among cable cores.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to power cable technology, and more particularly to a triplex type crosslinked polyethylene insulated power cable formed by twisting three cables.

[0002]

2. Description of the Related Art A method proposed in this kind of cross-linked polyethylene insulated power cable manufacturing technique includes coating a cross-linked polyethylene resin on a sector-shaped conductor, combining a plurality of the cross-linked polyethylene resins and twisting them in a circular cross section. Further, a protective sheath made of plastic is provided thereon to produce a circular cross-linked plastic-coated electric wire (Japanese Patent Laid-Open No. 55-86013).
No.).

[0003] In the case of a paper insulated power cable, a method has been widely used in which insulating paper is wound on a conductor with pre-shoops, which is combined in a circular shape and twisted, and then covered with a metal sheath and an anticorrosion layer.

On the other hand, an ordinary triplex-type cross-linked polyethylene insulated power cable is obtained by simply twisting three round cores, and this structure has been widely used at present.

In the case where three circular cables are twisted together with a fan-shaped conductor, the latter has a smaller outer diameter of about 90% even if the insulation thickness is the same. This can be effective when the cable outer diameter is restricted by laying a pipeline or the like.

[0006]

In the above-mentioned cross-linked polyethylene insulated cable of the prior art, the insulator is coated on the fan-shaped conductor with pre-shape in a uniform thickness so as to cope with high pressure or ultra-high pressure. In order to do so, a technique such as rotating the core of the extruder in accordance with the pre-shape of the conductor is required, which involves great difficulty in manufacturing.

Further, although it is easy to extrude and coat an insulator on a fan-shaped conductor without preshape, a shielding layer or a sheath is coated thereon to form a finished product, which is then forcibly twisted and further rounded. When molded into a shape, there is a problem in that when the cable is pulled out for laying a cable or the like, the twist returns due to the rigidity of the crosslinked polyethylene, the cable core warps, and the circular shape collapses.

Therefore, the problems to be solved by the present invention (objects)
An object of the present invention is to provide a method for efficiently manufacturing a crosslinked polyethylene insulated power cable capable of maintaining a good circular shape on the premise of a fan-shaped conductor whose outer diameter can be reduced.

[0009]

The manufacturing method provided by the present invention is characterized in that a core having a sector shape is twisted into a circle and then annealed to maintain the shape. . That is, the first means of the present invention,
After cross-linking polyethylene is extrusion-coated on a fan-shaped conductor without preshoot, and three of the fan-shaped cross-linked polyethylene insulated power cables extruded with a plastic sheath are twisted so as to have a circular cross section, and then the twisted circular shape is formed. A method for producing a crosslinked polyethylene insulated power cable that anneals as it is.

Generally, when a cross-linked polyethylene insulated power cable is connected, if the insulation thickness is large, a habit of a drum winding or the like remains, and even if it is stretched in a straight line, it immediately returns to its original state. The straightening is performed by a so-called annealing process of about 6 ° C. × 6 hours.

In view of the above, the present invention comprises a method of twisting a completed cable and then performing an annealing process to maintain its shape.

The temperature and time for annealing are 60 ° C.
80 ° C. × 1 day to 2 days is sufficient. However, when the insulating thickness is large and the annealing process is insufficient, it can be dealt with by further extending the time.

[0013] A second means provided by the present invention is to extrude a crosslinked polyethylene onto a fan-shaped conductor without preshoot and further extrude a plastic sheath to form three fan-shaped crosslinked polyethylene insulated power cables having a circular cross section. A method for manufacturing a cross-linked polyethylene insulated power cable, comprising: twisting so as to finish, winding a bind tape around the twisted circular shape, and annealing thereafter.

[0014] According to the above, the rigidity of the insulator is high, and after twisting, when the shape may be broken before annealing, the twisted shape is not broken by the binder tape bound at the time of twisting. Note that the binder tape may be any polyester tape or the like as long as it does not cause melting or deterioration at the temperature during the annealing process. Further, the binder tape may be removed after the annealing treatment, may be removed at the time of laying the cable, or may be laid while being bound.

A third means of the present invention to provide an alternative to the above binder tape is to provide a fan-shaped cross-linked polyethylene insulated power cable in which a cross-linked polyethylene is extrusion-coated on a fan-shaped conductor having no pre-shoop and further a plastic sheath is extrusion-coated. After twisting three wires into a circular cross section, an adhesive or a thermosetting resin is applied between the cables in the twisted circular shape, and then annealed. is there.

Alternatively, as a fourth means of the present invention, a fan-shaped cross-linked polyethylene insulated power cable in which a cross-linked polyethylene is extrusion-coated on a fan-shaped conductor without preshoot and a plastic sheath is extrusion-coated, and a cross-section circle is formed. A method of manufacturing a crosslinked polyethylene insulated power cable, comprising twisting around an interposition as an axis so as to obtain a finished shape, applying an adhesive or a thermosetting resin between the interposition in the twisted circular shape and each cable, and then annealing. I will provide a.

As described above, when an adhesive or a thermosetting resin is applied between the cable cores, the cables can be fixed more easily than the labor of the binder tape, and the circular shape after the annealing treatment is firmly held. Is done. In addition, if the center portion of the twisted portion and the cable core are bonded as described above, the circular shape after the annealing treatment can be further well maintained. Note that an adhesive or a thermosetting resin may be applied at intervals in the longitudinal direction of the cable with or without interposition so that the three-wire core can be easily spread when connecting the cable. Incidentally, a commercially available adhesive is sufficient.

[0018]

FIG. 1 shows an example of a cross section of a cross-linked polyethylene insulated power cable manufactured according to a manufacturing method based on a second means according to the first means of the present invention.

That is, in the fan-shaped cross-linked polyethylene insulated power cable 1 of this example, a cross-linked polyethylene insulator 12 is extrusion-coated on the outside of the conductor 1 having a fan-shaped cross section, and PV is further applied.
The three cable cores 1 provided with the C sheath 13 are twisted with each other, bound from outside with a binder tape 2, and then annealed to manufacture a crosslinked polyethylene insulated power cable having a circular shape.

When the thickness of the crosslinked polyethylene insulator is 5-6
When the thickness is about mm or less, the shape is sufficiently maintained only by annealing after twisting, but when the thickness of the insulator is about 10 mm or more, the rigidity of the insulator is increased, and the sector shape is easily inverted. . Therefore, the means for maintaining the shape by performing bonding between the cable cores by applying an adhesive or a thermosetting resin by the binder tape or the third means as described above is important depending on the thickness of the insulator. .

[0021]

According to the present invention as described above, a method for efficiently manufacturing a crosslinked polyethylene insulated power cable capable of maintaining a good circular shape on the premise of a sectoral conductor whose outer diameter can be reduced. The intended task (objective) of providing the information can be achieved. In addition, by realizing a compact cross-linked polyethylene insulated power cable with the same performance and smaller outer diameter as the conventional triplex type cable, etc. This also has the effect that a relatively large cable can be applied.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a structural example of a crosslinked polyethylene insulated power cable manufactured by a manufacturing method based on a second means of the present invention.

[Explanation of symbols]

 Reference Signs List 1 fan-shaped cross-linked polyethylene insulated power cable 2 binder tape 11 fan-shaped conductor 12 cross-linked polyethylene insulator 13 PVC sheath

Claims (4)

[Claims] A cross-linked polyethylene is extruded onto a fan-shaped conductor without preshoot, and three fan-shaped cross-linked polyethylene insulated power cables obtained by extrusion-coating a plastic sheath are twisted together so as to obtain a circular cross section. A method for producing a crosslinked polyethylene insulated power cable, which anneals with the twisted circular shape. 2. A fan-shaped cross-linked polyethylene insulated power cable extruded and coated with a plastic sheath on a conductor having no pre-shoop, and three of the fan-shaped cross-linked polyethylene insulated power cables, which are extruded and coated with a plastic sheath, are twisted so as to have a circular cross section. A method for manufacturing a crosslinked polyethylene insulated power cable, comprising winding a bind tape around a twisted circular shape, followed by annealing. 3. A fan-shaped cross-linked polyethylene insulated power cable extruded and coated with a plastic sheath and extruded with a plastic sheath on a conductor having no pre-shoop and twisted so as to obtain a circular cross-section. A method for producing a crosslinked polyethylene insulated power cable, in which an adhesive or a thermosetting resin is applied between the cables in a twisted circular shape and then annealed. 4. A fan-shaped cross-linked polyethylene insulated power cable obtained by extrusion-coating a cross-linked polyethylene on a conductor having no pre-shoop and further extruding a plastic sheath and twisting around an intervening shaft so as to obtain a circular cross-section. Then, an adhesive or a thermosetting resin is applied between the cables in the twisted circular shape and between the cables, and then annealed, followed by annealing.