JPH0142891Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to an improvement to the Grover sheath type rubber and plastic insulated power cable. For example, high-voltage rubber and plastic insulated power cables that use voltages of 3,300 V or more are not only required to have extremely high electrical properties, but also the amount of power transmitted has increased in recent years due to the increase in power demand. Therefore, it is strongly desired to improve the thermal characteristics of the cable. One of the causes of such deterioration of various properties of the power cable is the intrusion of moisture from outside the power cable and the low heat resistance of the resin used in the water-shielding tape. Glover sheath type rubber or plastic power cables generally have a metal layer for electrical shielding such as metal tape or drain wire on the outside of the cable core, a water-shielding tape made of laminated tape around the outer periphery of the metal layer, and a water-shielding tape made of laminated tape around the outer periphery of the water-shielding tape. A laminate tape having insulating rubber and plastic layers on both sides of a metal tape is used as the water-shielding tape, and by extruding the sheath around the outer periphery of this water-shielding tape, the heat generated during extrusion is used to The adhesive insulating rubber and plastic layer on the outer surface of the water tape is melted and softened to fuse and integrate the water-shielding tape, the sheath, and the laps of the water-shielding tape. And the insulating rubber on the inner surface of the water-shielding tape,
The plastic layer remains as an insulating layer between it and the metal shielding layer. However, when an induced voltage is generated in the metal tape in the water-shielding tape due to lightning surges or switching surges, or when abnormal voltage enters the power cable, a voltage may be generated between the metal tape in the water-shielding tape and the metal shielding layer. A potential difference occurs, and this potential difference becomes larger than the dielectric strength of the insulating rubber and plastic layer on one side of the water-shielding tape, which is interposed as an insulating layer between the metal tape and the metal shielding layer in the water-shielding tape, and the water-shielding An unavoidable problem is that an arc occurs between the metal tape in the tape and the metal shielding layer, and as a result, the metal tape in the water-shielding tape melts and the original water-shielding properties of the water-shielding tape are quickly lost. Therefore, the inventors first proposed a power cable in which a laminated tape, which is a metal tape with conductive plastic layers on both sides, was used as the water-shielding tape, and the conductive plastic layer was fused and integrated with the sheath. It achieved results (Jitsugan No. 57-51800). On the other hand, power cables having such a structure still have some problems in maintaining the above-mentioned water-shielding properties over a long period of time under severe usage conditions such as high-voltage power transmission as described above. In order to solve this problem, we conducted a thermomechanical test on the power cable and found that the metal of the water-shielding tape was welded to the metal shielding layer and the intervening resin during cable manufacturing, which caused the breakage. It was confirmed that this resulted in a loss of water impermeability. As a result of intensive study to solve this problem, the inventors interposed a conductive tape layer based on a resin with a melting point of 150°C or higher between the water-shielding tape and the metal shielding layer, and manufactured a cable for both. He discovered that avoiding the unification of time had a surprising effect and perfected this idea. That is, this invention provides a rubber or plastic insulated power cable having a structure in which a metal shielding layer and an anti-corrosion sheath are provided on the outside of a cable core in which an inner conductive layer, an insulator layer and an outer conductive layer are sequentially provided on the conductor. A conductive tape based on a resin with a melting point of 150°C or higher is wrapped on the shielding layer, and a plastic layer is placed on both sides of the metal tape on top of this.
A laminate water-blocking tape, at least one of which is a conductive plastic layer, is wrapped in such a way that the conductive plastic layer side faces the conductive tape side, and an anti-corrosion sheath is further coated thereon. Rubber and plastic insulated power cable. In this invention, there are various resins with a melting point of 150°C or higher that serve as the base of the conductive tape provided on the metal shielding layer, but polyester, polypropylene, polyamide, etc. are particularly preferred, and these are used as the base resin as appropriate. It is something. In order to manufacture conductive tape using these resins, an appropriate amount of conductive carbon black is mixed into the resin to form a tape, or a woven or non-woven fabric made of fibers made of the resin is mixed with butyl rubber,
This is carried out by applying or filling a conductive mixture made by mixing an appropriate amount of conductive carbon black into a rubber compound such as ethylene propylene rubber or acrylic rubber. The thickness of these conductive tape layers is preferably 0.1 mm or more, because if the thickness is less than this, the inherent mechanical resistance becomes insufficient. The reason why we limited the melting point of these resins to 150℃ or higher is that Grover sheath type cables are generally made of resins with a melting point of 90 to 140℃ so that the water barrier layer can be fused with the resin by the heat during sheath extrusion. This is because the resin of the conductive tape is not fused at this temperature, and the conductive tape is softened at the temperature during sheath extrusion and does not undergo significant elongation or plastic deformation. In addition, when using a conductive tape obtained by applying and filling a conductive mixture onto a woven or nonwoven fabric, the surface of the conductive tape that is in direct contact with the metal shielding layer and the water-shielding tape is made of the conductive mixture as described above. However, since it is rubber-based and vulcanized, it does not have a melting point and will not soften and fuse at the extrusion temperature. Next, in this invention, copper, lead, aluminum tape, etc. are used as the metal tape of the waterproof tape. The plastics laminated on both sides of this metal tape include low, medium, and high density polyethylene, polypropylene, polybutene-1, polymethylpentene, ethylene propylene copolymer, ionomer, ethylene-ethyl acrylate copolymer, and ethylene-ethyl acrylate copolymer. Rubbers such as vinyl acetate-vinyl chloride graft copolymer, ethylene-acrylic acid copolymer, chlorinated polyethylene, chlorosulfonated polyethylene, asoprene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber, polyvinyl chloride, Plastic material is used, and to make it conductive plastic, an appropriate amount of conductive carbon black is mixed into the rubber and plastic material, and the volume resistivity is set to 10 ⁷ Ωcm.
Do the following. As mentioned above, it is important that the plastic layer facing the sheath side constituting this water-blocking layer is integrated with the sheath, and for this purpose, the conductive or non-conductive plastic layer of the laminate tape must be connected to the sheath. It is desirable to select a material that is compatible with the resin used in the material. Furthermore, it is desirable that the specific resistance of the conductive plastic layer of the laminate tape is 10 ⁷ Ωcm or less, and if it exceeds this, unnecessary potential differences may occur between the metal tape constituting the water-blocking layer and the metals of the shielding layer. This is undesirable. The reason why plastic layers are provided on both sides of the metal tape in the laminated waterproof tape is that, as mentioned above, the plastic layer on the side facing the sheath has the role of adhesion and integration with the sheath. The plastic layer on the side facing the cable core is required to be conductive, and has the role of equalizing the potential between the metal tape of the water-blocking layer and the shielding metal layer. Furthermore, the reason why a plastic layer is provided on both sides of the metal tape is that the plastic layers on both sides are fused and integrated at the lap part of the laminate water-blocking tape, thereby making the water-blocking property more complete. This is to improve the bending resistance, damage resistance, fatigue resistance, and handling properties of the waterproof tape by protecting it from both sides. The figure shows an embodiment of this invention, in which an inner semiconducting layer 6a, an insulator 2, and an outer semiconducting layer 6b are provided on a conductor 1 in this order on a cable core.
A metal shielding layer 3 is provided, and the above-mentioned conductive tape 7 is further arranged, and a laminate tape 4 in which a conductive plastic layer 4b and a plastic layer 4c are laminated on both sides of a metal tape 4a is placed on the outside and covered. , the sheath 5 is extruded and coated. As is clear from the above explanation and the examples below, this invention consists of disposing a conductive tape based on a resin with a melting point of 150°C or higher on the metal shielding layer of a Grover sheath type power cable, and placing a metal tape on top of the conductive tape. By wrapping conductive plastic tape laminated on at least one side with the conductive plastic side facing the metal shielding layer side,
By extrusion coating the sheath, the conductive layer or non-conductive layer of the laminate tape and the sheath layer are integrated, and an amazing water-shielding effect can be obtained. It is possible to avoid wear and tear of the metal tape due to discharge etc. due to the above-mentioned potential difference without generating any necessary potential difference, and to significantly improve the reliability of the water-shielding property, and furthermore, the conductive tape is interposed between the water-shielding layer and the metal shielding layer. The effect of solving the above-mentioned problems, such as preventing the two from being integrated and properly preventing deterioration of these properties due to heat cycles, etc., is truly great from an industrial perspective. This invention will be specifically explained below using examples. Example 1 When manufacturing a 154KV1×2000mm2 water ^- shielded cable according to the configuration shown in the figure, a 1.2φ annealed copper wire shield was provided as a metal shielding layer, and conductive butyl rubber was applied to a woven fabric using polyester thread on top of it. Wrap two filled conductive tapes (ρ: 10 ³ Ω・cm) in a 1/2 wrap to a thickness of 1.0 mm, and then conductive PVC (100 μ thick)/Pb (50 μ thick)/PVC (50 μ thick) on top. ) After preparing a laminated tape of the configuration, PVC was extruded and coated on top of it to complete a Grover-type sheath. Example 2 When manufacturing a 6.6KV1× ^250mm2 water-shielding cable according to the configuration shown in the figure, a 1.2φ annealed copper wire shield was provided as a metal shielding layer, and conductive acrylic latex rubber was placed on top of the woven fabric using nylon thread. A conductive tape (ρ: 10 ⁵ Ω cm) coated with 1/2 wrap is wound to a thickness of 0.5 mm, and on top of that is conductive PVC (50μ thick) / Cu (20μ thick) / conductive PVC. (thickness: 50μ) After measuring the laminated tape, place it on top of it.
The Grover type sheath was completed by extrusion coating PVC. Example 3 When manufacturing a 6KV1×250mm2 water ^- shielding cable according to the configuration shown in the figure, a 0.1mm thick annealed copper tape was used as the electrical shielding layer, and conductive chloroprene rubber was applied and filled onto a woven fabric using polypropylene thread. 1/2 lap of conductive tape (ρ: 10Ω・cm)
A sheet of conductive PE (thickness
After measuring a laminate tape consisting of 50μ) Pb (30μ thick)/conductive PE (50μ thick), PE was extruded and coated on top of it to complete a Grover-type sheath. Comparative Example 1 A conductive tape (ρ: 10 ³ Ω・
The procedure was the same except that cm) was used. Comparative Example 2 The same procedure was carried out except that instead of the conductive cloth tape made of chloroprene in Example 3, a single conductive nonwoven tape made of polyethylene fiber was wound to a thickness of 0.5 mm. The following tests were conducted using each of the above cables. Trauma test: 900Kg/m, 1200 for each table above
After applying a lateral pressure load of Kg/m, the cable was pulled at a pulling speed of 10 mm/min. Fatigue test: Each cable above was strained to 0.15 at a temperature of 60℃.
% and 0.2%, fatigue tests were conducted 2×10 ⁴ times and 10 ⁴ times, respectively. Bend test: Each of the above cables was subjected to a 5-reciprocating bend test using a diameter 10 times larger. After the above test, the cable was disassembled and the damage to the metal of the water-shielding tape was investigated.The results are shown in the table below.

[Table] As seen from the above results, according to the present invention, trauma test,
This is extremely useful in practical terms because it allows the production of water-shielded cables that are superior to comparative examples in both thermomechanical properties such as thermal fatigue tests and bend tests.

[Brief explanation of the drawing]

The figure is a sectional view of an embodiment of the power cable of the present invention. DESCRIPTION OF SYMBOLS 1... Conductor, 2... Insulator, 3... Metal shielding layer, 4a... Metal tape, 4b... Conductive plastic layer, 4c... Plastic layer, 4... Laminated tape, 5... Sheath, 6a , 6b...inner, outer semiconductive layer, 7... conductive tape.

Claims (1)

[Scope of utility model registration request] A rubber or plastic insulated power cable having a structure in which a metal shielding layer and an anti-corrosion sheath are provided on the outside of a cable core in which an inner conductive layer, an insulator layer and an outer conductive layer are sequentially provided on the conductor, on the metal shielding layer, A conductive tape based on a resin with a melting point of 150°C or higher is wrapped, and a laminate water-shielding tape with plastic layers on both sides of the metal tape, at least one of which is a conductive plastic layer, is wrapped around the conductive plastic. 1. A rubber or plastic insulated power cable, characterized in that the cable is vertically wrapped so that the layer side is the conductive tape side, and a sheath is further coated thereon.