JPH10321051A - Lightweight, low dip overhead wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight, low dip overhead wire by arranging a plurality of conductors on the outside of a tension member, formed by twisting a plurality of organic tensile strength wire materials in which the surfaces of polyparaphenylene benzobisoxazole fibers are covered with a heat resistant resin layer. SOLUTION: An organic tensile strength wire material A1 has a core made of polyparaphenylene benzobisoxazole(PBO) fibers, and the surface is covered with a heat resistance resin layer 2. A tension member is formed by twisting a plurality of organic tensile strength wire materials, and a plurality of conductors are arranged on the outside. Since the organic tensile strength wire material A1 is formed by covering the surface of the PBO fibers 1 with the heat resistant resin layer 2, light is shut off with the resin layer 2, deterioration due to light of the PBO fibers 1 is prevented, and mechanical damages are hardly received. Since the whole of the tension member is made of the organic material, it is markedly lightweight compared with a steel core, and since the PBO fibers having negative coefficient of linear expansion are used, a low dip overhead wire is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-weight, low-sagging overhead electric wire, and more particularly, to a light-weight and low-strength overhead electric wire, which is made of an organic material, and is thermally expanded even when exposed to high temperatures. In addition, the present invention relates to a lightweight low-slack overhead electric wire which exhibits an excellent effect of suppressing sag at high temperatures by using an organic tensile wire having excellent weather resistance as a tension member.

[0002]

2. Description of the Related Art Conventionally used overhead power transmission lines are:
A steel core obtained by twisting a plurality of steel wires is used as a tension member, and a transmission line made of, for example, Al or an Al alloy is twisted and arranged outside the tension member. Then, the whole is stretched between the steel towers with high tension to form a transmission line. By the way, in the case of an overhead transmission line, the transmission capacity is increased by increasing the load current. Therefore, it is necessary to transmit a large current to the overhead transmission line in order to increase the transmission capacity.

However, in the case of the above-described steel core Al stranded wire, since the linear expansion coefficient of the steel core is a positive value, the temperature of the wire is increased due to an increase in load current, and the temperature is changed based on a change in climate or weather conditions. As a result of the rise, the steel core thermally expands, the wire length becomes longer, and the overhead transmission line sags. Moreover, since the weight of the steel core is large, the steel core Al stranded wire itself tends to hang down.

[0004] For this reason, in the case of the steel core Al stranded wire, when the wire is laid, a work such as carrying out the wire laying work in anticipation of the increase in the sag due to the temperature rise or constructing a sufficiently high steel tower is taken. It is necessary to carry out the application, which raises a problem that the overhead wire and the construction cost increase.
In place of the above-mentioned steel core, for example, there is known an electric wire in which a carbon fiber is used as a reinforcing material and an FRP wire made of various resins as a matrix is used as a tension member.

[0005] Generally, the above-mentioned FRP wire is a material having a light weight, a small coefficient of linear expansion, and high tensile strength. However, even if such an FRP wire is used as a tension member, the obtained overhead transmission line has a coefficient of linear expansion of about 18 × 10 ⁻⁶ / ° C., and the sag increases as the wire temperature increases. Come.

[0006] Further, when the shared tension is applied to the tension member by 10%.
Even when the temperature rises to or above the transition point temperature at which 0% shift occurs, the FRP wire (tension member) elongates, and the sag of the overhead transmission line increases with the temperature rise.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the conventional tension member, has high tensile strength, is lightweight because the whole material is made of an organic material, and can be used in a high-temperature environment. It is an object of the present invention to provide a lightweight low-slack overhead electric wire having a tension member formed by twisting a plurality of organic tensile strength wires that do not undergo elongation due to thermal expansion and do not deteriorate.

[0008]

In order to achieve the above-mentioned object, in the present invention, a polyparaphenylene benzobisoxazole fiber is formed by twisting a plurality of organic tensile strength wires each having a surface coated with a heat-resistant resin layer. A light-weight, low-sagging overhead electric wire is provided, in which a plurality of conductors are arranged outside a tension member.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an organic tensile wire will be described. The tensile strength wire A _1, as shown in FIG. 1, the core portion is polyparaphenylene benzobisoxazole fiber (poly (p-phenylene-2,6 -benzobisoxazol) fiber,
(Hereinafter referred to as PBO fiber) 1 and its surface is
It is covered with a heat-resistant resin layer 2 described later.

The PBO fiber has the following formula:

[0011]

Embedded image

Is a fiber obtained by spinning liquid crystal of polyparaphenylene benzobisoxazole having a repeating unit of This PBO fiber has a tensile strength (Ts) of 5 to 6 GPa, an elastic modulus (E) of 260 to 300 GPa, and a melting point of 600 to 6 GPa.
50 ° C., oxygen index 50-55, density (ρ) 1.5-1.5.
6 g / cm ³ , a coefficient of linear expansion (α) of about −6 × 10 ⁻⁶ / ° C., high strength, high elasticity, excellent heat resistance and flame retardancy, and light weight. Since the coefficient of linear expansion is a negative value, it has a property that it contracts with increasing temperature.

However, when the PBO fiber is irradiated with ultraviolet rays, its strength properties, especially its tensile strength, decrease with time, and its tensile strength is impaired. In order to overcome the weaknesses of the PBO fiber, the tensile strength wire used in the present invention has the surface of the PBO fiber covered with a heat-resistant resin layer, thereby blocking light with the resin layer and preventing light deterioration of the PBO fiber. ing.
Further, the provision of the heat-resistant resin layer prevents the PBO fiber from being mechanically damaged by the external force, for example, even if it receives some external force.

The resin layer functioning as such a protective layer includes a heat-resistant resin which maintains its strength characteristics without being melted or thermally decomposed even when the electric wire temperature rises to about 200 ° C. Is used. For example, a thermosetting resin such as a polyimide resin or a polyamide imide resin can be given, and a thermoplastic polyimide resin, polyether ether ketone, polyphenylene sulfide, polyether ketone, polytetrafluoroethylene, polyperfluoro Thermoplastic heat-resistant resins such as ethylene and ethylene tetrafluoroethylene copolymer can be given.

In the case of forming the resin layer with the former thermosetting heat-resistant resin, first, a resin liquid of an uncured heat-resistant resin is prepared, and the PBO fiber is immersed or continuously immersed in the resin liquid. By running, the surface of the PBO fiber is covered with a resin liquid. Further, an uncured resin may be applied to the PBO fiber to cover it. Thereafter, by heating the whole to a predetermined temperature, the drying of the resin liquid is advanced, and the heat-resistant resin is thermally cured. As a result, the thermosetting heat-resistant resin is baked on the surface of the PBO fiber, and the two are integrated.

When the resin layer is formed of the latter thermoplastic heat-resistant resin, the heat-resistant resin is applied to the outer periphery of the PBO fiber by applying the extrusion coating method applied to the conductor coating in the field of electric wire production. Extrusion coating may be applied. That is, the heat-resistant resin may be heated to a predetermined temperature to soften the resin, and the heat-resistant resin may be continuously extruded together with the PBO fiber from an ordinary extruder to cover the PBO fiber.

The thickness of the resin layer thus formed is not particularly limited, but if it is too thick, the PBO fiber thermally contracts in a high-temperature environment, and the resin layer generally expands thermally. Thermal stress begins to occur at the interface of the resin and phenomena such as peeling between them and the occurrence of microcracks in the resin layer are likely to occur.If the thickness is too thin, the above-mentioned problems are unlikely to occur, but on the other hand, as a protective layer Of the PBO fiber, and light deterioration and mechanical damage of the PBO fiber are easily caused. Therefore, the thickness of the resin layer is 100 μm to 2.
Preferably, it is about 5 mm. Further, an ultraviolet absorber may be mixed into the heat-resistant resin layer to further enhance the effect of preventing light deterioration.

The tensile strength wire used in the present invention may cover the outer periphery of each single PBO fiber to form a resin layer having the above-mentioned thickness. However, as shown in FIG. A plurality of PBO fibers 1 are bundled, and the whole bundle 1 'is immersed in, for example, a resin solution of a heat-resistant resin to impregnate the resin between the fibers 1 and 1' so that the surface of each fiber is made of resin. Coating, so-called resin 2 as a matrix, PBO
Complex to reinforcement fiber bundles 1 '(composite) may be a structure A _2.

Next, as shown in FIG. 3, the tension member B used in the present invention is manufactured by twisting a plurality (seven in the figure) of the organic tensile wire A ₁ or A ₂ . Since this tension member is entirely made of an organic material, it is significantly lighter than a conventional steel core, and has a negative linear expansion coefficient PBO.
Since the fibers are used, they do not undergo thermal expansion and do not increase in sag even when placed in a high-temperature environment. Moreover, since a resin layer made of a heat-resistant resin is formed as a protective layer on the outside of the PBO fiber, even if the temperature of the electric wire increases, the resin hardly deteriorates, and the PBO fiber deteriorates due to light and mechanical damage. Is effectively prevented, and thus can function as a tension member for a long time.

The above-mentioned tension member B is used as a core material,
By arranging a plurality of conductors on the outside, the lightweight low-loose overhead wire of the present invention can be obtained. As the conductor, any conductor may be used as long as it has been conventionally used as a conductor of an overhead transmission line. For example, an aluminum conductor or a conductor of an aluminum alloy can be used as a suitable conductor.

In the case of this electric wire, the tension member B is lightweight as described above and is unlikely to cause an increase in the sag in a high-temperature environment. Does not cause a large increase in the sag. As shown in FIG. 4 (a) and FIG. 4 (b), for example, as shown in FIG. 4 (a) and FIG. 4 (b), the tension member B shown in FIG. C ₁ and C ₂ having a structure of being twisted and arranged can be given.

Further, in the case of this lightweight low-relaxation overhead electric wire, as shown in FIG. 5, the tension member B and the conductor 3 are arranged in parallel so that they do not come into contact with each other. it may be a C ₃ ones are integrated both structures by both whole surface and the surface of the conductor 3 to form a resin coated covering layer 4, such as polyvinyl chloride or polyethylene.

In the case of the electric wire C ₃ , even if the load current increases and the temperature of the conductor 3 increases, the heat transfer to the tension member B is moderated to some extent by the coating layer 4.
The heat load on the tension member B is reduced, and the sag suppression hardening is further improved.

[0024]

【Example】

(1) Organic tensile strength line Toyobo Co., Ltd. PBO fiber (linear expansion coefficient: -6 × 10
^-6 / ° C.) to form a bundle having a thickness of about 0.79 mm, which is continuously run through an uncured polyimide resin, and then passed through a die to remove excess resin. by thermal curing of the polyimide resin by introducing further heating furnace, and a wire a ₂ of the composite structure shown in FIG. The wire diameter of the wire was about 0.85 mm. This is referred to as wire 1.

After drying, a part of the wire 1 is separated and each PBO
When observing the surface of the fibers, a thermoset polyimide resin was interposed between each PBO fiber,
It was confirmed that the surfaces of the PBO fibers were all covered with the polyimide resin. With respect to the obtained wire 1, the coefficient of linear expansion, tensile strength, elastic modulus, and weight per unit length were measured.

The light deterioration of the wire 1 was examined as follows. That is, an ultraviolet irradiation test was performed, the relationship between the ultraviolet irradiation time and the tensile strength of the wire 1 was measured, and the change over time of light deterioration was examined. Table 1 shows the above results. The tensile strength in the table is shown as a relative value when the tensile strength before ultraviolet irradiation is set to 100.

The bundle of PBO fibers used in the production of the wire 1 was extrusion-coated with an ethylene tetrafluoroethylene copolymer to produce a wire having a diameter of 1.1 mm. Also in this case, when the surface of the PBO fiber was observed by separating the wire, the PBO fiber in the surface layer was in a state of being covered with the copolymer. This is referred to as wire 2. This wire 2
As for the wire rod 1, various characteristics and the state of light deterioration were examined as in the case of the wire rod 1. The results are shown in Table 1.

For comparison, various characteristics and the state of light deterioration of the bundle of PBO fibers used in the production of the wire 1 were also examined, and the results were used as a comparative example wire as shown in Table 1.
It was shown to.

[0029]

[Table 1]

As is apparent from Table 1, the wires 1 and 2 of the present invention are materials having a remarkably low coefficient of linear expansion and not thermally elongating under a high temperature environment. Further, it can be seen that the mass per unit length is extremely small, and the weight is extremely light. this is,
This is because the reinforcement is made of PBO fibers. Further, in these wires 1 and 2, since the PBO fiber is protected by the resin layer, light deterioration is suppressed, and it can be seen that the wire can be sufficiently used as a tensile wire used outdoors for a long period of time.

Seven wires 1 and 2 are twisted, and the outer periphery thereof is covered with an ethylene tetrafluoroethylene copolymer to obtain a wire having a wire diameter of about 4.3 mm. And a wire diameter of 4.5 m around it
The m equivalent aluminum conductors arranged 26 present by twisting them, and the overhead conductors C ₂ as shown in FIG.

The span length (S) of the obtained two overhead electric wires was changed as shown in Table 2 under the following overhead wire design conditions, and the slack when the electric wire temperature became 20 ° C. and 200 ° C. The degree was calculated. Overhead wire design conditions: Maximum operating tension 25.5 GPa, high temperature season temperature 15 ° C, wind pressure 10.2MPa, low temperature season -15 ° C, wind pressure 5.
1 MPa, ice coverage 6 mm, specific gravity 0.9.

For comparison, the same calculation was performed for a conventional invar core aluminum stranded wire having the same sectional structure. The above results are shown in Table 2 collectively.

[0034]

[Table 2]

As is clear from Table 2, the overhead wire according to the present invention suppresses the increase in the sag even when the wire temperature increases. For example, when the span length is 500 m, a sag difference of 3.0 m occurs at a temperature of 200 ° C. even when compared with an Invar electric wire under the same conditions.

[0036]

As is apparent from the above description, since the organic tensile strength wire used in the present invention uses PBO fiber having a negative linear expansion coefficient as a reinforcing material, the effect of suppressing the sag in a high temperature environment is obtained. Good and useful as a tension member for overhead transmission lines. Since the surface of the PBO fiber is covered with a layer of heat-resistant resin, it is protected from light deterioration and mechanical damage.

Therefore, the overhead electric wire of the present invention, which is a tension member formed by twisting a plurality of the tensile strength wires, is lightweight, and has a small increase in sag even if the wire temperature increases due to an increase in load current. Therefore, the overhead power transmission line can reduce the load on the tower, and can also lower the tower. In other words, conversely, even if the light-weight, low-sagging overhead electric wire of the present invention is installed in an existing steel tower, a larger load current can be applied to the electric wire than in the past to increase the power transmission capacity.

[Brief description of the drawings]

FIG. 1 shows an organic tensile strength wire A used for an overhead electric wire according to the present invention.
FIG. ₂ is a sectional view showing ₁ .

Is a sectional view showing an example of Figure 2 another organic tensile strength wire A _2.

FIG. 3 shows a tension member B used for an overhead electric wire according to the present invention.
FIG.

FIG. 4 is a cross-sectional view showing the lightweight low-sagging overhead electric wires C ₁ and C ₂ of the present invention.

5 is a cross-sectional view showing another light weight low sag overhead conductors C ₃ of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 PBO fiber 1 'Bundle of PBO fiber 1 2 Layer of heat resistant resin 3 Aluminum conductor 4 Resin coating layer

Claims (6)

[Claims] 1. A plurality of conductors are arranged outside a tension member formed by twisting a plurality of organic tensile strength wires each having a surface of a polyparaphenylene benzobisoxazole fiber covered with a heat resistant resin layer. Lightweight, low sag overhead wire. 2. A lightweight low-loose overhead electric wire, wherein a plurality of the tension members are twisted to form a core material, and a plurality of conductors are arranged outside the core member. 3. The light-weight, low-sagging overhead electric wire according to claim 1, wherein the conductor is made of aluminum or an aluminum alloy. 4. The light-weight, low-sagging overhead electric wire according to claim 1, wherein the tension member and the conductor are arranged substantially in parallel in a non-contact state, and are entirely covered with resin to be integrated. 5. The lightweight, low-loose overhead wire according to claim 1, wherein the heat-resistant resin layer is a baked layer of a polyimide resin. 6. The heat-resistant resin layer is an extrusion coating layer of any one of thermoplastic resins selected from the group consisting of thermoplastic polyimide resin, fluorine resin, polyetheretherketone, and polyphenylene sulfide. 4. Lightweight, low sag overhead wire.