JP2847787B2 - Overhead transmission line - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an overhead power transmission line, and more particularly, to an overhead transmission line, which is configured to achieve a reduction in weight of the transmission line itself and to suppress a decrease in overhead line sag, and at the same sag. Is a new overhead transmission line that can greatly increase the current carrying capacity, lower the height of the tower when the transmission capacity is the same, and reduce the construction cost of the transmission line. It is about.

[Prior Art] Steel core aluminum stranded wires have conventionally been used for overhead transmission lines that are connected between towers and transmit power from a power source. That is, a galvanized steel wire serving as a tension member is twisted to form a steel core, and an aluminum wire as a conductive member is twisted around its outer periphery to form a stranded wire.

In recent years, the demand for electric power has been increasing remarkably, and there is a tendency to reduce the total cost by using the same transmission line to increase the transmission capacity as much as possible or to construct the tower as low as possible. Is gradually increasing.

The following proposals have been made as a means for increasing the transmission capacity of a transmission line without increasing the outer diameter of the transmission line or increasing the height of a steel tower.

(1) Increase the specific strength (tensile strength / weight) of the steel core,
The sufficient tension can be maintained by the thin steel wire, and the cross-sectional area occupied by the aluminum wire as a member is increased by the thinned steel core.

(2) For example, in the case where an invar wire having a small coefficient of thermal expansion is used as a steel core instead of the conventional galvanized steel wire, the current carrying capacity of the transmission line is increased to generate heat by energization, and the entire transmission line is thermally expanded. The member wire having a small coefficient of thermal expansion serves as a tension member, thereby preventing a reduction in sag of the overhead wire.

(3) Instead of the galvanized steel wire or Invar wire, an FRP wire which is made by binding extremely light weight aramid fiber, carbon fiber, etc. with a strong resin such as polyester resin or epoxy resin is used. It is used to reduce the weight of the electric wire itself while securing the strength as a tension member, and consequently reduce the decrease in the sag due to the weight of the electric wire.

[Problems to be Solved by the Invention] FIG. 5 shows a specific example of an invar core aluminum stranded wire in which the invar wire 10 is used as a tension member and the aluminum wire 2 is twisted around its periphery, among the various proposals described above. It is sectional drawing.

Since the coefficient of linear expansion of Invar is approximately 1.0 × 10 ^-6 ,
Compared to the fact that zinc wire is about 12.0 × 10 ^-6 , its coefficient of thermal expansion is much smaller, even if it transmits large-capacity power and the temperature of the transmission line rises significantly due to its current flow, The decrease in the sag can be sufficiently suppressed. For this reason, it has already been adopted and put to practical use in some actual lines. However, although the coefficient of linear expansion can be reduced, the strength of the Invar wire itself is smaller than that of steel wire, the cross-sectional area of the steel core has to be rather large, and the overhead wire tension is rather higher than that of the conventional steel core aluminum twist. Tends to be larger than the line. Further, Invar has a certain kind of brittleness, and although the brittleness can be alleviated by adding elements or heat treatment, it cannot be said that there is no fear that unexpected disconnection will occur even under a large overhead wire tension. .

In the case of using FEP wire, carbon fiber or silicon carbide fiber tied with epoxy resin has been put into practical use, so that light-weight stranded wires with light weight can be applied as tension members of transmission lines. became. This FR
P has a fiber content of about 60%, a specific gravity of about 1.5 when an epoxy resin is used as a matrix, and is about 1/5 of a steel wire, which is extremely light. The coefficient of linear expansion is 2 × 10
^-6 and a value almost equivalent to that of the Invar line. However, a drawback of FRP using carbon fibers and silicon carbide fibers is that the matrix binding the fibers is plastic. That is, since the epoxy resin is used, the problem of poor heat resistance cannot be avoided. Although the heat resistance of the above fiber alone is extremely high, from 1200 to 2500 ° C., the use temperature in the case of constituting FRP is 150 at most.
° C, and its effect is far lower than that using the Invar wire.

Furthermore, thermal degradation is expected even for long-term use,
Rather, it has too many disadvantages as a tension member for overhead power transmission lines that requires long-term reliability.

Therefore, an attempt to use an FRM using a metal for the matrix instead of the FRP using a plastic as the matrix has been proposed. However, while the reactivity between the inorganic fiber and the matrix metal is small, it has to have the opposite property that the wettability must be good, which is an essential condition for FRM production, and it has been developed as a general structural material. Has progressed remarkably in recent years,
An FRM suitable for use as an electric wire, particularly as an overhead power transmission line, has not yet been found.

As a known wire using FRM, a wire having a configuration as shown in FIG. 6 has been proposed. This is a copper matrix 21
Copper carbon fiber composite wire 22 with composite carbon fiber 20
And a copper jacket 23 is applied to the outer periphery thereof. However, if the matrix and the jacket are copper, they are unsuitable and cannot be used as overhead power transmission lines. In addition, since the wettability of carbon fiber and copper is poor and cannot be directly combined, it is necessary to pre-process the carbon fiber with copper before plating or vapor-depositing it before forming a composite wire. There are many problems from the standpoint of strategic productivity.

Those skilled in the art will easily come up with the idea that if the composite wire is manufactured using an aluminum matrix, an FRM wire suitable for overhead power transmission lines would be available.
However, the wettability between carbon fiber and aluminum is poor as in the case of copper, and even if such an aluminum carbon fiber composite wire is manufactured, carbon fiber easily reacts with aluminum, and Al ₄ C Recent studies have increasingly shown that carbides of the _third grade are formed, which can be degraded by moisture in the air, resulting in a significant reduction in strength.

An object of the present invention is to solve the above-mentioned problems of the prior art, achieve a remarkable weight reduction of the transmission line itself, and have a very small coefficient of linear expansion as compared with the conventional transmission line,
A new overhead wire that can greatly reduce the sag when the wire temperature rises due to energization and at the same time reduces the overhead wire tension, thereby increasing the transmission capacity or reducing the tower height. It is something to offer.

[Means for Solving the Problems] The present invention provides an aluminum silicon carbide composite in which aluminum or an aluminum alloy is used as a matrix, and long silicon carbide fibers are integrated into the matrix at a volumetric composite ratio of 15 to 75%. Aluminum or aluminum alloy with a wall thickness of 0.
A core portion is formed by twisting a plurality of aluminum-coated composite wires having a thickness of 5 mm or more, and an aluminum wire is twisted around the outer periphery of the core portion.

[Operation] When carbonized silicon element fibers are combined with aluminum, the wettability with aluminum is good, and there is almost no risk of causing the above-described reaction with aluminum. Therefore, the aluminum silicon carbide fiber composite material can be sufficiently used as a power transmission line instead of the steel core of the aluminum core stranded wire. However, from the viewpoint of securing high strength as an overhead transmission line and demanding for a lighter weight required by the present invention, the volume composite rate of the carbonized silicon element fiber is reduced to 15%.
It is necessary to make the above, to secure the bending radius in manufacturing as an electric wire to allow the brittleness of the silicon carbide fiber and to maintain the ease of production and overhead wire construction, while maintaining the electrical conductivity required for the electric wire To secure, the composite rate is 75%
It is necessary to: An increase in bending radius and a decrease in conductivity due to the brittleness are caused by 0.05 mm on the outer periphery of the composite wire.
It is remarkably improved by coating aluminum having the above thickness, and the usefulness as an electric wire can be remarkably improved.

Examples Hereinafter, the present invention will be described with reference to examples.

Fig. 1 shows an aluminum pipe with aluminum silicon carbide composite wire 1.
FIG. 4 is a cross-sectional view of an overhead transmission line according to the present invention in which a plurality of aluminum pipe-coated composite wires 4 covering 4a are twisted to form a core portion, and an aluminum wire 2 is twisted around the core portion to form an overhead transmission line according to the present invention. FIG. 2 is an enlarged cross-sectional view showing one of the composite wires 4 in FIG.

As can be seen from FIG.
Is a matrix 1b made of aluminum or an aluminum alloy, which is combined with a long fiber 1a of silicon carbide, and integrated to form a composite wire 1.
And the outer periphery thereof is coated with an aluminum pipe 4a.

In order to manufacture the aluminum silicon carbide composite wire 1 serving as the base of such a composite wire 4, there is no need for any plating treatment or vapor deposition treatment as a pretreatment unlike the above-mentioned copper carbon fiber composite wire. That is, the silicon carbide fiber yarn is spread at an appropriate interval, passed through a molten aluminum bath, then appropriately drawn with a drawing die, and finished so as to have a required wire diameter as a conductor. There is no risk of producing harmful compounds.

Aluminum silicon carbide composite wire 1 produced as described above
Although a stranded wire as shown in FIG. 1 may be formed by using an aluminum-coated wire, in this case, the volume ratio of silicon carbide of the composite wire 1 (hereinafter referred to as Vf) is in any range. The problem is whether or not is suitable as a transmission line.

FIG. 7 is a diagram plotting the relationship between Vf and tensile strength at room temperature, using pure aluminum as a matrix to produce a composite wire 1 having an outer diameter of 1 mm.

From FIG. 7, it can be seen that when Vf is 15% or less, there is almost no effect of improving the tensile strength of aluminum, and SiC is at least 15%.
It turns out that it is necessary to combine them. Thereafter, as Vf is increased, the tensile strength gradually increases. And
A sharp rise is seen above 75% Vf. This is thought to be due to the direct influence of the intrinsic tensile strength of SiC in the composite wire.

FIG. 8 shows the Vf of SiC using the same test material as in FIG.
FIG. 3 is a diagram plotting a relationship between the electric conductivity and the electric conductivity. It can be seen from the comparison between the two figures that the state of the change in the electrical conductivity in FIG. 8 is just the reverse of the state of the change in the tensile strength shown in FIG. Here, too, it is shown that when Vf exceeds 75%, the conductivity sharply decreases. This can be attributed to the fact that the volume of aluminum, which is a conductive member, is reduced, and the insulating properties of SiC itself appear.

Summarizing the behaviors of both Fig. 7 and Fig. 8, the upper limit of Vf of SiC that can be used as transmission line is 75%
It can be said that it is near. Therefore, taking the above into consideration, the SiC of the aluminum silicon carbide composite wire according to the present invention is
Vf of 15 to 75% is appropriate.

It is appropriate to set the Vf of SiC to 15 to 75% as described above. However, depending on the compounding ratio of the silicon carbide fiber, the brittleness of the silicon carbide fiber that is destined to be bent during the production or overhead wire as an electric wire. Can be a problem as an impact on

The inventors have found that the problem of bending caused by such brittleness can be solved by coating the outer periphery of the aluminum silicon carbide composite wire with aluminum or an aluminum alloy.
In other words, FIG. 9 shows that the outer circumference of an aluminum silicon carbide composite wire having a Vf of SiC of 60% and an outer diameter of 1 mm was coated with aluminum to various thicknesses, and the relationship between the thickness of the aluminum coating and the allowable bending radius was measured. It is a diagram showing the results, as is clear from this figure, it can be seen that the bending radius is extremely remarkably improved by performing aluminum coating, and that the coating thickness exhibits a large effect at 0.05 mm or more. .

Therefore, in order to increase the Vf of SiC, to increase the strength, the weight, and the low thermal expansion property, it is appropriate to coat the outer periphery of the aluminum silicon carbide composite wire 1 with aluminum or an aluminum alloy having a thickness of 0.05 mm or more. Thus, the problem caused by the increase in Vf of SiC can be sufficiently solved.

FIGS. 3 and 4 show the above aluminum silicon carbide composite wire 1.
FIGS. 3A and 3B show two examples in which an aluminum coating is applied to the outer periphery of FIG.
(B) shows an end view thereof, and FIG. 3 shows an aluminum tape-coated composite wire 3 obtained by winding an aluminum tape 3a around the outer periphery of an aluminum silicon carbide composite wire 1, and FIG. 1 shows a case where an aluminum pipe 4a is coated to form an aluminum pipe-coated composite wire 4.

In the case of FIG. 3, the aluminum tape 3a is tightly wound or wrapped and wound, and when the aluminum tape is longitudinally covered, the joint is seam-welded and then contracted with a die. . In the case of FIG. 4, the aluminum pipe 4a can be easily covered by the extrusion method.

In any case, it is not necessary to impart strength by plastic working as conventionally performed on metal wires, and it is rather necessary to take care not to cut the long fibers inside in the longitudinal direction. .

A plurality of such aluminum-coated composite wires 3 or 4 are twisted to form a core portion, and an aluminum wire 2 is twisted around the core portion to form an aluminum silicon carbide composite wire core aluminum stranded wire. in this case,
As a result, it is possible to provide an overhead transmission line that solves the above-mentioned disadvantages of the invar core aluminum stranded wire shown in FIG. 5, and it can be highly evaluated in terms of usefulness.

FIG. 10 is a diagram showing the results of measuring the high-temperature durability at 350 ° C. of a SiC Vf 40% aluminum silicon carbide composite wire and a pure aluminum wire of the same diameter. Pure aluminum wire has been softened in a very short time, but the composite wire of the present invention shows almost no decrease in tensile strength even after 1,000 hours,
It can be said that it demonstrates that it has very good high temperature properties.

By using the overhead transmission line according to the present invention having such high-temperature characteristics as well as low thermal expansion characteristics and also appropriate conductivity, it is possible to transmit power with a larger current carrying capacity at the same sag, and to achieve the same power transmitting capacity. On the other hand, the sag can be kept extremely small, so that the height of the steel tower can be considerably reduced, which can contribute to improvement of environmental problems.

[Effects of the Invention] As described above, according to the overhead transmission line according to the present invention, it is possible to reduce a large weight while maintaining sufficient strength of the electric wire, and it is possible to minimize a decrease in sag due to its own weight. Instead, it increases the current carrying capacity with a small coefficient of thermal expansion and extremely excellent heat resistance, so that even if the transmission line generates considerable heat, there is no decrease in strength or sagging due to thermal expansion, and for a long time Because stable performance can be maintained, the transmission capacity can be significantly increased using existing towers,
The height of the new tower can be reduced and its size can be reduced, so that it can not only cope with land shortages in and around the city, but also reduce the effects of wind pressure vibration on the electric wires, making it possible to take only minor measures. It can be said that there are immeasurable implications for the industry, such as being able to do so.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an electric wire according to the present invention, and FIG.
The figure is an enlarged cross-sectional view showing the configuration of the composite wire, and FIGS. 3 and 4 show the appearance of the outer periphery of the aluminum silicon carbide composite wire coated with aluminum. FIG. ,
Each figure (b) is an end view thereof, FIG. 5 is a sectional view of a conventional invar core aluminum stranded wire, FIG. 6 is a sectional view showing a specific example of an electric wire using a copper-carbon fiber composite wire, and FIG. Diagram showing the relationship between Vf and tensile strength of SiC, FIG. 8 also shows the relationship between Vf of SiC and electrical conductivity, and FIG. 9 shows the aluminum coating thickness and allowable bending radius of the aluminum-coated composite material strand. Diagram showing the relationship
FIG. 10 is a diagram showing the results of a high-temperature durability test. 1: Aluminum silicon carbide composite wire, 1a: Silicon carbide fiber, 1b: Aluminum or aluminum alloy matrix, 2: Aluminum wire, 3: Aluminum tape coated composite wire, 3a: Aluminum tape, 4: Aluminum pipe coated composite wire, 4a : Aluminum pipe.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-37606 (JP, A) JP-A-62-86606 (JP, A) JP-A-61-99205 (JP, A) JP-A-2- 223105 (JP, A) JP-A-52-7811 (JP, A) JP-A-61-34167 (JP, A) JP-A-61-170502 (JP, A) JP-A-1-252741 (JP, A) JP-A-62-149831 (JP, A) JP-A-59-93845 (JP, A) JP-A-49-26766 (JP, A)

Claims (1)

(57) [Claims] An aluminum or aluminum alloy is used as a matrix, and a long silicon carbide fiber is composite-integrated in the matrix with a volume composite ratio of 15 to 75%. An overhead transmission line made by twisting a plurality of aluminum-coated composite wires made of aluminum alloy with a thickness of 0.05 mm or more and twisting to form a core, and twisting an aluminum wire around the core.