JP6461570B2 - Transmission line and method for manufacturing transmission line - Google Patents

Description

  The present invention relates to a power transmission line and a method for manufacturing the power transmission line.

  The span length of overhead power transmission lines used for crossing straits and rivers may be 1000 meters or more. When using ACSR (steel core aluminum stranded) transmission lines for crossing the strait and rivers with a span length of 1000m or more, ensure sufficient spacing between the transmission lines and cargo ships passing under the line. In order to ensure it, it is necessary to increase the tensile load of the transmission line and to install the transmission line with high tension.

For example, in an ACSR using hard aluminum having a tensile strength of about 160 MPa (16.3 kgf / mm ² ) as an aluminum strand that carries a conductor portion through which a current flows, the tensile load of the transmission line is small, so the overhead wire tension Cannot be increased, and the sag (sag) of the transmission line increases, and there is a case where a sufficient distance between the transmission line and a cargo ship passing under the line cannot be secured.

Therefore, a high-strength aluminum alloy is used as an aluminum wire in a transmission line used for crossing the strait and rivers. High-strength aluminum includes aluminum-magnesium-silicon (Al-Mg-Si) -based aluminum No. (IAL), aluminum-zirconium-iron-copper (Al-Zr-Fe-Cu) -based high-strength aluminum. (KAL). The tensile strength of No. 1 aluminum (IAL) is 309 MPa (31.5 kg / mm ² ), the elongation is 3-4%, the conductivity is 52% IACS, and the tensile strength of high strength aluminum (KAL) is 226- 255 MPa (23.0 to 26.0 kg / mm ² ), elongation is 1.3 to 2.0%, and conductivity is 58% IACS. Note that the unit of conductivity “% IACS” is a ratio of conductivity when the conductivity of international standard soft copper (International Annealed Copper Standard) is 100%.

In recent years, Al-Mg-Si-based SI33 aluminum alloy has been used as a special aluminum alloy developed for crossing the strait and rivers. The tensile strength of SI33 is 294 to 333 MPa (30 to 34 kg / mm ² ), the elongation is 3.0%, and the conductivity is 54% IACS.

  In addition, various aluminum alloys and power transmission lines (steel core aluminum stranded wires) have been proposed (for example, Patent Documents 1 to 5).

JP 2004-27294 A JP 2004-327254 A JP-A-2005-203127 JP 2006-222021 A Japanese Patent No. 5014889

  In such transmission lines used across straits and rivers, aluminum alloys used as aluminum strands have improved tensile strength while improving electrical conductivity when manufacturing conditions are adjusted. When the thickness is improved, the conductivity tends to decrease. For this reason, in the transmission line used for crossing the strait and rivers, the tensile strength characteristic can be improved while making the current capacity characteristic equal to or higher than that of the long-diameter transmission line using the conventional SI33 aluminum alloy. It was difficult.

  An object of the present invention is to provide a power transmission line and a method for manufacturing a power transmission line that have improved current strength characteristics and improved tensile strength characteristics as compared with conventional long-span power transmission lines.

According to one aspect of the invention,
A steel core,
An external stranded portion provided by twisting a plurality of aluminum strands outside the steel core; and
Have
The aluminum strand contains magnesium and silicon, the balance consists of aluminum and inevitable impurities,
The electrical conductivity of the aluminum strand is 52% IACS or higher,
A transmission line is provided in which the tensile strength of the aluminum strand is greater than 324 MPa.

According to another aspect of the invention,
A method for manufacturing a power transmission line according to the above aspect,
The step of forming the aluminum strand includes
Provided is a power transmission line manufacturing method including an aging process in which after the aluminum strand is drawn, heat treatment is performed on the aluminum strand at a temperature of 140 ° C. to 160 ° C. for 10 hours to 15 hours. Is done.

  ADVANTAGE OF THE INVENTION According to this invention, compared with the conventional long span transmission line, the manufacturing method of the transmission line and the transmission line which improved the tensile strength characteristic while making the current capacity characteristic equal or better are provided.

It is sectional drawing orthogonal to the axial direction of the power transmission line which concerns on 1st Embodiment of this invention. It is sectional drawing orthogonal to the axial direction of the power transmission line which concerns on 2nd Embodiment of this invention. It is sectional drawing orthogonal to the axial direction of the power transmission line which concerns on a comparative example.

<First Embodiment of the Present Invention>
(1) Structure of power transmission line A power transmission line according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view orthogonal to the axial direction of the power transmission line 10 according to the present embodiment.

  The power transmission line (overhead power transmission line) 10 according to the present embodiment is configured to be used for crossing between major axes such as strait crossings and river crossings. The power transmission line 10 of the present embodiment has a current capacity characteristic equal to or greater than that of a conventional long-span transmission line, and a conventional long diameter, in particular, because the aluminum strand 300 has predetermined conductivity and tensile strength. It has a tensile strength characteristic larger than the tensile strength characteristic of the intermediate transmission line. Moreover, the steel core part 200 of this embodiment has both high strength and corrosion resistance. Details will be described below.

  In the following, the “axial direction” of the transmission line 10 refers to the longitudinal direction of the transmission line 10, and the “radial direction” of the transmission line 10 refers to a direction perpendicular to the axial direction of the transmission line 10, that is, the transmission line 10. The short direction is referred to, and the “circumferential direction” of the power transmission line 10 refers to a direction along the outer periphery of the power transmission line 10.

(Steel core)
As shown in FIG. 1, a steel core portion 200 that functions as a tension member that bears the tension of the power transmission line 10 at the time of an overhead line is provided at the center of the power transmission line 10. The steel core part 200 is provided extending in the axial direction. The steel core portion 200 is configured by twisting a plurality of core wires 100, for example, a first steel core layer 210 provided at the center and configured by one core wire 100, and a first steel core. Six cores 100 are twisted so as to cover the outer periphery of the layer 210, and twelve core wires 100 are twisted so as to cover the outer periphery of the second core layer 220. And a third steel core layer 230 to be provided.

  Each core wire 100 of the steel core portion 200 has a steel wire portion 120 at the center. The steel wire portion 120 is made of steel, for example. Specifically, the steel wire part 120 contains 0.7 mass% or more and 0.9 mass% or less of carbon (C), and consists of remainder iron (Fe) and inevitable impurities. Further, the core wire 100 is provided with a covering portion 140 so as to cover the outer periphery of the steel wire portion 120. In this embodiment, the coating | coated part 140 contains manganese (Mn), and the remainder consists of Al and an unavoidable impurity. When the covering portion 140 contains Mn, an Al—Mn-based intermetallic compound is formed and bonded to intervening particles (such as Fe) of corrosive inevitable impurities. Thereby, the corrosive action by a corrosive unavoidable impurity is negated and the corrosion resistance of the steel core part 200 can be improved.

  The Mn content of the covering portion 140 is, for example, 0.3% by mass or more and 1.0% by mass or less. When the content of Mn in the covering portion 140 is less than 0.3% by mass, an Al—Mn-based intermetallic compound may not be sufficiently formed. On the other hand, when the content of Mn in the covering portion 140 is 0.3% by mass or more, an Al—Mn-based intermetallic compound is formed, and the effect of improving the corrosion resistance of the steel core portion 200 is expressed. be able to. On the other hand, when the content of Mn in the covering portion 140 is more than 1.0% by mass, it is difficult to process the core wire 100, and fine defects are likely to occur on the surface of the core wire 100 during processing. There is sex. On the other hand, when the content of Mn in the covering portion 140 is 1.0% by mass or less, the core wire 100 can be easily processed.

  Note that the ratio of the cross-sectional area of the covering portion 140 to the cross-sectional area of the core wire 100 is, for example, 13% or more.

  In the core wire 100 of this embodiment, the tensile strength based on JIS C3002 is equal to or higher than the tensile strength (1770 MPa) of the special galvanized steel wire used in the conventional long-diameter transmission line. 1770 MPa or more. The upper limit value of the tensile strength of the core wire 100 is not particularly limited, but is, for example, about 2000 MPa or less.

  In the core wire 100 of this embodiment, the elongation based on JIS C3002 is, for example, 1.5% or more. When the elongation of the core wire 100 is 1.5% or more, the power transmission line 10 can be prevented from breaking when the power transmission line 10 snows. The upper limit of the elongation of the core wire 100 is not particularly limited, but is, for example, 10% or less.

  In the core wire 100 of this embodiment, the electrical conductivity based on JIS C3002 is 11.5% IACS or more, for example. The electrical conductivity when the steel wire part is covered with electrical aluminum is 14% IACS or more. The lower limit value (11.5% IACS) of the electrical conductivity of the core wire 100 of this embodiment is lower than the lower limit value (14% IACS) of the conductivity when the steel wire part is covered with electrical aluminum. This is because the conductivity of the Al—Mn-based covering portion 140 of this embodiment is lower than the conductivity of electrical aluminum (61% IACS). In addition, although the lower limit value of the conductivity of the core wire 100 of this embodiment is lower than the lower limit value of the conductivity when the steel wire part is covered with electrical aluminum, the conductivity of the core wire 100 of this embodiment is lower. The rate is a practically sufficient value as the electrical conductivity of the core wire. Moreover, if the thickness of the covering portion 140 of the core wire 100 is adjusted, the conductivity of the core wire 100 of the present embodiment can be made equal to the conductivity when the steel wire portion is covered with electrical aluminum. It is. On the other hand, the upper limit value of the conductivity of the core wire 100 of the present embodiment is not particularly limited, but is, for example, 20% IACS or less.

  As described above, the core wire 100 having the covering portion 140 made of an Al—Mn alloy and having the above-described characteristics is referred to as “a special corrosion-resistant aluminum-clad steel wire (a special corrosion-resistant AC wire)”. .

  In the present embodiment, the coating portion 140 of the core wire 100 of the steel core portion 200 contains Mn, and the corrosion resistance of the core wire 100 is improved, so that the steel core portion 200 is filled with, for example, anti-corrosion grease. It is not applied. In other words, the core wires 100 of the steel core part 200 are in direct contact with each other without interposing grease.

(External stranded wire layer)
On the outside of the steel core portion 200, an external stranded wire portion 400 is provided by twisting a plurality of aluminum strands 300 together. The external twisted wire portion 400 is configured as a conductor portion that mainly allows current to flow during power transmission. In the present embodiment, the external stranded wire portion 400 includes, for example, a first external stranded wire layer 410 provided by twisting 18 aluminum strands 300 so as to cover the outer periphery of the steel core portion 200, and a first external stranded wire. A second external twisted wire layer 420 provided by twisting 24 aluminum strands 300 so as to cover the outer periphery of the wire layer 410. Moreover, in this embodiment, the cross section of the aluminum strand 300 is circular in both the first external stranded wire layer 410 and the second external stranded wire layer 420.

Each of the plurality of aluminum strands 300 constituting the external stranded wire portion 400 is made of, for example, an Al—Mg—Si based aluminum alloy. When Mg or Si in the aluminum strand 300 is precipitated, for example, as Mg ₂ Si, the tensile strength of the aluminum strand 300 is improved.

The Mg content of the aluminum strand 300 is, for example, 0.4 mass% or more and 0.6 mass% or less, and the Si content of the aluminum strand 300 is, for example, 0.4 mass% or more and 0.6 mass% or less. It is below mass%. When the Mg content of the aluminum strand 300 is less than 0.4 mass% and the Si content is less than 0.4 mass%, Mg ₂ Si is not sufficiently precipitated, and the tensile strength of the aluminum strand 300 There is a possibility that the effect of improving the strength may not be exhibited. In contrast, it the content of Mg in the aluminum element wire 300 is more than 0.4 mass%, the content of the Si is more than 0.4 mass%, to precipitate a predetermined amount of _Mg 2 Si, The effect of improving the tensile strength of the aluminum strand 300 can be expressed. On the other hand, if the Mg content of the aluminum wire 300 is more than 0.6 mass% and the Si content is more than 0.6 mass%, the size of the Mg ₂ Si precipitate becomes too large, Tensile strength may be reduced. On the other hand, the Mg content of the aluminum strand 300 is 0.6 mass% or less, and the Si content is 0.6 mass% or less, so that the size of the Mg ₂ Si precipitate is large. It can suppress becoming too much and can suppress that tensile strength falls.

  The aluminum strand 300 of this embodiment has the following characteristics by adjusting the processing conditions of the aging process in the manufacturing process.

  In the aluminum strand 300 of this embodiment, the tensile strength based on JIS C3002 is larger than the tensile strength (324 MPa) of the SI33 aluminum alloy used in the conventional long-diameter transmission line. Preferably, for example, 350 MPa or more. In addition, although it does not specifically limit about the upper limit of the tensile strength of the aluminum strand 300, For example, it is 365 Mpa or less.

  In the aluminum strand 300 of this embodiment, the elongation based on JIS C3002 is larger than the elongation (3%) of the SI33 aluminum alloy used in the conventional long-diameter transmission line, and preferably, for example, 4% or more It is. When the elongation of the aluminum wire 300 is more than 3%, the power transmission line 10 can be prevented from breaking when the power transmission line 10 snows. The upper limit value of the elongation of the aluminum strand 300 is not particularly limited, but is, for example, 7% or less.

  In the aluminum strand 300 of this embodiment, the electrical conductivity based on JIS C3002 is substantially equivalent to the electrical conductivity (54% IACS) of the SI33 aluminum alloy used in the conventional long span transmission line. For example, 52 % IACS or more, preferably 53% IACS or more.

  As described above, the aluminum strand 300 made of an Al—Mg—Si-based aluminum alloy and having the above-described characteristics is referred to as a “special strong No. 1 aluminum alloy wire”.

  In the present embodiment, as described above, the covering portion 140 of the core wire 100 of the steel core portion 200 contains Mn, and the corrosion resistance of the core wire 100 is improved. Edible grease is not filled (applied). In other words, the aluminum strands 300 of the external twisted wire portion 400 are in direct contact with each other without using grease.

(Transmission line characteristics)
The nominal cross-sectional area of the power transmission line 10 (total cross-sectional area of the aluminum strand 300) is, for example, not less than 400 mm ^{2 and not} more than 500 mm ² , and is, for example, 450 mm ² in this embodiment. Moreover, the outer diameter (diameter) of the power transmission line 10 is 25 mm or more and 60 mm, for example, and is 33.3 mm in this embodiment, for example.

  In the present embodiment, the power transmission line 10 having the above configuration has the following characteristics.

  In the transmission line 10 of this embodiment, the (maximum) tensile load based on JIS C3002 is equal to or greater than the tensile load (456.9 kN) of the conventional long-diameter transmission line (SI33ACSR / EST). 450 kN or more. In addition, although it does not specifically limit about the upper limit of the tensile load of the power transmission line 10, For example, it is 850 kN or less.

  In the transmission line 10 of the present embodiment, the electrical resistance per unit length based on JIS C3002 is equal to or less than the electrical resistance (0.0726 Ω / km) of the conventional long span transmission line (SI33ACSR / EST), For example, it is 0.07Ω / km or less. In the present embodiment, the core wire 100 of the steel core portion 200 is not a galvanized steel wire, and the covering portion 140 is a strong corrosion-resistant aluminum covered steel wire made of an Al alloy, and a current during power transmission also flows through the covering portion 140. Therefore, the electrical resistance in the power transmission line 10 of the present embodiment is equal to or less than the electrical resistance of the conventional long span transmission line. In addition, although it does not specifically limit about the lower limit of the electrical resistance per unit length of the power transmission line 10, For example, it is 0.02 ohm / km or more.

  In the transmission line 10 of the present embodiment, the current capacity is equal to or greater than the current capacity of the conventional long span transmission line (SI33ACSR / EST). For example, the current capacity when the power transmission line 10 is always 90 ° C. is 900 A or more, and the current capacity when the power line 10 is always 100 ° C. is 1000 A or more. In the present embodiment, as described above, the core wire 100 of the steel core portion 200 is not a galvanized steel wire, and the covering portion 140 is a strong corrosion-resistant aluminum-covered steel wire made of an Al alloy. Since the current of the hour flows, the current capacity in the transmission line 10 of the present embodiment is equal to or greater than the current capacity of the conventional long span transmission line. The upper limit value of the current capacity when the transmission line 10 is always 90 ° C. and the upper limit value of the current capacity when the power line 10 is always 100 ° C. are not particularly limited, but are, for example, 3000 A or less and 3500 A or less, respectively.

(2) Manufacturing method of power transmission line Next, the manufacturing method of the power transmission line 10 which concerns on this embodiment is demonstrated.

(Core forming process)
First, the core wire 100 is formed as follows.

  An ingot (cast material) is formed by casting a molten aluminum alloy in which Mn is added at a predetermined content to an aluminum ingot having a predetermined purity. Next, the ingot is hot-rolled to form a roughing wire (hot-rolled material) made of a predetermined aluminum alloy. Next, a composite wire is formed by coating the steel wire portion 120 made of steel with an aluminum alloy using a rough drawn wire by a hot extrusion method. The obtained composite wire is cold-drawn by a single-head wire drawing machine to form a core wire 100 (aluminum-covered steel wire) having a predetermined diameter and having a steel wire portion 120 and a covering portion 140.

(Aluminum wire forming process)
Moreover, the aluminum strand 300 is formed as follows.

  An ingot (cast material) is formed by casting a molten aluminum alloy in which Mg and Si are added at a predetermined content to an aluminum ingot having a predetermined purity. Next, the ingot is hot-rolled to form a roughing wire (hot-rolled material) made of a predetermined aluminum alloy. Next, the rough drawn wire is heated at a temperature of 400 ° C. to 600 ° C. (for example, 500 ° C.) for 1 hour to 10 hours, and then subjected to a solution treatment by water cooling. Thereby, additives such as Mg and Si are sufficiently dissolved in the Al crystal. Next, the aluminum wire 300 having a predetermined diameter is formed by cold-drawing the rough drawn wire with a single-head wire drawing machine.

Next, heat treatment (aging treatment) is performed on the drawn aluminum strand 300 at a temperature of 140 ° C. or higher and 160 ° C. or lower for 10 hours or longer and 15 hours or shorter (aging step). Conventionally, the temperature of the aging process is 160 ° C. or more and 180 ° C. or less and the time of the aging process is 1 hour or more and 10 hours or less, whereas in this embodiment, the temperature of the aging process is low and the aging process is low. The time is long. By conducting the aging process at a low temperature for a long time, the electrical conductivity of the aluminum wire 300 can be improved, and Mg ₂ Si is prevented from precipitating excessively, and the tensile strength is reduced. Can be suppressed.

Specifically, the tensile strength of the aluminum strand 300 shows a convex relationship with the temperature of the aging process, and the conductivity of the aluminum strand 300 shows a monotonous increase. When the temperature of the aging step is less than 140 ° C., Mg ₂ Si is hardly precipitated in the aluminum strand, and the tensile strength of the aluminum strand may not be sufficiently improved. Moreover, there is a possibility that the electrical conductivity of the aluminum strand is not sufficiently improved. On the other hand, by setting the temperature of the aging step to 140 ° C. or higher, the aluminum strand 300 is cured in a state where Mg ₂ Si is precipitated, and the effect of improving the tensile strength of the aluminum strand 300 is exhibited. be able to. Moreover, the electrical conductivity of the aluminum strand 300 can be improved to a predetermined value or more. On the other hand, if the temperature of the aging process exceeds 160 ° C., the conductivity of the aluminum strand is improved, but the precipitation of Mg ₂ Si proceeds in a short time, the aluminum strand is over-aged, and the aluminum strand The tensile strength may be reduced. On the other hand, by setting the temperature of the aging step to 160 ° C. or less, the aluminum strand 300 is cured by gradually depositing Mg ₂ Si while improving the electrical conductivity of the aluminum strand 300 to a predetermined value. Thereby, the tensile strength of the aluminum strand 300 can be improved stably.

Further, when the time of aging process is less than 10 hours, Mg 2 _Si precipitation is insufficient, there is a possibility that the tensile strength of the aluminum element wire is not sufficiently improved. Moreover, there is a possibility that the electrical conductivity of the aluminum strand is not sufficiently improved. On the other hand, by setting the aging process time to 10 hours or more, a predetermined amount of Mg ₂ Si can be precipitated, and the effect of improving the tensile strength of the aluminum strand 300 can be exhibited. Moreover, the electrical conductivity of the aluminum strand 300 can be improved to a predetermined value or more. On the other hand, when the time of the aging process is longer than 15 hours, although the conductivity of the aluminum strand is improved, Mg ₂ Si may be excessively aggregated and the aluminum strand may be over-aged. On the other hand, by setting the time of the aging process to 15 hours or less, the electrical conductivity of the aluminum strand 300 is improved to a predetermined value, while suppressing the excessive aggregation of Mg ₂ Si, the aluminum strand Can be prevented from being over-aged.

(Steel core forming process)
By twisting the six core wires 100 so as to cover the outer periphery of the first steel core layer 210 with the twisting wire machine while sending out one core wire 100 to be the first steel core layer 210 by the sending machine, Two steel core layers 220 are formed. Next, the third steel core layer 230 is formed by twisting the twelve core wires 100 so as to cover the outer periphery of the second steel core layer 220 with a stranded wire machine. Thereby, the steel core part 200 is formed.

(External stranded wire forming step)
Next, the 18th aluminum strand 300 is twisted so that the outer periphery of the steel core part 200 may be covered with a strand wire machine, and the 1st external strand wire layer 410 is formed. Next, the 2nd external strand wire layer 420 is formed by twisting 24 aluminum strands 300 so that the perimeter of the 1st exterior strand wire layer 410 may be covered with a strand wire machine. Thereby, the external twisted wire portion 400 is formed outside the steel core portion 200.

  As described above, the power transmission line 10 according to the present embodiment is manufactured.

(3) Effects according to the present embodiment According to the present embodiment, the following one or more effects are achieved.

(A) According to the present embodiment, in the aluminum strand 300 containing Mg and Si, and the balance being Al and inevitable impurities, the conductivity according to JIS C3002 is SI33 used in the conventional long-span transmission line. It is almost the same as the conductivity of aluminum alloy (54% IACS), for example, 52% IACS or more. Moreover, the tensile strength based on JIS C3002 in the said aluminum strand 300 is larger than the tensile strength (324 MPa) of SI33 aluminum alloy used with the conventional long diameter transmission line, Preferably, it is 350 MPa or more, for example It is. By the way, the electrical conductivity and tensile strength of the aluminum strand 300 are in a trade-off relationship, and it has been difficult to improve both the electrical conductivity and tensile strength of the aluminum strand 300 so far. However, as a result of the intensive studies by the present inventors, the aluminum strand 300 having both improved conductivity and tensile strength as described above has been realized for the first time. As described above, when the electrical conductivity of the aluminum strand 300 is 52% IACS or more, the electrical resistance (per unit length) of the transmission line 10 of the present embodiment is changed to the conventional long span transmission line (SI33ACSR / EST). ), And the current capacity of the transmission line 10 can be equal to or more than that of the conventional long span transmission line. Moreover, when the tensile strength of the aluminum strand 300 is more than 324 MPa, the (maximum) tensile load of the power transmission line 10 of the present embodiment can be equal to or greater than the tensile load of the conventional long span transmission line.

(B) According to the present embodiment, the power transmission line 10 having the above characteristics can be realized by adjusting the conditions of the process of forming the aluminum strand 300. For example, in the step of forming the aluminum strand 300, after the aluminum strand 300 is drawn, the aluminum strand 300 is subjected to an aging treatment at a temperature of 140 ° C. to 160 ° C. for 10 hours to 15 hours. (Heat treatment) is performed. Thereby, the tensile strength of the aluminum strand 300 can be improved, maintaining the electrical conductivity of the aluminum strand 300 with the technology of No. 1 aluminum alloy which can be manufactured with the existing facilities. As a result, it is possible to provide the power transmission line 10 with improved tensile strength characteristics while making the current capacity characteristics equal to or higher than those of the conventional long-span power transmission lines.

(C) According to this embodiment, the coating part 140 in the core wire 100 of the steel core part 200 contains Mn, and the remainder consists of Al and inevitable impurities. When the covering portion 140 contains Mn, an Al—Mn-based intermetallic compound is formed and bonded to intervening particles (such as Fe) of corrosive inevitable impurities. Thereby, the corrosion resistance of the steel core part 200 can be improved.

(D) According to the present embodiment, the covering portion 140 of the core wire 100 of the steel core portion 200 contains Mn, and the corrosion resistance of the core wire 100 is improved. Edible grease is not filled (applied). Thereby, it can suppress that the corrosion resistance of the power transmission line 10 falls due to the oil loss of grease.

  Here, for reference, a case will be described in which the anticorrosion grease is filled (applied) in the steel core portion and the external twisted wire portion as in a conventional long-diameter transmission line (SI33ACSR / EST). The oil component of grease forms a water-impervious film on the surface of the grease, and has an effect of inhibiting the electrolyte solution containing NaCl or the like from penetrating into the grease. However, in the conventional long-span transmission line, when the transmission line coated with grease is used for many years in the vicinity of the strait, the oil content of the grease disappears, and the electrolyte solution penetrates into the transmission line after the oil content disappears. there is a possibility. For this reason, there is a possibility that the corrosion resistance of the transmission line (particularly the corrosion resistance of the aluminum element wire contacting the steel core) cannot be maintained. On the other hand, according to the present embodiment, no grease is applied to the steel core part 200, and the corrosion resistance of the steel core part 200 is determined by the covering part 140 including Mn provided in each core wire 100. Maintained. Thereby, it can suppress that the corrosion resistance of the power transmission line 10 falls due to the oil loss of grease.

<Second Embodiment of the Present Invention>
A second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view orthogonal to the axial direction of the power transmission line according to the present embodiment.

  This embodiment is different from the first embodiment in the configuration of the first external stranded wire layer. Hereinafter, only elements different from those of the first embodiment will be described, and elements substantially the same as those described in the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

(1) Transmission line structure (external stranded wire)
As shown in FIG. 2, in the power transmission line 12 of the present embodiment, the external stranded wire portion 402 is a first wire provided by twisting 16 first aluminum strands 310 outside the steel core portion 200. It has an external stranded wire layer 412 and a second external stranded wire layer 420 provided by twisting 24 second aluminum strands 320 on the outside of the first external stranded wire layer 412.

  In the first external stranded wire layer 412, each cross section of the first aluminum strand 310 has a fan shape, for example. Each of the first aluminum strands 310 has a side surface along the radial direction. The first aluminum strands 310 are in contact with each other on the side surface (surface contact), and are provided side by side in the circumferential direction. As a result, the first aluminum strand 310 is densely filled in the first external stranded wire layer 412.

  In the second external stranded wire layer 420, the cross section of the second aluminum strand 320 is circular.

(Transmission line characteristics)
Nominal cross-sectional area of the transmission line 12 of this embodiment is, for example, 400 mm ² or more 500 mm ² or less, in the present embodiment, for example, is 460 mm ^2. In addition, the outer diameter of the power transmission line 12 of this embodiment is equal to the power transmission line 10 of 1st Embodiment, for example, is 33.3 mm.

  In the transmission line 12 of the present embodiment, the (maximum) tensile load based on JIS C3002 is equivalent to the tensile load (456.9 kN) of the conventional long span transmission line (SI33ACSR / EST), for example, 450 kN That's it. In addition, although it does not specifically limit about the upper limit of the tensile load of the power transmission line 12, For example, it is 850 kN or less.

  In the transmission line 12 of the present embodiment, the electrical resistance per unit length based on JIS C3002 is equal to or less than the electrical resistance (0.0726 Ω / km) of the conventional long span transmission line (SI33ACSR / EST). Moreover, the electrical resistance of the power transmission line 12 of this embodiment is lower than the electrical resistance of the power transmission line 10 of 1st Embodiment. The electrical resistance of the power transmission line 12 of this embodiment is, for example, 0.07Ω / km or less. In addition, although it does not specifically limit about the lower limit of the electrical resistance per unit length of the power transmission line 12, For example, it is 0.02 ohm / km or more.

  In the power transmission line 12 of the present embodiment, the current capacity is equal to or greater than the current capacity of the conventional long span transmission line (SI33ACSR / EST). Moreover, the current capacity of the power transmission line 12 of this embodiment is larger than the current capacity of the power transmission line 10 of the first embodiment. For example, the current capacity when the power transmission line 12 is always 90 ° C. is 900 A or more, and the current capacity when the power line 12 is always 100 ° C. is 1000 A or more. The upper limit value of the current capacity when the transmission line 12 is always 90 ° C. and the upper limit value of the current capacity when the power line 12 is always 100 ° C. are not particularly limited, but are, for example, 3000 A or less and 3500 A or less, respectively.

(2) Effects according to the present embodiment According to the present embodiment, each of the first aluminum strands 310 has a side surface along the radial direction. The first aluminum strands 310 are in contact with each other on the side surfaces (surface contact). In the first external stranded wire layer 412, the first aluminum strand 310 is densely filled. Thereby, the ratio for which the cross-sectional area of the 1st aluminum strand 310 in the cross-sectional area of the 1st external twisted wire layer 412 can be increased. Therefore, the tensile load of the power transmission line 12 of this embodiment can be made larger than the tensile load of the power transmission line 10 of the first embodiment configured by the aluminum strand 300 having a circular cross section. Moreover, the electric capacity of the power transmission line 12 of this embodiment can be made larger than the electric capacity of the power transmission line 10 of the first embodiment configured by the aluminum strand 300 having a circular cross section.

<Other Embodiments of the Present Invention>
As mentioned above, although embodiment and modification of this invention were described concretely, this invention is not limited to the above-mentioned embodiment and modification, and can be variously changed in the range which does not deviate from the summary.

  In the above-described embodiment, the case where the steel core portion has, for example, three steel core layers has been described. However, the steel core portion has one or two steel core layers, or four or more steel core layers. It may be.

  Moreover, although the above-mentioned embodiment demonstrated the case where an external twisted wire part has a 2 layer external twisted wire layer, the external twisted wire part may have an external twisted wire layer of 3 layers or more, for example. .

(1) Manufacture and performance evaluation of aluminum strand and core (core of Example 1)
As shown in Table 1 below, a core wire (strength corrosion-resistant aluminum covered steel wire) used for the steel core portion of the transmission line sample of Example 1 was manufactured. Specifically, an ingot (cast material) was formed by casting a molten aluminum alloy to which 0.3% by mass or more and 1.0% by mass or less of Mn was added. Next, the ingot was hot rolled to form a roughing wire made of a predetermined aluminum alloy. Next, a composite wire was formed by coating a steel wire portion made of steel with an aluminum alloy using a rough drawn wire by a hot extrusion method. The obtained composite wire was cold-drawn with a single-head wire drawing machine to obtain a core wire having a diameter of 3.7 mm.

  Among the manufactured core wires, the wire diameter, tensile load, tensile strength, elongation, electrical resistance, mass, and conductivity were measured for 10 core wires in accordance with JIS C3002. Further, the appearance of the core wire was evaluated. Moreover, the thickness of the coating part was measured with the magnifier.

  Moreover, one end of the core wire was fixed, the other end was twisted, and the number of twists when the core wire was broken was determined. Thereby, the toughness of the core wire was confirmed. Further, the core wire was wound eight times on a cylinder having a diameter five times the diameter of the core wire, and it was confirmed whether the covering portion of the core wire was not peeled off. Moreover, it wound around the cylinder which has the same diameter as the diameter of a core wire 8 times, and then rewound. Thereby, the toughness of the core wire was confirmed.

  As a result, it was confirmed that the core wire of Example 1 had a tensile strength of 1770 MPa or more, an elongation of 1.5% or more, and a conductivity of 11.5% or more. That is, it was confirmed that the tensile strength of the core wire of Example 1 was equivalent to the tensile strength (1770 MPa) of the special galvanized steel wire used in the conventional long span transmission line. Moreover, it confirmed that the external appearance of the core wire of Example 1 was favorable. It was also confirmed that the core wire of Example 1 had good toughness. Moreover, it was confirmed that there was no peeling of the covering portion in the core wire of Example 1.

(Aluminum wire of Example 1)
As shown in Table 2 below, an aluminum strand (special high strength aluminum alloy wire) used for the external stranded portion of the transmission line sample of Example 1 was manufactured. Specifically, aluminum in which 0.4 mass% to 0.6 mass% Mg and 0.4 mass% to 0.6 mass% Si are added to an aluminum ingot having a predetermined purity. The molten alloy was cast to form an ingot. Next, the ingot was hot rolled to form a roughing wire made of a predetermined aluminum alloy. Next, after heating at a temperature of 500 ° C. for 1 hour or more and 10 hours or less with respect to the rough drawing line, a solution treatment by water cooling was performed. Next, the rough drawn wire was cold-drawn by a single-head wire drawing machine to form an aluminum strand having a diameter of 3.7 mm. Thereafter, the drawn aluminum strand was subjected to an aging treatment at a temperature of 150 ° C. or lower for 10 hours to 15 hours.

  Among the manufactured aluminum strands, the wire diameter, tensile load, tensile strength, elongation, electrical resistance, mass, and conductivity were measured for 10 aluminum strands in accordance with JIS C3002. Moreover, the external appearance of the aluminum strand was evaluated.

  As a result, in the aluminum strand of Example 1, the measured value of tensile strength was 350 MPa or more, the measured value of elongation was 4.0% or more, and the measured value of conductivity was 53% or more. confirmed. That is, in the aluminum strand of Example 1, the tensile strength is larger than the tensile strength (324 MPa) of the SI33 aluminum alloy used in the conventional long-span transmission line, and the elongation is the elongation of the conventional SI33 aluminum alloy ( 3%), and the conductivity was confirmed to be almost equivalent to the conductivity of the conventional SI33 aluminum alloy (54% IACS). Moreover, it confirmed that the external appearance of the aluminum strand of Example 1 was favorable.

(Core of Example 2)
As shown in Table 3 below, a core wire (corrosion-resistant aluminum-covered steel wire) used for the steel core portion of the transmission line sample of Example 2 was manufactured. The core wire of Example 2 differs from the core wire of Example 1 in that the wire diameter is 3.9 mm.

  Among the manufactured core wires, the wire diameter, tensile load, tensile strength, elongation, electrical resistance, mass, and conductivity were measured for 10 core wires in accordance with JIS C3002. Further, the appearance of the core wire was evaluated. Moreover, the thickness of the coating part was measured with the magnifier. Further, the toughness of the core wire was confirmed by the same method as in Example 1.

  As a result, it was confirmed that the core wire of Example 2 had a tensile strength of 1570 MPa or more, an elongation of 1.5% or more, and a conductivity of 11.5% or more. That is, it was confirmed that the tensile strength of the core wire of Example 1 was almost equal to the tensile strength (1770 MPa) of the special galvanized steel wire used in the conventional long span transmission line. Moreover, it confirmed that the external appearance of the core wire of Example 2 was favorable. Moreover, it was confirmed that the toughness of the core wire of Example 2 was also good. Moreover, it was confirmed that there was no peeling of the covering portion in the core wire of Example 2.

(Aluminum wire of Example 2)
As shown in Table 4 below, a (second) aluminum strand (special strength Y aluminum alloy wire) used for the external twisted wire portion of the transmission line sample of Example 2 was manufactured. The aluminum strand of Example 2 differs from the aluminum strand of Example 1 in that the wire diameter is 4.0 mm.

  Among the manufactured aluminum strands, the wire diameter, tensile load, tensile strength, elongation, electrical resistance, mass, and conductivity were measured for 10 aluminum strands in accordance with JIS C3002. Moreover, the external appearance of the aluminum strand was evaluated.

  As a result, in the aluminum strand of Example 2, the measured value of tensile strength was 350 MPa or more, the measured value of elongation was 4.0% or more, and the measured value of conductivity was 53% or more. confirmed. That is, in the aluminum strand of Example 2, the tensile strength is larger than the tensile strength (324 MPa) of the SI33 aluminum alloy used in the conventional long span transmission line, and the elongation is the elongation of the conventional SI33 aluminum alloy ( 3%), and the conductivity was confirmed to be almost equivalent to the conductivity of the conventional SI33 aluminum alloy (54% IACS). Moreover, it confirmed that the external appearance of the aluminum strand of Example 2 was favorable.

(2) Production of Transmission Line Sample and Performance Evaluation As shown in Table 5 below, the transmission line sample of Example 1 corresponding to the first embodiment was produced. Specifically, the steel core portion was formed by twisting 19 core wires of Example 1 described above. Next, 42 external strands of Example 1 were twisted together so as to cover the outer periphery of the steel core, thereby forming an external stranded portion. In addition, grease was not apply | coated to the steel core part and the external twisted wire part. In this way, the transmission line sample of Example 1 was manufactured.

  Moreover, as shown in Table 5 below, a transmission line sample of Example 2 corresponding to the second embodiment was manufactured. Specifically, the steel core portion was formed by twisting 19 core wires of Example 2 described above. Next, 16 first aluminum strands having a fan-shaped cross section are twisted so as to cover the outer periphery of the steel core, thereby forming a first external stranded wire layer and covering the outer periphery of the first external stranded wire layer. A second external stranded wire layer was formed by twisting 24 second aluminum strands of Example 2 together. In addition, grease was not apply | coated to the steel core part and the external twisted wire part. In this way, the transmission line sample of Example 2 was manufactured.

Moreover, in Table 5 and FIG. 3, the transmission line sample (SI33ACSR / EST) of a comparative example is shown as a conventional long span transmission line sample.
In addition, FIG. 3 is sectional drawing orthogonal to the axial direction of the power transmission line which concerns on a comparative example.
As shown in FIG. 3, the transmission line sample of the comparative example is manufactured as follows, for example. A steel core portion 920 is formed by twisting 19 core wires 910 made of a special strong galvanized steel wire. Next, 42 external strands 940 are formed by twisting 42 aluminum strands 930 made of an SI33 aluminum alloy. Grease is applied to the steel core and the external stranded wire. Table 5 below exemplifies a comparative transmission line sample manufactured in this way.

Mass, elastic modulus, coefficient of linear expansion, electric resistance, electric capacity, and tensile load were measured for the manufactured transmission line sample of Example 1, the transmission line sample of Example 2, and the transmission line sample of Comparative Example.
The mass was measured with an electronic balance.
The elastic modulus was measured by the following method. After each transmission line sample is attached to the tensile tester, a load is applied to 60% of the tensile load standard value, and then the load is unloaded to 0 kN. Measure the elongation of the transmission line sample when the load increases or decreases with a dial gauge. Thereby, an elastic modulus is calculated | required. The length of the transmission line sample when measuring the elongation of the transmission line sample is about 2 m.
The linear expansion coefficient was measured by the following method. With the load of 20% of the standard value applied to the transmission line sample, the temperature of the transmission line sample is raised by energization. The elongation of the transmission line sample when the temperature of the transmission line sample rises is measured with a dial gauge. Thereby, a linear expansion coefficient is calculated | required. The length of the transmission line sample when measuring the elongation of the transmission line sample is about 2 m.
Moreover, the electrical resistance was measured by a 4-terminal double bridge method.
Further, the current capacity was calculated by an equation in CIGRE (Conference International des Grands Research Electrics a Haute). The equation for determining the current capacity in CIGRE is the IEEJ Technical Report No. 660 “Current capacity of overhead transmission line”.
Moreover, the tensile load was measured based on JIS C3002. Specifically, both ends of the transmission line sample are gripped by a tensile tester, and a load is applied to the transmission line sample by moving one gripping head hydraulically. Then, pull until the transmission line sample breaks. The load when the transmission line sample breaks is determined as the tensile load.

  As a result, in each of the transmission line sample of Example 1 and the transmission line sample of Example 2, the electrical resistance was 0.07 Ω / km or less, and the electrical resistance of the comparative transmission line sample (0.0726 Ω / km). km) or less.

  Moreover, in each of the transmission line sample of Example 1 and the transmission line sample of Example 2, the current capacity at 90 ° C. is always 900 A or more, and the current capacity at 100 ° C. is always 1000 A or more. It was confirmed that That is, it was confirmed that the electric capacity in each of the power transmission line sample of Example 1 and the power transmission line sample of Example 2 was equal to or greater than the current capacity of the power transmission line sample of the comparative example.

  Moreover, in each of the transmission line sample of Example 1 and the transmission line sample of Example 2, it was confirmed that the tensile load was 450 kN or more, which was equivalent to the tensile load of the transmission line sample of the comparative example. . In addition, although the tensile strength of the core wire in the transmission line sample of Example 2 is smaller than the tensile strength of the core wire in the transmission line sample of the comparative example, the tensile strength of the aluminum strand in the transmission line sample of Example 2 is By being larger than the tensile strength of the aluminum strand in the power transmission line sample of the comparative example, the tensile load of the power transmission line sample of Example 2 can be made equal to the tensile load of the power transmission line sample of the comparative example. It was confirmed.

(3) Slackness As shown in Table 6 below, the span length is set for the transmission line sample of Example 1, the transmission line sample of Example 2, and the transmission line sample of Comparative Example. The sag of the transmission line sample was calculated at a continuous allowable temperature of 90 ° C. and a short-time allowable temperature of 100 ° C., assuming that the maximum working tension was 132.4 kN.

  As a result, the sag of the power transmission line sample of Example 1 at 100 ° C. was 1.7 m smaller than the sag of the power transmission line sample of the comparative example. Further, the sag of the power transmission line sample of Example 2 at 100 ° C. was 0.4 m smaller than the sag of the power transmission line sample of the comparative example. Therefore, it was confirmed that the power transmission line sample of Example 1 and the power transmission line sample of Example 2 can reduce the sag compared to the power transmission line sample of the comparative example.

(4) Corrosion acceleration test As shown in Table 7 below, a corrosion acceleration test was performed on the above-described transmission line sample of Example 1 and the transmission line sample of Example 2. In the accelerated corrosion test, the transmission solution sample was heated by spraying the corrosion solution onto the surface of the transmission line sample and passing a current through the transmission line sample. Assuming sea salt and acid rain as the corrosive solution, a solution of NaCl and H ₂ SO _{4 was used} , and the pH of the corrosive solution was set to 5. The temperature of the transmission line sample was maintained at 90 ° C. The period of the accelerated corrosion test was 4.5 months.

  Here, the Institute of Electrical Engineers of Japan Technical Report No. 968 “Electric Corrosion Phenomenon of Overhead Transmission Lines” p. Table 8 shows the aluminum corrosion rate under the general environment described in No.13. As shown in Table 8, the corrosion rate of aluminum in the marine atmosphere is 48 μm / year. Therefore, the pitting corrosion depth in 10 years in the marine atmosphere is 480 μm.

  On the other hand, the period (4.5 months) of the accelerated corrosion test in Table 7 corresponds to 10 years or more in the marine atmosphere. According to Table 7, the pitting corrosion depth of each part in each of the transmission line sample of Example 1 and the transmission line sample of Example 2 is less than or equal to the pitting corrosion depth (480 μm) of 10 years in the marine atmosphere. confirmed. Therefore, it was confirmed that the power transmission line sample of Example 1 and the power transmission line sample of Example 2 have good corrosion resistance.

  As in Example 1 and Example 2 above, a transmission line with improved tensile strength characteristics and corrosion resistance is provided while maintaining a current capacity characteristic equal to or greater than that of a conventional long span transmission line (comparative example) Confirmed that you can.

10, 12 Transmission line 100 Core wire 120 Steel wire portion 140 Cover portion 200 Steel core portion 210 First steel core layer 220 Second steel core layer 230 Third steel core layer 300 Aluminum strand 310 First aluminum strand 320 Second Aluminum strands 400, 402 External stranded wire portions 410, 412 First external stranded wire layer 420 Second external stranded wire layer

Claims (10)

A steel core having a plurality of core wires ;
An external stranded portion provided by twisting a plurality of aluminum strands outside the steel core; and
The power transmission line to have a,
Each of the plurality of cores is
A steel wire part,
It is provided so as to cover the outer periphery of the steel wire part, contains 0.3% by mass or more and 1.0% by mass or less of manganese, the remainder is made of aluminum and inevitable impurities, and has a thickness of 0.08 mm or more. A covering part;
Have
The tensile strength of the core wire is 1570 MPa or more,
Each of the plurality of aluminum strands contains magnesium and silicon, the balance is made of aluminum and inevitable impurities,
The electrical conductivity of the aluminum strand is 52% IACS or higher,
The tensile strength of the aluminum strands, Ri 324MPa ultra-der,
The electric resistance of the power transmission line is 0.07 Ω / km or less,
The transmission line has a tensile load of 450 kN or more . The current capacity when the transmission line is always 90 ° C. is 900 A or more,
The current capacity of the power transmission line at 100 ° C. is always 1000 A or more.
The power transmission line according to claim 1. The average tensile strength of the plurality of core wires is 1634 MPa or more.
The power transmission line according to claim 1 or 2. The tensile strength of the core wire is 1770 MPa or more.
The power transmission line according to any one of claims 1 to 3. The steel wire portion contains 0.7 mass% or more and 0.9 mass% or less of carbon, and is composed of the remaining iron and inevitable impurities.
The power transmission line according to any one of claims 1 to 4. The transmission line according to any one of claims 1 to 5, wherein an elongation of the aluminum element wire is more than 3.0%. The power transmission line according to any one of claims 1 to 6, wherein the plurality of core wires are in direct contact with each other without using grease. The external twisted wire part is
A first external stranded wire layer formed by twisting a plurality of first aluminum strands outside the steel core;
A second external stranded wire layer provided by twisting a plurality of second aluminum strands outside the first external stranded wire layer;
Have
Each of the plurality of first aluminum strands of the first external stranded wire layer has a side surface along a radial direction,
The power transmission line according to any one of claims 1 to 7 , wherein the plurality of first aluminum strands are in contact with each other on the side surface in a circumferential direction. Forming a plurality of core wires;
Forming a plurality of aluminum strands;
Forming a steel core portion having the plurality of core wires;
Twisting the plurality of aluminum strands on the outside of the steel core, and forming an external stranded portion;
A method of manufacturing a transmission line having
The step of forming the plurality of core wires includes:
A covering portion containing 0.3% by mass or more and 1.0% by mass or less of manganese so as to cover the outer periphery of the steel wire portion, the balance being made of aluminum and inevitable impurities and having a thickness of 0.08 mm or more Having a process of forming,
In the step of forming the plurality of core wires,
The tensile strength of the core wire is 1570 MPa or more,
In the step of forming the plurality of aluminum strands,
Containing magnesium and silicon, forming the aluminum strand consisting of aluminum and inevitable impurities,
The electrical conductivity of the aluminum strand is 52% IACS or higher,
The tensile strength of the aluminum strand is over 324 MPa,
When the transmission line is manufactured,
The electric resistance of the power transmission line is 0.07Ω / km or less,
The tensile load of the power transmission line is 450 kN or more.
A method of manufacturing a transmission line. Forming a pre-Symbol aluminum strands,
After drawing the aluminum strand, the aluminum strand is heat-treated at a temperature of 140 ° C. to 160 ° C. for 10 hours to 15 hours.
The manufacturing method of the power transmission line of Claim 9 .

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