JP2000090744A - Steel core aluminum strand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel core aluminum strand with an increased capacity and low looseness and at low cost. SOLUTION: Soft aluminum strands 23a, 23b having a conductivity of not less than 63% are used instead of conventional steel core aluminum strands such as XTA1, UTA1 and ZTA1 to thereby make shared stress of aluminum almost 0(zero) by applying a per-stretching with the use of a come-along or the like after drawing, and a line expansion coefficient depends on an expansion of the steel core. A steel core aluminum strand 20 is therefore obtained which has an increased capacity and low looseness and is at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a steel core aluminum stranded wire.

[0002]

2. Description of the Related Art The following are examples of a steel core aluminum stranded wire as an increased capacity wire and a low sag wire.

(1) Loose electric wire Loose electric wire has both capacity increase and suppression of sag as a measure for strengthening existing transmission lines. To increase capacity, super heat-resistant aluminum alloy wire is used for the aluminum wire, and to reduce sag, the target performance is achieved by reducing the stress (looseness) of the aluminum wire.

FIG. 4 is an explanatory diagram for explaining loosening of an electric wire.

[0005] The loosening method is as follows. An electric wire 3 between the drum gantry 1 and the drum gantry 2 is placed between the steel towers 4, 5, 6 and 7.
The wire is pulled by the winch 10 via the cams 8 and 9 and is set to a predetermined tensile strength while checking the tension applied to the electric wire 3 by the tension meter 11. In this method, a traveling roll machine 12 having a relatively small diameter roll is pressed against the electric wire 3 in a vertical direction or a horizontal direction of the electric wire 3. According to this method, the aluminum strand of the electric wire 3 is deformed and plastic elongation occurs, a subtle difference in length is generated as compared with the steel wire, the shared tension of the aluminum strand is reduced, and the coefficient of linear expansion of the electric wire 3 is reduced. The coefficient of linear expansion of the steel wire alone is substituted, making it difficult to elongate with a rise in temperature, and suppressing an increase in sag.

(2) Invar electric wires To increase the capacity, aluminum heat-resistant aluminum wires (UT)
Al) or a special heat-resistant aluminum wire (XTAl) is used.
The conductivity is about 57-60%. In addition, instead of steel wire, a low expansion coefficient (2.5 to 4.5 × 10 ^-6 ) is used to reduce the sag.
/ ° C) using an Fe-Ni-based or Fe-Ni-Co-based invar wire.

(3) Soft Aluminum Wire As a measure for increasing the capacity, a conventional aluminum wire (ECAl, conductivity 61%) is subjected to a suitable heat treatment and soft aluminum (AAl, conductivity 63% or more) is used. As a countermeasure for reducing the sag, an appropriate pre-stress is applied after the overhead wire to make the stress of Al substantially zero, and all the stress is shared by the steel wire. By this action, the linear expansion coefficient of the electric wire is replaced by the linear expansion coefficient of only the steel wire.

(4) SiC / Al composite electric wire An SiC / Al element wire which is a composite of SiC and Al having high heat resistance, low linear expansion and high strength is used.

[0009]

However, the above-described prior art has the following problems.

(1) Loose electric wire Loose electric wire is used after aluminum wire to give elongation to aluminum strand.
It is necessary to run the traveling rail machine 12 (FIG. 4). Such a loose processing is troublesome and the processing cost accounts for about 40% of the total cost.

(2) Invar wire Invar wire instead of steel wire, UTAl, X instead of ECAl
The use of TAl, ZTAI, etc. makes the price 4 to 5 times higher than ACSR (steel core aluminum stranded wire). In the power industry where cost reduction is required, few machines are used.

(3) Soft aluminum wire In Japan, the use of soft aluminum was not permitted according to the provisions of Electric Technology (technical standards for electrical equipment). However, this electric wire is an excellent electric wire in which the conductivity is dramatically improved only by heat-treating ECAl, and the sag is reduced only by the prestressing operation after the overhead wire. One of the drawbacks of soft aluminum wire is that soft aluminum (tensile strength, 6 kgf / mm ² ) is used, so the tensile strength as a stranded wire is lower than that of conventional wires. Has to lower the maximum tension Tmax.

[0013] The soft aluminum wire is stretched by the press operation, and the aluminum and iron are elastically integrated with each other to lower the temperature range. For this reason, the linear expansion coefficient and the elastic coefficient can be made to depend on iron from a low temperature. Low sag can be achieved.

(4) The price of SiC / Al electric wire is about 180 times that of ACSR, and a significant cost reduction is required for practical use.

An object of the present invention is to solve the above-mentioned problems and to provide a steel core aluminum stranded wire having increased capacity, low sag, and low cost.

[0016]

Means for Solving the Problems To achieve the above object, the present invention provides a steel core having a plurality of twisted invar wires,
An aluminum stranded wire comprising a plurality of soft aluminum wires stranded on the outer periphery of the steel core portion, wherein a soft aluminum wire having a conductivity of 63% or more is used in the aluminum portion. is there.

In addition to the above configuration, the steel core aluminum stranded wire of the present invention may be configured such that the shape of the soft aluminum wire is a fan-shaped cross-section and a substantially annular aluminum portion is formed to improve the wheel-passing characteristics.

In addition to the above configuration, the steel core aluminum stranded wire according to the present invention has a fan-shaped cross-sectional shape of the soft aluminum wire located in the outer layer among the soft aluminum wires, and some of the opposing soft wires are thick in the radial direction. The low noise characteristics may be improved by forming the protrusions.

According to the present invention, instead of the conventional steel core aluminum stranded wire of XTAl, UTAl and ZTAl, the conductivity is 63%.
By using a soft aluminum wire having the above, if pre-stretching is performed using a cam-along or the like after drawing, the shared stress of aluminum becomes substantially “0”, and the coefficient of linear expansion depends on the elongation of the steel core. As a result, a high capacity, low sag, low cost steel core aluminum stranded wire can be obtained.

[0020]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an embodiment of a steel core aluminum stranded wire according to the present invention.

The steel core aluminum stranded wire 20 may be a single galvanized invar wire having a circular cross section (aluminum-covered Fe-Ni-based invar wire, aluminum-covered Fe-Ni-Co-based invar wire, etc.). A steel core portion 22 in which six similar galvanized invar wires 21b are twisted around the outer periphery of 21a, and ten soft aluminum (AAl) strands 23a having a circular cross-sectional shape are twisted around the outer periphery of the steel core portion 22, Further, an aluminum portion 24 is formed by twisting 16 similar soft aluminum wires 23b around the outer periphery of the soft aluminum wires 23a.

The aluminum portion 24 is made of soft aluminum having a conductivity of 63% or more, which has been subjected to an appropriate heat treatment.

The steel core aluminum stranded wire 20 is pre-stretched by using a cam-along or the like after the wire is drawn, so that the stress shared by the aluminum is substantially "0". By performing this work, the coefficient of linear expansion depends on the elongation of the steel core (invar wire). The continuous allowable temperature and the short-time allowable temperature of the soft aluminum invar electric wire (SB type 400 mm ² ) are set to 210 ° C and 230 ° C, similar to ZTACIR.
Table 1 shows the comparison between the current value and the sag when set to ° C.
Shown in

[0025]

[Table 1]

As shown in Table 1, the soft aluminum invar wire is ZTA
2.4% in current capacity compared with CIR400mm ^{2 (2}
It can be seen that this is an epoch-making capacity-increasing and low-sagging electric wire which is improved by 10 ° C) and reduced by 11% (210 ° C) in sag. For comparison, a design example of a round type (410 mm ² ) soft aluminum invar electric wire is also shown.

FIG. 2 is a sectional view showing another embodiment of the steel core aluminum stranded wire of the present invention.

The difference from the embodiment shown in FIG. 1 is that the soft aluminum element wire is changed from a circular sectional shape to a segment type having a fan sectional shape.

The steel core aluminum wire 30 shown in FIG. 2 has a steel core portion 32 in which six similar invar wires 31b are twisted around the outer circumference of one circular invar wire 31a, and a steel core portion 32.
Twenty segment-type soft aluminum wires 33a having a conductivity of 63% or more are twisted around the outer periphery of the soft aluminum wire 33a, and 16 soft aluminum wires 33b are wound around the outer periphery of the soft aluminum wire 33a.
It is composed of a main twisted aluminum portion 34.

In the steel core aluminum stranded wire 30, the cross-sectional shape of the soft aluminum wires 33a and 33b is SB (Smooth Bo).
dy), the surface becomes smooth, and the nicking characteristics due to the passing of the wheel while the wire is being drawn are greatly improved.

Here, nicking means that when a stranded wire having an inner layer and an outer layer is produced by twisting a plurality of strands, contact between the inner layer strand and the outer layer strand is only at a point of intersection. It comes into contact. This means that the wire is deformed at the contact portion. That is, the nicking characteristic indicates the degree of deformation.

FIG. 3 is a sectional view showing another embodiment of the steel core aluminum stranded wire of the present invention.

The difference from the embodiment shown in FIG. 2 is that, among the soft aluminum wires, the shape of the soft aluminum wire located in the outer layer has a fan-shaped cross section, and some of the facing soft aluminum wires are thicker in the radial direction. This is the point that the projection is formed.

The steel core aluminum wire 40 shown in FIG. 3 has a steel core portion 42 in which six similar invar wires 41b are twisted around the outer periphery of one invar wire 41a having a circular cross-sectional shape, and a steel core portion 42. An inner aluminum portion 44 in which nine soft aluminum wires 43a having a circular cross section having a conductivity of 63% or more are twisted around the outer periphery, and 15 similar soft aluminum wires 43b are twisted around the outer periphery thereof. Conductivity 63 on the outer periphery of aluminum part 44
% Of soft aluminum wires 45 having a fan cross section having a
a and a soft aluminum wire 4 having a conductivity of 63% or more
The outer aluminum portion 46 is formed by twisting eight soft aluminum wires 45b having a fan-shaped cross section that is thicker in the radial direction than 5a.

In particular, the steel core aluminum stranded wire 40 is characterized in that four of the eight soft aluminum wires 45b are twisted so as to face each other to form a projection. By having such protrusions, a low noise, low sag, and increased capacity type LN (Low Noise) -soft aluminum invar electric wire can be obtained.

As described above, according to the present invention, (1) a conventional invar electric wire (ex. ZTACIR 400 mm
² ) By using soft aluminum (conductivity of 63% or more) for the aluminum part, the current capacity is improved by 2.4% and the sag is reduced by 1%.
Reduce by 1%.

(2) By changing the electric wire structure from the round type to the SB type, the wheel-passing characteristics are dramatically improved.

(3) By forming protrusions on the soft aluminum portion of the outermost layer, a low-noise, low-sag, high-capacity steel core aluminum stranded wire can be obtained.

Although the number of strands is shown in each of the above embodiments, the number is not limited.

[0040]

In summary, according to the present invention, the following excellent effects are exhibited.

It is possible to provide a high-capacity, low-sag, low-cost steel core aluminum stranded wire.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a steel core aluminum stranded wire of the present invention.

FIG. 2 is a sectional view showing another embodiment of the steel core aluminum stranded wire of the present invention.

FIG. 3 is a sectional view showing another embodiment of the steel core aluminum stranded wire of the present invention.

FIG. 4 is an explanatory diagram for explaining loosening of an electric wire.

[Explanation of symbols]

 Reference Signs List 20 steel core aluminum wire 21 galvanized invar wire (invar wire) 22 steel core 23a soft aluminum wire 24 aluminum

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Hiroshi Kubokawa 5-1-1, Hidaka-cho, Hitachi-shi, Ibaraki Hitachi Power Systems Co., Ltd. (72) Toshinobu Tsuji 4-chome Kawajiri-cho, Hitachi-shi, Ibaraki No. 10 No. 1 F-term in Toyoura Plant of Hitachi Cable, Ltd. (reference) 5G307 EA03 EA06 ED01 EE01 EF05 EF07 EF10

Claims (3)

[Claims] 1. A steel core aluminum stranded wire comprising: a steel core portion in which a plurality of invar wires are twisted; and an aluminum portion in which a plurality of soft aluminum wires are twisted around the steel core portion. Characterized by using a soft aluminum wire having a conductivity of 63% or more in the portion. 2. The steel core aluminum stranded wire according to claim 1, wherein the shape of the soft aluminum wire is a fan-shaped cross-section, and a substantially wheel-shaped aluminum portion is formed to improve the wheel passing characteristics. 3. The soft aluminum wire of the soft aluminum wire located in the outer layer has a fan-shaped cross-section, and some of the opposed soft aluminum wires are thickened in the radial direction to form projections, thereby reducing noise. 2. The steel core aluminum stranded wire according to claim 1, which has improved characteristics.