JP2001119822A - Overhead transmission line and method for re-stringing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which transmission lines can be re-stringed inexpensively in a short time without numerous dangerous works on a steel towers. SOLUTION: In a method for re-stringing overhead transmission line, the uppermost upper-phase transmission line of three-phase transmission lines stringed between steel towers is re-stringed by utilizing an existing line 1 and the lowermost lower-phase transmission line is re-stringed by using a sag suppressing aluminum conductor steel reinforced 3 which can exhibit such a large sag suppressing effect that can secure a sufficient separating vertical distance from a ground structure 8. The intermediate middle-phase transmission line is re-stringed by using a sag suppressing aluminum conductor steel reinforced 2 which exhibits a smaller sag suppressing effect than the aluminum conductor steel reinforced 3 does, but can secure necessary separating distances 5 and 6 from the upper- and lower-phase transmission lines. Since the quantity of the transmission line re-stringing work is reduced, the period and cost of the work can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for replacing a transmission line in order to increase the current carrying capacity in an existing overhead transmission line, and an overhead transmission line constructed by the method.

[0002]

2. Description of the Related Art In recent years, the current carrying capacity of existing overhead transmission lines has been actively increased. At that time, there is a strong demand for economical implementation by using existing equipment to extend the life. Increasing the current carrying capacity increases the wire temperature. Therefore, as shown in FIG. 4, the sag 7 of the existing wire 1 such as a steel core aluminum stranded wire becomes large, and depending on the track, there may be places where the ground clearance 4 from the ground structure 8 cannot be secured. Therefore, as shown in FIG. 5, a method is used in which the entire circuit is replaced by using a sag-restraining type steel-core aluminum stranded wire 3 to secure a high clearance 4 above the ground and clearances 5 and 6 with electric wires of each phase. Is being done. As shown in FIG. 7, the sagging suppression type steel core aluminum stranded wire is plastically deformed by previously stretching the aluminum layer 15 of the steel core aluminum stranded wire, and the steel core 16 and the aluminum layer 1 are deformed.
5 has a structure having a gap 17. When the temperature rise due to energization occurs in the steel core aluminum stranded wire, the coefficient of linear expansion becomes the combined value of steel and aluminum, and as a result, the value approximates the coefficient of linear expansion of aluminum, so the sag increases. . However, in the sag restraint type steel core aluminum stranded wire, the aluminum layer does not share the overhead wire tension when the temperature rises by plastically deforming the aluminum layer in advance, and only the steel core shares the overhead wire tension. Since steel has a coefficient of linear expansion about half that of aluminum, it can suppress elongation when the temperature rises and, consequently, sag of electric wires (see Japanese Patent Publication No. 56-19936). According to the conventional method, after removing all the existing wires such as steel core aluminum stranded wire, work to replace the wire with a sag-reduction type steel core aluminum stranded wire is performed, and even if the current carrying capacity increases The separation distance from the phase electric wire was secured.

[0003]

In the conventional method, since the entire line is replaced, the construction takes time, the work on dangerous steel towers increases, and the construction cost also increases. In addition, if the construction takes time and the power supply stop state is prolonged, a problem arises in terms of stable power supply. SUMMARY OF THE INVENTION An object of the present invention is to provide an electric wire replacement method and equipment capable of reducing the wire replacement work, shortening the construction period, reducing the cost, and the like when increasing the current carrying capacity of the existing overhead transmission line.

[0004]

According to the present invention, an existing wire such as a steel core aluminum stranded wire is partially used as it is, and a part thereof is replaced by using a sag suppressing type steel core aluminum stranded wire. It is a solution to the problem in the prior art.
Normally, three-phase electric wires are stretched on the overhead power transmission line. Here, for convenience, the highest electric wire in the overhead state is the upper electric wire, the middle electric wire is the middle electric wire, and the lowest electric wire is the lowest electric wire. Will be referred to as the lower-phase wires. According to the present invention, the upper phase electric wire, and in some cases, the upper phase and the middle phase electric wire use the existing wire such as a steel core aluminum stranded wire as it is, and only the other phase electric wires are made of the sag suppressing type steel core aluminum stranded wire. Replace it with
As the sag suppressing type steel core aluminum stranded wire, one having a different sagging suppressing effect is used in combination, or a sag suppressing type steel core aluminum stranded wire having a desired sag suppressing effect is used depending on a location condition. The sag suppression effect can be arbitrarily changed by selecting a sag suppression type steel core aluminum stranded wire having different transition points.

Here, the transition point will be described. FIG. 6 shows a comparison of the characteristics of the sag change of the electric wire depending on the temperature between an ACSR (steel core aluminum stranded wire) and a plurality of sag suppressing type steel core aluminum stranded wires having different transition points.
The sag indicates a value at a distance between the towers of 300 m. Transition point 1
The 5 ° C sag-reducing steel core aluminum stranded wire changes in sag with the same characteristics as the ACSR up to a temperature of 15 ° C, and when the temperature exceeds 15 ° C, the sag-suppressing effect appears and the sag change is reduced. Similarly, each of the sag-restraining-type steel core aluminum stranded wires at the transition points of 30 ° C. and 45 ° C. exhibits a sag suppressing effect at temperatures of 30 ° C. and 45 ° C. or higher, respectively. That is, the transition point used in the present invention refers to the temperature of the electric wire at which the tension sharing shifts to the steel core and the sag control begins. The transition point can be arbitrarily changed according to the degree of plastic deformation of the aluminum layer. However, if the transition point is high, the effect of suppressing the sag becomes small, and if the transition point is lower than 15 ° C., the mechanical strength of the electric wire is adversely affected. At room temperature, the difference in the sag between the steel core aluminum stranded wire and the sag-reduction-type steel core aluminum stranded wire is not so large, but the difference in the sag increases as the temperature increases. The combination of the existing wire and the sagging-suppressing steel core aluminum stranded wire will be described in detail in the following sections.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. A three-phase electric wire is stretched between steel towers having a span length of 10 m and a tower height 9 of 32 m. The highest phase wire is the upper phase wire, the next height is the middle phase wire, and the lowest wire is the lower phase wire. At the tower position, the distance 11 between the upper-phase and middle-phase wires is 2.5 m, the distance 12 between the middle-phase and lower-phase wires is 3.0 m, and the distance 13 from the lower-phase wires to the structure 8 is 15 m. . The separation distance between the upper and lower wires of the upper phase and the middle phase, and the upper and lower wires of the middle and lower phases must be 1.5 m or more, and the clearance above the ground that must be ensured between the lower phase wires and the structure is 6.0 m or more.
If the existing wire 1 such as a steel core aluminum stranded wire is used as it is for the upper phase wire, the current carrying capacity of the existing wire 1 increases (wire temperature 12
(0 ° C.) is about 10 m. On the other hand, if the existing wire is used as it is for the lower phase wire, the ground clearance at the time of increasing the current carrying capacity will be insufficient, so the sag restraint type steel core aluminum stranded wire 3
Replace it with In this case, when the energizing capacity is increased (wire temperature 1
(20 ° C) with a dip of about 8.5 m, the distance to the structure is 6.5 m, and the required clearance above ground can be secured. Next, even if the middle phase is the existing line, it is calculated to be 1.5.
Although a separation distance 5 of m can be ensured, in order to allow a margin in consideration of the actual use state, the wire is replaced with a sag-restraint type steel core aluminum stranded wire 2 having a reduced sag-restraining effect. Transition point 60 ° C
When the degree of sag control steel core aluminum stranded wire is selected, the sag when the current carrying capacity is increased (wire temperature 120 ° C.) is about 9.3 m, so the separation distance 6 from the upper-phase wire is 1.8 m, and the lower distance is 1.8 m. The separation distance 5 from the phase electric wire is 2.2 m, and the required separation distance can be secured in any case. Although the above description has been made with respect to one electric wire, the same method is applied to each line in the case of two power transmission lines.

[0007] A second embodiment of the present invention will be described. As shown in FIG. 2, when the distance between the towers is small, the increase in the sag due to the increase in the wire temperature is small even when the current carrying capacity is increased. In such a case, it is necessary to use the existing wire 1 such as a steel core aluminum stranded wire as it is for the upper phase and middle phase wires, and replace only the lower phase existing wire with a sag-reducing type steel core aluminum stranded wire. What is necessary is just to secure the clearance 4 above the ground. Therefore, it is possible to sufficiently cope with the use of the sagging suppression type steel core aluminum stranded wire 2 in which the sag suppressing effect is reduced.

[0008] A third embodiment of the present invention will be described. As shown in FIG. 3, the distance 11 between the upper phase and the middle phase wires, the distance 12 between the middle phase and the lower phase wires 12 at the tower position, and the narrow transmission distance 4 above the ground, at the tower position, For the phase wire, use the existing wire 1 such as a steel core aluminum stranded wire as it is, and for the lower phase wire, remove the existing wire 1 so that the required clearance above ground and the required distance from the middle phase wire can be secured. It is replaced with a steel core aluminum stranded wire 3 having a large sag-reducing effect with a large sag-reducing effect.

[0009]

According to the method of the present invention, the upper phase electric wire or the upper phase and the middle phase electric wire of the existing overhead transmission line are used as they are, and the electric wires of the other phases are replaced with the sag suppressing type steel. By simply replacing the core aluminum stranded wire, the current carrying capacity can be increased, the construction period is shortened, work on dangerous towers is reduced, and costs can be reduced. Shortening the construction period can also contribute to a stable supply of power. Furthermore,
By using the existing equipment, the current capacity can be increased economically.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first example of an overhead power transmission line adopting the method of the present invention.

FIG. 2 is a schematic configuration diagram showing a second example of an overhead power transmission line employing the reshuffling method of the present invention.

FIG. 3 is a schematic configuration diagram showing a third example of an overhead power transmission line employing the reshuffling method of the present invention.

FIG. 4 is a schematic configuration diagram showing the sag when the current carrying capacity is increased in an existing overhead transmission line.

FIG. 5 is a schematic configuration diagram showing an example of an overhead transmission line using a conventional replacement method.

FIG. 6 is a diagram showing a relationship between a wire temperature and a change in sag for a plurality of sag-restraint-type steel core aluminum stranded wires having different transition points from the ACSR.

FIG. 7 is a structural diagram of a sag suppressing type steel core aluminum stranded wire.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Existing wire 2 Aluminum wire with restrained sagness aluminum stranded wire 3 Aluminum wire with restrained sagness aluminum wire 4 High ground separation 5 Separation distance between middle and lower phase wires 6 Separation distance between upper and middle phase wires 7 Relaxation Degree 8 Structure 9 Tower height 10 Spanning length 11 Distance between upper and middle phase wires at tower position 12 Distance between middle and lower phase wires at tower position 13 Distance from lower phase wires to structure 14 Distance between the lowermost point of the upper phase electric wire and the lowermost point of the lower phase electric wire 15 Aluminum layer 16 Steel core 17 Air gap 18 Suppression-reduced steel core aluminum stranded wire

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Jun Yamada 4-10-1, Kawajiri-cho, Hitachi City, Ibaraki Prefecture Inside the Toyoura Plant, Hitachi Cable Co., Ltd. (72) Hiromitsu Takagi 4--10, Kawajiri-cho, Hitachi City, Ibaraki Prefecture 1 Hitachi Cable Co., Ltd. Toyoura Plant (72) Inventor Yuichi Komuro 4-1-1 Kawajiri-cho, Hitachi City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Toura Plant (72) Inventor Kyoji Kobayashi 4-chome Kawajiri-cho, Hitachi City, Ibaraki Prefecture No.10 No.1 F-term in Toyoura Plant of Hitachi Cable, Ltd. (reference) 5G367 FA02

Claims (5)

[Claims] Claims: 1. In a method of reconstructing an overhead transmission line composed of upper-phase, middle-phase, and lower-phase electric wires, each of which is wired with a predetermined distance between the towers in the vertical direction, at least an upper-phase electric wire is provided. Use existing wires such as steel core aluminum stranded wires, and use wires of other phases for clearance above ground required even when sag increases due to wire temperature rise due to increase in current carrying capacity, separation between wires of each phase A method of rebuilding an overhead power transmission line, characterized in that the rebuilding is carried out using a steel core aluminum stranded wire with reduced sag so as to secure the required space. 2. In the method of rebuilding an overhead transmission line composed of upper, middle and lower phase electric wires, each of which is overhead with a predetermined vertical distance between the towers, the upper phase electric wires are Using existing wires such as steel cored aluminum twisted green, the middle and lower phase wires are required to have a high clearance above the ground, even when the sag increases due to a rise in wire temperature due to an increase in current carrying capacity, and separation from wires in each phase. An overhead power transmission line replacement method characterized in that reconnection is performed using a sag-restraint type steel core aluminum stranded wire having different sag-response effects so that a distance can be secured. 3. An overhead transmission line construction method comprising upper, middle, and lower phases of electric wires, each of which is arranged with a predetermined distance between the towers in the vertical direction. Existing wires, such as steel core aluminum stranded wires, are used for the wires, and the lower-phase wires are separated from the middle-phase wires by the clearance above the ground, which is necessary even when the sag increases due to the rise in wire temperature due to the increase in current carrying capacity. A method for rebuilding an overhead power transmission line, wherein the rebuilding is carried out using a steel core aluminum stranded wire with reduced sag so that the distance can be secured. 4. An overhead power transmission line composed of upper phase, middle phase, and lower phase electric wires, each of which is wired with a predetermined separation distance in the vertical direction between the towers, wherein the upper phase electric wire is a steel core aluminum stranded wire. The medium-phase electric wire is a slackness-restricted steel that can secure the required separation distance from the upper-phase and lower-phase electric wires even when the sag increases due to an increase in the electric wire temperature due to an increase in the current carrying capacity. The lower-phase electric wire is made of a core aluminum stranded wire, and the lower-phase electric wire has a greater sag suppressing effect than the middle-phase electric wire, so that even when the sag increases, the required sagging clearance-type steel core can be secured. An overhead power transmission line, comprising an aluminum stranded wire. 5. In an overhead power transmission line composed of upper-phase, middle-phase, and lower-phase electric wires, each of which is overhead with a predetermined vertical distance between the towers, the upper-phase and medium-phase electric wires are steel cores. It consists of existing wires such as aluminum stranded wires, and the lower-phase wires can secure the necessary clearance above ground and the middle-phase wires even when the sag increases due to the rise in wire temperature due to the increase in current carrying capacity. An overhead power transmission line, comprising a steel core aluminum stranded wire capable of suppressing sag.