JPS6037681B2 - Transmission line overhead line construction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction method for overhead power transmission lines, particularly power transmission lines having an aluminum stranded wire layer on reinforced stranded wires such as ACSR, so that the increase in sag due to power transmission is minimized.

Conventionally, overhead power transmission lines have generally been installed with a certain degree of slack between the steel towers.

It is preferable that this sag be as small as possible in order to reduce the lateral swing of the overhead power transmission line, but the sag is set to an appropriate value in consideration of the tensile force of the overhead power transmission line. Therefore, power transmission lines, such as ACSR, have been developed in which an aluminum lacquered wire layer is provided on high-strength twisted wires to increase the tensile strength of overhead power transmission lines, and the overhead power lines are installed with low sag. However, even in such an ACSR, if both the aluminum stranded wire and the hammer core wire bear tension after the overhead wire is connected, the increase in sag will be greater than if only the steel core bears tension. Therefore, when ACSR is wired, it is necessary to apply pre-stress or rotation after drawing the ACSR so that only the steel core bears the tension to cause permanent elongation in the aluminum stranded wire.
Before the wire is stretched, a tension within the elastic limit of Senshin is applied to the ACSR to give the aluminum stranded wire an extra length due to elongation. The ends of the core and the aluminum stranded wires are aligned, and the aluminum stranded wire layer is loosely placed on the steel core in the middle), and the wires are stretched and overhead wired with appropriate tension. However, the former method requires special tools and requires a large-scale overhead wire, and in the latter method, the elongation given to the aluminum stranded wire before the wire is stretched is squeezed with a metal wheel during the wire stretching, and the elongation is reduced. This may cause problems such as uneven distribution over substantially the entire length of the wire, or a crack in the middle of the wire. In view of this, the present invention provides a power transmission line having an aluminum woven layer on a strongly twisted wire, such as an ACSR, by giving a predetermined extra length to the aluminum stranded wire in advance, and applying tension to cause the wire to elongate beyond the extra length. The wire is stretched, and then the wire is tied to the tower with a tension less than the tension at the time of wire stretching.

That is, when the wire is stretched, a large tension is applied to the aluminum stranded wire and the steel core, and when the wire is stretched, only the key core is loaded with tension, thereby creating a wire with low sag. Next, this will be explained in more detail based on the drawings.

At the beginning of the technique, before ACSR wire extension, AC was applied within the elastic limit of the steel core.
Tension is applied to SR, and extra length ΔS is given to the aluminum stranded wire layer due to permanent elongation.

When applying such tension, a suitable clamp such as a wire clamp is attached to the end of the ACSR. Therefore, an ACS with extra length given to the aluminum stranded wire layer like this
R has a structure in which the ends of the steel core and the aluminum stranded wires are aligned after the tension is removed, and the aluminum strands are loosely arranged on the steel core in the middle. Next, the ACSR in which the aluminum stranded wire layer is given an extra length of ΔS in this manner is drawn while applying a tension that causes an elongation equal to or greater than the yarn length ΔS.

For the wire extension, a known method is used, for example, a wire extension clamp is attached to the end of the ACSR, and the wire is taken up by a take-off device (engine vehicle) and the wire is extended. The wire tension is adjusted by adding back tension using a wire rolling car placed in the drum field. After the wire has been stretched, it is held to the tower with a tension that is less than the tension at the time of wire stretching.

Therefore, the ACSR overhead wire tension T, in which an extra length of △S is given to the aluminum stranded wire, is determined by the elongation of the steel core △S (the tension at this time is T,
) When the tension is smaller than △S, only the steel core receives tension along straight line 1 shown in the figure, and when the tension is such that the elongation of the steel core is greater than △S, the steel D and aluminum strands are applied together. The tension at this time is the sum of the tension 3 of the aluminum stranded wire and the tension 4 of the steel core along the straight line 2.

Therefore, if the wire is drawn with a tension that causes an elongation of more than the extra length △S, both the aluminum twisted groove spring and the steel core will bear the tension, but if the tension causes an elongation that is less than △S, only the steel core will bear the tension. That is, when the wire is extended, the ACSR as a whole bears the tension, and when the wire is tied to the steel tower, the aluminum stranded wire does not bear the tension, but only the steel core carries the burden, so the wire can be wired with low sag. In addition, the linear expansion coefficient of the steel core in this case is 11.5 x 10-6/℃, that of the aluminum stranded wire is 23 x 10-6/℃, and the linear expansion coefficient of the entire stranded wire (ACSR) is 18 to 21 x 10-6/℃, but T,
The following tension loads are 11.5×10-6/. ○,
The linear expansion coefficient is smaller than that of a hot wire, the wire elongates less due to temperature changes, and the wire sag increases by 4.
. Furthermore, the extra length △S given to the aluminum stranded wire in advance can be arbitrarily determined, but this △S is determined by the temperature change due to heat generated by power transmission after the power transmission line is tied to the tower with a predetermined sag. It is preferable that the amount of elongation is greater than the elongation of the Tachibana strongly twisted wire, for example, steel D. As explained above, according to the present invention, a power transmission line having an aluminum stranded wire, for example, an ACSR, is stretched on a reinforcing stranded wire with an extra length given to the aluminum stranded wire, with a tension large enough to cause the wire to elongate beyond the extra length. As a result, the stranded aluminum wire and the aluminum stranded wire receive tension together, and the aluminum stranded wire is not squeezed when passing through the metal wheel. Both steel cores bear the tension, but after the steel core is tied to the tower, only the steel core bears the tension, so there is an advantage that a low-sag overhead wire can be easily obtained.

[Brief explanation of the drawing]

The drawing is a graph showing the relationship between ACSR elongation and overhead wire tension.

Claims (1)

[Claims] 1. A power transmission line having an aluminum stranded wire layer on the reinforcing stranded wire is made by giving a predetermined extra length to the aluminum stranded wire in advance, and stretching the wire with a tension that causes the wire to extend beyond the extra length, and then when the wire is stretched. An overhead line construction method for power transmission lines that is characterized by anchoring them to steel towers with a tension less than or equal to the tension of .