JPH0146964B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in anti-corona wires.

Generally, an electric wire immediately after manufacture has a smooth surface and has oil attached thereto, and therefore has poor hydrophilicity. When such electric wires are installed overhead,
Rainwater tends to form small lumps and adhere to the surface of the wires.

On ultra-high-voltage overhead power transmission lines, corona is generated from water droplets that adhere to the surface. In order to prevent corona, the surface of the wire can be treated with hydrophilic treatment so that water droplets adhering to the wire can quickly collect and flow away.

By the way, when the diameter of an electric wire that has been hydrophilized in this way is relatively small (for example, the diameter of a 240 ^mm2 steel-core aluminum stranded wire), water droplets may adhere to it due to the relationship between the surface tension of the electric wire and the water. 1 wraps around the bottom end of the wire main body 2 as shown in Figure 1, but when the wire diameter becomes thick (for example, about the diameter of a steel core aluminum wire of 810 mm ² ), the attached water droplet 1 wraps around the bottom end of the wire body 2 as shown in Figure 2. It often adheres to the left and right sides of the lower surface of the wire body 2.

Furthermore, when viewed in the longitudinal direction of the electric wire, the attached water droplets 1 are dispersed in dots as shown in FIG.
They often do not aggregate.

In order to improve this problem, a corona-preventing electric wire has recently been proposed in which the surface of the wire body is subjected to hydrophilic treatment and is made of stranded wires with thin grooves formed on the surface of the outermost wire.

However, even such a corona-preventing electric wire has the drawback of not having sufficient drainage properties.

An object of the present invention is to provide a corona-preventing electric wire that can improve the ability to remove adhering water droplets from the surface of the electric wire.

The present invention provides a corona-prevention electric wire in which the surface of a wire main body is made of a stranded wire with thin grooves or lines formed on the surface of the outermost layer of the wire, and the surface of the wire is subjected to hydrophilic treatment. The striations are characterized in that they are provided at an angle greater than the angle between the strands and the axis of the electric wire.

Hereinafter, the structure of the corona prevention electric wire according to the present invention will be specifically explained together with the manufacturing method thereof. When drawing a strand 3 such as an aluminum wire, a fourth die is used on the surface of the strand 3 after drawing using a rising die having protrusions on the inner surface.
A pattern of thin grooves or stripes 4 as shown in FIG. 5 is created. Such strands 3 are used at least when forming the outermost layer and are twisted together to obtain an electric wire main body 2 made of twisted wires as shown in FIG. At this time, the angle of the groove or striation 4 with the electric wire axis is determined to be larger than the twisted angle of the strands 3, as shown in the figure. This is because the water droplets are guided along the grooves or striations 4 over the shortest distance into the grooves between the strands 3. If the angle between the wire axis and the groove or striation 4 is equal to or less than the angle at which the wire 3 is twisted, the wire 3
This is undesirable because it actually obstructs the mutual guidance of the grooves into the grooves. Next, the surface of the electric wire main body 2 is subjected to sandblasting treatment to degrease the surface and make it smooth. Thereafter, the electric wire main body 2 is degreased and cleaned and treated with boehmite, for example, by exposing it to steam at 150° C. or higher for about 10 minutes or immersing it in boiling distilled water for about 10 minutes. The surface of the electric wire main body 2 is subjected to hydrophilic treatment by such sandblasting and boehmite treatment.

In this way, a corona-preventing electric wire with good drainage properties can be obtained. The total area of the grooves or stripes 4 provided in the wire 3 is 15% of the circular cross-sectional area of the wire.
It is desirable to do the following. If it exceeds 15%, the strength of the compression connection of the wire will be too low.

Further, when the hydrophilic treatment is performed by sandblasting and boehmite treatment, there is an advantage that deterioration of hydrophilicity over time is small and the water drainage performance can be maintained for a long time.

The grooves or lines 4 provided on the surface of the wire 3 can be formed by using a die 6 or 7 having protrusions 5 at rough or narrow intervals on the inner periphery, as shown in FIGS. 7 and 8, for example. 7 can be provided by drawing the wire while rotating it.

As explained above, in the present invention, the thin grooves or streaks formed on the surface of the outermost wire are formed at an angle larger than the angle between the wire and the wire axis, so that the thin grooves or streaks are formed on the surface of the wire. The water droplets collected in the grooves between the strands can be quickly gathered in the grooves between the strands over a short distance and flowed down, significantly improving the drainage performance compared to conventional products of this type, and further improving the corona prevention effect. . In particular, according to the present invention, the draining performance is improved by simply changing the angle at which the grooves or stripes are formed compared to conventional ones, so the cost of measures to improve the draining performance does not increase, and the draining performance is improved. This is very suitable for practical use.

[Brief explanation of drawings]

Figures 1 and 2 are cross-sectional views showing the relationship between conventional electric wires and water droplets, Figure 3 is a side view showing the state of water droplet adhesion on conventional electric wires, and Figures 4 and 5 are used in the present invention. 6 is a side view showing an example of the corona-preventing electric wire according to the present invention, and FIGS. 7 and 8 are cross-sectional views showing two examples of strands of wire, and FIGS. FIG. 3 is a front view showing two examples of upward dice. 1...Water droplet, 2...Electric wire body, 3...Element wire, 4
...grooves or streaks.

Claims (1)

[Claims] 1. In a corona-prevention electric wire in which the surface of the electric wire body is made of stranded wires with thin grooves or striations on the surface of the outermost layer of wire, the surface of the wire is subjected to hydrophilic treatment, and the grooves or striations on the surface of the wire are A corona-preventing electric wire characterized by being provided at an angle greater than the angle formed between the strands and the electric wire axis.