JPH047529Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a multi-purpose overhead bare electric wire that prevents the accumulation of snow on the wire surface, the generation of wind noise, the generation of slight wind vibration, etc. It is related to.

(Prior art and its problems) When snow adheres to the surface of overhead bare wires such as power transmission lines and overhead ground wires made of stranded conductors during snowfall, the snow gradually develops and eventually accumulates in a cylindrical shape around the outer periphery of the wires. It turns out.

The cause of such cylindrical accumulation of snow can be found in the structure of the overhead bare electric wire.

In other words, since overhead bare electric wires generally have a stranded wire structure made up of a large number of wires with round cross sections twisted together, the wires can move relative to each other, and as a result, the torsional rigidity of the overall structure is low. It is low.

Considering the case of overhead bare wires with low torsional rigidity in snowy conditions with reference to Figure 3,
Now, as shown in Figure A, there is snow S on a part of the surface of the electric wire W.
If the snow builds up and develops to a certain size, it becomes an eccentric load, and the electric wire W with low torsional rigidity receives a rotational moment and is twisted in the circumferential direction of itself as shown by the arrow (A), causing the snow buildup S to occur. The position of changes as shown in FIG. 3B. Then, new snow S adheres to the area on the outer periphery of the electric wire W that was previously occupied by snow S, as shown in Figure B, and as before, this eventually becomes a large eccentric load, causing the electric wire W to further twist and rotate. , thereafter, similar actions are repeated as shown in Fig. 8 C-E, and finally snow accretion S occurs on the outer periphery of the electric wire W.
- is deposited in a cylindrical shape.

This cylindrical accumulation of snow is largely due to the low torsional rigidity of bare electric wires, as mentioned above.For this reason, conventional methods have been used to attach weights to electric wires and torsionally rotate the electric wires due to snow accumulation. Techniques designed to prevent
However, in this case,
There is a risk of fatigue due to stress concentration on the wires at the weight attachment point and the possibility of the weight falling off, so the track must be inspected strictly, which significantly increases the burden of maintenance work, and An increase in the weight of the wires causes an increase in the tension required to maintain the wires at a predetermined level of slack, creating problems such as the need to make structures such as steel towers more solid.

(Purpose of the invention) This invention is designed to prevent snow from accumulating in a cylindrical shape on the surface of electric wires, as well as to prevent the generation of wind noise and slight wind vibration. It provides electric wires.

(Structure of the invention) This invention consists of two types of segment wires having different thicknesses in the radial direction being alternately twisted adjacent to each other.
The overhead bare electric wire has an outermost layer in which the mutually contacting side surfaces of both of the segment wires have an engaging side surface structure that prevents the thin segment wires from separating radially outward.

(Example) A first example of this invention will be described with reference to FIG. The outermost layer 1 of the overhead bare electric wire W is formed by twisting two types of segment wires 2 and 3 adjacent to each other alternately. That is, the thick segment wire 2 has a cross-sectional shape that is approximately a curved rectangle, and one of its cross-sectional dimensions, in this example, the thickness in the radial direction in the twisted state is a relatively large value t1. and a thin segment wire 3 whose thickness is also a relatively small value t2 are twisted together so that their respective side surfaces 2A, 3A are in contact with each other.

Therefore, the side surface 2A of the thick segment wire 2
There are protrusions 21 projecting in the circumferential direction at both radially outer ends of the thin segment wire 3, so that the thin segment wires 3 overlap the protrusions 21 of the thick segment wires 2 on both sides.
It is locked to prevent it from coming off in the radial direction (lifting up or popping out). In this way, the side surface 2A of the thick segment wire 2 and the side surface 3A of the thin segment wire 3 have an engaging side surface structure in which displacement in the radial direction from each other is prevented.

FIG. 2 shows a second embodiment of this invention, in which a thick segment wire 2 having a relatively large thickness t1 in the radial direction and a relatively small thickness thereof are shown in FIG. Thin segment wires 3 having a value t2 are arranged alternately in the circumferential direction and twisted to form the outermost layer 1, and the side surfaces 2A of the thick segment wires 2 are oriented radially inward. The side surface 3A of the thin segment wire 3 becomes a sloped side surface with a slope in the opposite direction that becomes wider as it radially inwards. Similarly, the engaging side surface structure is such that the thin segment wire 3 does not escape radially outward.

As seen in the embodiments described above, in this invention, the outermost layer 1 is constituted by alternately arranging and twisting two types of segment wires having different wall thicknesses in the radial direction. A plurality of grooves 4 are substantially formed in the circumferential direction of the surface, and a large number of unevenness exists in the circumferential direction. For this reason, it becomes difficult to generate a Karman vortex street behind the electric wire W where the crosswind acts.

Furthermore, since the outermost layer 1 is formed of segment wires and the contact surfaces of adjacent segment wires 2 and 3 have an engaging side structure that does not allow radial displacement, the overall rigidity of the outermost layer 1 is increased. increases,
As a result, the torsional rigidity (polar moment of inertia of the cross section) increases, and the above-mentioned factor causing snow to accumulate in a cylindrical shape is eliminated.

(Effects of the invention) According to this invention, the outermost layer of the bare wire is formed by alternately arranging and twisting two types of segment wires with different wall thicknesses, so the surface becomes rich in irregularities. Therefore, no Karman vortex street is generated behind the bare wire where the crosswind acts, and wire noise and vibration caused by wind pressure are prevented. Since the outermost layer is formed of segmented wires and the contact surfaces between the segmented wires have an engaging side surface structure, the torsional rigidity of the outermost layer as a whole is increased and cylindrical adhesion of snow is prevented. Effects such as this can be obtained.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing each embodiment of this invention, and FIG. 3 is an explanatory diagram illustrating the progress of cylindrical accumulation of snow on an overhead bare electric wire. 1... Outermost layer, 2... Thick segment wire,
3... Thin segment wire, 4... Concave groove, W...
…Overhead bare wires.

Claims (1)

[Scope of utility model registration request] Two types of segment wires 2 and 3 having different wall thicknesses in the radial direction are twisted together alternately and adjacent to each other, and the thin segment wires 3 are arranged so that the mutually contacting surfaces of both segment wires 2 and 3 are connected in the radial direction. An overhead bare electric wire having an outermost layer 1 having an engaging side surface structure that prevents it from coming off outward.