JPS61227304A - Snow repelling type aerial wire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a snow-resistant construction for power transmission lines, ground wires, etc., which prevents snow adhering to the surface of electric wires from accumulating and developing into a cylindrical shape. It concerns overhead power lines.

[Prior art and its problems]

When snow adheres to the surface of overhead electric wires made of stranded conductors such as power transmission lines and ground wires during snowfall, the snow gradually develops and eventually accumulates in a cylindrical shape around the outer periphery of the electric wires.

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

In other words, since overhead power lines such as power transmission lines and ground wires generally have a stranded wire structure in which a large number of wires with a circular cross section are twisted together, the relative motion of the wires that make up the stranded wires is difficult. It has a large degree of freedom, and therefore has low torsional rigidity as an overall V4 structure.

Considering the third case where an overhead power line with low torsional rigidity is under snowy conditions, now the same 1i21(Δ)
As shown in the figure, snow S■ adheres to a part of the surface of the electric wire W, and when this grows to a certain size, it becomes an eccentric load, and the electric wire W with low torsional rigidity receives a rotational moment, as shown by the arrow (A). It is twisted and rotated in its own circumferential direction, and the position of the snow deposit S2 changes as shown in FIG. 3(B). 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 Fig. 3 (B), and as before, this eventually becomes a large eccentric load and causes the electric wire W to become The wire is further twisted and rotated, and the same action is repeated as shown in FIGS. 3(C) to 3(E), and finally, snow S1 to S2 is deposited in a cylindrical shape on the outer periphery of the electric wire W.

This cylindrical accumulation of snow is largely due to the low torsional rigidity of the overhead electric wire W, as mentioned above.For this reason, conventionally, a weight was attached to the above electric wire to create an electric wire based on snow. Technology to prevent twisting and rotation of
No. 233, Utility Model Publication No. 59-28234, etc.), but in this case, there are concerns such as fatigue due to stress concentration of the electric wire at the heavy bell attachment part and accidents such as falling of the heavy bell, etc. Railway lines must be inspected strictly.
As a result, the burden of maintenance work increases significantly, and the substantial increase in the amount of wires results in an increase in the tension required to keep the wires at a predetermined level of slack, making structures such as steel towers more rigid. This led to problems such as having to do so.

In addition, especially in the case of an overhead wire that has a built-in protection pipe containing optical fibers, such as an optical fiber composite overhead ground wire, if the wire W is twisted as described above,
When a similar twist acts on the above-mentioned optical fiber and the weight of the electric wire W increases substantially due to accumulation of snow and the elongation of the electric wire becomes significant, excessive tension acts on the optical fiber with small elongation, and as a result, eventually There is a risk that the transmission characteristics of the optical fiber may deteriorate, or in the worst case, the optical fiber may become disconnected and become unusable.

[Object of the Invention] The first invention is to improve the torsional rigidity of electric wires to eliminate the cause of accumulation of snow in a cylindrical shape, thereby preventing snow from accumulating and developing in a cylindrical shape. The purpose of the second invention is to provide an electric wire, and further, the second invention is similar to the first invention, by preventing snow from accumulating and developing into a cylindrical shape. This is to prevent any negative effects on the cable.

[Structure of the Invention J The M snow-covered overhead wire of the first invention is such that at least the outermost layer of the overhead wire made of stranded wires has a roughened contact surface and has a cylindrical shape as a whole. It is constituted by a plurality of twisted segment wires having a truncated fan-shaped cross section, and the second invention is one in which an optical fiber cable is housed inside the overhead electric wire of the first invention.

[Configuration and operation of embodiments] Each embodiment of the first and second inventions will be described below with reference to the drawings.

FIG. 1 shows an example of the j1 snow-covered overhead electric wire of the first invention, and the overhead electric wire is generally designated by the reference numeral 1.

This overhead electric wire 1 is made up of multiple layers of many strands (4W in the figure).
J) are twisted together, and the outermost layer 2 and the layer 3 located inside the outermost layer 2 are each made of a plurality of segment wires 4 twisted together to form a cylindrical shape. It is configured. Each of the segment wires 4... has a truncated fan-shaped cross section with a thick aluminum coating 6 formed around a steel wire 5, and each surface in surface contact with each other has an uneven rough surface 7. has been done. In addition, on the outer periphery of two segment wires 4a and 4b (positioned point-symmetrically in the figure) among the segment wires 4 . Projections 8a and 8b are formed.

According to such an overhead electric wire 1, in particular, at least the outermost wire 2 is constituted by twisting a plurality of segment wires 4 having a truncated fan-shaped cross section, and the cross-sectional area factor thereof is extremely large. In addition, since the surfaces of the segment elements 112 that are in surface contact with each other are formed into uneven and rough surfaces 7, and the frictional force between adjacent segment element wires is extremely large, the degree of freedom of relative movement between the element wires is extremely small. , Therefore, the outermost layer 2 has a structure almost similar to a pipe, and the value of the polar moment of inertia of the area is significantly thicker than that of the conventional layer made of twisted wires with a round cross section (
In other words, the resistance to twisting in the circumferential direction is significantly improved. Therefore, even if an eccentric load occurs on the outer periphery of the overhead wire 1 due to snow accumulation S as shown in FIG. j
2 does not easily twist and rotate in the circumferential direction, and therefore, the development of snow S into a cylindrical pile is effectively prevented.

Incidentally, if the inner layer 3 has the same structure as the outermost layer 2 as in this embodiment, the above-mentioned effects become more remarkable. In addition, if protrusions 8a and 8b are formed on the outer periphery of the segment wires 4a and 4b to extend in the longitudinal direction of the segment wires 4a and 4b as in the illustrated embodiment, they will adhere to the surface of the wire 1 and will be attached to the wires by their own weight. When snow that is about to develop by sliding in the circumferential direction occurs, it can be expected that the snow will collide with the protrusions 8a and 8b and be sheared and fall.

Next, FIG. 2 shows an example of a snow-resistant overhead electric wire according to the second invention.

The overhead electric wire 10 of this example includes a protective pipe 12 made of aluminum or the like provided in the center of the overhead electric wire 1 shown in FIG.
The optical fiber cable 11 is housed in the protective pipe 12. According to such an overhead electric wire 10, the same effect as the overhead electric wire 1 shown in FIG. 1 is prevented from twisting and the accumulation of snow is prevented, so twisting and excessive tensile force are not applied to the optical fiber cable 11 housed inside, and it can be reliably protected.

Therefore, there is no risk of deterioration of the transmission characteristics of the optical fiber cable 11 or breakage caused by snow accumulation as in the conventional case.

[Effect of the invention 1] As explained above, according to the NV snowflake overhead electric wire of the first invention, the torsional rigidity of the outer layer of the electric wire can be significantly increased without attaching a weight as in the conventional case, and thus the weight is reduced. It is possible to effectively prevent snow from accumulating and developing into a cylindrical shape without causing the various problems described above caused by the attachment of the weight.

Furthermore, in the second aspect of the invention, the optical fiber cable incorporated therein can be reliably protected due to the above-mentioned effects, and therefore, the transmission characteristics of the optical fiber cable may be affected by snow accumulation as a factor, unlike the conventional one. There is no risk of deterioration or breakage of the optical fiber cable.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an embodiment of a snow-resistant overhead electric wire according to the first invention, FIG. 2 is a schematic cross-sectional view showing an embodiment of the second invention, and FIG. ) to E) are explanatory diagrams showing the process of the cylindrical development phenomenon of snow accretion on the outer periphery of the electric wire. 1.10... Overhead electric wire, 2... Outermost layer, 4... Segment wire, 7... Uneven rough surface, 11... ...Optical fiber cable.

Claims (2)

[Claims] (1) Each of the wires constituting at least the outermost layer of the overhead electric wire is formed by segment wires having a truncated fan-shaped cross section, and the surfaces of the segment wires that are in surface contact with each other are roughened. This is a snow-resistant overhead power line that is characterized by: (2) Each strand constituting at least the outermost layer of the overhead electric wire is formed by segment strands having a truncated fan-shaped cross section, and each surface of the segment strands that is in surface contact with each other is made into an uneven surface, and the overhead A snow-resistant overhead electric wire featuring an optical fiber cable housed inside the wire.