JP2009295326A - Overhead transmission line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an overhead transmission line capable of being inexpensively manufactured to maintain stable low sag property for a long period. <P>SOLUTION: The overhead transmission line comprises an aluminum layer arranged on the outer periphery of a copper core with a gap therebetween, the gap being filled with silicone grease, or an aluminum layer arranged on the outer periphery of a copper core with a gap therebetween, the gap being filled with grease in which lubricant is mixed. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an electric wire, and more particularly to an aerial power transmission line that has a low sag and a large current capacity.

Conventionally, as an aerial power transmission line, one using a steel core aluminum stranded wire in which an aluminum strand layer made of an aluminum stranded wire is arranged on the outer periphery of a steel core portion is known.
A normal electric wire has a drawback that when a large current is applied, the temperature of the electric wire becomes high, resulting in an increase in temperature and an increase in sag. For this reason, a series of wires called low-sag increasing capacity wires that have a large allowable current and suppress the sag during operation at high temperatures have been developed. Conventionally, invar electric wires and gap electric wires have been used as low-sag increasing electric wires.

The invar electric wire uses an invar alloy having a small temperature elongation (linear expansion coefficient) for the steel core, thereby minimizing the temperature elongation and the increase in sag associated therewith.
However, while ordinary wires use inexpensive galvanized steel wires for steel cores, invar wires use invar alloy wires, which are special alloys made of Fe-Ni, for steel cores. There was a drawback of becoming.

On the other hand, the structure of the gap wire is as shown in the example of FIG. 5, and the greatest feature is that a gap (gap) 13 is provided between the steel core 11 and the aluminum layer 12. The steel core 11 can be applied with a normal galvanized steel wire. Since the purpose of the aluminum layer 12 is to increase the capacity, aluminum wires called “heat-resistant aluminum alloy wires” or “super heat-resistant aluminum alloy wires” that can be used at higher temperatures than ordinary hard aluminum wires have been used. The gap electric wire is constructed by filling the gap 13 with mineral oil-based grease to reduce the friction between the aluminum layer 11 and the steel core 12, and by constructing the aluminum wire 11 so as not to share the tension. The expansion coefficient is reduced to suppress increase in sag (for example, Patent Document 1). In addition, by filling the grease with a gap between the steel core and the aluminum layer, even if the innermost aluminum layer collides with the steel stranded wire due to the slight wind vibration of the transmission line, the anti-friction effect of the grease makes the aluminum It is disclosed that both steels are difficult to wear (for example, Patent Document 2).
JP 2006-318869 A Japanese Utility Model Publication No. 54-25630

Conventional gap wires are filled with grease to reduce the friction between the aluminum layer and the steel core, but the normal heat resistance temperature of mineral oil-based grease is around 180 ° C, and it can be used for a long time at temperatures above this. In this case, there is a drawback that the grease deteriorates and a large friction is generated between the aluminum layer and the steel core, and the sag characteristic is extremely deteriorated. Even when used at relatively low temperatures, ordinary mineral oil grease has the disadvantage that due to its viscosity, there is a considerable frictional force between the aluminum layer and the steel core, and a sufficient sag suppression effect is not exhibited. .
Then, an object of this invention is to provide the overhead power transmission line which can be manufactured at low cost and can maintain the stable low sag characteristic for a long period of time.

The present invention
(1) An electric wire in which a gap is provided on the outer periphery of the steel core and an aluminum layer is disposed, and the overhead transmission line is characterized in that the gap is filled with silicone grease,
(2) An electric wire in which a gap is provided on the outer periphery of the steel core and an aluminum layer is disposed, wherein the gap is filled with grease mixed with a lubricant,
(3) An overhead electric power transmission line characterized in that a gap is provided on the outer periphery of the steel core and an aluminum layer is disposed, and the gap is filled with silicone grease mixed with a lubricant.
(4) The steel core is formed of a steel stranded wire made of three or more steel wires, and at least the silicone grease mixed with a lubricant is not filled in the steel stranded wire (1) to ( The overhead power transmission line according to any one of 3), and (5) the outermost layer of the steel stranded wire is formed substantially smoothly, and the steel stranded wire is filled with at least a silicone grease mixed with a lubricant. The overhead power transmission line according to any one of (1) to (4) is provided.

The overhead power transmission line using the silicone grease having high heat resistance as the grease of the present invention does not increase the friction between the steel core and the aluminum layer even when used at a high temperature, and can maintain stable low-sag characteristics for a long period of time.
Further, the overhead power transmission line in which a lubricant is added to the grease of the present invention has low friction between the steel core and the aluminum layer, and stable low-sag characteristics can be expected.
In addition, by filling the steel core with grease in the necessary minimum range without using grease, the amount of expensive silicone grease used can be reduced, and an increase in the cost of the wire can be suppressed.
Furthermore, the overhead power transmission line of the present invention does not require a special and expensive material such as Invar alloy and can be manufactured at low cost.

One embodiment of the overhead transmission line of the present invention is an electric wire in which a gap is provided on the outer periphery of a steel core and an aluminum layer is disposed, and the gap is filled with silicone grease.
Suitable silicone greases for this embodiment include dimethyl silicone as a base oil and silica added as a thickener. A preferable concentration of the thickener is 2 to 10% by mass. A normal mineral oil-based grease has a heat resistant temperature of about 180 ° C., whereas silicone grease can be used up to 240 ° C.

Another embodiment of the overhead power transmission line of the present invention is an electric wire in which a gap is provided on the outer periphery of a steel core and an aluminum layer is disposed, and the gap is filled with grease mixed with a lubricant.
In this embodiment, by adding a lubricant to the grease, the lubricity of the grease is increased and the friction between the aluminum layer and the steel core is reduced. As the lubricant, fine powders such as carbon graphite and magnesium silicate are suitable. Carbon graphite is a layered material of turtle shell made of carbon, and is excellent in heat resistance and corrosion resistance, and at the same time, has an effect of improving lubricity. Magnesium silicate is a mineral generally called talc and wax, which consists of magnesium hydroxide and silicate, and the fine powder has excellent lubricity.

The base grease to which the above-mentioned lubricant is added may be a conventionally used mineral oil-based grease, but is preferably the above-mentioned silicone grease.
The content of the lubricant is preferably 10 to 50% by mass, more preferably about 40% by mass in the entire grease including the lubricant.

  As the steel core used in the present invention, a steel core used in a conventional gap electric wire can be used. For example, a steel core formed by twisting 7 to 19 galvanized steel wires can be used. A special strong galvanized steel wire or a super strong galvanized steel wire may also be used. The special strong galvanized steel wire and the super strong galvanized steel wire are described in detail in the “Aerial Power Transmission Regulations” issued by the Japan Electric Association.

  When the steel core is composed of three or more strands of steel wire, it is relatively expensive compared with normal grease that the above-mentioned grease is not filled in the stranded wire surrounded by the steel wires. It is preferable because the amount of silicone grease used can be reduced. In addition, the weight of a long overhead power transmission line can be reduced.

  As an aluminum layer used in the present invention, an aluminum layer used in a conventional gap electric wire can be used. For example, a twisted aluminum element wire such as a super heat-resistant aluminum alloy wire or a heat-resistant aluminum alloy wire is used. Can do. The super heat-resistant aluminum alloy wire and the heat-resistant aluminum alloy wire are described in detail in the above “Overhead Power Transmission Regulations”.

The electric wire before filling with grease of the present invention can be prepared in the same manner as a conventional gap electric wire. Moreover, the filling of the above grease can be performed in the same manner as the filling of the mineral oil-based grease in the conventional gap wire. Further, when the steel core is not filled with grease, it is sufficient that the grease is not filled when aligning the steel cores of the inner layer.
In addition, deformation of the wire during winding of the drum at the manufacturing stage, deformation of the wire when passing through a metal wheel (with a pulley-like structure) during wire drawing work, and rotation history due to construction during the terminal treatment of the wire Opening or the like may cause a gap between the steel wire and the grease to penetrate into the steel core.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to this.

Example 1
FIG. 1 is a cross-sectional view of an example of the overhead power transmission line of the present invention. This electric wire is composed of 10 super heat-resistant aluminum alloy wires with a steel core 1 including seven galvanized steel wires having a diameter of 3.5 mm at the center and a gap (gap) 3 having a minimum length of 0.6 mm around the core 1. The inner layer 2a of the aluminum layer 2 and the outer layer 2b of the aluminum layer 2 formed by twisting 18 super heat-resistant aluminum alloy wires arranged so as to be in contact with the outer periphery of the inner layer 2a are provided. The super heat-resistant aluminum alloy wire of the inner layer 2a has a substantially trapezoidal segment structure so that the gap 3 is not crushed due to passage of a gold wheel during wire drawing work. The height of this substantially trapezoid (the thickness of the inner layer 2a) is 4.15 mm. The outer layer 2b is formed by twisting circular super heat-resistant aluminum alloy wires having a cross section of 4.0 mm in diameter.
The gap 3 is filled with a grease in which silica is mixed with dimethyl silicone oil as a base and 40% of carbon graphite is added as a lubricant.
The interior 4 of the steel core 1 is also filled with grease added with carbon graphite based on the above silicone grease.

Next, the temperature-sag characteristic of the wire of Example 1 at a span length of 300 m was measured. For comparison, the temperature-sag characteristics were measured in the same manner for the wire prepared in the same manner as in Example 1 except that the grease was changed from a silicone grease containing a lubricant to a normal mineral oil-based grease. . FIG. 2 shows the measurement results of the wire temperature and the sag by energization.
As shown in FIG. 2, the electric wire using the silicone grease with lubricant has a lower sag at the same temperature than the electric wire using ordinary grease, and exceeds the heat resistant temperature of ordinary grease of 180 degrees. Even at a temperature, it can be used with low sag.
The calculation conditions for the temperature-sag characteristics are about 28 mm in outer diameter of the wire, and about 1.678 kg / m in weight of a normal grease-filled wire or a lubricant-filled silicone grease-filled wire.

Example 2
FIG. 3 is a cross-sectional view of another example of the overhead power transmission line of the present invention. The electric wire shown in FIG. 3 has the same structure as the electric wire of Example 1 shown in FIG. 1 except that there is a difference in grease filling. In Example 1, grease is also filled in the inside 4 of the seven steel wires constituting the steel core 1, whereas in Example 2, only the gap 3 between the steel core 1 and the aluminum layer 2 is filled. Grease is filled, and the inside 4 of the steel core 1 is not filled. Compared with the wire of Example 1, the amount of silicone grease used in the wire of Example 2 can be reduced by about 15%.

Example 3
FIG. 4 is a cross-sectional view of another example of the overhead power transmission line of the present invention. The electric wire of Example 3 shown in FIG. 4 has the same structure as the electric wire of Example 1 shown in FIG. 1 except that the configuration of the steel stranded wire is different.
In addition, you may provide the inner layer 2a and the outer layer 2b of the aluminum layer 2 similar to Example 1. FIG. Further, for example, by increasing the thickness of the inner layer 2a, the electric resistance of the electric wire is reduced, so that the current capacity can be increased.
Furthermore, if the distance from the approximate center of the cross section of the wire to the inside of the inner layer 2a is r1 (wire outer diameter is d1) in FIG. 3 and r2 (wire outer diameter is d2) in FIG. If the inner layer 2a is provided and the outer layer 2b around the inner layer 2a is arbitrarily designed, the outer diameter of the electric wire of Example 3 can be set to d1 <d2. Therefore, compared with the electric wire having the structure as in the first embodiment, the electric wire having the structure as in the third embodiment can reduce the outer diameter and reduce the influence of the wind pressure even if the current capacity is approximately the same. be able to.

It is sectional drawing of the overhead power transmission line of Example 1. FIG. It is a graph which shows the temperature-sag characteristics measurement result of the overhead power transmission line of Example 1. It is sectional drawing of the overhead power transmission line of Example 2. FIG. It is sectional drawing of the overhead power transmission line of Example 3. It is sectional drawing of the conventional gap electric wire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel core 2 Aluminum layer 2a Inner layer of aluminum layer 2b Outer layer of aluminum layer 3 Gap (gap)
4 Inside of copper core 11 Steel core 12 Aluminum layer 13 Crevice (gap)

Claims (5)

  An overhead electric power transmission line, wherein an aluminum layer is provided with a gap provided on an outer periphery of a steel core, and the gap is filled with silicone grease.   An overhead electric power transmission line comprising an aluminum layer with a gap provided on an outer periphery of a steel core, wherein the gap is filled with grease mixed with a lubricant.   An overhead electric power transmission line comprising an aluminum layer with a gap provided on an outer periphery of a steel core, wherein the gap is filled with silicone grease mixed with a lubricant.   The said steel core is formed with the steel twisted wire which consists of 3 or more steel wires, The silicone grease which mixed the lubricant at least inside is not filled with the inside of the said steel twisted wire. The overhead power transmission line according to item 1.   The outermost layer of the steel stranded wire is formed substantially smoothly, and the silicone grease mixed with at least a lubricant is not filled in the steel stranded wire. Overhead power lines.

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