JPH03101005A - Aerial power-transmission line - Google Patents

Abstract

PURPOSE:To prevent any damage to a specific conductive ceramics layer while inhibiting generation of pinhole by forming an oxide interlayer on the surface of a twisted wire, and then forming the ceramics layer on the surface of the interlayer. CONSTITUTION:A twisted wire 1 prepared through the process of intertwisting 7 pieces, for example, of metallic element-wires 1 is covered with an interlayer 2 made of an oxide and then is covered with a conductive ceramics layer 3 made of the nitride of transition metal IV/V groups, the carbide thereof and the biboride thereof. The carbide, nitride and biboride respectively of the transition metal IV/V groups all have excellent conductivity so that covering the twisted wire with this ceramics material layer results in improvement in the lightning surge resistance of an aerial power-transmission line. Moreover, metallic elements of same kind of composition contact each other at the interface between the twisted wire 1 and the interlayer 2 while ceramics contact each other at the interface between the interlayer 2 and the conductive ceramics layer 3 so that every interfacial affinity may become excellent to improve every interfacial adhesion as well as to relax stress due to differential thermal expansion. Damage to the conductive ceramics layer 3 is thus prevented while because of the oxide making the interlayer 2, formed by directly oxidizing the twisted wire 1, no defect occurs and covering the periphery of the interlayer with the conductive ceramics layer 3 can prevent generation of a pinhole.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an overhead power transmission line (including an overhead ground wire) with excellent lightning resistance.

[Conventional technology and its issues]

Generally, overhead power transmission lines are made of single metal wires such as bare copper, aluminum, or steel, or stranded wires made by twisting composite wires of these wires. The most common accident that occurs on overhead power transmission lines is snow damage, and there is a strong demand for an overhead power transmission line that can prevent these accidents.

When an overhead power transmission line encounters a lightning strike, the strands of the stranded wires will melt and the wires will melt due to the heat generated by the lightning current, making it difficult to prevent this from happening.

In view of this, we have previously proposed an overhead power transmission line in which the surface of stranded wires is coated with a ceramic layer that is conductive and has a melting point higher than that of iron (Japanese Patent Application No. 180476). This overhead power transmission line showed an excellent effect of significantly improving lightning resistance. However, due to the difference in thermal expansion between the stranded wire and the conductive ceramic, damage such as cracking or peeling tends to occur in the ceramic layer, and contamination or defects on the surface of the stranded wire can cause pinholes.

[Problem to be solved by the invention]

The present invention was made as a result of ``ζ study'' on the above-mentioned problem, and it has excellent lightning resistance, improves the affinity between the stranded wire and the conductive ceramic layer, reduces the difference in thermal expansion, and prevents cracking of the ceramic layer. The company has developed an overhead power transmission line that does not suffer from damage such as peeling, reduces surface contamination and defects, and suppresses the occurrence of pinholes.

[Means and effects for solving the problems] The present invention forms an intermediate layer made of an oxide on the surface of a stranded wire made of metal wires, and a transition metal (III), a group V carbide, or a nitride as the outermost layer on the surface of the stranded wire. This is an overhead power transmission line characterized by forming a conductive ceramic layer containing at least one type of diboride as a main component.

In other words, the present invention improves the affinity between the stranded wire and the conductive ceramic layer by oxidizing the surface of the stranded wire to form an oxide as an intermediate layer between the stranded wire and the outermost conductive ceramic layer, thereby reducing thermal expansion. This is a smaller difference.

Transition metals of the ■ and ■ groups, such as Ti, Zr, Hf, V, Nb
, Ta carbides, nitrides, diborides, etc. have strong oxidation resistance and sulfidation resistance, high hardness and melting point, little wear, good properties, and good electrical conductivity. Therefore, when overhead power lines are coated with this material, the lightning resistance of the overhead power lines is improved compared to conventional overhead power lines. Also, since the time for lightning current to flow is short, on the order of μsec, the amount of heat transferred from the coating layer to the internal conductor metal is small.
Melting loss of the internal conductor metal can be prevented. Furthermore, in order for the overhead ground wire to perform a lightning protection function, its outer layer must be conductive, and its volume electrical resistivity is 100 μΩ-c.
It is desirable that it be less than m.

By the way, if this continues, the ceramic layer will crack or peel due to the difference in thermal expansion coefficient between the twisted wire and the conductive ceramic layer.

Therefore, in the present invention, the outer periphery of the stranded wire is oxidized to form an oxide intermediate layer, thereby increasing the affinity between the stranded wire and the conductive ceramic layer and reducing the difference in thermal expansion. By doing this, the stranded wire and the intermediate layer are made of the same type of metal, and the intermediate layer and the conductive ceramic are in contact with each other as ceramics, so they have good affinity, improve adhesion, and alleviate stress due to the difference in thermal expansion. Prevent damage to the conductive ceramic layer. Further, since the oxide of the intermediate layer is formed by directly oxidizing the stranded wire, there is no defect, and since the outer periphery of the oxide is coated with a conductive ceramic layer, it serves to prevent the occurrence of bottle balls.

In the present invention, the oxide of the intermediate layer can be formed by heat treating the twisted wire in the air or in an oxidizing atmosphere, or by anodizing.

Further, as the metal wire, wires used as wires of other overhead power transmission lines, such as copper wire, aluminum wire, and steel wire, can be used.

Furthermore, the outermost conductive ceramic layer is one whose main component is one of transition metals, carbides, nitrides, and diborides of Ti, Zr, Hf, V, Nb, and Ta of groups 1 and 2. used.

〔Example] An embodiment of the present invention will be described below.

As shown in Figure 1, a metal wire (1
) is coated with an intermediate layer (2) made of an oxide, and then coated with a conductive ceramic layer (3) of a transition metal ■, group V nitride, carbide, or diboride. state

Example 1 After oxidizing the surface of a stranded wire made of seven aluminum wires by anodizing treatment to form an intermediate layer, a ZrBz layer with a thickness of 70 μm was formed on the surface by chemical vapor deposition, and the wire was transported overhead. An electric wire was made.

Example 2 After oxidizing the surface of a stranded wire consisting of seven copper wires twisted together in the atmosphere to form an intermediate layer, a ZrN layer with a thickness of 60 mm was formed on the surface by reactive vapor deposition. An overhead power transmission line was fabricated.

Example 3 After oxidizing the surface of a stranded wire made of seven hard steel wires by heat treatment in an oxygen atmosphere to form an intermediate layer, a 13° Ti layer of 11001B was applied to the surface by low pressure plasma spraying.
An overhead power transmission line was fabricated by forming it to a thickness of .

Comparative Example 1 Ti was applied to a strand of seven hard steel wires by plasma spraying.
An overhead power transmission line was manufactured by forming a Bz layer to a thickness of 100 Ina.

Comparative example 2 An overhead power transmission line was made by twisting seven hard steel wires together.

The above-mentioned overhead power transmission line thus produced was examined for heat cycle tests, oxidation resistance, and sulfidation resistance.

The results are shown in Table 1.

Table 1 Note) O...Good Good ×...Poor -...
In the heat cycle test, an overhead power transmission line was heated from room temperature to 400° C. for 100 cycles, and cracks in the appearance of the conductive ceramic layer were observed.

Oxidation resistance was determined by leaving an overhead power transmission line in the atmosphere at 400°C for 500 hours and observing the degree of oxidation based on the surface condition. The sulfidation resistance was determined by leaving an overhead power transmission line in an atmosphere with a relative humidity of 90% and a hydrogen sulfide content of TOPPM for 1000 hours and observing the surface condition.

As is clear from Table 1, the overhead power transmission line of the present invention has good oxidation resistance and sulfidation resistance, and it can be seen that the conductive ceramic layer is not damaged due to the difference in thermal expansion in the heat cycle test.

〔effect〕

As explained above, according to the present invention, it has lightning resistance,
Moreover, it is possible to obtain an overhead power transmission line that improves adhesion, alleviates stress caused by thermal expansion, prevents damage to the conductive ceramic layer, and prevents the occurrence of pinholes, which has a significant industrial effect. be.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an overhead power transmission line according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Metal wire, 2... Intermediate layer, 3... Conductive ceramic layer.

Claims (1)

[Claims] An intermediate layer made of an oxide is formed on the surface of a stranded wire made of metal wires, and the outermost layer on the surface is mainly composed of at least one of carbides, nitrides, and diborides of transition metals IV and V groups. An overhead power transmission line characterized by forming a conductive ceramic layer.