JPH01246714A - overhead insulated wire - Google Patents

Abstract

PURPOSE:To an aerial insulated wire constructed with strands and coated with insulating film, to use strands generating no stress-corrosion cracking so as to make the filling up of watertight compound unnecessary by constructing the strand with hard copper core material coated with corrosion resistive copper alloy. CONSTITUTION:The strand 12 of an aerial insulated wire is made of hard copper core material 14 coated with corrosion resistive copper alloy film 14, and it generates no stress corrosion-cracking. By using such strands generating no corrosion cracking, an aerial insulated wire, the core material 14 of which can not be immersed with corrosive rain and which needs no watertight compound, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an overhead insulated wire made by twisting a plurality of wires together and applying an insulation coating to the twisted wires.

[Prior Art] It is known that overhead insulated wires made of multiple hard copper wires twisted together and coated with insulation may suffer from stress corrosion cracking and disconnection accidents if used for a long period of time. It is being

This stress corrosion cracking is thought to be caused by the interaction between corrosion factors and stress factors.

In this case, the cause of corrosion is that rainwater enters from the end of the wire, accumulates in the voids inside the wire, becomes concentrated, becomes corrosive, oxidizes the hard copper, and forms a thick black copper oxide film on the surface of the wire. rainwater further penetrates into the wire through the cracks in this film and dissolves the hard copper.The stress factors are residual stress from twisting and drum winding during wire manufacturing, and residual stress during overhead wire manufacturing. This is dynamic stress caused by wind, etc.

Conventionally, in order to prevent this stress corrosion cracking, electric wires have been manufactured by filling a hard copper strand with a watertight compound.

[Problem to be solved by the invention]

For electric wires filled with such watertight compounds, removing the watertight compound during electrical work is not only troublesome, but also poses the problem that if the watertight compound is not removed sufficiently, the electrical conductivity of the connection part will decrease. Ta.

The present invention provides an overhead insulated wire that does not require filling with a watertight compound by using wires that do not cause stress corrosion cracking.

[Means for Solving the Problems] The overhead insulated wire of the present invention is an overhead insulated wire in which a plurality of wires are twisted together and an insulation coating is applied thereto, in which the wires are attached to a core material made of hard copper. It is coated with a corrosion-resistant copper alloy.

[Function] Each strand of the overhead insulated wire of the present invention is formed by coating a core material made of hard copper with a corrosion-resistant steel alloy, and the surface of the strand is extremely resistant to oxidation. Therefore, corrosive rainwater does not infiltrate the internal hard copper, and the corrosion factor that is one of the causes of stress corrosion cracking is removed, so stress corrosion cracking does not occur in the conductor strands. .

In addition, since the core material of the wire is made of hard copper having tensile strength, the tensile strength of the electric wire will not be insufficient during overhead wiring.

[Example] The present invention will be further explained based on Examples below.
The present invention is not limited to these embodiments.

The figure shows a cross section of a stranded conductor in an overhead insulated wire according to an embodiment of the present invention, and seven strands 12 are twisted to constitute the stranded conductor. The wire 12 has a core material 14 made of hard copper and a coating layer 16 made of a corrosion-resistant copper alloy formed around the core material 14 .

The hard copper that is the core material 14 is electrolytic copper used for ordinary wire conductors, and may be either tough pitch copper or oxygen-free copper.

As the corrosion-resistant copper alloy that is the coating layer 16, for example, Fe
O, 3-0.9% by weight, AJ) 0.5-2.5% by weight,
and the balance consisting of Cu (JP-A-50-141519
(see Japanese Patent Laid-Open No. 51-8142), 1 to 5% by weight of Sn, 1 to 4.5% by weight of Si, and the balance Cu
8), and 0.03 to 3% by weight of Si, Z
Examples include those consisting of n1O to 20% by weight and the balance Cu (see JP-A-51-93391).

In the wire 12, since the coating layer 113 is formed of the above-mentioned corrosion-resistant copper alloy, the surface of the wire 12 is extremely unlikely to be oxidized. Therefore, corrosive rainwater does not enter the core material 14, and the corrosive factors are removed, so stress corrosion cracking does not occur in the wire 12.

The thickness of the coating layer 1B is preferably 175 or less of the radius of the wire 12 so that the insulated wire does not lack tensile strength during overhead contact.

In order to manufacture the strands used in the present invention, for example, dip
Corrosion-resistant copper alloy coated rough drawn wire obtained by the forming method may be drawn. That is, a hard copper wire is used as a seed wire, this hard copper wire is pulled up from the bottom of a crucible containing molten corrosion-resistant copper alloy, and the corrosion-resistant copper alloy is attached to the hard copper wire to obtain a rough drawn wire. The rough drawn wire may be drawn until it reaches a predetermined wire diameter.

The wires thus obtained are twisted together to have a desired conductor cross-sectional area, and then covered with an insulating material such as vinyl chloride resin or polyethylene to obtain the overhead insulated wire of the present invention.

Next, the results of a corrosion test performed using an embodiment of the overhead insulated wire of the present invention and a conventional overhead insulated wire will be shown.

Example: A hard copper wire was coated with 0.6% by weight of corrosion-resistant copper alloy (A) using the dip forming method.

After adhering 3% by weight and the balance Cu) to make a rough drawn wire, the rough drawn wire was drawn to obtain a wire having an outer diameter of 2.0 mm.

The thickness of the coating layer (corrosion-resistant copper alloy layer) in this wire is 0
．． It was 12 mm.

Next, 19 of these wires are twisted together to create a cross-sectional area of 60I+11.
A stranded conductor of No. 2 was formed, and an insulating coating was applied to this with polyethylene to obtain an overhead insulated wire.

A 30c+n length sample was cut from the insulated wire thus obtained and immersed in an ammonia aqueous solution with a concentration of 100 ppm for 8 weeks. During immersion, a heat cycle of 60°C x 8 hours and room temperature x 16 hours was repeated, and the ammonia aqueous solution was replaced with a new one every week. After 8 weeks, the insulating coating was removed from the sample and the average thickness of the copper oxide film formed on the conductor was determined.

The average thickness of the copper oxide film in this example was less than 0.1 μm, and the hard copper inside was not corroded. Therefore,
In this example, it is determined that the corrosion factor, which is one of the causes of stress corrosion cracking, has been eliminated.

An overhead insulated wire was obtained in the same manner as in the example except that a hard copper wire with a comparative exception diameter of about 2.0 was used as the strand.

When the same corrosion test as in the example was conducted using this overhead insulated wire, the average thickness of the copper oxide film formed on the conductor was 0.
, exceeding 2 μm, and the occurrence of a slight rack was observed.

[Effects of the Invention] Since the overhead insulated wire of the present invention uses a conductor that does not cause stress corrosion cracking, there is no need to fill the stranded conductor with a honey compound.

Therefore, there is no trouble in removing the watertight compound during electrical work, and there is no possibility that the watertight compound is insufficiently removed and the electrical conductivity of the connection portion is reduced.

[Brief explanation of the drawing]

The figure is a cross-sectional view showing a stranded conductor in an overhead insulated wire according to an embodiment of the present invention. Explanation of symbols 12...Element wire 14...Core material (hard copper) 16...Coating layer (corrosion-resistant copper alloy) and 1 other person

Claims (1)

[Claims] 1. An overhead insulated wire in which a plurality of wires are twisted together and coated with an insulation coating, wherein the wire is made of a core material made of hard copper and coated with a corrosion-resistant copper alloy. Electrical wire.