JPS5919612B2 - Method for manufacturing strand insulated cable conductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a power cable conductor, particularly a bare wire insulated cable conductor with reduced skin effect used for large capacity power transmission.

A stranded wire made by twisting copper wires with a diameter of 2 to 31 mm is used for the power cable conductor.

It is also widely practiced to compact the wires by compression-molding them using rolls or the like after twisting to eliminate gaps between the wires. Furthermore, in the case of large capacity conductors, a desired number of segments, called split conductors, which are obtained by compression molding the strands of strands into a fan-shaped cross section, are used in combination to form a circular cross section. In such divided conductors, each segment is often insulated by wrapping paper or plastic tape. For example, conductor cross-sectional area 2
In the 00 Rei 12 6-segment conductor, each segment has a diameter of 2.3
After twisting 88 copper wires of n, the volume filling rate is 85 to 90.
% and shaped into a fan shape. As the capacity of AC power transmission increases, the size of conductors is becoming larger, and as the size of conductors becomes larger, transmission losses due to skin effect and proximity effect suddenly become more noticeable.

Skin effect loss is particularly important, and the essential countermeasure is to divide the conductor into multiple segments and insulate each segment, as well as insulate each strand to prevent current concentration on the outer surface of the conductor. Conventionally, there is an example of using an enamel-coated copper wire as a method of insulating wire.

To withstand the process of twisting strands and compression molding 2
This requires an enamel coating with a thickness of 0 to 30 μm or more, resulting in extremely high costs. For this reason, cheaper insulators and
There is an attempt to use copper wire with copper oxide formed on its surface. Copper oxide can be easily produced on the surface of a copper wire by oxidizing it in the atmosphere at high temperatures (eg, 300° C. or higher), but it is brittle and has poor adhesion, making it impractical. Instead, a method of chemical oxidation treatment using an oxidizing agent such as chlorous acid in an alkaline aqueous solution is adopted. Copper oxide wet-produced in this way is composed of microcrystals and has relatively good processability and adhesion. A film thickness of 2 to 3 μm or more is required to withstand the processing of twisting and compression molding, but forming such a thick film using a wet process requires a large amount of chemicals and a long time, which is costly. It is inevitable that the price will rise. In order to improve this problem, there has been an attempt to wet-form copper oxide after processing such as twisting or compression molding, that is, an attempt has been made to chemically treat the stranded wires or segments. However, with this method, in order to completely insulate the wires inside the twisted wires and segments, especially the contact parts of the wires that are formed by twisting or compression molding, it is difficult to completely insulate the wires inside the twisted wires or segments, especially when the treatment liquid enters between the wires due to the action of ultrasonic waves. Even if efforts were made to promote this, there was a drawback that an average film thickness of 1 μm or more had to be formed. The present invention was made as a result of intensive research in view of the above circumstances, and provides an economical and highly productive method for manufacturing a high-performance cable conductor with a large wire insulation effect.

That is, the present invention relates to the production of a strand insulated cable conductor, which is characterized in that a conductor made of stranded copper strands is held in a humidified atmosphere to form corrosion products with an average size of 0.1μ or more on the surface of each copper wire. It's a method.

The present invention eliminates corrosion products on the surface of copper wires, which are soft metals, and can quickly be deposited on the surface of the wires even in the minute and deep gaps where the wires are in contact with each other, where the copper wires are twisted or compressed into each other. 'This is a method of forming a film. In other words, in the present invention, the corrosion reaction of copper by oxygen and the like occurs rapidly by allowing moisture to enter in a gaseous state, which has better diffusivity than liquid, and converting it to liquid water. In short, the corrosion reacting substance is supplied to the details of the stranded wire in a gaseous state with good diffusivity, and the reaction therein is carried out in a liquid state with extremely high reactivity. Therefore, in the present invention, by simply holding a conductor made of twisted copper wires in a humidified atmosphere, oxygen and moisture in the air can easily enter the inter-wire details 4 in a gaseous state. In the liquid state, the oxygen dissolves in the liquid water to form dissolved oxygen, which rapidly reacts with the copper to form a film of corrosion products.

If the thickness of the coating thus formed is on average 0.1 .mu. or more, it can function as a stranded insulated cable conductor. In the present invention, the humidity of the humidified atmosphere is approximately 8 in terms of relative humidity.
It is sufficient if it is 0% or more, preferably 90% or more. The temperature at this time may be room temperature, but the reaction proceeds more rapidly when heated, so it is preferably about 40° C. or higher. The time required for the reaction varies significantly depending on humidity, temperature, atmosphere, etc.
In an atmosphere where the air is simply humidified, it usually takes 1 to 7 days.

The treatment method is not particularly limited; for example, a conductor made of twisted copper wires may be wound into a coil and left in a humidified and heated chamber. A black coating is formed on the surface of the wire.

Note that, rather than keeping the conditions within the chamber constant, it is advantageous to cyclically change the humidity or temperature up and down to further promote the reaction. Furthermore, in the present invention, by allowing a trace amount of sulfur or a sulfur compound to coexist in the humidified atmosphere, the time required for the reaction can be significantly shortened.

This is thought to be because sulfur compounds and sulfur catalytically promote the reaction. Examples of the sulfur compound or sulfur that can be used include hydrogen sulfide, sulfur dioxide gas, sulfur trioxide, and simple sulfur, among which hydrogen sulfide has the most remarkable effect. Hydrogen sulfide has a trace amount of 0.1 to 1-1 in a humidified atmosphere, about 100 times more, and sulfur dioxide gas has a 50 to 10
Even a small amount of 0% each exhibits about 10 times the reaction promotion effect. Therefore, in the present invention, by allowing a small amount of sulfur compound or sulfur to coexist in the humidified atmosphere, the time required for the reaction can be shortened from several hours to about one day.

Such a catalytic promoting effect of sulfur or sulfur compounds only occurs under heating. The corrosion product film thus obtained also contains a very small amount of copper sulfide, but this is not a problem. However, if an excessive amount of sulfur compounds are allowed to coexist in a humidified atmosphere, a brittle coating consisting mainly of copper sulfide will result, so the coexistence of large amounts of sulfur compounds must be avoided. Note that since the amount of sulfur compounds coexisting in the humidified atmosphere is small, it can be easily detoxified by desulfurizing the gas in the chamber after the treatment is completed. In the present invention, a conductor made by twisting copper wires is a conductor made by simply twisting a desired number of copper wires together, or a conductor obtained by compression molding this conductor, and there are no restrictions on the shape of the conductor. Not done.

For segmented conductors, it is common to treat each segment according to the present invention and then form the segments into segmented conductors. You may do so. As described above, in the present invention, since the moisture necessary for the wet corrosion reaction is first supplied in a gaseous state, the moisture is quickly and uniformly supplied to the minute gaps between the internal strands of the stranded conductor, where it condenses. As a result, an insulating coating is formed between the internal wires with a thickness that is almost the same as that of the wires on the surface of the stranded wire conductor.

Therefore, in the conventional wet oxidation treatment method, where there was a large difference in the thickness of the insulation coating formed on the strands inside and outside the conductor, the insulation coating formed on the strands located on the surface of the conductor was significantly thicker. However, in the present invention, as described above, the inner and outer wires are thicker than the average thickness of 2 to 3μ because the internal wires cannot be coated with the thickness necessary for electrical insulation. Since a film of approximately the same thickness as the wire is uniformly produced, the electrical function can be achieved with an average thickness of at least 0.1 μm.

Moreover, in the present invention, the film formation reaction itself is carried out wetly, so unlike conventional dry oxidation treatment methods, an insulating film that is dense, highly adhesive, and relatively processable can be easily obtained.

Next, the present invention will be explained using Examples and Comparative Examples.

Example 1 Diameter 2.37! Eighty-eight Lm annealed copper wires were twisted together and compression molded into a fan-shaped cross section to obtain segments.

This segment is wound approximately 120m into a coil, and this is
The sample was left in a chamber at a relative humidity of 95% and a temperature of 60° C. for 7 days. A part of the thus treated segment was cut and the average oxide film thickness was measured by cathodic reduction method (electrolyte solution 0.1N-KCl, electrolytic current density 0.5 mA/d) and found to be 0.15μ.

Next, six segments thus obtained were twisted together to form a six-divided conductor with a conductor cross-sectional area of 2000 m1.

DC resistance value (RD) and 50Hz for this 6-divided conductor
AC resistance value (RA) and skin effect coefficient RA are measured respectively.
When γ=111 was calculated, γ=0.08.

R1 ・Comparative example Example 1 without performing any corrosion generation treatment on one segment
A 6-segmented conductor was obtained in the same manner as above, and the skin effect coefficient γ and naturally formed oxide film thickness were determined in the same manner as in Example 1. γ = 0.14, and the average film thickness was 0.018μ. .

Example 2 Eighty-eight annealed copper wires each having a diameter of 2.3 mm were twisted together and compressed into a fan-shaped cross section to obtain segments.

Next, six of these segments are twisted together to create a conductor with a cross-sectional area of 20
After forming a 6-segmented conductor of 0.00 m2, 50 m of this conductor was left in a chamber at a relative humidity of 98% and a temperature of 50° C. for 15 days to undergo corrosion formation treatment. Regarding the conductor thus obtained,
When the average oxide film thickness and skin effect coefficient were determined in the same manner as in Example 1, the film thickness was 0.4 μm and the skin effect coefficient γ was 0.03.

Comparative Example 2 The average oxide film thickness and skin effect coefficient were determined for a conductor obtained in the same manner as in Example 2, except that the conductor was subjected to corrosion generation treatment for one day, and the film thickness was 0.07μ. The skin effect coefficient γ was 0.12.

Example 3 In Example 2, instead of leaving the sample in a chamber at a relative humidity of 98% and a temperature of 50° C. for 15 days, a relative humidity of 9001
), the conductor was treated in the same manner as in Example 2, except that it was left in a chamber at a temperature of 80° C. for 5 days.

The average oxide film thickness and skin effect coefficient γ of the thus obtained conductor, which were determined in the same manner as in Example 1, were each 0.7μ.
and 0.03.

Example 4 In Example 2, instead of leaving the sample in a chamber at a relative humidity of 98% and a temperature of 50°C for 15 days, a relative temperature of 800I was used.
), SO2 gas was added at 50°C, and the conductor was treated in the same manner as in Example 2, except that it was left in a chamber at a temperature of 50°C for 3 days.

The average film thickness and skin effect coefficient γ of the thus obtained conductor were determined in the same manner as in Example 1, and were 0.4μ and 0.4μ, respectively.
It was 05.

Example 5 Instead of leaving it in a chamber at a relative humidity of 98% and a temperature of 50°C for 15 days in Example 2, a relative humidity of 90q6,
H, S gas 0.5P! The conductor was treated in the same manner as in Example 2, except that 1 was added and the conductor was left in a chamber at a temperature of 50° C. for 2 days.

The average film thickness and skin effect coefficient γ of the thus obtained conductor were determined in the same manner as in Example 1, and were 065μ and 0, respectively.
．． It was 03.

Example 6 Instead of leaving the sample in a chamber at a relative humidity of 95% and a temperature of 60° C. for 7 days in Example 1, a temperature of 95% relative humidity and H2
A conductor was obtained in the same manner as in Example 1, except that S gas 1 was added and the sample was left in a chamber at a temperature of 60° C. for 12 hours.

The average film thickness and skin effect coefficient γ of the thus obtained conductor were determined in the same manner as in Example 1, and were 0.6 μ and 0, respectively.
．． It was 03.

As described above, according to the method of the present invention, the corrosion product film formed on the conductor strands is evenly formed between the strands inside the conductor, so even if the film thickness is thin, Not only can it effectively exert an electrical insulation effect, but since it is tightly adhered and dense, it can sufficiently withstand the mechanical and thermal deformation that the conductor undergoes while the cable is in use.

Furthermore, the treatment according to the present invention can be carried out with equipment that requires only a small space, as it consists of a chamber that can accommodate a coiled conductor and a simple and inexpensive device that generates and controls temperature, humidity, etc.

The process is as simple as leaving it for a predetermined period of time, then taking it out of the chamber and using it as a conductor. Therefore, it is significantly superior in both productivity and economy compared to conventional wet treatment methods that use large amounts of toxic chemicals and water and require wastewater treatment.

Claims (1)

[Claims] 1. A conductor made of stranded copper wires is held in a humidified atmosphere to allow moisture to enter the surface of each copper wire in a gaseous state, and then to be converted to liquid water and mixed with oxygen, etc. 1. A method for producing a stranded insulated cable conductor, which comprises reacting to form corrosion products with an average size of 0.1 μ or more. 2. The method for manufacturing a stranded insulated cable conductor according to claim 1, characterized in that a trace amount of sulfur or a sulfur compound is allowed to coexist in the humidified atmosphere. 3. The method for manufacturing a strand insulated cable conductor according to claim 1 or 2, wherein the conductor made of copper strands twisted together is a divided conductor. 4. The strand insulated cable conductor according to claim 1 or 2, wherein the conductor made of copper strands is a conductor that is compression-molded after stranding the copper strands. manufacturing method.