JPS6031047B2 - 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 each having two to three ribs in diameter is used for the cable conductor.

It is also widely practiced to compact the wires by compression molding them using an o-ru or the like after twisting to eliminate the gaps between the individual wires. Furthermore, in the case of a large capacity conductor, a desired number of segments, called split conductors, which are formed by twisting strands of wire and then compression molded 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 case of a 6-segment conductor of 0.000 mm, each segment is made by twisting together steel cables with a diameter of 2.3 ribs, compressing the conductor to a volume filling rate of 85 to 90%, and forming it into a fan shape. As the capacity of AC power transmission increases, the size of the conductor is becoming larger, and as the size of the conductor becomes larger, power transmission losses due to skin effect and proximity effect suddenly become noticeable.

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

To withstand the processing process of twisting and compression molding of Qin wire 2
This requires an enamel coating with a film thickness of 0 to 30 A or more, resulting in extremely high costs. For this reason, attempts have been made to use copper wire with oxidized nodes formed on its surface as a cheaper insulator. Oxidized steel can be easily formed on the surface of a copper wire by oxidizing it in the atmosphere at high temperatures (for example, 30,000 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. The copper oxide thus produced in an overflowing manner consists of microcrystals and has relatively good workability and adhesion. A film thickness of 2 to 3 ridges or more is required to withstand the processing of twisting and compression molding, but forming a film with such thickness using a wet method 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 have been attempts to wet-form oxidized steel after processing such as twisting and compression molding, that is, to chemically treat the strands or segments. However, with this method, in order to completely insulate the stranded wires and the wires inside the segments, especially the contact parts of the wires that are formed by twisting or compression molding, it is necessary to prevent the treatment liquid from entering between the wires by the action of ultrasonic waves. Even if measures such as acceleration are taken, it is necessary to form an average film thickness of lr or more, and although the processing cost is slightly lower than when chemical conversion treatment is applied to the strands before twisting, it is still necessary to form an average film thickness of 1 m This is not practical because processing must be carried out so that a film with a thickness greater than 100% is formed internally as well. 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 Qin wire insulation effect.

That is, in the present invention, a conductor made of twisted steel cables is maintained in a humidified oxidizing atmosphere containing ammonia or an aliphatic amine having a carbon number of 5 or less, and corrosion reaction products with an average concentration of 0.1 or more are formed on the surface of the steel cables. This is a method of manufacturing a plain green insulated cable conductor, characterized by forming a green insulated cable conductor.

The present invention is designed to rapidly remove mainly copper oxide from the surface of the wires, even in the minute deep gaps in the contact areas of the wires, which have been lightly bitten into each other by twisting or compression molding the soft metal steel wires. This method forms a film of corrosion products.

In other words, in the present invention, ammonia or aliphatic amine, water vapor, and oxygen (air) are allowed to enter between the strands in a gaseous state that has better diffusivity than liquid, and the surface tension that acts in the narrow gap causes ammonia or aliphatic amine to enter between the wires. By condensing water vapor containing water into liquid water, the corrosion reaction of the bowl caused by oxygen etc. takes place rapidly. In short, the corrosion reactant is supplied to the details of the pseudogreen line in a gaseous state with good diffusivity, and the reaction is carried out in a liquid state with extremely high reactivity. Therefore, in the present invention, by simply holding a conductor made of twisted steel cables in a humidified oxidizing atmosphere containing ammonia or an aliphatic amine having a carbon number of 5 or less, ammonia or amines in the air can be removed between the strands. Oxygen and moisture both easily enter in the gaseous state, where the moisture becomes a liquid state, ammonia or amine and oxygen are dissolved in liquid water, and the dissolved oxygen rapidly reacts with copper due to the catalytic action of ammonia or amine. This forms a film of corrosion products consisting mainly of copper oxides.

If the thickness of the coating thus formed is 0.1 mm or more on average, it can function as a stranded insulated cable conductor. In the present invention, the humidity of the humidified oxidizing atmosphere may be about 80% or more in terms of relative humidity, preferably 90% or more.

The temperature at this time may be room temperature, but the reaction proceeds more rapidly with flooding, so the temperature is preferably about 4°C or higher. Further, the oxidizing atmosphere here means that it contains oxygen, and generally air may be used, and the oxygen concentration may be increased by adding oxygen. Ammonia or aliphatic amine is thought to act catalytically in the oxidation reaction, and its amount may be trace or small, and can usually exert a practical accelerating effect. Ammonia has the greatest promoting effect, and its conductor, aliphatic amine, also exhibits sufficient effects, but as the number of carbon atoms increases, the effect decreases, and when the number of carbon atoms is 6 or more, it has no practical promoting effect. is difficult to obtain. Therefore, the aliphatic amine used in the present invention has 5 or less carbon atoms, such as methylamine, dimethylamine, ethylamine, propylamine, butylamine, etc., and is available as a volatile liquid or an aqueous solution. Ordinary twisted or compression-molded conductors have a small amount of organic film such as lubricating oil attached to the surface of the copper wire, so in an oxidizing atmosphere with only humidification, it takes a long time (for example, several hours) to obtain the desired oxide film thickness. Since it takes more than a day, productivity is poor and it may be impractical.

For this reason, it is possible to clean the conductor with the organic film attached in advance with an organic solvent such as toluene, but it requires a large amount of solvent and equipment, power, manpower, etc. to completely clean the gaps between the wires. Needless to say, this is essential. On the other hand, in the present invention, since ammonia or amine is contained in the humidified oxidizing atmosphere, an insulating film can be formed quickly even if the above-mentioned cleaning pretreatment is omitted, which is extremely advantageous industrially. .

Furthermore, the insulating coating obtained by the method of the present invention, that is, the corrosion product coating mainly consisting of copper oxide, is dense and has excellent adhesion to the steel interface, compared to the coating produced by conventional wet chemical conversion treatment. It is comparable in quality, and at the same time has a great advantage in that there is almost no adhesion or occlusion of substances other than corrosion products. That is, as mentioned above, in the conventional green processing method, a concentrated solution of alkaline non-bright salts is used, and therefore, a long cleaning time is required to sufficiently wash out the solution that has entered the gaps between the strands. Even so, there will be areas where cleaning is insufficient and salts will remain there, and in OF cables using such conductors, the performance of the insulating oil will deteriorate during operation, resulting in a fatal accident called dielectric breakdown. In the method of the present invention, ammonia or aliphatic amines having carbon atoms of 5 or less are volatile substances and are used only in small quantities, so traces of ammonia or amines are observed in the conductor after reaction treatment without cleaning. It is normal to not get it.

Therefore, the conductor does not require any cleaning after the reaction treatment.
Even if there is concern about residual ammonia or amines due to processing conditions, such as processing at low temperatures, the
In any case, the present invention does not require cleaning, since such residues can be completely eliminated by simply adding a simple step of heating at a temperature of ~80 oo or more for a short time. The time required for the reaction varies depending on humidity, temperature, atmosphere, etc., but is usually within 2 to 3 days.

The treatment method is not particularly limited; for example, it is sufficient to simply leave a conductor made of twisted steel wires in a coiled state, preferably in a chamber filled with humidification. A black coating is formed on the surface of the wire.

Note that, rather than keeping the conditions in the chamber constant, it is advantageous to cyclically change the humidity or temperature up and down to further promote the reaction. A certain amount of ammonia or amine can be injected into the chamber in a gaseous state, or it can also be used as an aqueous solution by placing it in the bottom of the chamber and generating its vapor. In the present invention, a conductor made of twisted steel cables is a conductor made by simply tying together a desired number of steel cables, or a conductor obtained by compression molding this conductor, and there are no limitations on the shape of the conductor.

For segmented conductors, it is common to process each segment by the method of the present invention and then form the segments into segmented conductors. Processing may be performed. As described above, in the present invention, since the moisture etc. necessary for the hot corrosion reaction are first supplied in a gaseous state, the moisture etc. are quickly and uniformly supplied to the minute gaps between the internal strands of the stranded conductor. There, it condenses into liquid water, and as a result, an insulating coating is formed between the internal strands with a thickness that is almost the same as that of the strands 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 insulating film formed on the inside and outside of the conductor, the thickness of the insulating film formed on the strands located on the surface of the conductor was significantly different. If the film is not treated until it becomes thick, a film with the thickness necessary for electrical insulation of the internal strands will not be generated, so the average thickness will be as thick as 2 to 3 r as a whole.In contrast, in the present invention, the above-mentioned As shown in FIG. 2, a coating having approximately the same thickness is uniformly formed on both the inner and outer strands, so that the electrical function can be achieved with an average thickness of at least 0.1 mm.

Furthermore, in the present invention, the film formation reaction itself is carried out in a wet manner, so unlike the conventional green oxidation treatment method, the insulating film, which is dense, highly adhesive, and relatively processable, is easily bound.

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

Example 1 Mild steel wires having a diameter of 2.3 mm were twisted together and compression molded into a fan-shaped cross section to obtain segments. This segment is wound into a coil at a relative humidity of 95% and a temperature of 70%.
was placed in the chamber. Air containing 70 g of blood ammonia gas was introduced into the chamber. After leaving it for one hour, the coiled segment was taken out.

A part of the thus treated segment was cut out and subjected to cathodic reduction method (electrolyte 0.1N-KC aqueous solution, tortoise current density 0.
The copper oxide film on the surface was measured using a method of measuring the thickness of the copper oxide film, and the average thickness was 0.41 mounds.

Next, six segments obtained in this way are twisted together to form a six-divided conductor with a conductor cross-sectional area of 2000, and the DC resistance value Ro
The skin effect coefficient y=Sagi-1 was calculated by measuring the 50Hz AC resistance value R^ and found to be 0.04.

In addition, the value of the segment that did not undergo any of the above processing is 0.1.
It was 5.

Example 2 An experiment was carried out in exactly the same manner as in Example 1, except that 50% methylamine solution was used in the chamber instead of ammonia gas inflow. As a result, the average thickness of the steel oxide film was 0.25 r. and the skin effect coefficient y is 0. It was a female.

Further, when the standing time in the chamber was 2 hours, the average thickness of the film was 0.52 peaks, and y was 0.05.

Example 3 When an experiment was conducted in exactly the same manner as in Example 1 except that the relative humidity was 90%, the temperature was 60%, and the ammonia gas concentration was 100Q, the average thickness of the copper oxide film was 0.
201, and y was 0.09.

Example 4 In Example 1, the relative humidity was % and the temperature was 80o.
o, Example 1 except that the ammonia gas concentration was 9 m
When an experiment was conducted in exactly the same manner as above, the average thickness of the copper oxide film was 0.52r, and y was 0.04.

Example 5 If an experiment was conducted in exactly the same manner as in Example 1, except that a 5% aqueous solution of propylamine was used in the chamber for 50 minutes instead of ammonia gas inflow, and the treatment time was changed to 24 hours, the film thickness would be as follows. The average is 0.37 peaks, y
was 0.07.

Example 6 The same six compression molded segments used in Example 4 were twisted together to form a 6-segment conductor, and then heated to a relative humidity of 95% and a temperature of 9.
Pi○, when I put it in a chamber with an ammonia gas concentration of 100 and left it for 2 hours, the average thickness of the oxide film was 0.4
8 Buddhas, and y was 0.05.

Comparative Example 1 When Example 1 was carried out in exactly the same manner as in Example 1 except that ammonia gas was not introduced, the average coating thickness was 0.07 mm, and y was 0.13.

Comparative Example 2 In Comparative Example 1, prior to treatment, the segment was immersed in an industrial aromatic solvent for 1 hour to degrease the segment, then dried, then placed in a chamber, and then subjected to the same conditions as Comparative Example 2. As a result of the treatment, the average film thickness was 0.13 mm, and y was 0.10.

As described above, according to the method of the present invention, the corrosion product film formed on the upper conductor strand is uniformly formed even between the strands inside the conductor, so that the average film thickness of the entire conductor is thin. Not only can it effectively exert an electrical insulation effect between each strand even when the cable is in use, but also it can sufficiently withstand the mechanical and thermal deformation that the conductor undergoes during use of the cable because it is close and dense.

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 0 and using it as a conductor. Therefore, the present invention is a method that is significantly superior in terms of productivity and economy compared to the conventional wet treatment method, which uses a large amount of toxic chemicals and water and requires wastewater treatment.

Claims (1)

[Claims] 1. A conductor made by twisting copper wires with ammonia or carbon number 5
1. A method for manufacturing a wire insulated cable conductor, which comprises maintaining the following in a humidified oxidizing atmosphere containing vapor of an aliphatic amine to form a corrosion reaction product having an average size of 0.1 μ or more on the surface of a copper wire. 2. The method for manufacturing a strand insulated cable conductor according to claim 1, wherein the conductor made of twisted copper strands is a split conductor. 3. The method for manufacturing a strand insulated cable conductor according to claim 1, wherein the conductor made of copper strands is a conductor that is compression-molded after stranding copper strands.