JPS6031049B2 - Method for manufacturing strand insulated cable conductor - Google Patents

Description

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

A stranded wire made of copper wires with a diameter of 2 to 3 wires is used for the power cable conductor.

It is also widely practiced to compact the fibers by compression-molding them with rolls or the like after twisting to eliminate the gaps between the individual fibers. Furthermore, for large capacity conductors, after twisting the strands together called split conductors,
A predetermined number of compression-molded segments having a fan-shaped cross-section are used in combination to have a circular cross-section. In such divided conductors, each segment is often insulated by wrapping paper or plastic tape. For example, in a 6-segment conductor with a conductor cross-sectional area of 2000, each segment has a diameter of 2.3
After twisting the side steel cables together, the volume filling ratio 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, 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, insulate each segment, and also insulate each strand to prevent current concentration on the surface layer of the conductor. Conventionally, as a method of insulating strands, there is an example of using an enamel-coated steel cable wire. In order to withstand the processing steps of twisting the strands and compression molding, an enamel coating with a thickness of 20 to 30 m or more is required, resulting in extremely high costs. For this reason, attempts have been made to use copper strands with oxidized steel formed on the surface as a cheaper insulator. Oxidized steel can be easily generated on the surface of a steel cable by oxidizing it in the atmosphere at high temperatures (for example, 300 oo or higher), but it is fragile and has poor adhesion to the copper interface, making it impractical. Instead, a method of chemical oxidation treatment using an alkaline aqueous solution with the aid of an oxidizing agent such as chlorous acid is adopted. The oxidized steel produced wet-processed in this way is composed of microcrystalline bodies, has the characteristics of being relatively resistant to processing and having excellent adhesion to the copper interface.
A film thickness of 2 to 3 meters 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. Higher costs are inevitable. In order to improve this, there has been an attempt to wet-process oxidized steel after processing such as twisting or compression molding, that is, an attempt to chemically treat the stranded wires or segments. However, with this method, in order to completely insulate the strands and wires inside the segments, especially the contact parts of the wires that are formed by twisting or compression molding, it is necessary to promote the infiltration of the processing liquid between the wires using ultrasonic waves. Even if such measures are taken, an average film thickness of 1 Am or more must be formed, and although the processing cost is slightly reduced compared to the case where the strands are chemically treated before being twisted, it is still necessary to form an average film thickness of 1 Am.
This is not practical since it is necessary to process the method so that the film thickness above is formed even on the surface of the strands inside the twisted conductor. Further, as a method of using ammonia or the like, there is a method of coexisting a vapor of ammonia or the like in an oxidizing humidified atmosphere.

Since this method uses poisonous gases such as ammonia, it requires equipment to ensure the airtightness of the container and to process the gas when taking out the conductor after the reaction, which inevitably increases costs. It was something. The present invention was made as a result of intensive research in view of the actual situation,
The object of the present invention is to provide an economical and highly productive method for manufacturing a high-performance cable chemical having a large wire insulation effect.

That is, in the present invention, after a conductor made of twisted copper wires is immersed in an aqueous solution containing ammonia or an aliphatic amine having carbon number of 5 or less, the conductor is held in an oxidizing humidified atmosphere, and an average layer is applied to the surface of the steel cable. This is a method for manufacturing a strand insulated cable conductor, characterized by forming a corrosion reaction product of 0.1 m or more.

According to the present invention, corrosion mainly consisting of copper oxide is generated even in the gaps between the contact points between the wires, which are created when the copper wires, which are soft metals, dig deeply into each other during the twisting process and the subsequent compression molding process. A coating of material forms quickly.

That is, oxygen is dissolved in the aqueous solution of ammonia or aliphatic amine as dissolved oxygen, and the dissolved oxygen rapidly reacts with copper due to the catalytic action of ammonia or aliphatic amine.
Forms a film of corrosion products consisting mainly of copper oxides. If the thickness of the coating thus formed is on average 0.1 m or more, it can function as a stranded insulated cable conductor. In the present invention, the time for soaking the conductor in the aqueous solution of ammonia or aliphatic amine depends on the shape of the conductor, etc., but is generally at least 3 minutes, preferably at least 5 minutes.

Further, at this time, it is effective to use ultrasonic waves or the like to make it easier for the aqueous solution to penetrate into the gaps between the strands of the conductor. The relative humidity of the oxidizing humidified atmosphere in the present invention may be about 60% or more, preferably 80% 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. Also,
The oxidizing nature of the oxidizing humidified atmosphere means that the atmosphere contains oxygen, but generally air may be used, and the oxygen concentration can also be increased by adding oxygen.

Ammonia or aliphatic amine is thought to act catalytically in the copper oxidation reaction, and a small amount is sufficient and a practical effect can usually be obtained by soaking the conductor in an aqueous solution of 0.01% or more.

Ammonia has the greatest effect of promoting this oxidation reaction.

Since the effectiveness of amines decreases as the number of carbon atoms increases, those with less than 5 carbon atoms can be used. Examples of such amines include methylamine, dimethylamine, ethylamine, propylamine, butylamine, etc., and they can be used as volatile liquids or aqueous solutions. be obtained. Ammonia or amine aqueous solutions attached to conductor wires evaporate and condense depending on the temperature of the atmosphere, etc., and can easily penetrate into noisy, narrow, close contact areas between wires due to capillary condensation, etc. It is something.

For this reason, a film of corrosion products is uniformly formed even in the extremely narrow areas where the strands are in close contact with each other. Ordinary stranded conductors and compression molded conductors have a small amount of organic film such as lubricating oil attached to the surface of the steel cables, so it takes a long time to obtain the desired oxide film thickness in an oxidizing humidified atmosphere where only humidification is performed. For example, since it takes several days or more, it may be unproductive and 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, it requires On the other hand, in the present invention, since ammonia or amine is contained in the oxidizing humidified atmosphere, an insulating film can be formed quickly even if the above-mentioned cleaning treatment 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, and is comparable to the coating produced by conventional wet chemical conversion treatment. At the same time, it has a great advantage in that there is almost no adhesion or occlusion of substances other than corrosion product coatings.

That is, as mentioned above, in the conventional wet processing method, since a concentrated solution of alkaline nonvolatile salts is used, a long cleaning time is required to sufficiently wash out the solution that has entered the gaps between the strands. Even so, there may be areas where cleaning is insufficient and salts may remain in those areas, and OF cables using such conductors will suffer from a decline in the performance of the insulating oil during operation, resulting in a fatal accident of insulation breakdown. In the method of the present invention, ammonia and aliphatic amines having 5 or less carbon atoms are both volatile substances, and only a small amount is used. It is normal that it cannot be recognized.

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, 7
In any case, the present invention does not require cleaning because such residues can be completely eliminated by simply adding a simple step of heating at a temperature of 0 to 8,000 or higher for a short time. The time required for the reaction varies depending on humidity, temperature, etc., but is usually within 2 to 3 days.

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

Note that it is better to keep the conditions in the chamber constant, but it is more beneficial to change the temperature or the temperature cyclically up and down to further promote the reaction. In the present invention, a conductor made of twisted steel cables is a conductor made by simply twisting a desired number of steel cables, or a conductor made by further compression molding this conductor.
It is a so-called compressed conductor, and there are no limitations on the shape of the conductor.

Although it is common for segmented conductors to treat each segment according to the method of the present invention and then form the segment into a segmented conductor, the present invention allows the segment to be formed into a segmented conductor without being treated to form corrosion products. Processing may be performed using a method. As described above, in the present invention, by soaking a stranded wire conductor in an aqueous solution of ammonia or aliphatic amine, the aqueous solution is trapped in the gaps between the strands, and this is caused by the temperature and humidity of the oxidizing humidified atmosphere. Because it tries to balance with the vapor pressure, it easily penetrates into noisy, narrow, close-contact areas between the strands due to capillary condensation, etc., and as a result, the strands on the conductor surface also enter between the strands inside the stranded wire conductor. An insulating film with almost the same thickness as the wire is formed.

Therefore, in the conventional wet oxidation treatment method, where there was a large difference in the thickness of the insulation coating formed on the inner and outer wires of the conductor, the thickness of the insulation coating formed on the outer wire located on the surface of the conductor was significantly thicker. However, in the present invention, as described above, the average wall thickness was as thick as 2 to 3 rm because a coating thick enough for electrical insulation would not be generated on the internal strands unless treated until Since a coating having approximately the same thickness is uniformly generated on both the inner and outer strands, the electrical function can be achieved with an average thickness of at least 0.1 m.

Moreover, in the present invention, the film formation reaction itself is carried out in a wet manner, so unlike conventional dry oxidation treatment methods, it is possible to easily obtain an insulating film that is dense in number, has good adhesion to the copper interface, and has relatively good workability. It will be done. Next, the present invention will be explained using Examples and Comparative Examples. Example [1] Annealed copper wires having a diameter of 2.3 mm were twisted together and compression molded into a suspended cross-section to obtain segments.

This segment was wound into a coil, soaked in 0.5% ammonia water for 10 minutes, kept in the atmosphere for 3 minutes to drain the liquid, and then placed in a chamber at a relative humidity of 85% and a temperature of 6000 for 1 hour. After leaving it for a while, the segment was taken out.

A part of the thus treated segment was cut out and subjected to cathodic reduction (electrolyte 0.1N KCI aqueous solution, fly flow density 0.
The copper oxide film on the surface was measured at 8hA/ground) and found to have an average thickness of 0.49mm.

Next, the six segments thus obtained were twisted together to form a six-divided conductor with a conductor cross-sectional area of 2000, and
CS-1 DC resistance value R of this conductor according to the existing measurement method
. The lateral skin effect coefficient y=stem-- was calculated for the 50-day 2-ac resistance value R^ and y=0.04.

Note that y of a six-segment conductor made from segments that were not subjected to any of the above treatments was 0.16.

Example ■Example {Thickness of steel oxide coating of a segment obtained in exactly the same manner as Example '1' except that a 5% dimethyl aqueous solution was used instead of 0.5% ammonia water in Example 1' was 0.22 m on average, and y of the 6-segmented conductor obtained in the same manner was 0.09.

Moreover, when the standing time in the chamber was set to 2 hours, the average thickness of the coating was 0.411 m, and y was 0.04.

Example [3] Example [...If the experiment was conducted in exactly the same manner as in Example 1, except that the ammonia water concentration was 3%, the relative humidity was 95%, and the temperature was 500C, the thickness of the coating was was 1.3 fm on average, and y was 0.02.

Example '4} In Example (1}, except that the aqueous ammonia concentration was 0.05%, the relative humidity was 95%, and the temperature was 6500, the experiment was conducted in exactly the same manner as in Example (1-).
The average thickness of the coating was 0.28 mm, and y was 0.09.

Example ■Example {1'' In a boiler, 3% propylamine aqueous solution was used instead of ammonia water, immersed between two vessels while applying ultrasonic waves, and left in a chamber for 2 hours.
When the experiment was carried out in exactly the same manner as in Example [1-] except that the time was 4 hours, the average coating thickness was 0.35 rm, and y was 0.
It was 07.

Comparative Example '1' When Example '1' was carried out in exactly the same way as Example '1' except that immersion in ammonia water was not carried out, the average film thickness was 0.06 mm, and y was It was 0.13.

Comparative Example ■ Comparative Example '111 In this case, before placing the segment in the chamber, the segment was immersed in an industrial allonutate solvent for 1 hour to degrease the segment, then dried, and then placed in the chamber. As a result of processing under the same conditions as Example '11, the average film thickness was 0.13 fm, and y was 0.
It was 10.

As described above, according to the method of the present invention, the corrosion product film, which is mainly made of copper oxide, formed on the conductor wire is uniformly formed even between the wires inside the conductor, so that the average film of the conductor as a whole is Not only can it effectively provide electrical insulation between each strand even if it is thin, but it also has excellent adhesion to the steel interface and is dense, so it is resistant to mechanical and thermal deformation caused by the conductor during cable use. can also be tolerated well.

The treatment according to the present invention also includes a container for first immersing the coiled conductor in an ammonia or amine aqueous solution;
It consists of a chamber that can store the conductor after the treatment, and a simple and inexpensive device that generates and controls temperature, humidity, etc., and can be carried out with equipment that requires only a small space.

The process is simple as it can be used as a conductor by simply immersing it in an ammonia or amine aqueous solution for a short time, leaving it in a chamber for a predetermined period of time, and taking it out. Therefore, the present invention is a method that is significantly superior in terms of 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 by twisting copper wires with ammonia or carbon number 5
A wire insulated cable characterized by being immersed in the following aqueous solution of aliphatic amine and then held in an oxidizing humidifying atmosphere to form a corrosion reaction product with an average size of 0.1 μm or more on the surface of the copper wire. Method of manufacturing conductors. 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.