JPS6120088B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a method of manufacturing an insulated conductor, which aims to reduce the AC resistance of the conductor in order to increase the power transmission capacity. Generally, the purpose of technological development in ultra-high voltage, high capacity power transmission cables is to increase the power transmission capacity per line of the cable, and to do so, (1) increasing the size of the conductor, (2) increasing the voltage of the cable, (3) ) It is necessary to reduce the cable loss. Reducing loss in cables has the effect of conserving resources in itself, but in the case of underground cables, for example, the power transmission capacity is limited by temperature rise due to heat generation in the cables. Reducing cable loss increases cable capacity and reduces cable size. Conventionally, in order to reduce this loss, various studies have been conducted on the conductor, insulator, and metal sheath that make up the cable. Regarding this inner conductor, research is being conducted on measures to reduce the skin effect caused by the large size of the conductor, but it is still in the prototype stage and has not yet been put into practical use. In the case of AC cables, the skin effect means that in addition to the normal ohmic loss, overcurrent loss occurs on the conductor surface due to the AC magnetic field. This overcurrent causes a skin effect and increases conductor resistance. In view of the current situation, the present invention has conducted extensive research on methods for reducing the skin effect of large-sized conductors, and has found that it is extremely effective to insulate the surface of the conductor, and that the skin effect can be formed on the surface of the conductor by oxidizing the conductor. The present invention was achieved by confirming that the copper oxide produced by the present invention has excellent insulating properties. That is, in the present invention, after a copper conductor is immersed in an oxidation treatment solution in which caustic soda and sodium hypochlorite are added and dissolved in a mixture of water and an organic solvent that is water-soluble and has a boiling point of about 100°C or less, The method is characterized in that a copper oxide film is formed on the surface of the copper conductor by heating it to a temperature at or near the boiling point of the organic solvent. To explain in detail the oxidation treatment liquid for oxidizing the surface of the conductor in the present invention, first, the organic solvent used for the mixture of organic solvent and water is one that is soluble in water and has a boiling point of about 100°C or less. For example, methanol and ethanol are preferred. The ratio of organic solvent to water is 1 part water to 0.2 part organic solvent.
Use a mixture in the range of 2 to 2. Caustic soda and sodium hypochlorite are added to this mixed solution as oxidizing agents, and the amount added is usually 10 to 10% of the above mixed solution.
It is preferable to dissolve 80 g of sodium hypochlorite and 50 to 150 g of sodium hypochlorite. The copper conductor is immersed in this treatment liquid to cause an oxidation reaction, but the reaction is not promoted when the treatment liquid is at room temperature. Therefore, it is used by heating to a temperature at or near the boiling point of the organic solvent, for example, about ±20°C. Note that sufficient oxidation can be achieved with a dipping time of about 1 to 3 minutes. Therefore, the conductor may be oxidized while passing through the treatment liquid. The reason why a mixture of water and an organic solvent was used as the medium for the above-mentioned treatment liquid is that when heated as described above, the organic solvent boils in the water and stirs the water, which prevents oxidation with the conductor. This is because the reaction is significantly accelerated. Regarding the amount of caustic soda and sodium hypochlorite added, it is dangerous if more than 80 g of caustic soda and 150 g of sodium hypochlorite are added to the above mixed solution 1, respectively. This is because if the amount of acid soda is less than 50 g, the oxidation reaction will not be promoted and an oxide film cannot be deposited on the surface of the copper conductor. In addition, in the method of the present invention, by applying ultrasonic waves of 5KC to 20MC to the above-mentioned processing solution and allowing it to react with the conductor, the penetration of the oxidation processing solution into the conductor and the oxidation reaction are greatly promoted, thereby shortening the oxidation processing time. I can do it. Further, the oxidation treatment time can be shortened by preheating the conductor to a temperature higher than the heating temperature of the oxidation treatment liquid by high-frequency induction heating or the like and passing it through the oxidation treatment liquid. Next, examples of the present invention will be described. Example A black oxide film was adhered to the conductor surface of a 1×2000 mm ² six-segment copper conductor under the treatment conditions shown in Table 1. In order to compare with the method of the present invention, an oxidation treatment solution with a different composition was used and the conductor surface was oxidized in the same manner as above, but no oxide film was formed and it remained almost copper-colored. .

【table】

[Table] Next, an AC potentiometer was used to measure the skin effect of the conductor of Example (2) and Comparative Example (1). The results are shown in Table 2.

[Table] As is clear from the above table, according to the method of the present invention, the skin effect of the conductor is approximately 1/3 that of a copper conductor without an oxide film.
Therefore, the effect of reducing conductor loss was clearly demonstrated. As detailed above, according to the method of the present invention, conductor loss can be reduced, so CV cables, OF
It is extremely useful for cables, conduits, underground cables, etc.

Claims (1)

[Claims] 1 After immersing a copper conductor in an oxidation treatment solution in which caustic soda and sodium hypochlorite are added and dissolved in a mixture of water and an organic solvent that is water-soluble and has a boiling point of 100°C or less, the boiling point of the organic solvent is A method for manufacturing an insulated conductor, which comprises heating the copper conductor to a temperature at or near that temperature to form a copper oxide film on the surface of the copper conductor.