JPS6250928B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently manufacturing a strand insulated cable conductor having excellent insulation performance.

Generally, in order to efficiently transmit large amounts of power, a conductor with a large cross-sectional diameter of, for example, 1,000 to 10,000 mm ² is used, which is made by twisting together a large number of copper wires or aluminum wires.
However, on the other hand, due to the large diameter, heat generation becomes significant and there is a risk of deteriorating the conductor. In order to reduce the amount of heat generated, a circulation path is provided inside the conductor for flowing insulating oil or the like. In order to create such a structure, it is widely used to compression mold a stranded wire in advance and combine several fan-shaped segments to form a circular conductor, as shown in FIG. In the figure, 1 is an internal flow path, 2 is a segment, and 3 is a wire.

However, in large-capacity AC power transmission, losses increase dramatically due to the skin effect and proximity effect caused by the strands. In order to prevent this, an insulated strand conductor is used in which at least a portion of the strands are insulated.

To obtain such a conductor, an insulating paint is applied and baked on the surface of the conductor, or the segments are treated chemically or electrochemically to coat the surface of the wire with an insulating non-metallic material such as 0.1 to several micrometers of copper. Alternatively, a method of converting aluminum into oxide has been used, but in the former method, when the wires are twisted and subjected to processes such as compression molding, a process of several tens of microns is required to withstand the deformation force caused by these processes. It requires a very thick coating. Therefore, the manufacturing process is extremely difficult. The latter method involves chemically oxidizing copper in a caustic soda solution containing an oxidizing agent such as zincate, or electrolytically (anodic) oxidation in a caustic soda solution, or oxidizing aluminum with chromic acid and carbonic acid. The so-called MBV treatment, which involves chemical oxidation in a mixed solution of soda, or sulfuric acid,
There is a method of electrolytic oxidation, so-called alumite, in a solution such as phosphoric acid. Even in this method, as described above, the thin oxide cannot withstand this deformation due to the steps such as wire twisting and compression molding, making it impractical. Therefore, the segment is the target. However, even if means such as ultrasonic irradiation are used in conjunction with methods such as ultrasonic irradiation, it takes a long time to sufficiently coat the oxide between the strands of wire that have been compressed and crushed. In order to improve this, it is sometimes done by forming slits between the strands twisted in the opposite direction to the twisting direction, but it is difficult to create slits uniformly over the entire length of the strands. , making the effect of wire insulation uncertain and unstable. Furthermore, even if sufficient treatment can be achieved by completely untwisting the material, further steps are required to return it to its original compression molded state, and the oxide film once formed will be destroyed. cannot achieve that purpose.

The present invention has been made as a result of extensive research aimed at improving these drawbacks, and as a result has discovered a method for efficiently forming an insulating film on the surface of a wire in a short period of time.
That is, the present invention provides a strand insulated cable in which a desired number of conductive strands are combined, a flow path is formed inside, and an insulating film is formed on the surface of at least some of the strands to insulate the wires from each other. In a method of manufacturing a conductor,
A reaction solution is introduced between the strands by forming a forced pressure difference between the outside of the strands and the flow path, and an insulating coating is generated chemically or electrochemically. It is something.

The method of the present invention focuses on the structure of large-capacity cable conductors and forcibly creates a differential pressure between the outside of the conductor and a continuous internal flow path provided as a cooling flow path, and pours a reaction solution between the wires. It is necessary to introduce
The differential pressure can be generated by, for example, injecting a reactive solution into the internal channel using a pump and letting the solution flow out of the conductor through the gaps between the wires, or by reducing the pressure in the internal channel and sucking in the solution from the outside. This is done by a method such as In this case, it is possible to carry out continuous processing while running the conductor, but normally drum-wound or coiled conductors are batch processed. For example, a coiled conductor 11 is placed in a container 12 as shown in FIG. The reaction solution 14 in the container is sucked up by the pump 15 and the solution is forced into the channel 1 of the conductor from both ends of the conductor through the pipe 16. Note that if this solution 14 requires a high temperature, it may be heated using a heat exchanger 17.

As described above, since the method of the present invention allows direct oxide treatment to the cable conductor, the processing speed is several tens of times faster than when processing strands as described above, and several times faster than when processing segments. I can do it.

Next, examples of the present invention will be described.

Example 1 2.3 A conductor with a cross-sectional area of 2000 mm ² made by twisting 88 copper wires and combining 6 compression-molded segments into a circular shape.
300m was wrapped around a drum with a diameter of 3m. Note that the internal flow path of the conductor is approximately 20 mm, and the outer diameter is approximately 60 mm.

After placing this drum into a steel container,
A mixture of NaOH 50g/, NaClO ₂ 50g/,
It was kept at 75°C and filled. Thereafter, the above solution was pumped into the internal channel at a rate of approximately 500/min over a period of 15 minutes using a high-pressure pump. Next, fresh water was circulated in the same manner, and the material was further heated with hot water and air-dried to obtain a stranded cable conductor according to the method of the present invention.

Comparison row 1 In Example 1, the conductor wound around the drum was immersed in the solution for 10 minutes without pressurizing the reaction solution to obtain a strand insulated cable conductor according to the method of Comparative Example.

The conductor of the present invention, the comparative example conductor, and the untreated conductor thus obtained were each cut into 5 m pieces, and the skin effect coefficient λ _S was measured using the following formula.

The results are shown in Table 1.

λ _S = (R _A /R _D -1) However, R _A is the resistance value for 50Hz AC,
R _D is a direct current resistance value.

Table 1 λ _S Appearance Example 1 0.04% Black Comparative Example 1 0.14% Same as above Untreated 0.14% Copper color As is clear from the above table, when simply immersed in the reaction solution as in Comparative Example 1, the outer surface was oxidized to black. However, due to insufficient reaction between the contact lines, it exhibited λ _s similar to that of the untreated conductor. In contrast, the conductor according to the present invention has a small λ _{s and} clearly exhibits insulating properties.

Example 2 5 m of the same conductor as in Example 1 was suspended and held in a steel tank, and the layer was filled with a solution of 200 g of NaOH at 80°C. After that, the conductor was connected to the positive electrode tank of the DC power supply to the negative electrode while press-fitting from both ends of the conductor using a high-pressure pump at a rate of 5/min.
A wire insulated cable conductor according to the present invention was obtained by applying current at 600A for 1 minute and for 5 minutes at 600A.

Comparative Example 2 Using the same conductor as in Example 2, an electrolytic treatment was performed without pressurizing the reaction solution to obtain a strand insulated cable conductor according to Comparative Example.

For the conductor of the present invention and the comparative conductor thus obtained, λ _S was measured using the same formula as above. The results are shown in Table 2.

Table 2 λ _S Appearance Example 2 0.03% Black Comparative Example 2 0.08% Black to brown As detailed above, according to the present invention, it is possible to improve the performance of a bare wire insulated cable conductor and manufacture high efficiency, while also reducing power loss. It has remarkable effects such as being able to realize large-capacity AC power transmission with extremely small amounts of electricity.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a large-capacity cable conductor, and FIG. 2 is a schematic explanatory view showing an example of an apparatus for carrying out the method of the present invention. DESCRIPTION OF SYMBOLS 1... Internal flow path, 2... Segment, 3... Element wire, 11... Coiled conductor, 12... Container, 1
3,13'...Sealing tool, 14...Reaction solution, 15
...Pump, 16...Pipe, 17...Heat exchanger.

Claims (1)

[Claims] 1. Manufacturing a wire insulated cable conductor that combines a desired number of conductive wires, forms a flow path inside, and generates an insulating film on the surface of at least some of the wires to insulate the wires from each other. In the method, a reaction solution is introduced between the wires by forming a forced pressure difference between the outside of the wire and the flow path, and an insulating film is chemically or electrochemically generated. A method for manufacturing a bare wire insulated cable conductor, characterized by: