JPH0124325B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field) The present invention relates to a method for manufacturing steel-core aluminum stranded wire (hereinafter referred to as ACSR) that reduces corona noise and is used in high-voltage power transmission lines. (Background Art) ACSR has traditionally been used in overhead power transmission lines, and has played a major role in power transportation. In recent years, due to the need for large-capacity power transmission, the transmission voltage has tended to be increased, but corona discharge, especially corona noise immediately after rain, is a problem in ACSR for ultra-high voltage that connects steel towers. The cause of this corona noise is that oil is deposited during the manufacturing process of ACSR, and this is caused when it rains or immediately after the rain.
The ACSR surface becomes unevenly wetted with water droplets, and the protrusions caused by the raindrops on the ACSR surface increase the surface potential gradient around the raindrops, generating corona discharge, which causes audible noise. Ta. The present invention provides a solution to this problem by improving the water wettability (hydrophilicity) of the ACSR surface.
It was discovered that water droplets on the surface of ACSR can be eliminated and corona discharge can be prevented. (Disclosure of the Invention) The present invention was made as a result of various studies on the above-mentioned surface treatment method for ACSR, which has a good surface hydrophilicity. The aim is to provide a manufacturing method for ACSR that reduces corona noise. In the present invention, the surface of ACSR, which is made by twisting aluminum wires around the outer circumference of steel strands, is roughened by a method such as sandblasting, and then exposed to high-pressure, high-temperature water at 1 atm of 100°C or higher. This is a method for manufacturing low-corona noise aluminum power transmission lines, which is characterized by generating a surface treatment film in steam. The present invention is a method in which the surface of an aluminum power transmission line is first roughened, and then a surface treatment film (boehmite film) is formed by the water or steam treatment described above. The roughened surface can actively cause capillary action in water droplets, and this roughened surface can be made into a boehmite film to produce an aluminum power transmission line that is hydrophilic and has a surface with good water wettability. Can be done. The surface roughening treatment used in the present invention is performed, for example, by sandblasting, shotblasting, or by roughening the surface of the power transmission line to have minute irregularities using a rotating wheel made of steel wire, steel wool, or the like. . This roughening requires uniformly creating minute irregularities on the surface of the power transmission line, and the surface roughness ranges from several microns to several hundred microns, preferably.
A thickness of around 100μ provides good water wettability after the surface treatment film is formed, and is also advantageous in terms of industrial production. If the surface of ACSR is simply roughened by blasting, etc., raindrops will turn into water beads on the ACSR surface, and the goal of reducing corona noise due to the same effect as protrusions cannot be achieved. By forming a boehmite film in water or steam at a high pressure of 1 atm - 100° C. or higher and a high temperature, water droplets spread quickly after deposition and can be wetted uniformly. Therefore, without forming protrusions, corona discharge can be significantly reduced and corona noise can be reduced. (Prior art) A conventional proposal of this type is to prevent large water droplets from adhering and improve water drainage by sandblasting the surface of the wires that make up the electric wire and dispersing the water droplets that adhere to the wire during rain. There is a method to do so (Special Publication No. 36-14185). However, with this method, many small-diameter water droplets adhere to the surface of the wire,
Still, only those that cause corona discharge can be obtained. Furthermore, a method has been proposed in which a layer of a hydrophilic compound having a hydroxyl group is formed on the surface of the strands constituting the electric wire to improve wettability with water and prevent the formation of water droplets (Japanese Patent Publication No. 36-14076). However, in this method, the spread of attached water droplets is slow and the range in which they spread is narrow, so the surface is not evenly wetted particularly during light rain such as drizzle or at the beginning of rain, and the effect of preventing corona discharge due to water droplets cannot be obtained. In the present invention, the surface of the aluminum power transmission line is first roughened by sandblasting, etc., and then treated in water or steam at high pressure and high temperature of 1 atm - 100°C or higher to perform surface treatment. Generates a film. Therefore, in the present invention, the surface of the aluminum power transmission line is roughened to remove oils deposited during the manufacturing process and to roughen the surface. The surface roughened by this can actively cause capillary action in water droplets. Furthermore, a boehmite film is formed on this roughened surface by the water or steam treatment described above, and the hydrophilicity of this film makes it possible to improve the wettability of water on the surface of the aluminum power transmission line. . In other words, the water wettability of the aluminum power transmission line surface is extremely improved due to the synergistic effect of improving wettability due to the capillary phenomenon between water droplets due to surface roughening treatment and water penetration due to the hydrophilicity of the boehmite film. The water or steam treatment is preferably carried out at a temperature of at least 1 atm - 100°C; lower temperatures make it more difficult to form a boehmite film, and conversely, at high temperatures and pressures, a boehmite film can be formed in a short period of time, making it difficult to produce. The benefits are great. Next, in order to generate a boehmite film in the method of the present invention, for example, as shown in FIG.
The aluminum power transmission line 1 is drawn into a pipe having a steam outlet 4, and steam can be blown therein for treatment. Note that 5 and 6 are packings at both ends of the pipe 2 to make it airtight. This steam treatment is usually preferably carried out for 30 seconds or more. FIG. 2 shows an example of an aluminum power transmission line 10 manufactured according to the present invention, in which a steel-core aluminum stranded wire (hereinafter referred to as
ACSR) 11 is roughened by forming minute irregularities 14, for example, by sandblasting, and then steam treated, for example, as shown in Fig. 1, to form a boehmite film (Al ₂ O ₃ H ₂ O)
An aluminum hydroxide (so-called aluminum oxide film) 15 is formed. (Example and Comparative Example) Example After blasting the surface of ACSR with a cross-sectional area of 810 mm ² with #100 alundum, it was heated to approximately 120°C (approximately 2 atm).
ACSR was produced by blowing steam of 30 seconds, 1 minute, and 3 minutes to form a boehmite film. Comparative Examples ACSR with a cross-sectional area of 810 mm ² without any treatment (Comparative Example 1), ACSR with a surface of #100 Alundum blasted only (Comparative Example 2), and ACSR with a cross-sectional area of 810 mm 2 without any treatment (Comparative Example 2) ACSR was produced by each method (Comparative Example 3) in which steam was heated at ℃ (approximately 2 atm) for 30 seconds, 1 minute, and 3 minutes. The appearance and uniform hydrophilicity of the above Examples and Comparative Examples are evaluated and shown in the following table.

[Table] Further, the samples based on the examples and comparative examples were energized while being injected with water using a cylindrical corona gauge, and the attenuation of the corona noise level for 3 minutes after the water infusion was stopped was measured at a potential gradient of 12.8 kV/cm. The results are shown in the graph of FIG. If A is 810mm ² ACSR as manufactured, B is 810mm ² which has only been blasted.C is 810mm ² which has been steam-blasted for 3 minutes.
ACSR, D is 810 mm ² This line shows the case of a product in which the surface of ACSR was blasted with #100 alundum and then steam at about 120°C (about 2 atm) was sprayed for 3 minutes. According to FIG. 3, the product produced by the method of the present invention
For ACSR (indicated by D), the noise level drops rapidly after water injection is stopped, and reaches approximately 44 dB after 3 minutes.
Comparative examples (indicated by A, B, and C) showed 59~ even after 3 minutes.
The noise level remains at a high level of 63dB, and the reduction in noise level is extremely small. (Effects of the Invention) As described above, the method for producing the low corona noise composite stranded wire of the present invention involves roughening the surface of the stranded wire, such as blasting, and in addition, Since a surface treatment film (boehmite film) is generated using water vapor, the hydrophilicity of the wire surface is extremely excellent due to the synergistic effect of the roughening of the blasting process and the hydrophilization and improvement of water wettability by underwater or steam treatment. As a result, raindrops do not form water droplets on the surface of the wire during rain, and are evenly wetted, resulting in no protrusions forming, reducing corona discharge, and significantly reducing corona noise immediately after rain. It can be effective.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an example of a method for forming aluminum hydroxide on the surface of an aluminum power transmission line, Fig. 2 is a cross-sectional view showing an example of the present invention, and Fig. 3 is a graph showing the results of an effectiveness test. It is. 10... Aluminum power transmission line according to the present invention, 11...
Steel core aluminum stranded wire (ACSR), 12...Steel wire, 13
...Aluminum wire, 14...Minute irregularities, 15...Aluminum hydroxide.

Claims (1)

[Claims] 1 After roughening the surface of the steel-core aluminum stranded wire, which is made by twisting aluminum or aluminum alloy wire around the outer periphery of the steel stranded wire, such as sandblasting, 1
A method for producing a low-corona noise aluminum power transmission line, which is characterized by producing a surface treatment film in high-pressure, high-temperature water or steam at -100°C or higher.