Page 596 - Book Hosokawa Nanoparticle Technology Handbook

APPLICATIONS 35 AC OVERHEAD TRANSMISSION LINE AUDIBLE-NOISE REDUCTION
Table 35.1
Surface properties of test power lines.
Type of power line Manufacturing Contact Features
method angle
Surface condition Adhesion Others
Super-hydrophobic Paint coating 156.5 Smooth Extremely Deterioration
power line low with years present
Hydrophobic Paint coating 107.8 Smooth High Deterioration with
power line years present
Super-hydrophilic Paint coating 5.3 Smooth High Deterioration with
power line years present
New power line – 98.6 Smooth, glossy – –
Aged power line Exposure to nature – Smooth, no gloss – –
Sandblasted power line Blasting 74.0 Undulating surface – –
Titanium oxide-blasted Blasting 87.6 Undulating surface – –
power line
Alumina thermal- Spraying 11.6 Undulating Extremely –
sprayed power line surface high
Titanium oxide Spraying 0.3 Undulating Extremely Has
thermal-sprayed surface high photocatalytic
power line function

line, and it is possible to change the surface wetting There are pores of 1 m diameter and cracks of 5 m
property of the line to the characteristics of the sprayed length in the surface of the sprayed titanium oxide film,
material itself. Depending on the spraying conditions, and there are fine spheres of sizes from 500 nm to about
it is possible to control the coated film thickness and 2 m. In addition, there are undulations on the
the structure as desired, and it is possible to obtain a micrometer order over the entire surface, the area is very
coating that has a high adhesion to the surface of the large, and hence the super-hydrophilicity is promoted.
power line and has a high durability. Even the thermal
spraying process can be realized easily as one of the 5. Audible-noise measurement
processes in the manufacture of power lines.
Further, since the measurement of the contact angle In the evaluation of the test power line during the
is difficult in case of a twisted wires structure, the experiments, the audible-noise measurements were
contact angles in Table 35.1 are the ones measured by made using a small-sized water-spraying voltage-
carrying out the same surface improvement on a sep- application equipment shown in Fig. 35.5. A uniform
arate flat aluminum plate. water spray simulating rain is made to fall onto the
test power line below from a water-injection nozzle
4. Features of titanium oxide thermal-sprayed films above. In this equipment, it is possible to set the sur-
face electric field of the test power line to any desired
In recent years, titanium oxide is a material that is value by adjusting the applied voltage.
attracting attention due to its photocatalytic effect. In the position relationship between the test power
Titanium oxide is excited by the ultraviolet rays in sun- line and the ground plane as in this equipment, the
light, etc. and decomposes organic material, or causes maximum electric field (G max ) on the surface of the
super-hydrophilicity. These functions maintain the sur- test power line occurs at the lowermost position facing
faces of outdoor constructions that are exposed to sun- the ground plane on the surface of the line, and can be
light clean without manual cleaning due to the obtained by calculation. In this study, the experiments
multiplied effects of direct decomposition of soiling were conducted under conditions of values of G max up
material and the cleaning effect of rain [4]. In the case to 12–16 kV/cm, which includes the range of values of
of transmission lines whose cleaning cannot be done actual use of the high-voltage AC overhead transmis-
easily, even if the wetting property is improved by sur- sion lines. The measured item is the A-weighted sound
face improvement, since there is the likelihood of those pressure level stipulated in the JIS (Japanese Industrial
characteristics being lost due to soiling of the surface, it Standard) C 1505 standards, and the measurements
is considered effective to apply self-cleaning functions. were made by placing a microphone at a location 2 m
The conditions of the surfaces of the thermal-sprayed from the power line.
films of titanium oxide sprayed power lines prepared Sample results of the experiments are shown in
during the present study are shown in Fig. 35.4. Fig. 35 6. The horizontal axis represents the contact

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