Evaluation of audible noise from surface processing conductors for AC overhead transmission line

Corona discharge may cause audible noise, and it is frequently generated from wet conductors of high-voltage AC overhead transmission lines. Audible noise arises more easily from new conductors that have lubricating oil on their surface than from aged conductors. In this paper, the corona characteristics, particularly the audible noise, of conductors having various wetting properties are presented for the purpose of developing a corona-free conductor for AC overhead transmission lines. It was found that a conductor having a super-hydrophobic surface exhibited a minimized audible noise level, but it does not have sufficient durability for practical applications. Furthermore, a conductor having a super-hydrophilic surface made by thermal spraying of TiO2 showed good performance regarding the suppression of audible noise. The thermal spraying of TiO2 seems to be an effective processing technique that has sufficient durability for practical applications. (c) 2007 Wiley Periodicals, Inc.