抄録
We have already developed a countermeasure against the wind noises from insulator strings of 500 kV (or less) overhead transmission lines. However, this countermeasure could not work effectively on insulator strings of 1000 kV overhead transmission lines. This is because that (1) The insulator strings consist of the High Strength Anti Pollution Insulator, which has deep ribs and the size is largest class in domestic use. (2) Insulator string length is approx. twice as long as that of 500 kV lines. (3) The 1000 kV overhead transmission lines sometimes locate at the remarkable strong wind area.
This paper presents the analysis results that can explain the reason of insufficiency of the countermeasure for the 1000 kV lines.In order to clarify these phenomena, we measured following items. (1) The fluctuation of wind velocity around the insulator unit (2) The oscillation of each part of insulator unit (3) The acoustic characteristics of insulator string.
Consequently, we could obtain the following three elements, which were deeply related to generation of wind noises. (1) The cavity tone at outermost rib. (2) The sound resonance of each insulator unit in the string allocated at equal interval. (3) The oscillation of each insulator unit. We could improve no amplified wind noises by mutual interference of these three elements.
Moreover, we developed “Waveform Sheet” confirmed that it had prominent effect to reduce wind noise generated from insulator strings of a 1000 kV overhead transmission line.
