Acoustic Noise Evaluation for Overhead Line Conductors Using an Anechoic Chamber

Emerging technologies associated with conductors and transmission towers require a re-evaluation of models of audible noise generated by overhead line conductors. Measurements on which existing commercial models were developed were typically performed on a single, classical design of conductor around 50 years ago. Within this paper, an ac testing facility employing a semianechoic chamber and a novel measurement procedure are proposed to give accurate determination of acoustic emission from overhead line conductors. The reproducibility of these measurements is significantly above traditional testing methods, but is shown to be heavily dependent on the chosen wetting technique. It is found that to achieve an accurate result, background acoustic noise control is essential especially for lower frequencies of power frequency harmonics. A direct comparison is reported for conductor samples with various physical characteristics. The analysis of results gives power utilities valuable information for selecting quieter conductors for overhead lines. The magnitude of high-frequency audible noise generated above 1 kHz is shown to be closely related to corona discharge activity, while the acoustic emission below 1 kHz is determined by the size distribution of droplets.