Comparative study on corona-generated audible noise and radio noise of ac long-term operating conductors with two bundle types

The corona-generated audible noise (AN) and radio noise (RN) of the long-term operating conductors with two bundle types was investigated and compared based on a corona cage measurement system. The surface morphologies of eight conductors were measured and the average surface roughness (Ra) was calculated. With the raise of conductor bundles, the maximum electric field distortion level (β4), the relative difference of ionization intensity (γ4) between long-term operating conductors and new conductors decreased. Adding the number of sub-conductors turned out to be an effective method to improve AN and RN of long-term operating conductors in the contaminated areas.