Hum noise performance of 6, 8, 10 conductor bundles for 1000 kV transmission lines at the Akagi test site: a comparative study with cage data

The hum noise performance of 6, 8, 10 conductor bundles (subconductor diameter: 3.84 cm) for 1000 kV transmission lines was measured at the Akagi test site and the results were compared with cage data. In general, hum noise levels calculated with cage data were higher than the long-term test results. It was found that the differences between calculated and measured levels were formulated with the maximum surface gradient. Based on this relationship a new prediction method for hum noise near AC transmission lines is proposed