Effect of bundle orientation on transmission line audible and radio noise

A bundle of four conductors may be used for the next generation of 500-kV lines at the Bonneville Power Administration (BPA). Among the many questions that needed answers were: (a) the optimal orientation of the bundle to minimize the audible (AN) and radio noise (RFI); and (b) whether trapezoidal conductors behaved differently than conventional stranded conductors. This paper shows the results of comparative tests conducted in BPA´s high voltage laboratory comparing the RI and AN from 4 Bunting (conventional round rod) and 4 Hood (trapezoidal) conductors oriented either in a square or a diamond configuration. To make the results more useful, similar tests were conducted on 2 Bunting and 2 Hood conductors oriented either horizontally or vertically and on 3 Bunting and 3 Hood conductors oriented in a vee or an inverted vee configuration. Tests on single Bunting and Hood conductors were also conducted. The tests showed that within the accuracy of noise measurements bundle orientation has little effect on the AN or RFI and that the conventional Bunting and the trapezoidal Hood conductors have essentially the same noise performance