Radio-Noise Levels of EHV Transmission Lines Based on Project EHV Research

The results of three years of experimental and theoretical research on transmission-line radio noise at Project EHV are presented. Computer programs were developed to process the data on a statistical basis, and as output provide both histograms and regression analyses for four test configurations operated at the 500-and 700-kV levels. Fair weather radio-noise levels were found to be significantly affected by relative humidity, relative air density, and absolute value of wind velocity, and these relationships are discussed. Wet-weather effects are presented and discussed. Both fair-weather and wet-weather experimental results are incorporated in a theoretical analysis of transmission-line radio noise resulting in a procedure which enables the transmission-line designer to predict, in advance of construction, average fair-weather and wet-weather radio-noise profiles for EHV transmission lines.