Corona and RI Caused by Particles On or Near EHV Conductors: I - Fair Weather

This study was made to identify, photograph, and establish the radio noise importance of the fair-weather coronas occurring on an ac high-voltage transmission line conductor. Excursions of fair-weather interference to over ten times the base value of the line noise are attributed to corona plumes from vegetable particles and insects attached to the conductor. Vegetable particles and insects are dielectrics whose plumes occur on the positive half- cycle of potential. Radio noise from these plumes overrides other corona noises associated with the dielectric particles, the noise from weathered metal protrusions on the conductor strands, and the normal noise from insulators, accessories, and hardware. The conductor surface gradient, the total conductor surface area, and the rate of gradient decay outward from the surface are important to both particle attachment and severity of plume formation.