Variations in Radio and Television Interference from Transmission Lines [includes discussion]

Growth of power utility loads is steeply upward with the resulting requirement of higher transmission voltages. Radio interference (RI) influence has been reported1 to be a limiting factor in choice of size of transmission conductors. There are still large gaps in the present knowledge of generation, propagation, attenuation, and measurement of interference, and approaches toward a more complete understanding of this problem are discussed. Line design, wind, and precipitation are considered to be the major factors determining interference levels in the 33- to 230-kv range investigated. Three representative lines were extensively explored with recording devices, many individual measurements were made on others, and laboratory experiments were carried out, giving information on the magnitude and causes of the variations of interference encountered in the New England area. Many of the findings can be applied to the high-voltage circuits above 300 kv.