Radio Influence Characteristics of Electrical Apparatus

Experience recorded in this paper with the method of measuring the radio influence factor of electrical apparatus recommended by the Joint Co-ordination Committee on Radio Reception of Edison Electric Institute, National Electrical Manufacturers Association, and Radio Manufacturers Association establishes its practicability and adequacy. This method fulfills the essential feature of all working standards in that the results are reproducible by quantitative measurements. Various types of output meters for determining the radio influence factor of apparatus have been investigated. For practically all applications, the present type of output meter gives an indication which is sufficiently close to the audio output. This characteristic, besides the additional advantages it has in simplicity and relative inexpensiveness, well justifies its use. Radio frequency influence factors vary in character, depending on the electrode insulation arrangement of the source, and also the dielectric medium. Humidity and relative density of the air affect the radio influence factor and accordingly certain correction factors for the atmospheric conditions need be recognized. The radio influence factor characteristics of insulation in air and oil, reported in the paper, establish that normally only apparatus in air need be considered for the effect of radio noise influence, as in coordinated apparatus design the strength of parts in oil will exceed those in air. Experience has shown that quantitative data are essential for this type of study.