Calculation of Corona-Starting Voltage in Air-Solid Dielectric Systems [includes discussion]

A method is described for determining the corona-starting voltage in air-solid dielectric systems when the thickness and the dielectric constants are known. The method is derived by applying data from Paschen´s law to the theoretical distribution of a voltage potential between air and a solid insulation. Two procedures for verifying the method and a determination of the accuracy are described. The extent of error due to field distortion and other factors is discussed. Examples showing how the method may be applied practically for air-solid dielectric systems containing more than one solid dielectric and the expected accuracy are included.