Progression of Positive Corona on Cylindrical Insulating Surfaces Part II: Effects of Profile on Corona

Characteristics of corona discharges over insulating surfaces are described. Two insulating materials, PTFE and porcelain are compared and contrasted using identical insulator surface profiles and dimensions and identical impulse voltage waveforms. The insulators were in the form of right cylinders and of similar shape but with a single shed, of practical dimensions added. Properties studied include the inception conditions, spatial development, light emission and changes in corona pattern. Results are discussed in terms of the relative permittivity of the materials, the surface profile and the physical effects of the surface upon corona properties.