Corona in Solid-Insulation Systems

The electrical avalanche mechanism that can occur in an insulation system is discussed and followed by an analysis of results of corona measurements on insulation systems containing artificial voids and on transformer insulation systems subjected to ac and/or dc electrical stresses. The object of this presentation is to show where the measured results correlate with existing corona models and where they do not. Emphasis is placed on the reproducibility of test results, and a method for making quick but reliable corona tests is described.