Evaluation of polyolefin high voltage insulating compounds - dendrite (tree) formation under highly divergent fields

When a high voltage gradient is applied to an insulating material and a dielectric puncture results, the failure may occur progressively rather than instantaneously. If a sharp point is used as an electrode, the electric stress adjacent to it is high compared with that of the rest of the stressed insulation. Dielectric failure begins at this point and progresses to the other electrode. With such a nonuniform field the growth of the failure channel can be observed in a transparent insulation. The rate of progression of the failure can be adjusted to any desired value by control of geometry and stress. Because of their shape, the incomplete failure channels are referred to as "dendrite" or "treed" These phenomena suggest the development of research test methods to compare the behavior of insulating compounds.