Stress relief in insulation

Increasing demand for compactness leads to the steadily increasing use of hard insulation, which may be a solid or a hardened liquid. The insulation thickness required to separate potentials above nominal levels generally create volume variations by expansion and contraction which may be appreciably different from that of the surrounding enclosure. This volume deviation between the insulation and its available space leads either directly to holes or "voids" or, in case of the material overflowing, to voids when earlier conditions are restored. This relative motion of the insulation can result in bending or breaking of wires or electric hardware suspended therein or to excessive potential stress when voids occur in regions already highly stressed. Restricting this volume variation to regions of low stress and segments therein carrying no component resolves the problem.