Mechanical Uniformity of Paper-Insulated Cables

Application of a recently developed method whereby it is possible virtually to see the voids in the layer structure of high voltage cable insulation shows most such insulation to be mechanically irregular. Lack of mechanical uniformity in the cable as manufactured is responsible for much of the ionization after the load cycle, and probably to a great extent for ionization breakdown. Application of the method and of supplementary methods should lead to better load cycle stability, improved installation practice, and ultimately to reduced insulation thicknesses.