The dielectric strength and life of impregnated-paper insulation — I: The influence of the density of the paper

PAPER as used in the spiral laminated impregnated insulation of high-voltage power cables is available over wide ranges of density and thickness. There result important variations in the ordinary physical properties of the paper such as flexibility, tearing, tensile, and bending strength. Variations in the electrical properties of conductivity, dielectric constant, and breakdown strength also result. The peculiarly severe conditions imposed by the manufacture, transportation, installation, and operation of high-voltage cables have emphasized the importance that full attention be paid to all physical properties of the insulation, especially those relating to permanence of mechanical structure and of high insulating properties. Manufacturers of cables often utilize the several types of variation referred to in designing cable insulation to meet the particular requirements of cables for different types of service.