Abridgment of residual air and moisture in impregnated paper insulation — II

In an earlier paper⁴ has been described a series of studies of the influence of residual air and moisture in impregnated paper insulation, such as used in high-voltage cables. Briefly, the method used was to prepare samples in groups of three, to dry them in accordance with a standard program, to impregnate them at different values of absolute air pressure, and to study the resulting influence on the power-factor — voltage curves. This gave information as to the influence of residual air. Separate studies were made of the dielectric absorption and residual conductivity of the paper before and after impregnation for different states of initial dryness. These studies, in conjunction with the resulting power-factor — voltage curves, gave information as to the influence of moisture.