Diagnosis of Moisture in Oi /Paper Distribution Cables, Part II: Water Penetration in Cable Insulation (Experiment and Modeling)

Dynamics of water penetration in mass impregnated cable insulation has been studied. For experimental purposes, artificial damage was inflicted to a 40 cm long cable sample, and water ingress has been monitored continuously by frequency response measurements. A similar experiment was conducted on a 2.8 m long cable sample, where both frequency response and time domain reflectometry (TDR) measurements have been performed. After termination of both experiments, actual moisture content has been measured radially and axially. Based on dielectric measurements a model of water ingress has been developed and diffusion coefficients have been estimated for mass impregnated cable paper.