Conductivity of interconnected channels in water treed cross-linked polyethylene

Fundamental and 3rd harmonic waves of ac loss current through a non-penetrated water treed polyethylene have been studied based on a model where current density j through open channels interconnecting micro-voids is assumed to depend on electric field E as j=(σ₀ /h).sinh (h.E), where h is a parameter which characterizes the electric field dependence of j and σ₀ is conductivity in low electric fields. It has been found that σ₀ does not show a large change for applied voltage and applied voltage period in spite of the growth of conductive interconnected open channel region. It was also found that σ₀ is proportional to frequency of applied voltage and estimated at the order of 10^-7 S/m at 500 Hz