Dynamism of interconnected channels in water-treed polyethylene

Loss current through non-penetrated water treed polyethylene increases with exposure time at 1000 V, 500 Hz. The increment is discussed by taking the capacitance of the water treed sheet sample to be the Maxwell-Wagner type capacitor composed of two layers: the capacitance both for the non-treed region and the unfilled channel region is connected in series to the parallel combination of the capacitance and the conductance for the water-filled channel region. By assuming a non-ohmic dependence of the conductance, the fundamental and 3rd harmonic components of the loss current have been calculated numerically, based on the equivalent circuit. The numerical results give a good agreement with the observed changes of the magnitudes of fundamental and 3rd harmonic components I₁ and I₃, and their phase angles θ₁ and θ₃, respectively, for the exposure time. It has been concluded that the water-filled channel region in the water treed region grows with exposure time. It is also concluded that the conductivity of the water-filled channel region increases slightly with its growth