Résumé
The defects on the surfaces or inside of medium and high voltage cables' insulations determine a local increase of the electric field in their vicinities. This leads to the reduction of the partial discharges and electrical and water trees inception voltages, respectively to the intensification of the degradation processes and insulations lifetime reduction.
In this paper, an experimental study regarding the surface defects influence on the absorption/resorption currents and the volume resistivity of low density and crosslinked polyethylene is presented. The experiments were made on samples without and with defects having different curvature radii and depths, obtained by pressing the samples with abrasive paper. Some of the samples have been submitted to the alternative electric field stresses and in the presence of the NaCl solution (E = 4 kV/mm and f-5 kHz) and the absorption/resorption currents values have been measured.
The results show that the absorption/resorption currents values and the average volume resistivity of the samples are influenced by the density and dimensions of the defects.