Investigation of temperature effect on electrical trees in XLPE cable insulation

In this paper, combined with the methods of real-time microscopic digital imaging and partial discharge (PD) continuous measurements, the effect of temperature on electrical tree propagation and PDs characteristics in XLPE cable insulation was investigated using an embedded needle electrode arrangement over a range of applied voltages from 9 to 15 kV rms. The temperature of the experiments varied from 10 °C up to 70 °C, which lay within the rated operating temperature range of XLPE cables. The results obtained show that temperature has dominant effect on electrical tree shapes and growth time. As the electrical tree shapes at lower voltages are influenced by the change of tree channel conductivity, this process appeared to be accelerated greatly by increase of experimental temperature. The tree growth time at higher voltages was decreased at higher temperatures due to the change of material morphology and it was accompanied by intensive PD activity.