Space charge accumulation due to ultra-fast charge packets in XLPE insulated cables: the effect of temperature and field

Small but repetitive charge packets injected from both electrodes, that cross insulation very rapidly and accumulate at the counter electrodes, are observed in polyethylene-based insulating materials. The results presented in this paper show that the charge packet amplitude remains almost independent of field and temperature, while mobility and repetition rate are thermally activated quantities. This indicates that a minimum quantity of charge is needed for the packet to be injected and transported through the insulation, while at higher temperatures the number of packets per unit time and the mobility increases.