Space Charge Measurement in Xlpe Material Filler with Zinc Oxide and Natural Graphite Additives

In the field of HVDC systems the space charge accumulation phenomenon plays an important role on the dielectrics lifetime. Considering that the electric field distribution within the insulating layers depends on the interfacial and space charge, in critical conditions of charge accumulation the electric field can greatly exceed its nominal value. To reduce the amount of accumulated charge filler are typically added to the dielectric based material. Based on this, in the present work the effect of fillers like Zinc Oxide and Graphite have been added with different percentages on the XLPE based material. Three different composed specimens have been prepared and tested with the PEA technique for the detection of accumulated space charge. The electric field distributions have also been calculated and reported in the paper. Measurement results, carried out by stressing all specimens with 15kV/mm, show that the specimen with lower percentage of Zinc Oxide accumulates high quantity of homocharge, while the other two with higher percentage of fillers shows a more stable space charge and electric field behaviour over time.