The Influence of Positive Temperature Coefficient Material on the DC Electric Field within Epoxy Composites

Negative temperature (NT) coefficient electrical resistivity of insulating materials causes the distortion of DC electric field, increasing the design and manufacture difficulty of HVDC equipment. The ceramic with positive temperature coefficient (PTC) electrical resistivity was doped into epoxy resin to weaken its temperature dependence of electrical resistivity (0~35 wt%). The electric field and temperature distribution under temperature gradient were simulated. The PTC effect of fillers is able to mitigate the distortion of electric field under temperature gradient, which is through the synergistic optimization of both electrical resistivity-temperature characteristic and thermal conductivity. The optimization of electric field distribution within insulation via BT60/epoxy composites has potential to be used in HVDC electrical equipment.