Thermal Conductivity and Arcing Resistance of Micro or Hybrid BN Filled Polyethylene under Pulse Strength

In this work, in order to investigate the effects of thermal conductivity on arcing resistance from the view of thermal accumulation under pulse strength, a range of polyethylene (PE) based composites filled with micro or hybrid boron nitride (BN) particles at different loadings (0, 3, 6 and 9 wt%) were prepared. Thermal conductivity and relative permittivity were measured to characterize the basic properties of various samples. Influences of thermal conductivity on thermal accumulation and arcing resistance were discussed through surface dielectric breakdown test. Obtained results show that the thermal conductivity of BN filled PE composite is obviously improved and the relative permittivity could maintain a relatively low value. At the same pulse frequency, with increasing filler concentration from 0 to 40 wt%, thermal conductivity and the time to surface dielectric breakdown all present increase trend, whereas sample surface maximum temperature and damage degree reflect the opposite tendency. It implies that the increased thermal conductivity contributes to reduce thermal accumulation during arcing discharge, which can help to promote the resistance to arcing discharge. Moreover, PE/hybrid-BN composite presents a higher thermal conductivity, a longer time to surface dielectric breakdown and a lower surface damage degree at the same filler content. It is concluded that adding hybrid-BN filler into PE resin can suppress thermal accumulation and improve arcing resistance more effectively.