Effect of Micronscale and Nanoscale Boron Nitride Fillers on AC Breakdown Performances of Polytetrafluoroethylene

During the breaking process of high voltage circuit breaker (HVCB), the arcs generated between the contacts may cause severe electrical breakdown of the nozzle, shortening the life of HVCB. Therefore, nozzles with superior performance are urgently needed. Our previous experiments prepared several polytetrafluoroethylene (PTFE) samples doped with different micron-scale and nanoscale boron nitride (BN) to study the influence of these fillers on the arc ablation resistance. The experiment results show that the addition of micron-BN can greatly improve the arc ablation resistance of PTFE. However, the influence of those fillers on the breakdown performances is still unclear. And the actual nozzle needs to have both excellent ablation and breakdown resistance. So PTFE filled with different size of micron-BN and nano-BN was prepared in this paper to study the effect of micron-scale or nanoscale BN on the AC breakdown performance of PTFE. The change of trap depth and trap density will influence the composites' charge transport properties. The AC breakdown experiment was done to test the samples' breakdown strength. The experiment results of different samples are compared to get the best particle size of the BN fillers. And the relationship between the breakdown performance and the trap parameters is discussed. These factors are considered to be closely related.