A Study on Time Variation of ${\phi}-a$ Distribution Patterns due to Treeing Propagation in low Density Polyethylene

저밀도 폴리에틸렌에 있어서 트리잉 진전에 따른 ${\phi}-a$ 분포양상의 시간적 변화에 관한 연구

In this study, in order to observe treeing of prebreakdown phenomena, time variation of acoustic emission properties due to initiation and propagation of tree in LDPE was investigated under AC voltage. The experimental results were as following, pulse number and average amplitude of AE were increased along with near breakdown rather than tree initiation, also, according to increasing of applied voltage, tree propagation was blunted, while pulse number and average amplitude of AE was promoted. In each applied voltage, ${\phi}-a$ distributions during propagation of tree were changed to special patterns, skewness S and kurtosis K reflected well time variation of ${\phi}-a$ distribution patterns. It is thought that initiation and propagation state of tree can be easily monitored, so long as time variation of pulse number and average amplitude of AE, skewness Sand kurtosis K of ${\phi}-a$ distribution are always monitored.