Initiation and growth of electrical trees in LDPE generated by impulse voltage

Abstract

Using the molded LDPE specimen with the metal foil electrode, the initiation and growth of electrical trees generated by positive and negative impulse voltage were studied. The Weibull plots of the numbers of impulse voltage shots up to the tree initiation and to the puncture of the specimen were analyzed. The difference between the plots of positive impulse shots and those of negative ones demonstrates the difference between the initiation and growth of a positive impulse tree and those of a negative one. Taking account of the results of the electric field calculation in the vicinity of the electrode, the tree initiation mechanism was examined. The difference of the tree initiation between a positive impulse tree and a negative one is suggested to be due to the difference between the tree growth following the initiation process of positive impulse tree and that of negative one.

Electrical tree characteristics of XLPE under repetitive pulse voltage in low temperature

“…It was reported that tree initiation ratio increased due to high impulse voltage, and no trees appeared when DC voltage was up to 70 or -60 kV, and the electric field at the needle tip was up to 3.8  10 3 or -3.257  10 3 kV/mm [28]. Sekii studied initiation and growth of electrical trees in low-density polyethylene (LDPE) generated by positive and negative impulse voltages and found that once the field strength exceeded dielectric breakdown strength of the XLPE, the original tree initiation started [29]. These studies focused on the analysis of the initiation and the growth of electrical trees, but paid little attention to the impact of pulse voltage on electrical tree morphology.…”