The Distribution in Length of Vented Water Trees

The length and number distributions of vented water trees have been measured in different olefinic dielectric materials; peroxide crosslinked polyethylene, silane crosslinked polyethylene and thermoplastic EPR base resin. Measurements were carried out in the nominally uniform field region in compression ion molded Rogowski-profiled samples. We note the difference in shape of the length distribution density observed and that reported for bow-tie trees. It is argued that these results imply that the distribution of inception times is peaked and material dependent.