Statistical analysis of partial discharge data evolved during tree growth

Partial discharges (PD) have been traditionally used to monitor tree growth in electrical insulation. In this work perspex (PMMA) samples with a needle plane gap have been aged with an AC voltage. The tree growth is monitored simultaneously with collection of PD at regular intervals of time and micro photographing without interrupting the aging voltage. The partial discharge pulse amplitude records are clustered together into groups of class intervals. The first four moments of the PD pulse amplitude distribution are determined and the type of distribution is identified based on. these moments. An algorithmic representation of the /spl beta//sub 1/ and /spl beta//sub 2/ plane is used to identify the distribution type. A complete program is developed which identifies the type of distribution and the parameters. The PD quantities pertaining to bush and branch type trees are analyzed within this framework. The results of the work are presented.