Fractal analysis of 3D reconstructed patterns of real electrical tree

In this paper, we studied voltage-dependent characteristics of the tree shapes in cross-linked polyethylene (XLPE). We also studied the effect of voids on the tree shapes. In the case of the voidless samples, the tree length shows nonmonotonic behavior. In the case of samples with recessed voids, the tree length increases with increasing applied voltage. The tree shape is considered to consist of multiple groups of branches.