Non-conventional characterisation of MV measurement transformers solid insulation systems through analyses of digitally acquired PD patterns

Partial discharges (PD) digital measurement systems have been recently developed. They supply useful information to implement diagnostics on insulation systems. Such systems output consists of data about the amplitude, the number and the occurrence phase of the PD. Such acquired data (PD patterns) information is contained in 3D matrices and can be processed aiming at the identification of the morphology of defects. This preliminary work is part of a research focused on the “measurements” of defects, possibly present and acting as PD sites, in the insulation system of measurement transformers (VT) for medium voltage (MV), cast-resin type. “Non-conventional” PD testing procedures have been studied and applied acquiring the PD patterns in numerous and different test conditions. The comparative analysis performed on the PD patterns results allowed identification of some relations between the similarity (or the differences) of the examined tested components