An approach to develop a partial discharge investigation

Partial discharge represents a physical phenomenon, in which discharges are involved in electrically weak regions of solid insulation materials (most often gaseous or liquid inclusions). They cause damage of the insulation and often start from the voids enclosed in it and/or at interface defects. The time, during which technical insulation is still in good operation condition, is of great practical interest. The same is valid for effects of partial discharge resulting in failure of the dielectric much before the expected life-time. For this reason this topic is subjected to many investigations. The present paper treats discharge phenomena inside enclosed cylindrical cavities. An electrical model has been developed for the tested dielectric. The model has been built using the tools of OrCAD's PSpice software for analogue design and simulation. Experimental results have been compared with the model data. The experimental data obtained from testing of polyethylene samples with artificially created cylindrical voids have been used for this comparison. The electrode configuration used is plane-plane, and the electrodes are parallel to the ends of the cylindrical void. The parameters of the electrical model have been calculated by means of data taken from the experimental set-up used.