Identification Of Partial Discharge Sources In Oil-Pressboard Insulation With Single Type Defect Through TF Mapping

One of the major insulation degradation processes that enhances the risk of equipment failure is partial discharges (PD). The severity of the damage caused by PD will depend on the type of PD source present in the insulation system, ie. Corona discharges, voids, surface discharges, etc. Therefore, early detection and identification of PD sources are very useful for the proper assessment of insulation health. The insulation material investigated in the present case is an oil-impregnated pressboard. Three types of PD sources, void, corona, and surface discharges, were identified from PD signals measured using a high-frequency current transformer (HFCT). It was observed that Time-Frequency mapping is an efficient technique to discriminate corona, surface discharges, and void discharges when they are present standalone in the insulation.