Characterization of Pre-breakdown Discharge Mechanisms in Insulating Oil by Electrical Measurement at Lightning Impulse Voltage Stress

This paper offers an approach for systematic investigations of pre-breakdown discharges and their quantity in mineral oil by performing experiments under lightning impulse voltage stress. For this purpose, all discharges that occur between the discharge inception and breakdown are measured electrically. A systematic distinction between the displacement component and current caused by partial discharges is made. Thus, conclusions on the actual charge value caused by pre-breakdown phenomena can be drawn. Furthermore, measurements on strongly non-uniform arrangements under lightning impulse voltage stress and the analysis of the discharge behavior will be presented.