Understanding fundamentals and practical applications of Partial Discharge (PD) with aging switchgear and cables

摘要

The inception of faults in the solid insulation systems of power cables and switchgear manifest themselves as small voids. Under electrical stress from the power system operating voltage, minute discharges occur across these voids. Because the discharges are within the voids and do not bridge the whole insulation system between the high voltage conductors and earth screens/they are known as 'partial discharges'. Over time the discharges within these voids will grow under the electrical stresses until they form a discharge path which develops into a breakdown path. At this stage the discharge ceases to be partial and full electrical breakdown occurs with the destructive failure of the switchgear and cables.