Time varying characteristics of ϕ-q-n patterns from natural voids in resin

The measurement and assessment of partial discharge (PD) activity is used both for condition assessment of high voltage plant (by operators) and for quality control (by manufacturers). Except for the online circumstances, the measurement usually lasts for a short period of time while higher than working stress is applied. The resulting pattern of discharge data, when compared with a knowledge base of PD patterns of different types of defects is a crucial factor in diagnosing the condition of the insulation system in the plant.