On excess current during and after partial discharge activity

Among the factors influencing partial discharge (PD) activity in insulation systems, deposition of electric charges on dielectrics significantly impact the subsequent behaviour. This work presents a measurement technique that allows studying the charge released during PD events by measuring the resulting excess current. The method, being similar to the dielectric response analysis, measures the current flowing through a test object before, during and after a PD event. By comparing the dielectric (capacitive) and the total currents, the charging process as well as its decay can be explored. The applicability of the method is demonstrated when analysing PD activity in a twistedpair test object exposed to a square voltage waveforms.