Electro-optical measurement of breakdown time lag along dielectric surfaces in transformer oil

Fig.1 shows a typical current trace for Kapton with a negative point. The symbols ON, OFF and Bin this figure correspond to the onset of voltage application, the start of voltage reduction and the time of the actual breakdown current onset, respectively. The first large current pulse which occurs just after voltage onset is the combination of injection current and displacement current. The prebreakdown current follows this initial pulse and includes many small pulses of high recurrence rate.