Current pulse measurement system using LED in dielectric liquids under impulse voltage conditions

The time response and the charge sensitivity of an LED (light emitting diode) current pulse measurement system (LCPMS) are evaluated. In addition, the current pulse and the streamer initiation in dielectric liquids are measured simultaneously by using this system and a high-speed shadowgraph system under impulse voltage conditions. It is concluded that the LCPMS can measure partial-discharge (PD) pulses under impulse voltage conditions. The charge sensitivity of the LCPM is markedly increased by applying an optimal DC drive current to the LED. PD inception and streamer initiation were measured in cyclohexane under impulse voltage conditions. A PD current pulse of 8.2 pC was measured during negative streamer initiation.