Pulse measurements using LED in dielectric liquids under impulse voltages

Abstract

Current pulses, in the form of partial discharges, are known to be precursors of electrical breakdown in dielectric liquids.The precise measurement of these pulses is of great value for the understanding of the breakdown mechanism. The measurement of current pulses under impulse voltage is very difficult when using conventional electrical measurement systems. To overcome this difficulty, a novel measuring system using fiber optics and a light emitting diode (LED) has been developed. In this paper, the improvements in time response and charge sensitivity of such a LED current-pulse measurement system are described. Using this system and a high speed shadowgraph assembly under impulse conditions, the current pulse and the streamer initiation in dielectric liquids are measured simultaneously.

Preliminary study on detection of PD under oscillatory impulse voltage

“…Up to present, researches on PD under impulse voltage have been focused on the following aspects. One is the optical measurement method [4][5][6][7], which is unsuitable for on site detection due to its own defects. Another approach is to use filtering technique that effectively suppresses the contribution from the applied voltage [8].…”

Observation of prebreakdown light emission phenomena in liquid nitrogen

“…An impulse voltage (200 ns x 540 ps) was applied to the needle point. The PD current pulses were measured using LED Current Pulse Measurement System (LCPMS) [2] which h a s a minimum sensitivity of 5.5 pC.…”