Impulse partial discharge and breakdown characteristics of rod–plane gaps in air and N2 gases

In response to growing environmental concerns, we attempted to develop switchgear without using SF₆ gas. In our research, we used compressed air and pure N₂ as an electrical insulation gas, because of their low global warming potential. In this paper, we examined the impulse breakdown and impulse partial discharge characteristics under various conditions related to nonuniformity of the electric field. The experimental results show that the breakdown voltage (BDV) of air is higher than that of pure N₂ gas under highly nonuniform field conditions in the rod–plane gap. On the other hand, the discharge inception voltage of air and N₂ were almost the same. Furthermore, first partial discharge (PD), leader discharge, and its transition to the breakdown were successfully observed through the measurement of discharge current and light emissions under impulse voltage application. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 36–43, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10277