Dielectric breakdown in nonuniform field air gaps

The sparkover characteristics of rod-rod and rod-plane gaps in air under DC voltages are reviewed. The linear characteristics of both configurations are associated with the prominence of streamer discharges during the prebreakdown phase. The limits of linearity are shown to be a function of humidity, gap spacing and electrode profile, all of which determine the predischarge mode. It is shown that the rod-plane gap offers a wider range of linearity than the rod-rod gap and that it can have a valid role as a DC voltage measurement tool.<
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