BPA's Extra High Voltage DC Tests: II - Outdoor Flashover

Laboratory tests were conducted to determine the dc flashover characteristics of rod gaps, line-to-tower air gaps, and suspension insulator assemblies. Direct current flashover for test voltages to 725 kV has been shown to be a linear function of specimen length for either polarity or for either wet or dry test conditions. Comparative data are presented for dc, ac, and switching surge test voltages.