Characteristics of epoxy resin insulators flashover in multi-component gas mixtures

SF
₆
gas mixtures are expected to replace SF
₆
gas and applied in gas insulated equipment. This paper presented the characteristics of epoxy resin insulators flashover in pure SF
₆
, SF
₆
-N
₂
and SF
₆
-CO
₂
binary gas mixtures which the ratio was 2:8 and 3:7, SF
₆
-CF
₃
I-N
₂
and SF
₆
-CF
₃
I-CO
₂
ternary gas mixtures which the ratio was 1:2:7 between 0.1MPa and 0.25MPa gas pressure under uniform electric field, and AC voltage and negative polarity DC voltage were applied. The experimental results showed that the AC flashover voltages and DC flashover voltages of epoxy resin in the pure SF
₆
and its gas mixtures both increased linearly with gas pressures increasing; the DC flashover voltages of insulators in binary gas mixtures were always higher than that in ternary gas mixtures under the same pressure; in pure SF
₆
and SF
₆
-N
₂
, SF
₆
-CO
₂
binary gas mixtures which contained 30% SF
₆
, when the gas pressure was higher than a certain critical value, the DC flashover voltages of insulators were higher than the AC flashover voltages, and the former would be lower than the latter when the gas pressure was lower than the critical value. The results of this paper can provide reference informations for application of SF
₆
gas mixtures in gas insulated equipment.