PURPOSE: To prevent a trip accident occurring due to abnormal voltage caused by thunderbolt surge, by conducting a conductive layer, provided by a specific condition to the flange of host earth electric potential, and providing a gap, causing voltage higher than that by arrestor operation, in a space with a flange of the high pressure electric potential lower part.

CONSTITUTION: Withstand voltage in a radius direction between a conductive layer 4 and a resistant element 1 is ensured by a gas insulating part 2, between a withstand voltage vessel 3 and the resistant element 1, and the withstand voltage vessel 3 itself; and withstand voltage in a direction along the axis core of the conductive layer 4 and of the lower part flange 6, a high-voltage electric potential member, is ensured by a gap between the conductive layer 4 in the boundary, between the withstand voltage vessel 3 and a polymer rib 5, and the flange 6. Insulating distance is easily ensured compared with a former arrestor. That is, not only flush-over in series gaps due to thunderbolt surge is more ensured to surely protect a transmission and delivery facility from abnormal voltage due to thunderbolt surge, but also insulating distance can be easily ensured compared with a former arrestor.