The utility model discloses a three pillar insulators are used to gas -insulated generating line, three pillar insulators are used to gas -insulated generating line be including being used for the base member is connected with the conducting rod cartridge, and the interval is equipped with the insulating pillar of three radial extension at least on the base member periphery wall, wherein the top of at least one pillar that insulates be equipped with be used for with pipe inner wall roll complex roll proportioning plant, the roll proportioning plant includes the device body, locate rolling element on the device body and right the rolling element carry on spacing, prevent its limit structure who drops. For the insulator among the prior art, add the limit structure to the rolling element, can prevent the rolling element in the insulator is to the pipeline in the installation rolling element drop easily, it is easier to assemble.