Pillar type insulator is mainly used for outdoor purpose. Outdoor pillar type is divided into pillar rod type insulator, pillar needle type insulator and piled-cone insulator.
      Outdoor rod type insulator has solid round porcelain pillar including umbrella. Umbrella is used to keep some surface of insulator dry in rainy day and improve leakage distance along porcelain surface between electrodes to increase wet flashover voltage.
      Rod type insulator may be affected by bending moment in operation. Bending moment may increase along with voltage rising and increasing of insulator height. Therefore it shall be manufactured by high strength porcelain.