Composite post insulator sheds are made of silicone rubber. Possessing excellent insulation properties

the composite post insulator sheds are more and more used in substations and converter stations. The design of existing composite pillars relies on the experimental results of the original porcelain pillars

and it is not economical. So it is necessary to research the external insulation properties of composite pillars

to optimize the design of composite pillar umbrella structures for UHV stations

to improve external insulation properties

and to reduce project cost. Consequently

we carried out experiments of artificial contamination

ice coating

and rain tests of four kinds of umbrella-shaped composite post insulators

and compared them with the experimental results of porcelain pillars. The results show that no significant differences exist in the flash voltage gradient along the creepage distance between the composite pillar and the ceramic pillar under the hydrophilicity test results. Compared with the porcelain pillars

the properties of the composite pillars with full recovery of weak hydrophobic and hydrophobic properties will be increased by 24.3%～29.8% and 58.9%～65.6%. When the requirements of creepage distance are satisfied

the umbrellas of one big and one small umbrellas/one big and two small umbrellas are recommended.For the ice-covered flashover voltage of composite pillar is lower than that of the pollution and rain

the UHV composite post insulator with an anti-ice umbrella skirt is designed

and contamination and ice tests are carried out. Thereby

the artificial pollution flashover characteristics and the ice-flashing characteristics of the UHV composite pillar original and optimized umbrella shape are obtained

and the ice-flashover voltage of optimized UHV composite post insulator can be increased by 27.1%.