To optimize the structure of tri-post insulator in 1 100 kV GIL

we used the finite element software COMSOL to establish a model of UHV AC tri-post insulator and calculate the potential and electric field distribution. The maximum value of tangential and total electric field of tri-post insulator surface as well as the electric field strength of metal insert surface were defined as optimization indexes. Thereby

according to the effect laws and degree concluded by researching the influences of the key structure parameters on indexes value

the optimization direction was obtained. By analyzing structure parameters and effect laws

a dumbbell structure of UHV AC tri-post insulator was proposed. The calculation results showed that

the maximum field value of metal insert surface was decreased by dumbbell structure from 14.7 k V/mm to 10.6 k V/mm

without affecting the electric field distribution of insulator surface significantly. This structure effectively improved the electric field distribution on the surface of the metal insert and improve the comprehensive electrical performances.