Reasonable insulator string arrangement is one of the effective ways to improve the pollution flashover voltage.At present

most of the existing references of the forms of insulator strings are mainly related to insulator string arranged in V-type and inverted V-type

but rarely related to insulator string arranged in inverted T-type. We adopted a uniform increase voltage method to test XWP-70 and other two inverted V-type insulator strings and compared with the ordinary hanging string. Through the experiments

it can be found that the flashover voltage of the inverted T-type insulator string has a power function relation to ESDD. Compared with the ordinary hanging string

the inverted T-type insulator string flashover voltage increases by 11.6%～22.3%; and with the increase in salt density

the percentage of flashover voltage improvement also increases. According to the results

the equivalent coefficient of the inverted T-type insulator string in each pollution area is calculated

and it will be convenient to select the inverted T-type insulator string’s length.