Pollution Characteristic of Insulator Strings for 1000 kV with Transmission Line Double Circuit on the Same Tower

We researched the artificial pollution withstand voltage characteristic of 1000 kV double circuit transmission line insulator strings in real layout. Using up-and-down test methods,the 50% flashover voltage of insulator strings under polluted condition have been obtained according to GB/T 4585-2004. The characteristic of artificial pollution withstand voltage in different insulator types or string types,the impact of NSDD and non-uniform pollution of up-and-down surface to artificial pollution withstand voltage were also researched. Results show that the pollution withstand voltage characteristic of V type is better than that of I type;U50% of insulator will be decreased with the increment of NSDD;U50% of insulator is higher in non-uniform pollution condition than uniform pollution condition. The achievement is very important for type choice of insulator strings and pollution insulation configuration of 1000 kV UHV double circuit transmission line.