External Insulation Characteristic for UHVAC Transmission Line with Double-circuit on the Same Tower

Proper external insulation design is an important factor for safe running of power transmission line,so,in order to ensure the insulation strength and optimize the tower design of the first UHVAC transmission line with two circuits on the same tower in China,the external insulation characteristic of the tower gap and the withstand voltage characteristic of long polluted insulator strings were investigated.The power frequency voltage,different wave-front switching impulse voltage and lightning impulse voltage flashover were tested by real tower method.On the basis of the UHVAC transmission line,and the withstand voltage was tested on the long polluted insulator at the pollution test hall.Several important air gap flashover characteristic curves and withstand voltage characteristic curves of polluted insulators were gotten.According to the test results and the overvoltage simulation conclusion,the insulation co-ordination problem of the line was analyzed,and the minimum safe insulation air gap and insulator configuration were determined,which has been used as the base for the design of this power transmission project.