The influence of the 500kV insulating aerial device on minimum approach distance in live working

The application of 500kV insulating aerial device to provide technical means for safety and reliability of power transmission lines, but influence of conductive work platform on the insulation of tower windows gaps are not clear. The switching discharge tests were applied to determine the minimum approach distance in live working. Firstly, test samples were processed according to the typical single circuit 500kV transmission lines and insulating aerial device, and the switching impulse discharge test at 1:1 ratio scale simulated tower were performed on different typical live working positions . It was shown that the work platform reduces the discharge voltage of complex gaps by 15%. Based on the test results, the minimum approach distance and complex gaps of are 3.8m and 4.7m in middle phase ,and, are 3.2m and 3.8m in outer phase according to live working insulation coordination and risk calculation. Considering the size of work platform and the air gaps of tower window , the insulation length of air gaps would be less than the minimum approach distances and complex gaps when work platform is located between the conductors and the tower. So when the insulating aerial device are applied in live working on 500kV lines, the work platform should avoid locating in the outer phases close to the tower and the middle phase, because the minimum approach distances and complex gaps couldn't meet the safe requirements.