Research on the upward leader emerging from transmission line by simulation experiments

This paper presents some simulated experimental results and characteristics of upward leader emerging from transmission line, which carried out at the Ultra High Voltage Engineering Technology (Kunming) National Engineering Laboratory. Different measurements were conducted in a 6 m plane-conductor gap under positive and negative polarities impulses of 1 to 3 MV with waveform of 200/2000 μs. The process of discharge was observed by using the high speed camera and the current was measured with the current shunt with frequency response of at least DC-6.5MHz. Upward leader from the conductors were captured during the process of discharge. The velocities of upward leader have been estimated to be 1-3 cm/μs, which is in accordance with the velocities of leader that observed in the process of discharge in rod-plane gap under positive pulse with waveform of 200/2000 μs. The experimental results were compared with those in the natural lightning and some parameters of the equality were discussed. Obviously, the upward leader will occur during natural lightning.