Observation of Lightning Current and Ground Potential Rise in Artificially Trigged Lightning Experiment

Lightning current and ground potential rise (GPR) results of artificially trigged lightning experiment in Binzhou of Shandong Province during the summer of 2006 are described in this paper. The variation of grounding resistance of grounding electrode is analyzed according to the data of experiment. From the waveform of lightning current, it can be found that the process of lightning flash has two return-strokes. The amplitude of the first return-stroke is 41.59 kA with 6.02/20.24 mus waveform, and that of the second return-stroke is 29.59 kA with 4.8/11 mus waveform. The previous study done by other authors on impulse ground resistance is always limited in the laboratory, which can provide the standard impulse current instead of the factual circumstance. Transient grounding resistance (TGR) including two small return-strokes response is obtained. ATP Simulation is used to calculate the impulse grounding resistance which compares to the factual circumstance. There is time difference between peak current and peak voltage, but the simulation can not tell the difference, which means their front time T_f and time to half value T_t are identical. That is because the simulation model did not take the spark discharge and its electrical parameter change into consideration. The results can help study the process of artificially trigged lightning, meanwhile it proposes the necessity to consider grounding electrode´s impulse characteristics under lightning current.