Performance of large air gaps under lightning overvoltages: experimental study and analysis of accuracy predetermination methods

The authors summarize the results of research on the performance of large air gaps under impulses simulating lightning overvoltages. Tests were performed on various gap configurations and with several impulse shapes of both polarities. The impulse characteristics were varied to cover most cases of practical interest. Attention was paid to breakdown parameters and to physical aspects associated with the discharge mechanism. A systematic check of the accuracy of existing semi-empirical models against experimental data was undertaken. It was verified with relatively good accuracy. Based on elements derived from physical analysis, an improvement of existing models was also proposed