CN Tower current wavefront parameters

This work is focused on the establishment of comprehensive statistics concerning the characteristics of the lightning current measured at the CN Tower during five years (1992-1996). Negative lightning currents are characterized with two distinguished impulses: short risetimes’ impulses, and impulses with substantially larger risetimes and larger current peaks in comparison with fast impulses. The slower negative current impulses were found to occur either in single stroke flashes or as first strokes in multiple stroke flashes, suggesting that they may belong to downward-initiated lightning to the CN Tower. The statistical analysis illustrates that there is a substantial difference in current wavefront parameter of ordinary negative fast wavefront impulses and those for slow wavefront negative impulses. The obtained statistics are very important for building lightning protection means against direct strikes to power lines, substation and communication equipments, as well as against lightning occurring in their vicinities.