Impact of Lightning Channel Base Current (CBC) Function Modeling on Computed Lightning Induced Overvoltage Waveshapes.

Adverse effects of lightning strike are studied through the modeling of the lightning-induced overvoltage (LIOV) using the channel-base current (CBC) functions. A lightning current is characterized by the parameters like current peak value (Im), time-taken by the current to reach Im (tm), maximum rise-rate of the current (di/dt)max (steepness), and charge transferred at the contact point of the strike (Q). Using the CBC functions, the lightning electromagnetic fields are calculated to compute the LIOV using a coupling model. Since the choice of CBC function plays an important role in LIOV computation, this article studies its effect on the computed LIOV for matching and zero load impedance. As a case study, two functions: Heidler's and NCBC functions were examined. It was shown that a-sort-of delay characteristic from the NCBC function is reflected in the computed LIOV and also the tripolar nature of the LIOV for the case of imperfect ground. The difference between the LIOV computed using NCBC and Heidler's function shows space-time reflections of the order of 104 magnitude. [ABSTRACT FROM AUTHOR]