Parameters of Lightning Stroke Currents Defining Their Mechanical and Thermal Effects

Mechanical and thermal effects of lightning strokes depend on values of the impulse charge and specific energy of a lightning discharge current. For typical lightning currents and different lightning protection levels (LPL) as defined in IEC Std. 62305 these values can be calculated as the integral of channel-base current function and integral of the square of that function. The results presented in this paper for the new channel-base current function (NCBC) are in good agreement with experimentally measured values of these quantities. This function is used for approximating lightning channel-base currents and it provides a very simple calculation procedure. Values of the impulse charge and specific energy are useful for estimating reliability of some lightning protection structure and its parts for the defined LPL.