OpenETran
Electric power system transient simulator
..., insulators, surge arresters, non-linear grounds, and lightning strokes. It efficiently calculates energy and charge duty on surge arresters, and iterates to find the critical lightning current causing flashover on one or more phases. It is also suitable for use in substation insulation coordination. Capacitor switching, TRV, and other applicaitons may be added.
EPRI originally had permission to use code from the Numerical Recipes book in LPDW. These routines have been removed in favor of GSL.