During some research I was doing regarding some rather unusual effects of lightning strikes, I came across an interesting package for analyzing electrical transients called ATP-EMTP, which stands for "Alternative Transients Program- ElectroMagnetic Transients Program". This is a bit of a diversion away from the OpenSource community, since, although the program is available at no cost, there are some minor restrictions to the license.

From the web site:

"ATP is a universal program system for digital simulation of transient phenomena of electromagnetic as well as electromechanical nature...The birth of ATP dates to early in 1984, some of the original developers did not approve of proposed commercialization of BPA (Bonneville Power Administration) EMTP by DCG (the EMTP Development Coordination Group) and EPRI (the Electric Power Research Institute)...

"ATP is not in public domain. It is, however, available free of all charge to anyone in the world who has not participated voluntarily in the sale or attempted sale of any electromagnetic transients program. ATP licensing is mandatory...After the licensing agreement has been approved, that party is eligible to use ATP program. "

In other words, it is free, but not OpenSource. This program is of primary interest to those who deal with electrical power generation and distribution systems. This program can be used to simulate complex networks and control systems of arbitrary structure. Among the applications they list for the program:

* Lightning overvoltage studies(the area that caught my attention)

* Switching transients and faults

* Statistical and systematic overvoltage studies

* Very fast transients in GIS and groundings

* Machine modeling

* Transient stability, motor startup

* Transformer and shunt reactor/capacitor switching

* Power electronic applications

* Circuit breaker duty (electric arc), current chopping

* Harmonic analysis, network resonances

Among other applications.

There is a very active support group for this package, and extensive documentation, which makes it usable even for a novice such as me. The package is available for multiple platforms (Windows, Linux, MAC).