a fourth 345-kV line was lost—this one because it was being asked to carry more current than it could safely transport—followed almost immediately by fifteen 138-kV lines shutting themselves off automatically. This is a self-preservation technique designed into electrical conductors (“conductor” is the technical term for an electric transmission line) when giant waves of unstable voltage threaten to fry, melt, or otherwise disable them. At this point, 3:41 P.M., about thirty minutes before the actual blackout started, trees ceased being the problem. Line failures were fast becoming commonplace
...more
