When everything goes dark, Swissgrid must ensure that the electricity flows again as quickly as possible. There is a process for this called «automatic start-up».
First the lines have to be switched off in all the regions affected by a power failure, because otherwise the grid would crash again after every attempted start-up. Then the ten or so power plants in Switzerland capable of automatic start-up come into play. Every power plant needs electricity to produce electricity, but the power plants capable of automatic start-up can generate this electricity themselves. These are used to create small illuminated islands that can then be gradually connected via the 140 Swissgrid switching substations to form a functioning grid.
The film «Schwarzstart» (automatic start-up) shows how Swissgrid can rebuild the grid with the help of the Oberhasli power plant and how collaboration with the Swiss army works in an emergency. The army would provide additional communication tools.