Frequency Variations

The interconnected continental commercial networks (as is the case with most of the European ones) supply an almost invariable frequency which is very close to nominal frequency. This is because it is controlled through a mega-system which includes a very large number of synchronized machines, with an enormous overall strength and an almost infinite inertia.

On the contrary, on many islands and in other isolated areas or at independent installations with small electrical stations (or electrogen groups) substantial frequency variations are often produced. The variations are practically inevitable when there are connections or disconnections of comparable strength to the total strength of the system.