You can think of it like the rotor of a generator is spinning at 50Hz under a certain load. If you now reduce this load, the generator experiences less counter

You can think of it like the rotor of a generator is spinning at 50Hz under a certain load. If you now reduce this load, the generator experiences less counter force, but its input is still the same, so it starts to spin faster, increasing its frequency to say 50.1Hz. The opposite is also true, if you suddenly increase the load on the generator, the generator will start spinnging less fast and the frequency drops to say 49.9Hz. This is all very carefully monitored, and there are multiple automatic (massive) power breakers throughout a power network to detect these changes. Imagine all power lines of a large part or entire country suddenly dropping away. The network outside of that country would suddenly experience a large decrease in load and its frequency would go up, while inside the country the load would have a large increse, reducing the frequency in that country. If the change is so large that the frequency goes above 52.5Hz or below 47.5Hz, then the automatic circuit breakers trigger to prevent damage to the entire network (basically adjusting the load of the network). If it can't adjust enough, more circuit breakers will trip, causing larger outages. Example of these are the 2003 Italy blackout and 2003 US/Canada Northeast blackout. Reconnecting a blacked out part to the grid isn't easy either. People tend to leave things on during a blackout, such as airconditioners and TL lights. Now when the power comes back, these things draw a low of power for a short period of time during startup. Normally this isn't bad, but when they all do it at the same time the load is massive (think of a power spikes of 7-8x the normal usage), usually tripping the same huge circuit breaker again. As for the clock deviation, apparently running below 50Hz for a longer period of time has been condoned by the people in charge of the EU power grid. Maybe for too long. There are two solutions: - generate more power in the EU, but that costs money. They could sell the power to the slackers (which I guess they don't want to pay for) - cut the slackers off (which is very drastic and does not help the EU's idea of looking out for each other). But a decision has to be made. Looks like more power is currently being generated, as the frequency is now on 50.010Hz.