Microwaves, ovens and clock radios in countries connected to the continental European electricity grid have suddenly started to lose a minute here and there. This happens to devices whose time display is controlled by the electricity grid. Unlike clocks with internal crystal oscillators or those synchronized to broadcast time signals, these clocks do not have an internal time source.
But what causes these clocks to show the wrong time? In recent weeks there were rumours that the cold snap could have caused the problem. The actual answer is even stranger: a political dispute in Kosovo is what tipped the scales. Ultimately, it was electrical power transfers between the Balkan countries that caused the loss of time on clocks in countries connected to the continental European electricity grid. In Denmark it affects clocks in the Western part of the country while Sweden and the UK are not affected.
Since mid-January, electricity generating companies in Kosovo have not been meeting their delivery obligations, resulting in a shortfall of 300 to 400 megawatts of capacity in the pan-European grid. The outcome is now clear to see on clock displays across the continent, as reported by the European Network of Transmission System Operators (ENTSO-E). The deviations came from the electricity grids of Kosovo and Serbia. The two countries were embroiled in a political dispute about delivery quantities between the competent authorities.
It has since been revealed that former Environment Minister Klaus Töpfer (CDU) will now attempt to settle the energy dispute between Kosovo and Serbia. Töpfer confirmed to the Frankfurter Allgemeine Zeitung that he is planning to visit both countries next week. According to the article, the former minister will conduct talks with the Serbian Prime Minister, Ana Brnabić, and her counterpart in Kosovo, Ramush Haradinaj.
50 Hertz is the gold standard in the electricity grid
Let's get back to the affected clocks and the physical principles. They measure time via AC voltage cycles, which saves on the cost of having a built-in stable oscillator. Normally, the frequency of the electrical grid in Europe is exactly 50 Hz, which equates to 50 cycles per second. As long as this frequency is kept largely stable, clocks that use the AC line frequency as a reference will keep the time accurately.
As previously mentioned, there has been a power shortage in the pan-European electrical grid since mid-January, with the result that the frequency was below 50 Hz for an extended period. It was, in fact, only 49.996 Hz. While this may look like a very small deviation, it ultimately resulted in a time difference of around six minutes when six weeks had elapsed.
On the website of the Swiss network operator Swissgrid you can see the current difference and the actual frequency in real time to three decimal places. The shortfall was 346 seconds at 10 a.m. in the morning on Wednesday 7 March.
Catching up by around 6 minutes
According to ENSO-E, this prolonged deviation in grid frequency – extending over several weeks – has never been seen before. Slight variations in the frequency of the grid voltage are perfectly normal, but up to now these deviations have always balanced themselves out, so the target frequency of 50 Hz was maintained overall. Now the frequency will need to be raised slightly during the coming weeks in order to catch up with the actual time. That means if you manually adjust your lagging clocks now, you may have to adjust them again in a few weeks – in the opposite direction.