Jun 15 11:37 2018, Henri Derksen wrote to Robert Bashe:
HD> I donot know the exact time, but it were some weeks in March 2018? HD> It was on the 20:00 hour tv news several times. HD> First many clocks running at 230 Vac~ were walking about 5 minutes to HD> slow. When the distributers remarked it, they corrected it by higher HD> up the frequency almost the same amount, so that the clocks were in HD> sync again, if the user did not remarked and changed it in the HD> meanwhile. The source of the problem were in some eastern EU countries HD> at the High Voltage network, and affected most countries here as they HD> all are connected together. Your country too.
It was caused by a dispute between Kosovo and Serbia. Kosovo didn't provide sufficient power for the grid and Serbia should have compensated that but didn't because they had a dispute about the costs. All clocks using the grid frequency of 50Hz as time source were affected, e.g. stove clocks.
The grid frequency is an interesting topic since it's an indicator of the balance between power stations and the load (consumers). Therefore it's used to keep the grid balanced. If there's not enough power fed into the grid the frequency goes down, and if there's too much power it goes up.
