There was a ~45 minute power cut in the centre of Copenhagen last month, starting at about 1:30am. There was another (several hours) in 2018, which I think is the one that made the news. (I was at home, awake, for both.) They're a bit more common than you remember, but I suspect most of these Tweets are affecting fairly small areas, e.g. construction work cutting cables etc: https://twitter.com/radiuselnet
I have some servers in Copenhagen, and from their logs they've lost mains power about every 2-3 years. They have a UPS, but I certainly don't bother for a desktop computer.
I'm from Jutland which might be part of the explanation. Also, I left 20 years ago.
I'm not sure what you mean by "most of these Tweets"; I'm reporting on my experience living in Silicon Valley, California, where power goes out a couple of times a month on avg.
I have all servers etc on UPSes but wish I could find bigger UPSes as most can only hold up about 1 hour which often isn't enough.
I'll go look again, but last I did I didn't find much [affordable].
I do have an (no longer in production?) APC Smart UPS which can be extended with an external battery, alas vastly overpriced.
Of note, if various online resources are to be believed, you can't just hack and extend the battery capacity for longer run-times as they likely aren't rated for the corresponding higher thermal load.
they're not cheap, but i've bought cheaper and that stuff costs even more in the end.
power electronics that are safe and reliable costs.
> you can't just hack and extend the battery capacity for longer run-times as they likely aren't rated for the corresponding higher thermal load.
thermal load... of batteries?
i'd expect you'd confuse the microcontroller in the UPS. more batteries will require longer to bring up to voltage than it expects, which implies something is wrong. further all of the time remaining estimations it presents will be wrong.
[Following your advise I did find some Tripp-Lite that are almost reasonable]
Thermals referred to the power electronics which do get hot.
Yes certainly better to get equipment designed for it rather than risk burning down the house.
I have some servers in Copenhagen, and from their logs they've lost mains power about every 2-3 years. They have a UPS, but I certainly don't bother for a desktop computer.