@penguin42 @th

there are two stickers in that picture. one of them is at least partially successful at deterring people from plugging in their laptop.

@th ... I also wonder how you select voltage/frequency and waveform... is it just random / could it change at any time? 😱

@attie this is on the IC train from Osnabrück to Amsterdam, which switches engines at Bad Bentheim from 15kV AC in Germany to 1500V DC for the Netherlands. maybe it depends on the catenary input?

@th @attie Apparently https://en.wikipedia.org/wiki/15_kV_AC_railway_electrification 50/ 16.2/35Hz/16.7 is common in Germany; (50/3) - but wth is this thing based on 60Hz and 60/4 ?

@attie @th You don't select it - it's provided by the locomotive.
For more info see "head-end power" and this is a RIC standardized car.

@attie @th Or rather it depends on what waveform and voltage the locomotive provides through HEP.

@Makdaam @th Interesting... I went for a bit of a dive and found out about all sorts of unexpected / wonderful things like 15 Hz / 16 Hz and near-but-not-quite...

I wonder what the origins of these systems are, perhaps the railways generated their own power?

Surely it's a pain to produce now?

... too many questions! 🫣

@Makdaam @th (presuming it's not generated by the loco itself...)

@attie @th Divide 50Hz by 3 :) that was the frequency of many long-haul high voltage lines in Germany, Austria, Switzerland.
I'm guessing 15Hz over here is just a lower bound since 16.7Hz is a long thing to put on a sticker, and precision isn't really required.

@Makdaam @th
It's the 15 Hz here... 16Hz there... 16.66 Hz here! that gave me a chuckle... 🙃

Not to mention all the others (25, 40, 45, 50, 60 Hz)

https://en.wikipedia.org/wiki/List_of_railway_electrification_systems#Two_wires

@attie @th These are only the 2 wire train lines (with 3 phases: 2 on the wires, one in the rails).
Which should add another set of questions :) like I said, endless fractals of questions.

The answer to the first one is: because 3 phase synchronous motors were the most practical solution for a time (no need to worry about brushes, just switching how coils are connected in a given mode of operation).

@attie @th also MUAHAHAHAHA at taking "a bit of a dive". :>

This is an endless cave system of fractal paths that can take you to a lot of useless trivia about anything from alloys used in overhead electric wires through cart suspension design, different breaking systems, couplers, to communication systems which are their own niche.

@attie @th One voltage on each pin, obviously.

@attie @th the train itself runs on 16 ⅔ Hz AC in germany, so that might be where these are coming from.