In Europe the further you head away from former Soviet countries the more likely it is that your train will be electrically powered, but there are many different ways to supply that electrical power.
Most southern English trains use a third rail for their power, but if you head further north they use overhead wires, as do most French inter-city trains, but at a different voltage to the UK.
German trains use an even lower voltage at a lower frequency still, and Dutch trains are lower still again and also have to put up with a different frequency and voltage on certain lines in Belgium.
Sometimes the voltage changes while you’re on the train, or even when the train is stationary in a station, and the different voltages are separated by a neutral section of overhead cable.
Finally, all this rail electrification infrastructure needs to get its power from somewhere, and that somewhere is increasingly less likely to be a dedicated railway owned power station.
Instead, it’s more likely to involve a grid connection and some form of rectifier in the case of DC lines.
The posts talks about many other aspects of train electrification in Europe and other parts of the world.
