How do trains work? Especially, how does the electricity flow between the power lines and the train, for example, while changing tracks?
In: Technology
I’m not entirely sure what your question is. There’s live current that flows through the wires, through the train and it’s motor, and into the ground. The train is the least resistant path that the electricity can take to the ground, so that’s where it goes.
The details of the power supply change per country. Most systems use 2 overhead power lines, a single overhead and a return through the rails, or a third rail and return through the normal rails. This can be done with AC or DC.
When a train changes tracks it usually loses power supply for a short while. Batteries can be used to bridge the gap while switching to the new supply. Again, the details change depending on the location
Trains run on DC, meaning that the one electrical terminal will always be positive and the other will always be ground. For trains, the positive terminal is the overhead cabling. The rails it drives on is the ground terminal.
So when a train extends its boom and contacts the overhead cables, the electric circuit is closed.
The rails are literally electrified. However, it’s safe as the are kept at the same potential as the ground you walk on.
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