How is electric power transmitted to trains with the overhead cable?

Question by Snow C: How is electric power transmitted to trains with the overhead cable?
Since the overhead cable is only one contact, and any circuit needs to be closed, where does the current flow out of?

Best answer:

Answer by Marc Robertson
The circuit has the live power on the overhead cantilevers and is grounded by the rails which complete the circuit. This way there is no live power and ground right next to each other that humans or animals can be killed by.

Ironically, every locomotive is electrically powered. Most locomotives are diesel electric because a traditional transmission won’t work. Basically the power is fed from a huge diesel motor into a huge generator. The power goes through a drive which controls the power. Then it goes to multiple traction motors simular to electric trains.

Correction: Every diesel locomotive is electrically powered, China still runs steam powered locomotives…

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