It might be surprising to know that in electric trains, the power collected from the overhead lines ends up in the grounding cable of the track after flowing through the wheels. Three phase power conversion, regenerative braking and zig-zag overheadlines - all these make electric train technology quite unique.

Early electric railways functioned by converting electrical energy from a central powerhouse into mechanical motion via an onboard motor. The first commercial systems, pioneered by Werner von Siemens in the 1880s, typically used a third rail or an overhead line to transmit direct current (DC) to the train. A "collector" (like a contact roller or a pantograph) would pick up the electricity and send it to a series-wound motor, which used iron bars and electromagnets to rotate the axles. To complete the circuit, the electricity would return to the power station through the running rails. Later systems introduced alternating current (AC) for more efficient long-distance transmission, using rectifiers to convert it back to DC for the traction motors. A key innovation was the Multiple-Unit (MU) control, which allowed a single driver to control motors on multiple cars throughout the train. This transition from steam to electricity was largely driven by the need to eliminate noxious smoke in urban tunnels and subways, paving the way for the modern rapid transit systems we use today.