# Rail traction

Electric trains and metros on overhead wires, and diesel-electric locomotives.

Source page: https://www.materialinsights.org/energy/e_rail_traction/

Conversion and use · Transport systems · No. 113

- Conversion and use
 Conversion and use · Transport systems · Foundation · Energy

An electric train turns about 80% of its wire power into motion and hands some back every time it brakes.

Chart: Illustration: Rail traction

##### Where it comes from

Chart: Map of where it comes from

A pantograph slides along a 25,000-volt wire; a transformer and fast transistor switches feed the axle motors. Reversed, the motors brake the train and return about 10-30% of traction energy.

##### Three things to know

1. The Americas have only 0.5% of rail route-km electrified, against 56.8% in Europe and 62.8% in Asia Pacific.
2. A diesel-electric locomotive delivers only about 29% of its fuel energy as useful work, a third of an electric train's figure.
3. Electric trains cost over 35% less to run than diesel, but wires only pay off on busy lines.

##### The journey

1. 1 **Contact wire**Pantograph collects 25 kV AC or DC
2. 2 **Transformer**Steps line voltage down, about 94% efficient
3. 3 **Converter**IGBTs make variable-frequency three-phase power
4. 4 **Traction motors**Axle motors and gearboxes turn wheels
5. 5 **Braking**Motors regenerate power back to the line

##### Go deeper pick a tab to open it in full

## Other sections

- [Overview](https://www.materialinsights.org/energy/e_rail_traction/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_rail_traction/correlation/index.md)
- [Science and limits](https://www.materialinsights.org/energy/e_rail_traction/science/index.md)
- [Value chain](https://www.materialinsights.org/energy/e_rail_traction/valuechain/index.md)
- [Unit economics](https://www.materialinsights.org/energy/e_rail_traction/economics/index.md)
- [Engineering methods](https://www.materialinsights.org/energy/e_rail_traction/methods/index.md)
- [Equipment and suppliers](https://www.materialinsights.org/energy/e_rail_traction/equipment/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_rail_traction/links/index.md)