Railway electrification system 电气化铁路
（重定向自Electrified railway）
![Electric locomotives under the wires in Sweden.](/Images/godic/202501/10/Three_engines_of_type_Rc43245.jpg")
![Electrification systems in Europe:
non-electrified
750 V DC
1.5 kV DC
3 kV DC
15 kV AC
25 kV AC
High speed lines in France, Spain, Italy, United Kingdom, the Netherlands, Belgium and Turkey operate under 25 kV, as do high power lines in the former Soviet Union as well.](/Images/godic/202501/10/Europe_rail_electrification_en.svg3245.png")
![Railroad rotary converter at Illinois Railway Museum](/Images/godic/202501/10/Rotary-Converter3246.jpg")
![Mercury arc rectifier](/Images/godic/202501/10/Mercury_ars_rectifier_Šumperk_33246.JPG")
A railway electrification system supplies electric power to railway trains and trams without an on-board prime mover or local fuel supply. Electrification has many advantages but requires significant capital expenditure. Selection of an electrification system is based on economics of energy supply, maintenance, and capital cost compared to the revenue obtained for freight and passenger traffic. Different systems are used for urban and intercity areas; some electric locomotives can switch to different supply voltages to allow flexibility in operation.