城市轨道交通的供电系统一般采用直流供电，并以轨道作为回流的通路。

In DC rail transit systems, the running rails are usually used as the return conductor for traction current.

youdao

城市轨道交通的供电系统一般采用直流供电，并以轨道作为回流的通路。

In DC rail transit systems, the running rails are usually used as the return conductor for traction current.

youdao