关角隧道是中国最长的铁路隧道，该隧道富水区长22.5 km，涌水量大，施工难度高。以关角隧道5#斜井为背景，通过对排水设备的选型和组合，实现斜井的自动排水。介绍使用PLC控制器及软启动器实现自动排水的原理，对传统泵站的缺点进行分析，并对自动排水系统与传统排水系统进行比较。结果证明，自动排水系统的经济性和可靠性均优于传统排水系统，该自动排水系统在关角隧道的施工中得到了有效的应用,并降低了工程成本。

Guanjiao tunnel is the longest railway tunnel in China. The waterrich section of the tunnel reaches 22.5 km long. Due to the serious water inflow, there is great difficulty in the construction of the tunnel. Proper water pumping equipment is selected for No. 5 inclined shaft of Guanjiao and automatic water pumping is realized. In the paper, the principle of the automatic water pumping based on PLC controller and soft starter is presented, and comparison and contrast is made between the automatic water pumping system and the conventional water pumping system. It is concluded that the automatic water pumping system is superior to the conventional water pumping system in terms of economical efficiency and reliability. The automatic water pumping system has been successfully used in the construction of Guanjiao tunnel, and the construction cost has been reduced.