The article analyzes the operating principles and the circuit of regulating system SCR-D for AC automatic submerged-arc welding machine, which takes place of regulating system F-D, at the same time gives its viewpoint of automatic striking the arc. 本文阐述了用SCR-D调节系统代替F-D调节系统的交流自动埋弧焊机的工作原理和电路分析,同时也对该焊机自动引弧提出见解。