According to the automatic switch-in principles of stand-by power and the application case of the automatic throw-in equipment of stand-by power supply in Dongguan 10 kV power system, the shortages of CSB 21A automatic throw-in equipment of stand-by power supply are analyzed and corresponding correcting suggestions proposed. 根据东莞10kV备用电源自动投入装置的备自投原则和实际应用情况,分析了CSB21A型备用电源自动投入装置存在的问题,提出了相应的整改建议。