当工作电源失去电压时,备用电源由自动装置立即投入,从而保证供电的连续性,电力系统经常采用两个或两个以上的电源进行供电,并考虑相互之间采用适当的备用方式。 When the working power supply loses its voltage, the backup power source is put into operation immediately by the automatic device so as to ensure the continuity of power supply. The power system often uses two or more power supplies for power supply and considers the appropriate standby mode for each other.