The operation mode of sectionalized single-bus is similar to that of internal bridge scheme in 110 kV substation.Due to different primary connecting modes,protection configuration and other aspects,there are differences in operation logic of automatic switchover.The problem in automatic switchover of sectionalized single-bus scheme and different blocking and action situations of backup automatic switch with dead-zone fault of section switch are analyzed in this paper.Dead-zone fault judgment logic and action strategy in different operation modes is proposed.On the basis of ensuring safety,the action logic for automatic switchover of sectionalized single-bus scheme is optimized,which makes automatic switchover isolate the fault section reliably and restore power supply quickly when dead-zone fault occurs,and improve the recovery rate of power supply and power supply reliability.