Abstract: In view of the inadequacy of conventional automatic switchover device when the breaker is abnormal or failure occurs on bus at the internal bridge connection substation,the application of substation area automatic switchover device based on the process layer network is proposed.An elaboration is made of how the range of automatic switchover device is expanded by the improved logic of the substation area automatic switchover device and and how zero load loss is attained during switchover for the whole station by unified control of the high and low voltage side switches.