Abstract: Voltage type switches are currently the mainstream configuration in distribution network automation. Its action logic is simple and reliable. Cooperating with switches in the substation can effectively isolate fault points and restore power supply to non fault points. In order to further leverage the power distribution automation function and reduce the power outage time at non fault points, some distribution networks are exploring the use of a "locked opening time" configuration. This article explores the delay locking and opening function of the voltage segmented device based on the logic principle and example analysis of the delay locking and opening action of the voltage segmented device. The proposal of 'blocking and opening time' is only valid for a single fault. For multiple line faults that occur in the distribution network before and after a certain period of time, not only does it not reduce the power outage time at non fault points, but it will also expand the power outage range. The definition of "locking and opening time" is a "chicken rib" functional configuration. It is recommended that the distribution network automation switch not use the "delayed locking and opening" function.