Abstract: There is a 30° phase difference in the 10 kV line. If the loop is directly closed, a large loop current will be formed between the two wires. Causing a tripping of the superior power supply, leading to a widespread power outage. In the past, the mode of power outage, load reversal, and power transmission has been adopted. Serious impact on power supply reliability. Now, by accurately calculating the closing current. Reasonably set the switch protection settings. All levels of protection cooperate with each other. Successfully achieved non power outage, loop closing, and power regulation through protection tripping. Reduce user perception of power outages and improve satisfaction with 'obtaining electricity'.