Abstract: In the 6 kV parent line of a petrochemical enterprise substation, it was found that during the process of self-investment testing, it was found that unreasonable zero-sequential overvoltage protection configuration may cause the ground protection misunderstanding the police, and it will cause trouble and trouble to operators who are performing power delivery operations. Through theoretical and verification test analysis, the configuration problem and misunderstanding the reason for the alarm of zero-sequential overvoltage protection were studied, and the corresponding solutions were proposed to verify its effectiveness through actual operation.