Abstract: Three phase three wire smart meters are widely used in neutral ungrounded systems, usually used for internal assessment checkpoints, electricity customer trade settlements, and other metering points. Based on the 10 kV high supply and high metering users, the reverse polarity of the C-phase current of the intelligent energy meter caused abnormal measurement data. Analyze the data change pattern before and after the reverse polarity of the C-phase current, calculate the amount of electricity to be refunded and supplemented, and propose detailed measures to prevent various risks.