Abstract: The V/V-12 wiring voltage transformer is widely used in neutral ungrounded and high impedance grounded systems. It is usually used for metering by 10 kV high supply and high meter users. When the voltage transformer experiences a phase failure, it may cause metering errors, leading to risks such as inaccurate metering and power supply service complaints. This article combines the 10 kV high supply and high meter users who use V/V-12 wiring voltage transformers. During operation, voltage phase failure caused abnormal power consumption. The change law of the collected system curve data before and after the fault is analyzed. Combined with the nature of the load, the refund and compensation power is calculated, and detailed preventive measures are proposed to effectively prevent various risks.