Abstract: According to national regulations, during the process of looped power transfer in low-voltage distribution areas, the two power sources must not be directly interconnected. Instead, one source must be disconnected before closing the low-voltage tie switch, resulting in short-term power outages. To address this issue, there is an urgent need for a device that can rapidly determine whether the dual power sources meet the conditions for loop closure. This paper presents the design of a low-voltage dual power supply loop detection device. By collecting voltage, frequency, phase, and phase angle data and applying a loop-closing algorithm, the device automatically determines the loop connection conditions, enabling seamless power transfer in low-voltage distribution areas with zero user perception. The device is also portable and supports one-to-many operations, effectively reducing equipment investment costs.