If the SPD indicator of a smart module is green, the SPD is running properly.

In Huawei data center power distribution design, theSPD (Surge Protective Device)provides overvoltage surge protection for sensitive loads by diverting transient energy to ground through internal protection components. The SPD status indicator is used for O&M judgment of protection availability. When the indicator isgreen, it indicates the SPD protection components arewithin normal working conditionand the surge protection path remains effective. When the indicator turnsred, it typically means the SPD’s internal protection element hasdegraded or disconnected(end-of-life or failure after cumulative surges), and the device can no longer provide the rated protection level. In this condition, the distribution system is left exposed to surge risk, especially during thunderstorms, switching operations, or upstream disturbances. Therefore, Huawei O&M practice treats ared SPD indicator as a replacement trigger, requiring immediate corrective action: confirm alarm/status, ensure safe isolation following electrical safety procedures, and replace the SPD module to restore protection and maintain power system reliability.