小电流接地保护装置基于“相不对称”接地故障检测原理，采用PAM(Phase Asymmetry Method)核心算法，变电设备一次侧无需安装零序电流互感器和零序电压互感器，仅通过采集线路三相电流即可对馈出线路进行绝缘实时监测预警和故障选线跳闸，具有检测精度高、抗干扰能力强等特点。
Based on the principle of "phase asymmetry" grounding fault detection, the small current grounding protection device adopts the core algorithm of PAM (Phase Asymmetry Method). There is no need to install zero-sequence current transformer and zero-sequence voltage transformer on the primary side of transformer equipment. It can monitor and warn the insulation of feeder line in real time only by collecting three-phase current of the line. Barrier line selection tripping has the characteristics of high detection accuracy and strong anti-interference ability.
截至发稿时，该装置成功动作3次，调度监控系统信息与现场查明故障点信息均核对一致，直接验证了小电流接地保护装置动作的正确性。
Up to the time of submission, the device operated successfully three times, and the information of dispatching and monitoring system was checked in accordance with the information of on-site fault locations, which directly verified the correctness of the action of the small current grounding protection device.