设计了一款以dsPIC30F4012为主控制器、PIC16F877A为从处理器的新型主从式选择性漏电保护系统。该系统在总开关处采用附加直流源检测原理检测是否发生漏电，在分支开关处使用零序功率方向检测原理判断发生漏电故障线路，给出了保护系统的硬件框图和软件流程图，并且采用速度更快的RS—485总线及光纤传输技术，实现了矿井低压电网漏电保护的瞬动性。实验结果验证了该保护系统的优越性能。

A novel selective leakage protective device in master-slave structure was proposed where dsPIC30F4012 was the master controller and PIC16F877A was the slave processor. The device used the principle of additional DC power supply in main feeding switch to examine the occurrence of the leakage and used the principle of direction of zero sequence power in branch feeding switch to judge the faulty line. The hardware diagram and the software flow chart of protective system were given and RS-485 bus and optical fiber communication technology were adopted. It could improve the action capability and anti-interference capability of the leakage protective device for power supply system in underground, and the experimental results confirmed the protection device proposed had good performance.