接地故障因数
earth fault current
在一定的系统结构下，接地故障时（系统中任一点的一相或多相接地故障），三相系统中的某选定点（一般指设备安装点）完好相的对地最高工频电压与无故障时该选定点对地工频电压有效值之比。
Ground Fault Factor：
the ratio of the voltage of the unfaulted phase at the point of ground fault to the phase voltage at that point before ground fault (for cases of 1 phase or 2 phases ground faults)