IEC 61557-9:1999
交流1000V和直流1500V以下低压配电系统中的电气安全 防护措施的试验、测量和监控设备 第9部分:IT系统中的绝缘故障定位设备
Electrical safety in low voltage distribution systems up to 1000 V a.c. and 1500 V d.c. - Equipment for testing, measuring or monitoring of protective measures - Part 9: Equipment for insulation fault location in IT systems