NF C42-198-7*NF EN 61557-7:2007 交流1000V和直流1500V以下低压配电系统的电气安全 保护措施的测试、测量或监测设备 第7部分:相位序列
Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. - Equipment for testing, measuring or monitoring of protective measures - Part 7 : phase sequence