IEC 61557-7 ED.2. Electrical safety in low voltage distribution systems up to 1000 V a.c. V d.c. Equipment for testing, measuring or monitoring of protective measures. Part 7. Phase sequence
IEC 61557-7第2版 低压配电系统的电气安全高达1000 V交流V直流保护措施的测试、测量或监测设备 第七部分 相序