IEC 60947-3:20 20适用于额定电压不超过1 000 V AC或1 500 V DC的配电电路和电机电路中使用的开关、隔离开关、隔离开关和熔断器组合装置及其专用附件。 本第四版取消并取代了2008年出版的第三版、修正案1:20 12和修正案2:20 15。本版构成技术修订版。 与上一版相比，此版本包括以下重大技术变更: 增加直流开关的临界负载电流试验（见9.3.9）； 增加了断路器、开关和由断路器保护的开关-断路器的条件短路额定值要求（见9.3.7.2）； 增加高效电机切换的新类别（见附件A）； 增加了新的附件E，用于与铝导体的连接； 增加了功率损耗测量的新附件F。

IEC 60947-3:2020 applies to switches, disconnectors, switch-disconnectors and fuse-combination units and their dedicated accessories to be used in distribution circuits and motor circuits of which the rated voltage does not exceed 1 000 V AC or 1 500 V DC.
This fourth edition cancels and replaces the third edition published in 2008, Amendment 1:2012 and Amendment 2:2015. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:

• addition of critical load current tests for DC switches (see 9.3.9);
• addition of requirements for a conditional short-circuit rating for disconnectors, switches, and switch-disconnectors protected by circuit-breakers (see 9.3.7.2);
• addition of new categories for high-efficiency motors switching (see Annex A);
• addition of new Annex E for connection to aluminium conductors;
• addition of new Annex F for power losses measurement.