IEC 60146-1-2:20 11（E）对IEC 60146-1-1:20 09中给出的规范的变更提供了指导，以使规范能够在特殊情况下以受控的形式扩展。还提供了有助于使用IEC 60146-1-1:20 09的技术要点的背景信息。本技术报告主要涵盖线路换向转换器，其本身不是规范，除非涉及某些辅助部件，因为现有标准可能无法提供必要的数据。与上一版相比，第四版包括以下主要变化: a)根据现行指令重新编辑整个文件； b)纠正一些错误。

IEC 60146-1-2:2011(E) gives guidance on variations to the specifications given in IEC 60146-1-1:2009 to enable the specification to be extended in a controlled form for special cases. Background information is also given on technical points which should facilitate the use of IEC 60146-1-1:2009. This technical report primarily covers line commutated converters and is not in itself a specification, except as regards certain auxiliary components, in so far as existing standards may not provide the necessary data. This fourth edition includes the following main changes with respect to the previous edition:
a) re-edition of the whole document according to the current Directives;
b) correction of some errors.