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.