IEC TR 60146-1-2:2019 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 facilitates 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 fifth edition includes the following significant technical changes with respect to the previous edition:
a) addition of annexes concerning the applications of converter transformers and of fuses for overcurrent protection;
b) changes of calculation methods related the inductive voltage regulation and changes of description on transformer losses to be consistent with the latest transformer standards;
c) addition and updates of references based on the latest information.