IEC TR 60146-1-2:1991

This report gives guidance on variations to the specifications in IEC 60146-1-1 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.
It primarily covers line commutated convertors 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.