IEC 60146-1-1:2009 specifies the requirements for the performance of all semiconductor power converters and semiconductor power switches using controllable and/or non-controllable electronic valve devices. It is primarily intended to specify the basic requirements for converters in general and the requirements applicable to line commutated converters for conversion of a.c. power to d.c. power or vice versa. Parts of this standard are also applicable to other types of electronic power converter provided that they do not have their own product standards. This fourth edition constitutes a technical revision and introduces five main changes: - re-edition of the whole standard according to the current directives; - correction of definitions and addition of new terms, especially terms concerning EMC, harmonic distortion and insulation co-ordination; - the service condition tolerances have been revised according to the IEC 61000 series; - the insulation tests have been revised considering the insulation co-ordination; - addition of three annexes.