IEC 61558-2-16:2021 deals with the safety of switch mode power supply units and transformers for switch mode power supply units.
This second edition cancels and replaces the first edition published in 2009 and amendment 1:2013. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:

1. adjustment of structure and references in accordance with IEC 61558-1:2017;
2. definitions of different voltage characteristics;
3. partial discharge and description of constructions moved to IEC 61558-1:2017;
4. alternative method for dimensioning of clearances;
5. removal of requirements for homogeneous field conditions.

It has the status of a group safety publication in accordance with IEC Guide 104.
This International Standard is to be used in conjunction with IEC 61558-1:2017.