IEC 61558-2-9:20 24 EXV包含国际标准及其扩展版本(EXV)。IEC官方标准的扩展版本仅提供英文版本，为用户提供了标准的全面内容。IEC 61558-2-9:20 24 EXV包括参考IEC 61558-1:20 17的内容。 IEC 61558-2-9:20 24涉及III类手电筒变压器和包含III类手电筒变压器的电源装置的安全性。包含电子电路的变压器也包括在本文件中。这第三版取消并取代了2010年出版的第二版。本版构成技术修订版。 与上一版相比，此版本包括以下重大技术变更: a)根据IEC 61558调整结构和参考文献-1:2017; b)为具有线性调节的输出电压的电源单元添加新符号； c)文件不仅对钨丝手电筒变压器有效。 根据IEC指南104，它具有团体安全出版物的地位。

IEC 61558-2-9:2024 EXV contains both the international standard and its extended version (EXV). This extended version of the official IEC Standard is available in English only and provides the user with a comprehensive content of the Standard. IEC 61558-2-9:2024 EXV includes the content of the references made to IEC 61558-1:2017.

IEC 61558-2-9:2024 deals with the safety of transformers for class III handlamps and power supply units incorporating transformers for class III handlamps. Transformers incorporating electronic circuits are also covered by this document. This third edition cancels and replaces the second edition published in 2010. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) adjustment of structure and references in accordance with IEC 61558-1:2017;
b) addition of a new symbol for power supply unit with linearly regulated output voltage;
c) document is not only valid for transformers for tungsten filament handlamps.
It has the status of a group safety publication in accordance with IEC Guide 104.