IEC 62505-3-1:20 20适用于用于测量、控制和保护的新型低压设备: -用于牵引系统中的室内或室外固定装置，以及 -与IEC 60850规定的交流线电压和频率的高压设备一起工作。 在合理可能的范围内，本文件也适用于除低压设备以外且未被特定铁路产品标准涵盖的测量、控制和保护设备。以本文件的要求为准。 第二版取消并取代了2009年出版的第一版。与上一版相比，此版本包括以下重大技术变更: -区分需求和应用指南 -包括对设备的要求，例如以前未包括的控制和保护继电器；-删除已包含在其他标准中的部分，例如用于保护原理的EN 50633，该标准旨在成为IEC标准。

IEC 62505-3-1:2020 is applicable to new low voltage devices for measurement, control and protection which are:
- for indoor or outdoor fixed installations in traction systems, and
- operated in conjunction with high voltage equipment with an AC line voltage and frequency as specified in IEC 60850.
This document also applies to measurement, control and protective devices other than low voltage devices and not covered by a specific railway product standard as far as reasonably possible. Requirements of this document prevail.
This second edition cancels and replaces the first edition published in 2009. This edition includes the following significant technical changes with respect to the previous edition:
- distinguish between requirements and application guides
- include requirements on devices for example control and protection relays not included before;
- remove parts already included in other standards, for example EN 50633 for protection principles, which is intended to become an IEC standard.