IEC 61051-2:20 21是一个分段规范，适用于连接到任何交流或DC电源系统的电子设备中使用的具有对称电压-电流特性的金属氧化物压敏电阻器。 这些压敏电阻旨在保护电子和其他敏感设备免受高瞬态电涌的影响。本部分规范范围内的变阻器不打算提供针对雷电浪涌的初级保护。 这些变阻器具有金属连接，旨在作为通孔组件安装或直接安装在印刷电路板上。 本文件的目的是规定优选的额定值和特性，从IEC 61051-1中选择适当的质量评估程序、测试和测量方法，并给出此类变阻器的一般性能要求。与上一版相比，此版本包括以下重大技术变更: 在可行范围内，根据ISO/IEC指令第2部分对结构进行修订，并与IEC 61051-1:20 18保持一致； 增加了附件十，以便与前一版进行比较； 增加了圆盘型和SMD型压敏电阻的两个优选额定电压列表； 在8.4.3的测试计划中，不合格项目的允许数量已设置为零（零故障）。

IEC 61051-2:2021 is a sectional specification and is applicable to metal oxide varistors with symmetrical voltage-current characteristics for use in electronic equipment connected to any AC or DC supply system.
These varistors are designed to protect electronic and other sensitive equipment from high transient surges. Varistors under the scope of this sectional specification are not intended to give primary protection against lightning surges.
These varistors have metallic connections and are intended to be mounted as through hole component or directly on to printed boards.
The object of this document is to prescribe preferred ratings and characteristics and to select from IEC 61051-1 the appropriate quality assessment procedures, tests and measuring methods, and to give general performance requirements for this type of varistors.
This edition includes the following significant technical changes with respect to the previous edition:

1. revision for the structure in accordance with ISO/IEC Directives, Part 2) to the extent practicable, and for harmonizing with IEC 61051-1:2018;
2. Annex X has been added for comparison with the previous edition;
3. two lists of preferred voltage ratings for disk type and SMD type varistors have been added;
4. permissible numbers of non-conforming items have been set to zero (zero fault) in the test schedule in 8.4.3.