IEC 60305:2021适用于具有陶瓷材料或玻璃绝缘部件的帽和销型串绝缘子单元，用于标称电压大于1 000 V、频率不大于100 Hz的交流架空线路。它也适用于变电站中使用的类似设计的绝缘子。本文件适用于带有球窝接头或U形夹和舌形接头的帽型和销型串绝缘子单元。本文件适用于清洁区和污染区架空线路上使用的串式绝缘子单元。为了在以非常重的污染水平为特征的区域中使用以及对于其他特定或极端的环境条件，可能需要改变某些尺寸，并且具有不同爬电距离、间隔和形式的绝缘体单元可能是优选的(例如，扁平轮廓、半球形等)。).用于DC系统的绝缘体也可能需要不同的尺寸。在任何情况下，适用的是保留本文的标准化机械特性和联接尺寸。这第五版取消并取代了1995年出版的第四版。与上一版相比，此版本包括以下重大技术变更: -范围内的措辞从“建议”改为“适用”； -增加了新的规范性参考； -第4条规定的机电或机械失效载荷； -增加了显示个人资料的新数字。

IEC 60305:2021 applies to string insulator units of the cap and pin type with insulating parts of ceramic material or glass, intended for AC overhead lines with a nominal voltage greater than 1 000 V and a frequency not greater than 100 Hz. It also applies to insulators of similar design used in substations. This document applies to string insulator units of the cap and pin type either with ball and socket couplings or with clevis and tongue couplings. This document applies to string insulator units for use on overhead lines in clean areas and polluted areas. For use in areas characterized by very heavy pollution levels and for other particular or extreme environmental conditions, it may be necessary for certain dimensions to be changed and insulator units having different creepage distances, spacing and forms may be preferred (for example, flat profile, hemispherical etc.). Insulators for use on DC systems may also need different dimensions. In any case, it is applicable that the standardized mechanical characteristics of this document and coupling sizes are retained. This fifth edition cancels and replaces the fourth edition published in 1995. This edition includes the following significant technical changes with respect to the previous edition:
- wording in Scope changed from "it is recommended" to "it is applicable";
- new normative references added;
- electromechanical or mechanical failing load in Clause 4 specified;
- new figures added showing profiles.