IEC/TR 60725:2012是一份技术报告，记录了在得出参考阻抗时可用的信息和考虑的因素，这些参考阻抗包含在IEC 60555中，现在也包含在IEC 61000-3的某些部分中。此外，还提供了与每相服务电流容量≤100 A相关的公共供电网络阻抗的信息。与上一版相比，第三版带来了两个主要的重大技术变化: -纳入了公共供应网络以60赫兹运行的国家的一项新调查和其他数据；和 -适用于50 Hz系统的建议现在被适用于60 Hz系统的新建议所反映。

IEC/TR 60725:2012, which is a technical report, records the information that was available and the factors that were taken into account in arriving at the reference impedances that were incorporated in IEC 60555 and which are now incorporated in some parts of IEC 61000-3. In addition, information is given on the impedances of public supply networks associated with service current capacities ≤100 A per phase. The third edition includes brings two mainly significant technical changes with respect to the previous edition:
- a new survey and other data from countries with public supply networks operating at 60 Hz have been included; and
- recommendations that were applicable to 50 Hz systems are now mirrored by new recommendations that are relevant to 60 Hz systems.