IEC 61557-8:20 14规定了绝缘监测装置（IMD）的要求，该装置永久监测出土交流电的射频对地绝缘电阻。交流的IT系统。具有电流连接直流电的IT系统。标称电压高达1 000伏交流电的电路，以及非接地直流电的电路。电压高达1 500 V DC的IT系统。独立于测量方法。IEC 60364-4-41以及其他文献中描述了IT系统。应注意其他标准中器械选择的附加数据。根据IEC 61557这一部分的IMD也可用于断电的TT、TN和IT系统或电器。这第三版取消并取代了2007年出版的第二版。本版本为技术修订版，与上一版本相比包含以下重大技术变更:-补充了术语和定义； -列出并解释了缩写； -已修订要求； -强制性和可选功能及其术语改编自IEC 61557-15； -增加了机械要求； -增加了有关操作说明的信息； -型式试验和常规试验已得到补充； -增加了附件C:“光伏系统绝缘监测装置（PV-IMD）”；和 -增加了附录D:“光伏逆变器(PV-IMF)或充电控制器中的绝缘监测功能”。 本出版物应与IEC 61557-1:20 07一起阅读。

IEC 61557-8:2014 specifies the requirements for insulation monitoring devices (IMD) which permanently monitor the insulation resistance RF to earth of unearthed a.c. IT systems, of a.c. IT systems with galvanically connected d.c. circuits having nominal voltages up to 1 000 V a.c., as well as of unearthed d.c. IT systems with voltages up to 1 500 V d.c. independent from the method of measuring. IT systems are described in IEC 60364-4-41 amongst other literature. Additional data for the selection of devices in other standards should be noted. IMDs according to this part of IEC 61557 can also be used for de-energized TT, TN and IT systems or appliances. This third edition cancels and replaces the second edition published in 2007. This edition constitutes a technical revision which includes the following significant technical changes with respect to the previous edition:
- terms and definitions have been complemented;
- abbreviations are listed and explained;
- requirements have been revised;
- mandatory and optional functions and their terminology have been adapted from IEC 61557-15;
- mechanical requirements have been added;
- information on operating instructions has been added;
- type tests and routine tests have been complemented;
- an Annex C: 'Insulation monitoring devices for photovoltaic systems (PV-IMD)' has been added; and
- an Annex D: 'Insulation monitoring function of a photovoltaic inverter (PV-IMF) or in a charge controller' has been added.

This publication is to be read in conjunction with IEC 61557-1:2007.