小于等于1000 V交流电以及1500 V直流电低压配电系统的电气安全.保护措施的测试, 测量或监测设备. 第8部分: IT系统用绝缘监测设备. 推荐的水平标准

[中文适用范围]： IEC 61557-8 规范了绝缘监测装置 (IMD) 的要求，用于在不接地交流 IT 系统（额定电压高达 1000 V）、带有 galvanically 连接的直流电路的交流 IT 系统（额定电压高达 1000 V）以及不接地的直流 IT 系统（电压高达 1500 V）中永久监测对地绝缘电阻 R_F，无论其测量方法如何。根据本标准的 IMD 也可用于断电的 TT、TN 和 IT 系统或设备。 [外文原描述]： 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 . The contents of the corrigendum of May 2016 have been included in this copy.