BS EN 61557-8:2015

1 Scope
2 Normative references
3 Terms, definitions and abbreviations
4 Requirements
5 Marking and operating instructions
6 Tests
7 Overview of requirements and tests for IMDs
Annex A (normative) - Medical insulation monitoring devices
        (MED-IMD)
Annex B (informative) - Monitoring of overload current and
        over-temperature
Annex C (normative) - Insulation monitoring devices for photovoltaic
        systems (PV-IMD)
Annex D (normative) - Insulation monitoring function of a photovoltaic
        inverter (PV-IMF) or in a charge controller
Bibliography
Annex ZA (normative) - Normative references to
         international publications with
         their corresponding European publications

Defines the requirements for insulation monitoring devices (IMD) which permanently monitor the insulation resistance R[F] to earth of unearthed a.c. IT systems, of a.c. IT systems with galvanically connected d.c. circuits having nominal voltages up to 1000 V a.c., as well as of unearthed d.c. IT systems with voltages up to 1500 V d.c. independent from the method of measuring.

This part of IEC61557 specifies the requirements for insulation monitoring devices (IMD) which permanently monitor the insulation resistance R F to earth of unearthed a.c. IT systems, of a.c. IT systems with galvanically connected d.c. circuits having nominal voltages up to 1000V a.c., as well as of unearthed d.c. IT systems with voltages up to 1500V d.c. independent from the method of measuring. IT systems are described in IEC60364‑4‑41 amongst other literature. Additional data for the selection of devices in other standards should be noted. NOTE Various standards specify the use of IMDs in IT systems. In such cases, the objective of the equipment is to signal a drop in insulation resistance R F below a minimum limit. IMDs according to this part of IEC61557 can also be used for de-energized TT, TN and IT systems or appliances.