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  • Insulation monitoring device for mobile generators
  • Protective separation with insulation monitoring and disconnection
  • According to IEC 60364-5-55 and IEC 61557-8
  • Optocoupler output for signalling the device status
  • Galvanically separated PWM output for the measuring value

The ISOMETER® IR123P monitors the insulation resistance RF of an unearthed AC system of 100...300 V against earth, that is supplied by a mobile generator according to DIN VDE 0100-551. The IR123 is suitable for AC systems with operating frequencies of 22...65 Hz as well as for AC systems including DC components. The maximum permissible system leakage capacitance Cemax is 5 μF.


  • Insulation monitoring for unearthed AC systems (IT systems) 100…300 V
  • Automatic adaptation to the existing system leakage capacitance
  • Optimised measurement technique for low-frequency control processes
  • Electrically isolated PWM output for the kΩ measuring value
  • Optocoupler output for signalling the device status
  • Automatic device self test
  • Certonal coating
  • Permanently set response value for the insulation resistance 23/46 kΩ
  • Second response range 40/80 kΩ selectable via a jumper


  • Monitoring of unearthed AC systems (IT systems) in mobile generators

ISOMETER® IR123P Variant(s)

TypeNominal system voltage* UnSupply voltage* USArt. No.
IR123P-4-2AC 22…460 Hz, 100…300 VUS = UnB91016308

* Absolute values

Downloads for ISOMETER® IR123P

Datasheets IR123P 619.2 KB DE2019/05/13 10:31:3413.05.2019 10:31:34D00113
Datasheets IR123P 210.5 KB EN2019/05/13 10:31:3513.05.2019 10:31:35D00113