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  • Insulation monitoring device for mobile generators
  • Protective isolation with insulation monitoring and shutdown
  • Two response values with settings between 5 and 200 kΩ (Factory settings 46 kΩ and 23 kΩ)
  • Communications interface supporting Modbus RTU, IsoData, and BMS
  • Overvoltage and undervoltage protection

The isoGEN423 monitors the insulation resistance of ungrounded AC, AC/DC and DC systems with nominal system voltages of 0…400 V. The monitored system can be single-phase AC, 3- or 4-wire AC, AC/DC mixed-phase, or DC.

Automatically adapts to the maximum permissible system-leakage capacitance of 5 μF. DC components existing in AC systems do not influence the operating characteristics, when a minimum load current of DC 10 mA flows. Using a separate supply voltage allows de-energized systems to be monitored.


  • Monitoring the insulation resistance for unearthed AC/DC systems
  • Measurement of the system voltage (true r.m.s.) with undervoltage and overvoltage detection
  • Measurement of DC system voltages to earth (L1+/PE and L2-/PE)
  • Two operating modes: GEn and DC
  • Automatic adaptation to the system leakage capacitance up to 5 μF
  • Selectable start-up delay, response delay and delay on release
  • Two separately adjustable response value ranges of 5…200 kΩ (Alarm 1, Alarm 2)
  • Alarm signalling via LEDs (AL1, AL2), a display and alarm relays (K1, K2)
  • Automatic device self test with connection monitoring
  • Selectable N/C or N/O relay operation
  • Measured value indication via multi-functional LCD
  • Fault memory can be activated
  • RS-485 (galvanically isolated) including the following protocols:
    - BMS interface (Bender measuring device interface) for data exchange with other Bender components
    - Modbus RTU
    - IsoData (for continuous data output)
  • Password protection to prevent unauthorised parameter changes


  • AC main circuits up to 400 V
  • DC main circuits up to 400 V
  • Generators according to DIN VDE 0100-551

Downloads for ISOMETER® isoGEN423

CE Declarations of Conformity isoXX425 152.0 KB 2022/08/12 06:17:2612.08.2022 06:17:26
Quickstarts isoGEN423 899.0 KB EN2021/03/18 13:27:2518.03.2021 13:27:25D00221
Manuals isoGEN423 2.4 MB EN2021/04/20 08:09:2720.04.2021 08:09:27D00221
Datasheets isoGEN423 385.5 KB EN2022/06/09 10:54:3709.06.2022 10:54:37D00221

Optional Accessories for ISOMETER® isoGEN423

TypeArt. No.
Mounting clip for screw mounting (1 piece per device)B98060008

ISOMETER® isoGEN423 Variants

TypeVersionArt. No.
isoGEN423-D4-4Push-wire terminalB71036325
isoGEN423-D4W-4Push-wire terminalB71036325W