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  • Instantaneous tripping 150 ms
  • Inverter disconnection
  • Modbus TCP
  • Tripping on shift voltage

The ISOMETER® isoNAV685-D is an insulation monitoring device for IT systems in accordance with IEC 61557-8. It is applicable for use in 3(N)AC systems with nominal system frequency 60 Hz.

  • Features
  • Applications
  • Accessories
  • Ordering information
  • Downloads
  • ISOMETER® for IT AC systems with galvanically connected rectifiers or inverters and for IT DC systems (IT = unearthed systems).
  • Automatic adaptation to the existing system leakage capacitance.
  • Combination of AMPPLUS and other profile-dependent measurement methods.
  • An adjustable response value for insulation monitoring in the range of 1 kΩ…10 MΩ (factory setting = 5 kΩ) and a response value of 150 V for the DC offset voltage.
  • High-resolution graphic LC display for excellent readability and recording of the device status.
  • Connection monitoring (monitoring of the measuring lines).
  • Automatic device self test.
  • Graphical representation of the insulation resistance over time (isoGraph)
  • History memory with real-time clock (buffer for three days) for storing 1023 alarm messages with date and time.
  • Current or voltage output 0(4)…20 mA, 0…400 μA, 0…10 V, 2…10 V (galvanically separated) which is analogous to the measured insulation value of the system.
  • Freely programmable digital inputs and outputs.
  • Remote setting via the Internet or Intranet (Webserver/Option: COMTRAXX® gateway).
  • Worldwide remote diagnosis via the Internet.
  • BCOM, Modbus TCP and web server.
  • AC/DC main circuits with directly connected DC components, such as rectifiers, converters, variable-speed drives
  • Systems including switch-mode power supplies
  • Systems including frequency inverters


Mandatory accessories for ISOMETER® isoNAV685-D

Type designationArt. No.
A set of screw terminals*B91067901
A set of push-wire terminalsB91067902
Enclosure accessories (terminal cover, 2 mounting clips)*B91067903
Front cover 144x72 transparent (for IP65)B98060005
* included in the scope of delivery
Suitable measuring instruments on request!


Variants of ISOMETER® isoNAV685-D

TypeNominal system voltage range UnSupply voltage USArt. No.
isoNAV685-DAC 0…690 V; 1…460 Hz/DC 0…1000 VAC 24…240 V; 50…400 Hz /
DC 24…240 V

Downloads for ISOMETER® isoNAV685-D



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