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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.


  • 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 (made available by Bender Service only)
  • 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

ISOMETER® isoNAV685-D Variant(s)

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

Optional 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

* included in the scope of delivery
Suitable measuring instruments on request!

Downloads for ISOMETER® isoNAV685-D

CE Declarations of conformity iso685 92.3 KB 2022/08/12 06:17:2512.08.2022 06:17:25
Certificates TÜV NORD - isox685x und FP200x 449.0 KB DE2023/01/12 14:43:2912.01.2023 14:43:29
Certificates TÜV NORD - isox685x and FP200x 443.4 KB EN2023/01/12 14:43:3712.01.2023 14:43:37
Quickstarts isoNAV685-D 1.6 MB DE2019/05/13 10:31:5713.05.2019 10:31:57D00215
Quickstarts isoNAV685-D 1.6 MB EN2019/05/13 10:31:5713.05.2019 10:31:57D00215
Manuals isoNAV685-D 2.7 MB DE2019/05/13 10:31:4613.05.2019 10:31:46D00215
Manuals isoNAV685-D 2.6 MB EN2019/05/13 10:31:5313.05.2019 10:31:53D00215
Datasheets isoNAV685-D 1.6 MB DE2021/03/11 13:30:4511.03.2021 13:30:45D00215
Datasheets isoNAV685-D 1.6 MB EN2021/03/11 13:31:0711.03.2021 13:31:07D00215
Datasheets isoNAV685-D 1.6 MB ES2021/03/11 13:31:3911.03.2021 13:31:39D00215
Datasheets isoNAV685-D 1.7 MB FR2021/04/21 10:11:1621.04.2021 10:11:16D00215
Product Brochures iso685 1.8 MB DE2019/05/13 10:30:5713.05.2019 10:30:57D00022
Product Brochures iso685 1.8 MB EN2019/05/13 10:31:0113.05.2019 10:31:01D00022
Product Brochures iso685 1.8 MB ES2019/05/13 10:31:2313.05.2019 10:31:23D00022