Innovative technologies for safe handling of electrical power to achieve high availability

Bender products are used worldwide and have been known for more than 65 years.

We offer you first-class quality and safety combined with global service and every support in resolving your monitoring problems.



  • Offline monitoring
  • 3 insulation levels are monitored
  • Modbus TCP
  • Reduced measuring voltage

The ISOMETER® isoNAV685-D-B is an insulation monitoring device for IT systems in accordance with IEC 61557-8. It is universally applicable in de-energised TN, TT or IT systems.


  • ISOMETER® to monitor the insulation resistance in de-energised systems
  • Automatic adaptation to the existing system leakage capacitance
  • AMPPLUS measurement method
  • An adjustable response value in the range 10 kΩ…1 MΩ (factory setting = 50 kΩ)
  • High-resolution graphic LC display for excellent readability and recording of the device status
  • Earth connection monitoring
  • 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
  • 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


  • Monitoring of de-energised loads and systems

ISOMETER® isoNAV685-D-B Variant(s)

TypeNominal system voltage range UnSupply voltage USArt. No.
isoNAV685-D-BofflineAC 24…240 V; 50…400 Hz /
DC 24…240 V

Optional Accessories for ISOMETER® isoNAV685-D-B

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
Possible measuring instruments on request!

Downloads for ISOMETER® isoNAV685-D-B

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-B 1.6 MB DE2019/05/13 10:31:5713.05.2019 10:31:57D00264
Quickstarts isoNAV685-D-B 1.6 MB EN2019/05/13 10:31:5713.05.2019 10:31:57D00264
Manuals isoNAV685-D-B 2.6 MB DE2020/09/04 05:48:2004.09.2020 05:48:20D00264
Manuals isoNAV685-D-B 2.5 MB EN2019/05/13 10:31:5313.05.2019 10:31:53D00264
Datasheets isoNAV685-D-B 1.8 MB DE2021/03/11 13:30:4711.03.2021 13:30:47D00264
Datasheets isoNAV685-D-B 1.7 MB EN2021/03/11 13:31:0911.03.2021 13:31:09D00264
Datasheets isoNAV685-D-B 1.8 MB ES2021/03/11 13:31:4211.03.2021 13:31:42D00264
Datasheets isoNAV685-D-B 1.9 MB FR2021/04/21 10:40:1421.04.2021 10:40:14D00264
Market Segment Brochures Insulation monitoring in earthed wind powered energy plants with the isoNAV685-D-B 2.0 MB EN2019/05/13 10:30:5913.05.2019 10:30:59D00264
Market Segment Brochures Isolationsüberwachung in geerdet betriebenen Windenergieanlagen mit isoNAV685-D-B 2.9 MB DE2019/05/13 10:30:5513.05.2019 10:30:55D00264
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