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  • Railway
  • universally applicable

The ISOMETER® isoRW685W-D-B is an insulation monitoring device for IT systems in accordance with IEC 61557-8 for railway applications and has been specifically tested according to DIN EN 50155. It is universally applicable in AC, 3(N)AC, AC/DC and DC systems. AC systems may include extensive DC-supplied loads (such as rectifiers, converters, variable-speed drives).


  • ISOMETER® for AC IT systems with galvanically connected rectifiers or converters and for DC IT systems (IT = unearthed systems)
  • Automatic adaptation to the existing system leakage capacitance
  • Combination of AMPPlus and other profiledependent measurement methods
  • Two separately adjustable response value ranges of 1 kΩ…10 MΩ
  • High-resolution graphic LC display
  • 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 13 days) for storing a maximum of 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 (web server/option: COMTRAXX® gateway)
  • Remote diagnosis via the Internet (only by Bender service)
  • isoData: Continuous uninterrupted data transmission
  • RS-485/BS (Bender sensor bus) for data exchange with other Bender devices via Modbus RTU protocol
  • BCOM, Modbus TCP und web server
  • ISOnet: Internal separation of the ISOMETER® from the IT system to be monitored (e.g. if several IT systems are interconnected)
  • ISOnet priority: Permanent priority of a device within the network
  • ISOloop: Special function for ring systems (all systems are coupled)


  • AC, DC or AC/DC main circuits
  • AC/DC main circuits with directly connected DC components, such as rectifiers, converters, variable-speed drives
  • UPS systems, battery systems
  • Heaters with phase control
  • Systems with switch-mode power supplies
  • IT systems with high leakage capacitances

ISOMETER® isoRW685W-D-B Variant(s)

TypeNominal system voltage range UnSupply voltage USArt. No.
isoRW685W-D-BAC 0…690 V; 0,1…460 Hz
DC 0…1000 V
AC 24…240 V; 50…400 Hz /
DC 24…240 V

Optional Accessories for ISOMETER® isoRW685W-D-B

Type designationTypeArt. No.
Coupling devicesAGH150W-4

Suitable measuring instruments on request!

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

Downloads for ISOMETER® isoRW685W-D-B

CE Declarations of conformity isoRW685 86.8 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
Manuals isoRW685W-D-B 11.9 MB DE2022/06/09 10:46:3509.06.2022 10:46:35D00419
Manuals isoRW685W-D-B 11.9 MB EN2022/06/09 10:48:2609.06.2022 10:48:26D00419
Datasheets isoRW685W-D-B 1.5 MB DE2022/06/09 10:53:5809.06.2022 10:53:58D00419
Datasheets isoRW685W-D-B 1.5 MB EN2022/06/09 10:54:4009.06.2022 10:54:40D00419
Datasheets isoRW685W-D-B 1.5 MB ES2021/07/13 13:07:5613.07.2021 13:07:56D00419
Datasheets isoRW685W-D-B 1.5 MB FR2021/07/13 10:24:1513.07.2021 10:24:15D00419
Quickstarts isoRW685W-D(-B) 1.2 MB DE2021/12/22 11:56:4922.12.2021 11:56:49D00419
Quickstarts isoRW685W-D(-B) 1.2 MB EN2021/12/22 11:56:4922.12.2021 11:56:49D00419
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