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.



  • 10GΩ measurement for oil and gas applications
  • Integrated web server and Modbus TCP communication
  • Early detection enhances operational safety and maintenance planning possibilities.
  • Synchronisation in systems coupled via capacitances
  • High adaptability to systems with different properties
  • For early warning and earth fault location

The ISOMETER® is an insulation monitoring device in accordance with IEC 61557-8 for IT systems. The devices are universally applicable in AC, 3(N)AC, AC/DC and DC systems. AC systems may include extensive DC-supplied loads (such as rectifiers, inverters, variablespeed drives).

This device is used for subsea cable fault finding, measuring up to 10GΩ to monitor and detect deterioration of insulation resistance levels at an early stage in the oil and gas industry. 


  • 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-specific measurement methods
  • Two separately adjustable response value ranges of 1 kΩ…3 GΩ for alarm 1 and alarm 2
  • 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).
  • Remote diagnosis via the Internet (made available by Bender Service only)
  • isoData: Continuous uninterrupted data transmission
  • isoSync: Timely synchronization of measurement processes
  • 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 including switch-mode power supplies
  • Coupled IT systems with high leakage capacitances
  • Monitoring of long capacitive coupled lines
  • Monitoring of submarine cables

ISOMETER® isoHR685W Variant(s)

TypeNominal system voltage range UnSupply voltage USDisplayArt. no.
isoHR685W–D–I–BAC 0…1000 V; 0.1…460 Hz /
DC 0…1300 V
AC 24…240 V; 50…400 Hz /
DC 24…240 V
isoHR685W–S–I–B + FP200W*AC 0…1000 V; 0,1…460 Hz /
DC 0…1300 V
AC 24…240 V; 50…400 Hz /
DC 24…240 V

* only available in combination

Optional Accessories for ISOMETER® isoHR685W

Type designationTypeArt. No.
Coupling devicesAGH150W-4

Possible measuring instruments on request!

DescriptionArt. No.
A set of screw terminals*B91067901
A set of push-wire terminalsB91067902
Enclosure accessories (terminal cover, 2 mounting clips)*B91067903
Transparent cover 144x72 (IP65) for FP200**B98060005
BB bus 6TE connectorB98110001

* included in the scope of delivery
** If the “transparent front cover 144x72 (IP65)” is used, the cutout in the control cabinet must be increased in height from 66 mm to 68 mm (+ 0.7 / -0 mm).

Downloads for ISOMETER® isoHR685W

CE Declarations of conformity iso685 92.3 KB 2022/08/12 06:17:2512.08.2022 06:17:25
Datasheets isoHR685W-x-I-B 1.9 MB DE2022/09/30 07:06:2030.09.2022 07:06:20D00261
Datasheets isoHR685W-x-I-B 1.9 MB EN2022/09/30 07:06:3130.09.2022 07:06:31D00261
Manuals isoHR685W-x-I-B 12.3 MB DE2022/06/09 10:46:3609.06.2022 10:46:36D00261
Manuals isoHR685W-x-I-B 12.4 MB EN2022/09/30 07:07:2930.09.2022 07:07:29D00261
Quickstarts isoHR685W-x-I-B 4.6 MB DE2021/12/01 07:03:1801.12.2021 07:03:18D00261
Quickstarts isoHR685W-x-I-B 4.6 MB EN2021/12/01 07:03:1801.12.2021 07:03:18D00261
Flyer Earth fault protection of umbilicals 450.1 KB EN2019/08/28 12:31:2728.08.2019 12:31:27
Datasheets isoHR685W-x-I-B 2.4 MB FR2021/07/13 13:08:1013.07.2021 13:08:10D00261
Datasheets isoHR685W-x-I-B 2.4 MB ES2021/07/13 13:07:5413.07.2021 13:07:54D00261
Software isoHR685(W)-S/D Update V1.27 6.3 MB 2021/11/17 05:51:2817.11.2021 05:51:28D00261
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