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ISOMETER® iso685-…-P

ISOMETER® iso685-…-P

  • Predefined measurement profiles
  • Reliable measurement of insulation resistance, voltage, capacitance and frequency
  • Integrated web server
  • Modbus TCP/RTU
  • History memory

The ISOMETER® is an insulation monitoring device for IT systems in accordance with IEC 61557-8 and IEC 61557-9. 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, inverters, variablespeed drives).

In combination with the insulation fault locators of the EDS44x series or the appropriate measuring current transformers, an insulation fault location system can be set up with the iso685-…-P.

Device variants
iso685-D-P: This device variant ISOMETER® iso685-D-P features a high-resolution graphic LC display and operating controls for direct operation of the device functions. It cannot be combined with an FP200.
iso685-S-P: This device variant ISOMETER® iso685-S-P features neither a display nor operating controls. It can only be used in combination with the FP200 and it is operated via this front panel.
Option "W": The ISOMETER®s with and without integrated display are available with option „W“ for extreme climatic and mechanical conditions (ISOMETER® iso685W-D-P and iso685W-S-P).



  • 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 AMPPlusand other profile-specific measurement methods
  • Two separately adjustable response value ranges of 1 kΩ…10 MΩ for Alarm 1 and Alarm 2
  • High-resolution graphical 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 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)
  • RS-485/BS (Bender sensor bus) for data exchange with other Bender devices
  • ISOnet: Internal separation of the ISOMETER® from the IT system to be monitored (e.g. if several IT systems are interconnected)
  • BCOM, Modbus TCP/RTU and web server
  • Locating current injection for selective insulation fault location
  • Indication of the insulation faults selectively located by the EDS system
  • Parameter setting of EDS systems
  • Customer-specific texts for each measuring channel


  • Insulation fault location in AC, 3AC and DC IT systems
  • Up to 12 measuring current transformers of the CTAC…, WR…, WS… measuring current transformer series can be connected
  • Response sensitivity insulation fault location: 
    EDS440 2…10 mA 
    EDS441 0.2…1 mA
  • Response sensitivity residual current measurement:
    EDS440 100 mA…10 A
    EDS441 100 mA…1 A
  • Communication of the components via BS bus (RS-485) or BB bus


  • 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
  • IT systems with high leakage capacitances
  • Installations with insulation fault location

ISOMETER® iso685-…-P Variant(s)

TypeNominal system voltage range UnSupply voltage USDisplayOption WArt. No.
iso685-D-PAC 0…690 V; 1…460 Hz
DC 0…1000 V
AC 24…240 V; 50…400 Hz
DC 24…240 V
iso685W-D-PAC 0…690 V; 1…460 Hz
DC 0…1000 V
AC 24…240 V; 50…400 Hz
DC 24…240 V
3K23, 3M12
iso685-S-P + FP200AC 0…690 V; 1…460 Hz
DC 0…1000 V
AC 24…240 V; 50…400 Hz
DC 24…240 V
iso685W-S-P + FP200WAC 0…690 V; 1…460 Hz
DC 0…1000 V
AC 24…240 V; 50…400 Hz
DC 24…240 V
3K23, 3M12

Optional Accessories for ISOMETER® iso685-…-P

Insulation fault locators

TypeSupply voltage USResponse valueArt. No.
EDS440-S-1AC/DC 24…240 V2…10 mAB91080201
EDS440W-S-1AC/DC 24…240 V2…10 mAB91080201W
EDS440-L-4AC/DC 24…240 V2…10 mAB91080202
EDS440W-L-4AC/DC 24…240 V2…10 mAB91080202W
EDS441-S-1AC/DC 24…240 V0,2…1 mAB91080204
EDS441W-S-1AC/DC 24…240 V0,2…1 mAB91080204W
EDS441-L-4AC/DC 24…240 V0,2…1 mAB91080205
EDS441W-L-4AC/DC 24…240 V0,2…1 mAB91080205W
EDS441-LAB-4AC/DC 24…240 V0,2…1 mAB91080207
EDS441W-LAB-4AC/DC 24…240 V0,2…1 mAB91080207W

Relay module

TypeSupply voltage USArt No.
IOM441-SDC 24 VB95012057
IOM441W-SDC 24 VB95012057W
Type designationArt. No.
A set of screw-type 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 connector***B98110001

* 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).
*** Necessary for the connection of the ISOMETER®s with an EDS44…-S

Downloads for ISOMETER® iso685-…-P

Certificates TÜV NORD - isox685x and FP200x 443.4 KB EN2023/01/12 14:43:3712.01.2023 14:43:37
Datasheets FP200 421.3 KB DE2019/05/13 10:31:3413.05.2019 10:31:34D00179
Datasheets FP200 420.1 KB EN2019/05/13 10:31:3513.05.2019 10:31:35D00179
Datasheets FP200 379.6 KB ES2019/05/13 10:31:3713.05.2019 10:31:37D00179
Datasheets FP200 2.2 MB ZH2019/05/13 10:31:3313.05.2019 10:31:33D00179
CE Declarations of conformity FP200 82.4 KB 2022/08/12 06:17:2412.08.2022 06:17:24
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
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
Quickstarts iso685-… 2.5 MB DE2021/03/02 13:36:1902.03.2021 13:36:19D00022
Quickstarts iso685-… 830.9 KB ZH2019/05/13 10:31:5713.05.2019 10:31:57D00022
Quickstarts iso685-… 2.5 MB EN2021/03/02 13:36:1902.03.2021 13:36:19D00022
Quickstarts iso685-… 2.5 MB ES2021/03/02 13:36:1902.03.2021 13:36:19D00022
Quickstarts iso685-… 2.5 MB FR2021/03/02 13:36:1902.03.2021 13:36:19D00022
Manuals iso685-… Modbus-Einstellungen 909.7 KB DE2021/12/21 14:12:5221.12.2021 14:12:52D00022
Manuals iso685-… Modbus settings 844.0 KB EN2021/08/25 07:16:4225.08.2021 07:16:42D00022
Manuals iso685-x-P 15.6 MB DE2022/06/09 10:46:4009.06.2022 10:46:40D00170
Manuals iso685-x-P 15.7 MB EN2022/06/09 10:48:3109.06.2022 10:48:31D00170
Datasheets iso685-x-P 2.2 MB DE2021/07/13 13:07:1613.07.2021 13:07:16D00170
Datasheets iso685-x-P 2.1 MB EN2021/07/13 13:07:3513.07.2021 13:07:35D00170
Datasheets iso685-x-P 2.1 MB ES2021/07/13 13:07:5313.07.2021 13:07:53D00170
Product Brochures iso685 1.8 MB ES2019/05/13 10:31:2313.05.2019 10:31:23D00022
Manuals iso685-… Webserver 547.9 KB DE2019/05/13 10:31:4613.05.2019 10:31:46D00022
Manuals iso685-… web server 560.5 KB EN2019/05/13 10:31:5313.05.2019 10:31:53D00022
Manuals iso685-x-P 15.2 MB ZH2021/07/13 07:13:0213.07.2021 07:13:02D00170
Manuals iso685-… Modbus 设置 907.0 KB ZH2021/12/23 06:35:5323.12.2021 06:35:53D00022
Datasheets iso685-x-P 2.1 MB FR2021/07/13 09:22:3713.07.2021 09:22:37D00170
Manuals Inbetriebnahme eines iso685-S…-Gerätes ohne angeschlossenes Display FP200(W) 1.4 MB DE2021/06/10 12:48:1210.06.2021 12:48:12D00022
Manuals Commissioning iso685-S… devices without a connected Display FP200(W) 1.4 MB EN2021/06/10 12:48:1210.06.2021 12:48:12D00022
Software iso685(W)-S/D-P Update V1.30 7.0 MB 2022/12/09 09:39:1109.12.2022 09:39:11
Quickstarts FP200 3.2 MB DE2021/06/28 04:56:3228.06.2021 04:56:32D00179
Quickstarts FP200 3.2 MB EN2021/06/28 04:56:3228.06.2021 04:56:32D00179
Quickstarts FP200 3.2 MB FR2021/06/28 04:56:3228.06.2021 04:56:32D00179
Quickstarts FP200 3.2 MB ES2021/06/28 04:56:3228.06.2021 04:56:32D00179
Quickstarts FP200 2.5 MB ZH2021/06/28 04:56:0528.06.2021 04:56:05D00179
Product Brochures Mining 11.7 MB ES2020/05/22 14:37:3122.05.2020 14:37:31
Software BCOM Group Manager 72.1 KB 2019/05/13 10:32:1313.05.2019 10:32:13