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ISOMETER® isoPV425 with AGH420

  • Insulation monitoring device for AC and DC IT systems
  • Application photovoltaic systems up to AC 690 V/DC 1000 V
  • Automatic adaptation to the system leakage capacitance up to 500 μF
  • Measurement of the nominal system voltage (RMS) with undervoltage and overvoltage detection

The ISOMETER® of the isoPV425 series monitors the insulation resistance of unearthed AC/DC main circuits (IT systems) with nominal voltages of 3(N)AC, AC, AC/DC 0…690 V or DC 0…1000 V.

DC components existing in AC/DC systems do not influence the operating characteristics. A separate supply voltage allows deenergised systems to be monitored as well. The maximum permissible system leakage capacitance is 500 µF.


  • Monitoring for unearthed AC and DC systems with galvanically connected rectifiers or inverters
  • Measurement of the nominal system voltage (r.m.s.) with undervoltage and overvoltage detection
  • Measurement of DC voltages system to earth (L+/PE and L-/PE)
  • Automatic adaptation to the system leakage capacitance up to 500 μF
  • Automatic device self-test with connection monitoring
  • Selectable start-up delay, response delay and delay on release
  • Two separately adjustable response value ranges of 1…500 kΩ (Alarm 1, Alarm 2)
  • Alarm signalling via LEDs (AL1, AL2), a display and alarm relays (K1, K2)
  • N/C operation or N/O operation selectable
  • Measured value indication via multi-functional LCD
  • Fault memory can be activated
  • RS-485 (galvanically isolated) including the following protocols:
    – BMS interface (Bender measuring device interface) for data exchange with other Bender components
    – Modbus RTU
    – isoData (for continuous data output)
  • Password protection to prevent unauthorised parameter changes


  • AC, DC or AC/DC main circuits
  • Solar systems with directly connected inverters
  • Solar systems with high system leakage capacitances
  • Solar systems with high but slow voltage fluctuations
  • Systems including switched-mode power supplies

ISOMETER® isoPV425 with AGH420 Variant(s)

TypeNominal system voltage* UnSupply voltage* USArt. No.**
isoPV425-D4 with AGH420DC 0…1000 V, AC 0…690 VDC 24…240 V, AC 100…240 VB71036303

* Absolute values
**(B7… = push-wire terminal / B9… = screw-type terminal)

Optional Accessories for ISOMETER® isoPV425 with AGH420

TypeArt. No.
Mounting clip for screw mounting (one piece per device)B98060008
Mounting frame XM420B990994 

Downloads for ISOMETER® isoPV425 with AGH420

Declarations of Conformity isoxx425 - UKCA 142.1 KB 2022/12/20 05:59:4420.12.2022 05:59:44
CE Declarations of conformity isoXX425 151.9 KB 2023/01/09 06:50:5109.01.2023 06:50:51
Quickstarts isoPV425 1.2 MB DE2022/12/02 11:08:2502.12.2022 11:08:25D00028
Quickstarts isoPV425 1.2 MB EN2022/12/02 11:08:2502.12.2022 11:08:25D00028
Manuals isoPV425 mit AGH420 1.4 MB DE2019/05/13 10:31:4613.05.2019 10:31:46D00029
Manuals isoPV425 with AGH420 1.4 MB EN2019/05/13 10:31:5313.05.2019 10:31:53D00029
Datasheets isoPV425 mit AGH420 369.7 KB DE2019/05/13 10:31:3513.05.2019 10:31:35D00029
Datasheets isoPV425 with AGH420 368.1 KB EN2019/05/13 10:31:3713.05.2019 10:31:37D00029
Datasheets isoPV425 con AGH420 341.0 KB ES2020/07/21 13:49:2121.07.2020 13:49:21D00029
Datasheets isoPV425 + AGH420 664.8 KB ZH2019/05/13 10:31:3313.05.2019 10:31:33D00029
Software Modbus RTU - Monitor isoxx425 V2.2.2 setup 7.1 MB 2019/05/13 10:31:5913.05.2019 10:31:59