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  • For stationary energy storage systems according to VDE-AR-E 2510-2 (application)
  • Insulation monitoring device according to product standard IEC 61557-8
  • Preset response values according to the recommendation of VDE-AR-E 2510-2
  • Multifunctional LC display

The ISOMETER® isoES425 monitors the insulation resistance of unearthed AC, AC/DC and DC systems (IT systems) for energy storage devices up to AC/DC 400 V.

The DC-supplied components existing in AC/DC systems do not influence the operating characteristics. The isoES425 is used to monitor and indicate the connection to earth during network operation. When operated as an isolated system, the isoES425 takes over the monitoring of the isolated system (IT system).


  • Insulation monitoring for unearthed systems AC/DC
  • Measurement of the mains voltage (r.m.s.) with undervoltage and overvoltage detection
  • Measurement of DC voltages system to earth (L1+/PE und L2-/PE)
  • Automatic adaptation to the system leakage capacitance up to 100 μF
  • Selectable start-up delay, response delay and delay on release
  • Two separately adjustable response value ranges of 1…990 kΩ (Alarm 1, Alarm 2)
  • Alarm signalling via LEDs (AL1, AL2), a display and alarm relays (K1, K2)
  • Automatic device self test with connection monitoring
  • N/C operation or N/O operation of the relays selectable
  • Measured value indication via multifunctional 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
    – IsoData (for continuous data output)
  • Password protection to prevent unauthorised parameter changes


  • Monitoring the earth connection during network operation and monitoring the electrical installation during isolated operation

ISOMETER® isoES425 Variant(s)

TypeSupply voltage USNominal system voltage UnSystem leakage capacitance CeArt. No.
isoES425-D4-4AC 100…240 V, 47…63 Hz/DC 24…240 VAC/DC 0…400 V, 15…460 Hz< 100 μFB71037020

Optional Accessories for ISOMETER® isoES425

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

Downloads for ISOMETER® isoES425

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
Datasheets isoES425 316.0 KB DE2019/05/13 10:31:3513.05.2019 10:31:35D00214
Datasheets isoES425 315.2 KB EN2019/05/13 10:31:3713.05.2019 10:31:37D00214
Manuals isoES425 1.2 MB DE2019/05/13 10:31:4613.05.2019 10:31:46D00214
Quickstarts isoES425 1.4 MB DE2019/05/13 10:31:5713.05.2019 10:31:57D00214
Quickstarts isoES425 1.4 MB EN2019/05/13 10:31:5713.05.2019 10:31:57D00214
Manuals isoES425 1.2 MB EN2019/05/13 10:31:5313.05.2019 10:31:53D00214
Datasheets isoES425 320.1 KB FR2020/02/03 10:41:1403.02.2020 10:41:14D00214
Datasheets isoES425 327.8 KB ES2020/04/27 06:03:5927.04.2020 06:03:59D00214