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  • Insulation monitoring device for AC and DC IT systems
  • Application control circuits
  • According to IEC 61557-8
  • Two separately configurable response values
  • Multi-functional LC display

The ISOMETER® of the IR425 series is designed to monitor the insulation resistance of un­earthed AC/DC control circuits (IT systems) 0…300 V. DC components existing in AC/DC systems do not influence the operating characteristics. An external supply voltage allows de-energized systems to be monitored too.

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  • Insulation monitoring for AC/DC control circuits 0…300 V
  • Two separately adjustable response values
  • Preset function (automatic setting of basic parameters)
  • Connection monitoring system/earth
  • LEDs: Power On, Alarm 1, Alarm 2
  • Internal/external test/reset button
  • Two separate alarm relays (one changeover contact each)
  • N/O or N/C operation, selectable
  • Fault memory behaviour, selectable
  • Self monitoring with automatic alarm
  • Multi-functional LC display
  • Adjustable response delay
  • Two-module enclosure (36 mm)
  • Push-wire terminal (two terminals per connection)
  • AC/DC control circuits in the industrial sector, mechanical engineering, power plants, elevators, automation systems etc.
  • AC/DC control and auxiliary circuits in accordance with DIN EN 60204-1 “Electrical equipment of machines”, IEC 60204-1, EN 60204-1
  • AC/DC auxiliary circuits in accordance with DIN VDE 0100-725 (VDE 0100-725)
  • Smaller AC/DC IT systems such as lighting systems


Optional accessories for ISOMETER® IR425-D4

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

Variants of ISOMETER® IR425-D4

TypeNominal system voltage* UnSupply voltage* USResponse value RanSystem leakage
capacitance Ce
Art. No.**
IR425-D4-1DC/AC 0…300 V,
15…460 Hz
DC 9,6…94 V/
AC 16…72 V, 15…460 Hz
1…200 kΩ< 20 µFB71036403
IR425-D4-2DC/AC 0…300 V,
15…460 Hz
DC 70…300 V/
AC 70…300 V, 15…460 Hz
1…200 kΩ< 20 µFB71036402
* Absolute values
**(B7… = push-wire terminal / B9… = screw-type terminal)

Downloads for ISOMETER® IR425-D4



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