México - english
Tue Mar 20 15:00:20 2018
Tue Mar 20 15:00:20 2018


  • Ground-fault monitoring device for AC and DC IT systems
  • Application control circuits
  • According to IEC 61557-8
  • Adjustable response value
  • Alarm relay with a potential-free changeover contact

The ISOMETER®s of the IR125Y series are designed to monitor the insulation resistance of ungrounded AC and DC control circuits (IT systems). External supply voltage is not required.
In contrast to ground-fault monitoring devices which evaluate the shift voltage for ground-fault detection, this series uses the active AMP measurement method. This creates the possibility to detect and indicate both symmetrical and asymmetrical ground faults.

  • Features
  • Applications
  • Accessories
  • Ordering information
  • Downloads
  • Insulation monitoring for AC and DC systems (IT systems)
  • Response values, adjustable 10…200 kΩ
  • LEDs: Power On LED, alarm LED to signal insulation faults
  • Internal combined test and reset button
  • Connection external reset button
  • Alarm relay with one potential-free changeover contact
  • N/C operation
  • Fault memory behaviour, selectable
  • AC and DC control and auxiliary circuits in accordance with DIN EN 60204-1 "Electrical equipment of machines", IEC 60204-1, EN 60204-1
  • DC auxiliary circuits in accordance with DIN VDE 0100-725
  • Simple battery systems


Optional accessories for ISOMETER® IR125Y-4

TypeArt. No.
Mounting plateB990056

Variants of ISOMETER® IR125Y-4

TypeNominal system voltage UnArt. No.
IR125Y-4AC 19,2…265 V, DC 19,2…308 V*B91023005
*Absolute value

Downloads for ISOMETER® IR125Y-4



Category Product Language Date Size Download