The ISOMETER® of the IRDH275 series is designed to monitor the insulation resistance of unearthed main circuits (IT systems) AC, AC/DC 0…793 V resp. DC 0…650 V. The AMPPlus measurement method meets the particular requirements of modern power supplies which often include rectifiers, converters, thyristor-controlled DC drives and directly connected DC components. In these systems often high leakage capacitances against earth occur due to interference suppression measures. The IRDH275 automatically adapts itself to the existing system conditions.
In combination with a coupling device, the devices can also be used for higher voltages. An external supply voltage allows de-energised systems to be monitored too. For door mounting into distribution panels, refer to type IRDH375(B).

Device features
• Insulation monitoring for unearthed AC, AC/DC systems 0…793 V, DC 0…650 V
• Nominal voltage extendable via coupling device
• Two separately adjustable response values1 kΩ…10 MΩ
• AMPPlus measurement method
• Automatic adaptation to the system leakage capacitance
• Info button to display device settings and system leakage capacitance
• Self monitoring with automatic alarm
• Automatic self test, selectable
• Connection for external kΩ indication
• Test and reset button
• External test/reset button can be connected
• Two separate alarm relays with two potential-free changeover contacts
• N/O or N/C operation, selectable
• Backlit LC display
• RS-485 interface