The insulation fault evaluator of the EDS460/490 series in combination with the ISOMETER®
IRDH575 or the insulation fault test device PGH is designed to localize insulation faults in
unearthed power supplies (IT systems). The test current signals generated by the insulation
monitoring device IRDH575 or the insulation fault test device PGH are scanned by measuring
current transformers and evaluated by the insulation fault evaluators. Up to 12 measuring
current transformers can be connected to one EDS. A total of 90 EDS evaluators can be
connected via one RS-485 interface (BMS protocol). Hence, up to 1080 circuits can be

Product Details


  • Insulation fault location and residual current measurement
  • For AC, 3AC, DC and IT systems
  • 12 measuring channels (circuits) for measuring current transformers of the W, WR, WS series
  • Up to 90 EDS evaluators in one system (1080 measuring channels)
  • Scanning time for all measuring channels 10 s
  • Response sensitivity
    EDS460/490 2…10 mA (100 Ω/V)
    EDS461/491 0.2…1 mA (1000 Ω/V)
  • History memory to store 300 events
  • Two alarm relays with one changeover contact each
  • N/O or N/C operation, selectable
  • Connection external reset / test button
  • Indication via graphical display resp. 7-segment display and alarm LEDs
  • BMS address range 1…90
  • Serial RS-485 interface
  • Continuous CT connection monitoring
  • Fault memory behaviour selectable
  • Device version EDS490/491 with one alarm contactor per channel
  • Additional residual current measurement


  • Insulation fault location in AC, AC/DC and DC IT systems
  • Main and control circuits in industrial installations and ships
  • Diode-decoupled DC IT systems in power stations
  • Systems for medical locations