Bender ISOMETER isoPV1685


The device is used for insulation and residual current monitoring of large photovoltaic systems
up to 1500 V designed as IT systems. The measurement method specially developed for slow
voltage fluctuations (MPP-Tracking) monitors the insulation resistance even in systems
equipped with large solar generator panels where extremely high system leakage capacitances
against earth exist due to interference suppression methods. Adaptation to system-related
high leakage capacitances also occurs automatically.
The device generates locating current pulses required for insulation fault location. That allows
the localisation of the insulation fault using permanently installed or mobile insulation fault
locators. Integrated residual current monitoring allows fast signalling of a measured insulation
faults on the AC side (inverter, transformer).

Product Details


  • Insulation monitoring of large-scale photovoltaic systems
  • Measurement of low-resistance insulation faults
  • Separately adjustable response values Ran1 (Alarm 1) and Ran2 (Alarm 2) (both 200 Ω…1 MΩ) for prewarning and alarm. Ran1 ≥ Ran2 applies.
  • Automatic adjustment to high system leakage capacitances up to 2000 μF, selectable range
  • Connection monitoring of L+, L- for reverse polarity
  • Integrated locating current injector up to 50 mA (isoPV1685P(FR) only)
  • Fast detection of insulation faults on the AC side by residual current monitoring (inverter, transformer) allowing fast disconnection (isoPV1685PFR only)
  • Residual current response values IΔn for prewarning and alarm (1…5 A) (isoPV1685PFR only)
  • CT connection monitoring (isoPV1685PFR only)
  • Device self test with automatic fault message in the event of a fault
  • Alarm relays separately adjustable for insulation faults, residual current faults and device errors (isoPV1685PFR only);
  • Alarm relays separately adjustable for insulation fault 1, insulation fault 2 (isoPV1685P, isoPV1685RTU only)
  • CAN interface to output measured values, statuses and alarms
  • RS-485 interface
    - isoPV1685(P)FR: BMS bus, e.g. to control the insulation fault location
    - isoPV1685RTU: BMS bus or Modbus (can be switched using the DIP switch)
  • μSD card with data logger and history memory for alarms


  • Photovoltaic systems with high leakage capacitances