Product: ISOMETER® isoPV425 AGH 420  
  Bender GmbH

ISOMETER® isoPV425 with coupling device AGH420

Insulation monitoring device for unearthed DC circuits (IT systems)

for photovoltaic installations up to 3(N)AC, AC 690 V/DC 1000 V

Product description

The ISOMETERR of the isoPV425 series monitors the insulation resistance of unearthed AC/DC main circuits (IT systems) with nominal voltages of 3(N)AC, AC, AC/DC 0…690 V or DC 0…1000 V.

DC components existing in AC/DC systems do not influence the operating characteristics.

A separate supply voltage allows deenergised systems to be monitored as well. The maximum permissible system leakage capacitance is 500 μF.


• AC, DC or AC/DC main circuits

• Solar systems with directly connected inverters

• Solar systems with high system leakage capacitances

• Solar systems with high but slow voltage fluctuations

• Systems including switch-mode power supplies


Device characteristics

• Monitoring for unearthed AC and DC systems with galvanically connected rectifiers or inverters

• Measurement of the nominal system voltage (r.m.s.) with undervoltage and overvoltage detection

• Measurement of DC voltages system to earth (L+/PE and L-/PE)

• Automatic adaptation to the system leakage capacitance up to 500 μF

• Automatic device self-test with connection monitoring

• Selectable start-up delay, response delay and delay on release

• Two separately adjustable response value ranges of 1…500 kΩ (Alarm 1, Alarm 2)

• Alarm signalling via LEDs (AL1, AL2), a display and alarm relays (K1, K2)

• N/C operation or N/O operation selectable

• Measured value indication via multifunctional LCD

• Fault memory can be activated

• RS-485 (galvanically isolated) including the following protocols:

– BMS interface (Bender measuring device interface) for data exchange with other

Bender components

– Modbus RTU

– isoData (for continuous data output)

• Password protection to prevent unauthorised parameter changes

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