The ISOMETER® monitors the insulation resistance (R mode) or the insulation impedance (Z mode) of unearthed AC/DC main circuits (IT systems) with nominal system voltages of 3(N)AC, AC, AC/DC or DC 0…400 V. DC components existing in 3(N)AC, AC/DC systems do not influence the operating characteristics when a minimum load current of DC 10 mA flows. Due to the separate supply voltage, de-energised systems can also be monitored. The maximum permissible system leakage capacitance Ce is 300 μF in R mode and 1μF in Z mode.

• AC control circuits in rolling stock according to EN 50155
• AC, DC or AC/DC circuits
• Systems including switched-mode power supplies
• Small AC-IT systems e. g. lighting systems

• Monitoring of the insulation resistance (R mode) or the insulation impedance (Z mode) of unearthed 3(N)AC, AC and DC systems (IT systems) with galvanically connected rectifiers or inverters
• Insulation impedance (Z mode) for 50 Hz or 60 Hz
• Measurement of the nominal system voltage (RMS) 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 300 μF in R mode and 1μF in Z mode
• Automatic device self test with connection monitoring
• Selectable start-up delay, response delay and delay on release
• Two separately adjustable response ranges of 1…990 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 multi- functional LCD
• Fault memory can be activated
• RS-485 (galvanically isolated) interface 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 changes of parameters