Function; Intended Use; Device Features - Bender ISOMETER isoRW425 Manual

Function

2 Function
2.1

Intended use

The ISOMETER® monitors the insulation resistance R
of unearthed AC/DC main circuits (IT systems) with nominal system voltages of 3(N)AC, AC, AC/DC or
DC 0...440 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. The separate supply voltage U
monitored as well.
The maximum permissible system leakage capacitance is 300 F in R mode and 1 F in Z mode.
In order to meet the requirements of the applicable standards, customised parameter settings must be made
on the equipment in order to adapt it to local equipment and operating conditions. Please heed the limits of
the range of application indicated in the technical data.
Any other use or a use that goes beyond this constitutes improper use.
To ensure that the ISOMETER® functions correctly, an internal resistance of ≤ 1 k must exist between L1/+
and L2/– via the source (e.g. PSU) or the load.
If the ISOMETER® is installed inside a control cabinet, the insulation fault message must be audible and/or
visible to attract attention.
2.2

Device features

• Monitoring of the insulation resistance R
unearthed 3(N)AC, AC and DC systems with galvanically connected rectifiers or frequency converters
• Insulation impedance Z
• Measuring the system voltage U
• Measuring the DC residual voltages U
• Selectable start-up delay, response delay and delay on release
• Alarm output via LEDs ("AL1", "AL2"), display, and alarm relays ("K1", "K2")
• Automatic device self test with connection monitoring
• Selectable n/c or n/o relay operation
• Measured value indication via multi-functional LC display
• Activatable fault memory
• Automatic adaptation to the system leakage capacitance C
• Two separately adjustable response value ranges from 1...990 k (prewarning, alarm)
• RS-485 (galvanically isolated) including the following protocols:
– BMS (Bender measuring device interface) for the data exchange with other Bender devices
– Modbus RTU
– IsoData (for continuous data output)
• Password protection against unauthorised changing of parameters
8 isoRW425_D00052_06_M_XXEN/09.2023
(R mode) or of the insulation impedance Z
F
(Z mode) for 50 Hz or 60 Hz
F
(True-RMS) with undervoltage/overvoltage detection
n
(between L1/+ and earth) and U
L1e
(R mode) or the insulation impedance (Z mode)
F
s
up to 300 F in R mode and 1 F in Z mode
e
allows de-energised systems to be
(Z mode) for
F
(between L2/– and earth)
L2e