Function
16
isoRW425_D00052_03_M_XXEN / 02.2017
If the values R
F
, Z
F
or U
n
do not exceed their release value (response value plus
hysteresis) for the period t
off
without interruption, the alarm relays will switch
back to their initial position and the alarm LEDs AL1/ AL2 stop lighting. If the
fault memory is activated, the alarm relays remain in alarm condition and the
LEDs light until the reset button "R" is pressed or the supply voltage is inter-
rupted.
The device function can be tested using the test button "T". Parameters are
assigned to the device via the LCD and the control buttons on the front panel;
this function can be password-protected. Parameterisation is also possible via
the BMS bus, for example by using the BMS Ethernet gateway (COM460IP) or
the Modbus RTU.
3.2.1 Monitoring of the insulation resistance (R mode)
The two parameters that monitor the insulation resistance, R1 and R2, can be
found in the response value menu "AL" (see table on Page 34). The value R1
can only be set higher than the value R2. Each time the mode is switched from
R mode to Z mode, parameters R1 and R2, and hence the monitoring of the
insulation resistance will be deactivated. In Z mode the insulation impedance
Z
F
is the main measured value and the measured insulation resistance R
F
can
have tolerances depending on the system condition. If required, the parame-
ters R1 and R2 can also be activated in Z mode.
If the insulation resistance R
F
reaches or falls below the activated values R1 or
R2, an alarm message will be signalled. If R
F
exceeds the values R1 or R2 plus
the hysteresis value (see table on Page 34), the alarm will be cleared.
3.2.2 Monitoring of the insulation impedance (Z mode)
The parameters Z1 and Z2 for monitoring the insulation impedance are avail-
able in the "AL" response value menu only when Z mode is activated. The val-
ue Z1 must be set higher than value Z2. The insulation impedance Z
F
for the
selected system frequency f
n
(50 Hz or 60 Hz in the "SEt" menu) can be calcu-
lated from the measured values R
F
and C
e
using the formula below:
Xce
l
2 π× f
n
× C
e
×()
------------------------------------------
=
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