Bender ISOMETER IRDH275, Manual

Page: 117 / 184

Function
25 IRDH275_D00122_03_M_XXEN/05.2017
Function input F1/F2 for connection or disconnection of
IT systems being monitored
The ISOMETER® can be disconnected from the IT system and set to STANDBY
mode with the function input F1/F2. If the input F1/F2 is bridged, the connec-
tions L1/L2 are switched off via internal coupling relays, the measuring func-
tion is stopped and the message "STANDBY" appears on the display. Software
version 1.4 or higher does not indicate the measured insulation resistance
during the disconnection, but indicates the value > 10 MΩ. Furthermore, the
alarm relays and alarm LEDs no longer provide alarm messages. After opening
the function input F1/F2, the connection to the IT system will be restored and
a completely new measuring cycle for insulation monitoring is started.
With this function, selective disconnection of an IRDH275B in interconnected
IT systems can be carried out via auxiliary contacts of the respective coupling
switch. One coupling switch each in a line-type or ring-type arrangement can
deactivate a subsequent IRDH275B. This arrangement guarantees that only
one ISOMETER® is active in each galvanically connected system. In a ring-type
arrangement with all coupling switches closed, it can be assumed that all
ISOMETER®s are deactivated. In order to prevent this, a BMS Master (IRDH275B
BMS address 1) monitors the condition of the function input F1/F2 of all slave
ISOMETER®s.
When all slave ISOMETER®s are in the STANDBY mode, the insulation monitor-
ing function of the Master ISOMETER® and hence the function input F1/F2 of
the Master are without function in this mode.
Details are shown in the graphic below.