Function
24
IRDH575_D00089_05_M_XXEN/01.2020
3.5.6 ISOnet function for central control of the insulation
monitoring process when several IRDH575 are
interconnected in IT systems
Up to 30 ISOMETER® can communicate with each other in an ISOnet network.
The ISOnet network can only be activated when a BMS bus is used for inter-
connection. A typical method with four devices is shown as an example. The
ISOnet function of all ISOMETER® in the ISOnet network must be activated in
the COM SETUP „ISOnet=ON“ menu, refer to page 76.
The BMS master (BMS address 1) with activated ISOnet function controls
the ISOnet slave devices via the BMS bus.
Address 1 must not be assigned to another BMS device on the respective BMS
bus.
When the master ISOMETER® has finished one measuring cycle, the authoriza-
tion for insulation monitoring is passed on to the next higher BMS address.
This authorization is returned by the slave with the highest BMS address to the
BMS master after a cycle has been completed.
During the insulation monitoring process, all other ISOMETER®, are in the
STANDBY mode. In this way it is prevented that ISOMETER®s influence each
other in interconnected IT systems.
At f = 50Hz and C
e
= 1 µF, an ISOnet device stays in the measuring mode for
12s and then changes to the STANDBY mode. The maximum response time of
the ISOnet device that made the last measurement, will be extended by the
number of devices x 12s, in our example 48s.
When an insulation fault is detected by an ISOMETER®, the insulation fault lo-
cation process is started. The device stays in the measuring mode during this
time. Only after completion of insulation fault location, the ISOnet device
stops the monitoring mode and passes the authorization for insulation moni-
toring on to the next device.
In the STANDBY mode, the ISOnet device displays the last measured insulati-
on resistance.
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