iso415R-x_D00401_00_M_XXEN / 04.2021 9
ISOMETER® iso415R
2.3.1 Insulation fault R
F
The insulation fault R
F
is measured in the range of 1 kΩ to 10 MΩ in unearthed 3(N)AC, AC, DC and
DC superimposed AC systems and output in the range of 1 kΩ to 1 MΩ via the value display LEDs.
R
F
can be read from the interface register "Insulation resistance" in the range of 1 kΩ to 10 MΩ.
With each update of the measured value R
F
, the Modbus register "Measured value update coun-
ter" is incremented.
The two response values R
an1
and R
an2
are available for the limit value comparison. The two values
are set either manually via the detent potentiometers or in the "Ext" position via the interface reg-
isters "Response value R
an1
" and "Response value R
an2
".
If R
F
falls below the limit values R
an1
or R
an2
without interruption for the duration of t
on
, the respec-
tive alarm AL1 or AL2 is set. If R
F
exceeds the respective limit values plus hysteresis without inter-
ruption for the duration of t
off
, the respective alarms AL1 or AL2 are deleted if the fault memory is
disabled.
The alarms AL1 and AL2 can be assigned to relay K1 via the interface registers "Alarm assignment
Alarm 1" and "Alarm assignment Alarm 2".
2.3.2 Insulation fault location R%
If the ISOMETER® detects a DC offset to earth of at least 10 V in the monitored system, the insula-
tion fault location R% is assigned to the positive or negative conductor with + or - 100 %. This can
occur when monitoring a DC system or an AC system with an insulation fault in the DC link. In the
case of symmetrical faults or below 5 V, R% is set to 0. The value of R% can be read via the inter-
face register "Insulation fault location".
2.3.3 System leakage capacitance C
e
If the measured value acquisition does not work due to an excessive system leakage capacitance
C
e
or excessive disturbances in the system, the message "max. C
e
/fault" appears and is indicated
by the LEDs. The message can be assigned to relay K1 via the interface register "Alarm assignment
max. C
e
/fault".
2.3.4 Connection monitoring L1/L2
The connection monitoring L1/L2 continuously checks the low-resistance connection between
the terminals L1 and L2 of the ISOMETER® via the system to be monitored. If the resistance is too
high, the alarm L1/L2 is triggered and indicated by the LEDs.
The alarm can be assigned to relay K1 via the interface register "Alarm assignment L1/L2".
If the fault memory is not enabled, the alarm is automatically cleared after the connection fault
has been eliminated. Connection monitoring can be disabled via the interface register
"Connection monitoring L1/L2".
