4
Connection
I
D
anger
!
Risk of fatal injury due to electric shock!
Touching live system parts can result
in fatal injuries. Ensure that there is no voltage in the installation area and follow the
rules for working on electrical equipment.
Terminal Connections
A1, A2
Connection to supply voltage
U
s
1
Socket for connection cable of measuring current transformer
T/R
Connection for a combined external test and reset button
11, 12, 14
Output relay K1 (alarm)
21, 22, 24
Output relay K2
i
To comply with IEC 60947-2 Annex M, the MRCDB423 must be operated according to the N/C
principle in combination with a circuit breaker with undervoltage release or shunt trip. The
circuit breaker must be able to switch off in less than 17 ms and comply with the IEC 60947-2
standard.
I
W
arning
!
An electric shock caused by excessively high fault currents can result in serious
injuries or death.
The MRCDB423 device must not be operated without a circuit breaker and
must only be used in switching applications!
After the output relay K2 switches off, an automa-
tic offset measurement is carried out, which takes an existing fault current as the basis for the
calibration. This may cause the protection to fail because the system does not switch off if the
fault current is too high.
> U
F 6A
L1
L2
L3
N
~
3~
CTBCx
CTUB101
+12V
-12V T
GND
S1(k) S2(l)
CTX...
MRCDB423
10 MRCDB423_D00396_01_M_XXEN/06.2021
Connection
