Installation and connection
21
RCMB300-series_D00372_01_M_XXEN/06.2019
4.5 Wiring diagram
Fig. 4.3: Wiring diagram RCMB30…(N/C principle)
• The use of a type 2 surge protection device (SPD) is mandatory due to possible
impulse voltages and in order to comply with normative requirements.
• The surge protection device must be connected upstream of the power supply unit
on the supply side.
• Features of the surge protection device:
– Nominal discharge current I
n
(8/20 μs): 20 kA
– Response time: 25 ns
– Two-stage: 1 varistor + 1 spark gab
Alternatively, the power supply unit must be connected to a CAT II supply without a
surge protection device.
F 6 A
L1
L2
L3
N
DC 24 V
AC
DC
21
GND
T/R
GND
24 V
L
N
22 24
21
22 24
11
12 14
3
RCMB301-CTBC...
SPD
Alarm Prewarning
SPD = surge protection device