Reference Lead Not Connected To The Protective Earth; Capacitive Load Of The Power Supply - Bosch IO-BOX32 Manual

8–4
8.2.2

Reference lead not connected to the protective earth

8.2.3

Capacitive load of the power supply

If the reference lead (N, 0 V) is not connected to the protective earth system,
a corresponding earth fault monitoring device must be deployed to detect
earth faults in order to avoid inadvertent activation in the case of insulation
faults. The supply circuit is thus a SELV circuit, see also section 8.1. Please
note that other connected resources can nullify the earth–free layout.
L1
L2
L3
N
PE
24 V
Earth 0 V
E
leakage
1
monitor
Capacitances are installed in the IO-BOX32 between the power supply
leads and protective earth for interference suppression. This is to be taken
into account if an earth fault monitoring device is deployed.
IO-BOX32
US
U1
U2
0 V shared reference
potential for US, U1, U2
if required
other IO-BOX32
X10
PE
against
Capacitance PE
5 nF
5 nF
5 nF
22 nF
1070 072 302-101 (01.06) GB