Siemens SIMATIC S5-100U System Manual page 62

Installation Guidelines
(1)
L1
L2
L3
N
PE
M
M
Figure 3-20. Non-Grounded Operation; 24 V DC Power Supply
Interference voltages are discharged to the ground conductor (PE) via a capacitor. You can prevent
static charges by connecting a high-ohmic resistor (approx. 100 k / W) parallel to the capacitor.
3-24
(2)
(8)
1 µF/
100 K
500 V AC
(3)
L+
(6)
(7)
L+
(with Safe Electrical Isolation According to DIN VDE 0160)
for Programmable Controller and I/Os
Install the standard mounting
rail electrically isolated
CPU
L+
M
DI DI DO DO
1
1 1
2
2 2
S5-100U
1
2
EWA 4NEB 812 6120-02b