Siemens S5-135U/155U System Manual page 335

The load can also be switched via a contact.
ELR
Output 1
Figure 8-11 Parallel Connection of Outputs for AC Voltage Outputs
Connection of Given here are two examples of the feeding of inputs and outputs of different
Input/Output
modules from two power supply units.
Modules to Two
With non-floating input/output modules, the negative terminals (L-) of the
Power Supply Units
power supply units are connected to reference potential (PE) because the
inputs of the 420 module are referred to chassis ground.
0 V
DI
DI
e.g. 420
e.g. 420
I I I I I I I
AC
+
230V
_
DC
24V
Figure 8-12 Feeding of Non-Floating Input/Output Modules from Two Power Supply Units
System Manual
C79000-G8576-C199-06
Manual ELR
Output 2
Load
0 V
L Q Q Q L
I I
+
2L+
1L+
_
L
Digital Input/Output Modules
Phase (L)
ELR = Electronic Load Relay
Neutral (N)
Central Ground Point
or Rack or the CC/EU
Reference Potential
0 V
0 V
DQ DQ
e.g. 441 e.g. 441
Q Q L Q L Q Q
+ + +
AC
+
230V
_
DC
24V
and Connection
to Protective
Conductor (PE)
8-23