Siemens S5-135U/155U - Manual (Page 335)

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