Siemens Simatic S7-400

Wiring the S7-400
4-2
Automation System S7-400 Hardware and Installation
A5E00850741-01
4.1 Supplying Power t o Modules
Power Supply Modules and Load Current Power Supplies
The modules of the S7-400 system are supplied with all the required operating
voltages by a power supply module, via the backplane bus of the rack. Which
power supply module you use in a rack depends on your system requirements (line
voltage, current consumption of the modules used).
You must provide load voltages and currents via external load current power
supplies.
The following figure s hows how the individual modules of the S7-400 are supplied
with current and voltage.
S7-400
power supply
module
S7-400
modules (DC
or AC)
Operating voltages
5 VDC and 24 VDC
via backplane bus
Load current via
front connector
Load current power
supply
Line voltage:
120/230 VAC
with supply
isolator
or 24 VDC
Note
The power supply modules must not be connected in parallel on their secondary
sides.