Siemens Simatic S7-400

Power supply modules
3
3.1 Common characteristics of the power supply modules
Functions of the power supply modules
The power supply modules of the S7-400 supply the other modules in the rack with their
operating voltages via the backplane bus. They do not provide load voltages for the signal
modules.
Common characteristics of the power supply modules
The power supply modules share the following characteristics in addition to their individual
specifications:
● Encapsulated design for use in racks of the S7-400 system
● Cooling via natural convection
● Plug-in connection of the supply voltage with AC - DC coding
● Protection class I (with protective conductor) in accordance with IEC 61140; VDE 0140,
Part 1
● Limitation of the inrush current in accordance with NAMUR Recommendation NE 21
● Short-circuit-proof outputs
● Monitoring of both output voltages. If one of these voltages fails, the power supply module
signals a fault to the CPU.
● Both output voltages (5 VDCand 24 VDC) share a common ground.
● Primary clocked
● Battery backup as option. The parameters set and the memory contents (RAM) are backed
up via the backplane bus in the CPUs and programmable modules. In addition, the backup
battery enables you to carry out a restart of the CPU. Both the power supply module and
the backed up modules monitor the battery voltage.
● Operating and fault/error LEDs on the front plate.
Note
A mains disconnecting device must be provided when installing AC power supply modules.
Switching the line voltage Off/On
The power supply modules have an inrush current limiter in accordance with NAMUR.
S7-400 Automation System Module Data
Reference Manual, Ausgabe 11/2016, A5E00850736-08 39