Siemens Simatic S7-400 - Manual (Page 82)

Power Supply Modules
3-2
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
3.1 Common Characteristics of the Power Supply Modules
Tasks 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 certain common characteristics in addition to
their special technical specifications. The most important common characteristics
are:
• Encapsulated design for use in mounting 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 60536;
VDE 0106, Part 1
• Limitation of making current in accordance with NAMUR recommendation part 1
of August 1998
• 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 VDC and 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.
Warning
A mains disconnecting device must be provided when installing AC power supply
modules.