System And Load Power Supply - Siemens SIMATIC S7-1500 System Manual

3.2

System and load power supply

Types of power supplies
The S7-1500 automation system/ET 200MP distributed I/O system distinguishes between
two types of power supply:
● System power supply (PS)
● Load current supply (PM)
System power supply (PS)
The system power supply has a connection to the backplane bus (U connector) and supplies
solely the internally required system voltage. This system voltage supplies parts of the
module electronics and the LEDs. A system power supply can also supply CPUs or interface
modules if these are not connected to a 24 VDC load current supply.
Load current supply (PM)
The load current supply feeds the input/output circuits of the modules, as well as the sensors
and actuators of the plant, if installed. The supply of the CPU/interface module with 24 V DC
is optional if you supply the voltage for the backplane bus via a system power supply.
Special characteristic of the load current supply
Load current supplies can be mounted on the "S7-1500 mounting rail" but do not have a
connection to the backplane bus.
Automation system
System Manual, 12/2014, A5E03461182-AC
Application planning
3.2 System and load power supply
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