Special Considerations For The Use Of A System Power Supply In The First Power; Segment - Siemens SIMATIC S7-1500 System Manual

3.2.2

Special considerations for the use of a system power supply in the first power

segment

Infeed options
There are three options for the infeed of the required system voltage in the backplane bus:
● Infeed via CPU/interface module
● Infeed via CPU/interface module and system power supply
● Infeed via system power supply only
Infeed via CPU/interface module
Infeed via the CPU/interface module generally suffices for small and medium hardware
configurations. The power consumption of the connected modules must not exceed the
power supplied by the CPU/interface module.
In this configuration variant, supply the CPU/interface module with 24 V DC from a load
current supply.
Procedure
To set up the supply by means of the CPU/interface module, follow these steps:
1. Open the "Properties" tab of the CPU/interface module in STEP 7 and select the "System
power supply" in the navigation.
2. Select the option "Connection to supply voltage L+".
Figure 3-6
Infeed via CPU/interface module and system power supply
For larger hardware configurations, infeed into the backplane bus by the CPU/interface
module alone no longer suffices. If the modules consume more power in total than the power
supplied by the CPU/interface module, insert an additional system power supply.
Supply the system power supply with the permissible supply voltage and the CPU/interface
module with 24 V DC from a load current supply.
Both the system power supply and the CPU/interface module feed current into the backplane
bus. The supplied power is summed.
Power addition: "Infeed power of the system power supply" + "Infeed power of the CPU/
interface module"
Automation system
System Manual, 12/2014, A5E03461182-AC
Supply voltage via CPU/interface module only
Application planning
3.2 System and load power supply
31