Siemens Simatic S7-300 CPU 31xC Series Installation And Operating Instructions Manual page 51

Example: S7-300 with load power supply from PS 307
The figure below shows the overall S7-300 configuration (load power supply unit and
grounding concept), with TN-S mains supply. The PS 307 supplies the CPU and the load
current circuit of the 24 VDC modules.
Note
The layout of the power connections does not correspond with their physical arrangement; it
was merely selected to give you a clear overview.
Example: S7-300 with load power supply from PS 307
S7-300, CPU 31xC and CPU 31x: Installation
Operating Instructions, Edition 08/2004, A5E00105492-05
4.10 Selecting the load power supply
Configuring
4-27