Use Of System Power Supplies - Siemens SIMATIC S7-1500 Automation System System Manual

Application planning
4.2 System and load power supply
4.2.1

Use of system power supplies

System power supplies are required, if the power fed from the CPU into the backplane bus is
not sufficient to supply all connected modules with power. In addition, you can use the
system power supply with 120/230 VAC and supply the CPU through the backplane bus.
The CPU then does not have to be supplied with 24 VDC.
Whether you need an additional system power supply for your configuration depends on the
power that the modules consume from the backplane bus. The power provided by the CPU
and the system power supplies via the backplane bus must be greater than the power
required by the I/O modules.
When planning with STEP 7, the supplied and required power are compared. If the required
power is too high, you receive a corresponding message from STEP 7.
Using system power supplies
The following slots may be used for system power supplies:
● A system power supply in slot 0, to the left of the CPU
● Up to 2 system power supplies in the slots to the right of the CPU (power segments)
Power segment
By using additional system power supplies on the right, next to the CPU, you divide the
configuration into power segments.
Configuration variants
Figure 4-3
32
Configuration variants with 3 power segments
S7-1500 Automation System
System Manual, 01/2013, A5E03461182-01