Siemens SIMATIC S7-1500 System Manual page 45

Application planning
4.3 Power balance calculation
Power balance calculation during planning with STEP 7
STEP 7 checks compliance with the power balance during the configuration.
Proceed as follows to evaluate the power balance calculation:
1. Configure the configuration of the S7-1500 with all the required modules.
2. In the network view, select the CPU or the system power supply.
3. Open the "Properties" tab in the inspector window.
4. Select the "System power supply" entry in the area navigation.
5. Check the "Power balance calculation" table, so see whether the power balance is
positive. If the power balance is negative, the underpowered modules will be marked in
red.
Figure 4-7
Power balance check by the CPU for overload
Compliance with a positive power balance is monitored by the CPU:
● At every POWER ON
● At every change of the installed hardware
Causes for overload
An overload can still occur despite a positive power balance during planning. The cause for
overload can be a hardware configuration that does not correspond to the configuration in
STEP 7, for example:
● More I/O modules are inserted in the actual configuration than were planned
● A system power supply that is necessary for operation is not inserted
● A system power supply that is necessary for operation is not switched on (power cable
connector and on/off switch)
● A system power supply that is necessary for operation has no U connector inserted
44
Example of a power balance calculation with STEP 7
S7-1500 Automation System
System Manual, 02/2014, A5E03461182-AB