Siemens SIMATIC S7-1500 System Manual page 46

Application planning
3.4 Power balance calculation
Power balance calculation when configuring with STEP 7
STEP 7 checks compliance with the power balance during the configuration.
Proceed as follows to evaluate the power balance calculation:
1. Perform the configuration of the S7-1500/ET 200MP with all the required modules.
2. In the network view, select the CPU/interface module 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 segment overview" table, so see whether the power balance is
positive. If the power balance is negative, the underpowered modules will be marked in
red.
Figure 3-10
Power balance calculation check for overload by the CPU/interface m odule
Compliance with a positive power balance is monitored by the CPU/interface module:
● 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 supply voltage L+ (24 V DC) that is necessary for operation is not connected when
system voltage infeed via the CPU/interface module is specified during parameter
assignment (see section Special considerations for the use of a system power supply in
the first power segment (Page 41))
● 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
connection plug or on/off switch)
● A system power supply that is necessary for operation has no U connector inserted
46
Example of a power balance calculation with STEP 7
Automation system
System Manual, 09/2016, A5E03461182-AD