Power Balance Calculation - Siemens SIMATIC S7-1500 Automation System System Manual

4.3

Power balance calculation

Introduction
In order to ensure the supply of the modules from the backplane bus, the infed power is
compared with the required power. In a power balance calculation the system checks
whether the power provided by the system power supplies including CPU is greater than or
equal to the power used by the consumers (modules).
In order to operate the configuration with its used modules, the power balance must be
positive for each power segment in use.
Negative power balance: The infed power is less than the power consumed by the modules
in the power segment.
Positive power balance: The infed power is greater than the power consumed by the
modules in the power segment.
Take care even during planning, that the power fed into the backplane bus is always greater
than or equivalent to the power drawn.
The power fed into the backplane bus from the CPU and system power supply is listed in the
technical data of the CPU in the corresponding Manual
(http://support.automation.siemens.com/WW/view/en/57251228).
The power drawn from the backplane bus by an I/O module or the CPU is listed in the
technical data of the CPU in the corresponding Manual
(http://support.automation.siemens.com/WW/view/en/57251228).
The power balance calculation is performed:
● During planning with STEP 7
● During operation by the CPU
S7-1500 Automation System
System Manual, 01/2013, A5E03461182-01
Application planning
4.3 Power balance calculation
35