Siemens SIMATIC S7-1500/ET 200MP System Manual page 124

Response of the CPU to negative power balance or failure of system power supplies
As soon as the CPU detects a negative power balance/overload, the following actions are
executed:
• The CPU stores the retentive data.
• The CPU enters the event in the diagnostics buffer.
• The CPU carries out a restart and repeats this until the cause of the negative power
balance is resolved.
Response of the interface module to negative power balance or failure of system power supplies
As a result of the overload, the interface module switches off all power segments. The I/O
controller or DP master can no longer access the I/O modules. The interface module provides
diagnostic information and periodically checks the connection to the backplane bus and re-
establishes the connection.
Exception: In the case of a voltage drop or a hardware fault in power segment 2 or 3, the
corresponding system power supply module switches off its power segment (and possibly the
following segments), and generates a diagnostic alarm, if possible.
More information on the behavior of the system power supply (PS) in the event of a fault can
be found in the manuals for the system power supplies.
Automation system
System Manual, 01/2023, A5E03461182-AK
Application planning
5.3 Power balance calculation
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