Siemens SIMATIC S7-400H - Failure and Replacement of a Power Supply Module; Initial Situation

Failure and Replacement of Components During Operation
10-5
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
10.1.2 Failure and Replacement of a Power Supply Module
Initial situation
Both central processing units are at RUN.
Failure How Does the System React?
The S7-400H is in redundant system mode
and one power supply module fails.
• Partner CPU switches to single mode.
• Partner CPU reports the event in the
diagnostics buffer and via OB 72.
Procedure
To change a power supply module in the central rack, perform the following steps:
Step What Has To Be Done? How Does the System React?
1 Turn off the power supply (24 V DC for
PS 405 or 120/230 V AC for PS 407).
• Entire subsystem is turned off
(system operating in single mode).
2 Replace the module. -
3 Switch the power supply module on
again.
• CPU executes the self-tests.
• CPU performs automatic LINK-UP
and UPDATE.
• CPU changes to RUN (Redundant
system mode) and now operates
as the standby CPU.
Note
If you use a redundant power supply (PS 407 10A R), two power supply modules
are assigned to one fault-tolerant CPU. If a part of the redundant PS 407 10A R
power supply module fails, the corresponding CPU keeps on running. The
defective part can be replaced during operation.
Other power supply modules
If the failure concerns a power supply module outside the central rack (e.g. in the
expansion rack or in the I/O device) the failure is reported as a rack failure (central)
or station failure (remote). In this case, simply switch off the power supply to the
power supply module concerned.