Description Of Internal Sequences In The Power Supply Unit - Siemens S5-135U/155U System Manual

4.3.5

Description of Internal Sequences in the Power Supply Unit

Given in this section is background information on internal sequences in the
power supply unit.
Behavior Upon
Failure of the
System Supply
When the System
The behavior of the power supply unit after a system supply failure is
Supply Fails
governed by the duration of the failure:
is shorter than the stored energy time
for power failure
is longer than the stored energy time
for power failure
Redundant Data
To ensure data backup, your CC and EU 185 are provided with a lithium
Backup
battery, and the power supply unit with a rechargeable battery.
In the event of system supply failure or switch-off, data backup is provided
by the lithium battery and, in the event of battery failure, by the rechargeable
battery which is permanently recharged to remain constantly operative.
After replacement of a defective lithium battery, the new one resumes data
backup and you must acknowledge the fault LED on the front panel.
As the rechargeable battery is withdrawn during the replacement of a power
supply unit, data backup is temporarily performed by the lithium battery.
System Manual
C79000-G8576-C199-06
Central Controllers and Expansion Units Power Supply Units
IF the system supply failure... THEN...
the PSU output voltages are within tolerance
ranges; no indication appears on the front plate
and no signal is sent to the S5 bus.
a data save routine is initiated on the
CPU/CPUs and an output inhibit is issued.
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