Setting The Backup Battery Monitor - Siemens S5-155U System Manual

6ES5 955-3NA12 Power Supply Unit
Setting the backup
battery monitor
4 - 74
As of Version 6 of PSU 6ES5 955-3NA12, you can set jumper RR-LL
to choose whether the signalling relay (monitor output) should switch
in the event of battery failure as well as fan failure:
• • Jumper RR-LL open (state when delivered): relay will signal only
a fan failure
• • Jumper RR-LL closed: relay will signal a fan and battery failure.
If the backup voltage fails or a fan is at standstill, or in both cases, the
signalling relay will drop out (monitor output). The "Batt. Low" LED
will also light up.
-
Relay contacts 2-1 closed: battery backup voltage in order and fan
running
-
Relay contacts 2-3 closed: backup voltage under 2.7 V or fan failure
Note
The signalling relay in the power supply unit will drop out in the
event of a fan fault or backup battery fault. The user's circuitry
for the signalling relay must therefore be suitable for both types
of fault.
If the signalling relay drops out because of a backup battery fault
and the programmable controller is therefore switched off, the
program in the main memory may be lost. Loss of program can
be avoided if an external backup voltage (3.4 V) is present at the
sockets on the front plate of the power supply unit during
shutdown of the programmable controller.
System Manual
C79000-B8576-C199-03