5.4 Brief Power Failure in Devices with an Interface
V
in
V
out
ok
Bat
Remote
from PC
Diagram 5: Brief power failure in devices with an interface
Resumption of power supply before the buffering time tp is up (t3 is temporally before t4):
In the input voltage of the DC UPS module drops (time t1), the "Bat" battery immediately assumes the direct
voltage supply. In this way, the output voltage Ua remains absolutely uninterruptible. The floating changeover
contact "OK/Bat" switches to its resting position "Bat." At time t2 selected by the user, the buffering time tp set at
the DIP switches is started using the "Remote Timer Start" signal (signal level = 0 at Pin 7 of the 9-pole serial
interface). If the "Output Ua Interruption" DIP switch setting is selected, the output voltage Ua is automatically
interrupted for approximately 5 seconds after the buffering time tp (time t4) is up. The battery is already switched
off because the input voltage has returned to time t3. The interruption of the output voltage Ua for 5 seconds
enables the automatic rebooting of industrial PCs even if the mains voltage (or the input voltage Ue on the DC
UPS module) – as seen in this example – returns while the PC is being shut down.
Note
: Without remote signal level=0 in case of a time period setting of t=max, the output voltage is not
interrupted in this case because the set buffering time does not start.
DIP switch settings: Buffering at the maximum buffering time with Switch 1 Off (right)
Buffering time tp with Switch 2 through 7 from 5 to 635 sec.
Interruption of Ua using Switch 8 On (left)
© Siemens AG, 2009 14/18
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