Backup - BEL LDX-U20 User Manual

LDX-U20
12 V / 24 V 20 A High Performance DC-UPS

3.2 BACKUP

The system is in backup if the supply for the output is sourced from the battery (input supply missing). During backup the battery is
monitored continuously to prevent over discharge (see §5.2.7).
A programmable backup timer (see §5.2.14) is also implemented in order to fix a maximum backup time during power outages. This
allows preserving the battery life and shortening the recharge time, avoiding discharging the battery when not needed.
During backup the internal Coulomb counter is used to give an estimation of the residual charge of the battery, this information is given to
the user on the LCD in form of remaining % and through the ready relay which starts toggling at 1Hz once the battery charge is < 20%.
3.3 PC SHUTDOWN AND AUTOMATIC RESTART
PC shutdown: In case the LDX-U20 is used to supply a PC it is possible to automatically shut down the PC after an adjustable time
of backup. For this the PC must run the POWERMASTER application (provided free) and must be connected through USB. Optionally
POWERMASTER can call a task on the PC before shutting down, for example to backup some sensitive data.
Automatic restart: LDX-U20 is able to automatically restart a PC which was powered OFF by mistake, for example in case of the
Operating System (OS) crash. The user may adjust an output current threshold and a timer used for detecting the PC OFF status. In
order to restart the PC the LDX-U20 toggles the output OFF and then ON again. User must enable in the PC BIOS the automatic start in
case of supply ON.
Note: The LDX-U20 cannot interrupt the supply flow from the input to the output. Therefore the user must use one of the LDX-U20
available relays (by activating the PC OFF signal on it) in order to enable automatic PC restart when the input supply is present. The
relay contact (rated 2A/30Vdc) must be wired in series to the device output using a 4A fast cartridge fuse (Littlefuse 0217004.HXP or
equivalent). Be careful to respect maximum current rating of the fuse.
In case the load (PC) current exceeds the LDX-U20 dry contact rating the use of an external relay with suitable current/voltage rating is
needed, relay coil voltage shall match output voltage. It should be driven by the LDX-U20 internal dry contact.
Figure 3. Internal relay Figure 4. External relay
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