8 Chapter 1 Overview
Liebert APM 90 Integrated Modular UPS User Manual
When the battery voltage drops to the EOD voltage, the battery converter shuts down automatically and the
battery is isolated to avoid further battery discharge. The EOD voltage is settable from 1.6V/cell to 1.75V/cell
(VRLA).
6. Battery low pre-warning time.
The battery low pre-warning time is adjustable between 3min and 60min. The default setting is 5min.
1.4.2
Advanced Function
The UPS provides battery maintenance test function. Battery maintenance test is also called as battery
self-test. At periodic intervals, 20% of the rated capacity of the battery will be discharged automatically, and
the actual load must exceed 20% of the UPS nominal capacity. If the load is less than 20%, the automatic
discharge cannot be executed. The periodic interval can be set from 30 to 360 days. The battery self-test can
be disabled.
Conditions: battery at float charge for at least 5h, load equal to 20%
~
80% of rated UPS capacity.
Trigger: manually through the command of Battery Maintenance Test on LCD or automatically.
Interval: 30 days
~
360 days (default setting: 60 days).
1.5
Battery Protection
The following battery protection functions are set by the commissioning engineer through background
software.
Battery low pre-warning
The battery low pre-warning occurs before the EOD. After this pre-warning, the battery should have the
capacity for three remaining minutes discharging with full load. The time can be configured from 3min to
60min.
EOD protection
When the battery voltage drops to the EOD voltage, the battery converter shuts down. The EOD voltage is
adjustable from 1.6V/cell to 1.75V/cell (VRLA).
BCB open alarm
This warning occurs when the BCB opens. The battery is connected to the UPS through the BCB, which is
manually closed and electronically tripped by the UPS control circuits.
