Liebert Series 600T - Manual (Page 69)

Operation 63
Figure 42 Battery Time Screen Example - 45 Minute Discharge
The Battery Time Remaining graph and the Calculated times are extremely helpful to the operator who has the
discretionary authority to order load-shedding activities. The Series 600T automatically samples battery voltage
and load current and recomputes every six seconds. This gives the operator fast and accurate feedback on efforts
to extend battery time remaining by shutting down non-critical loads.
The Series 600T dynamically adjusts the Battery Shutdown voltage based on battery characteristics and the
length of the current discharge event. If a discharge event extends past 15 minutes (i.e., the load is less than the
full design rating), the Battery Shutdown voltage setting is gradually and automatically increased, to protect the
batteries from deep discharge.
When the battery voltage decreases to a preset limit (see 3.1.6 - Alarm Limit Settings Screen), the Low Battery
Warning alarm message appears on the display screen. This warns the operator that the battery voltage is
approaching the Battery Shutdown level—about five minutes of time remaining at full rated load.
If the battery discharges to the Battery Shutdown level, represented by the lower line on the Battery Time screen,
the battery and input circuit breakers trip open and the UPS module is shut down. This protects the battery from
being damaged by an extended deep discharge.
NOTE
While every effort has been made to make the Rated and Calculated Time Remaining
values as accurate as practical, these values must be regarded as approximations. At
the beginning of the discharge cycle, the Calculated times could be off by as much as
±20% due to such variables as battery initial charge, age of battery, and the
subsequent load-shedding activities of the operator. Within a few minutes, however,
these calculations should settle into their design accuracy of ±10%, with the end-of-
discharge tolerance being +0, -10% of actual observed time. In addition, the
operator can adjust the settings affecting Rated Total Time after gaining experience
with the actual battery and connected load.
NOTE
The Low Battery alarm setting is designed to be useful at full load battery discharge
rates. Unlike the Battery Shutdown voltage, the Low Battery alarm setting is not
automatically increased and should not be relied upon as an indicator of battery time
remaining. Instead, the operator should consult the Battery Time screen or Present
Status screen to see the Calculated Time Remaining based on actual usage during the
discharge period.
0 10 20 30 40 50 60
Time (Minutes)
340
360
380
400
420
440
460
480
500
VDC
Battery Shutdown = 417
Battery Charge = 3%
Total 00:45 Remain 0:01
Rated Time (Hrs:Min)
Total 00:25 Remain 0:00
SELECT : MASTER MENU
Low Battery Warning
Calculated Time (Hrs:Min)