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To perform the shutdown procedure, transfer the critical load from the UPS system to the bypass line
(at the SCC). Then trip open the UPS module output and battery circuit breaker (MBD) and manually
open the UPS module input circuit breaker. The Control Power switch may be turned Off if
required for maintenance procedures.
Refer to 3.4.5 - Shutdown Procedures for more details, including module shutdowns for service and
emergency shutdowns.
3.2.11 Battery Time Screen (Module Only)
At the Master Menu, move the highlighted cursor to BATTERY TIME. Press the Select pad and the
Battery Time screen is displayed.
When AC power is not available to the UPS module, the UPS inverter uses DC power from the battery
to supply the critical load. This screen helps the operator assess his power resources to determine if
and when the critical load shutdown procedures need to be started.
The Battery Time screen is a line graph that tracks the present battery voltage versus the elapsed
time that the battery has been discharging (Figure 46). As the battery voltage decreases, the line
representing it moves closer to intersecting the line that represents the battery shutdown voltage.
When the battery starts to discharge, the screen displays a 15-minute graph. If the battery has been
providing power for more than 15 minutes, the screen displays a 30-minute graph. If battery power is
still available after 30 minutes, a 60-minute graph is displayed (Figure 47).
Figure 46 Battery time screen (15 minute discharge)
The screen also displays alarm messages (Battery Discharging, Low Battery Warning and Battery
Shutdown) and a set of five parameters that inform the operator of battery condition and time
remaining. The five parameters describing battery resources are:
• Rated Total Time, in hours and minutes, is the amount of battery backup time that should be
available under full rated load, based on system design.
• Rated Time Remaining is the Rated Total Time less the duration of the present discharge
event.
• Calculated Total Time is an estimate of the total battery backup time available, based on the
initial battery condition and actual performance while powering the connected load during the
discharge event.
• Calculated Time Remaining is a real-time estimation of battery time remaining—with the
actual connected load—before battery voltage drops to the Battery Shutdown setpoint.
• Battery Charge is the approximate percentage of total designed ampere hours of battery capac-
ity presently available based on recharge/discharge activity.
NOTE
If the UPS modules connect to independent battery plants, consult all the individual module
screens to get the complete picture. If the modules share a common battery, select one module
to do the monitoring and disregard the others.
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Time (Minutes)
340
360
380
400
420
440
460
480
500
VDC
Battery Shutdown = 384
Rated Time (Hrs:Min)
Total 00:10 Remain 0:00
Battery Charge = 5%
SELECT : MASTER MENU
Low Battery Warning
Calculated Time (Hrs:Min)
Total 00:15 Remain 0:01