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47
5.3.4 CHARGE Mode
To charge the Liebert FS, the Liebert FS will draw power from the UPS DC bus to accelerate the fly-
wheel (as long as the UPS DC bus voltage is higher than Vcharge). In this mode, the Liebert FS State
of Charge (SOC) will progressively increase from 0% to 100%.
Figure 48 CHARGE mode diagram
The Liebert FS will be in CHARGE mode as long as:
• Liebert FS’s SOC is between 0% and 100% and
• UPS DC Bus Voltage
≥ Vcharge.
5.3.5 READY Mode
When the SOC reaches 100%, the unit will automatically transition into the READY mode. This is the
mode in which the Liebert FS will spend most of its operating time. In this mode, the Liebert FS
maintains its State Of Charge greater than 99.5%. The Liebert FS’s SOC will be allowed to drift down
to SOC = 99.5%, at which point it will transition back into CHARGE mode and charge back up to
READY mode and SOC = 100%. During normal operation, the Liebert FS will continue to automati-
cally transition between the READY and CHARGE modes to maintain a SOC between 99.5 and 100%
until either a DISCHARGE or SHUTDOWN is initiated.
Figure 49 READY mode diagram
The Liebert FS will be in READY mode as long as:
• Liebert FS’s SOC is between 99.5% and 100% and
• UPS DC Bus Voltage
≥ Vcharge.
NOTE
While in CHARGE mode, the Liebert FS will be capable of supporting the UPS DC bus.
NOTE
While in READY mode—just as in CHARGE mode—the Liebert FS will be capable of
supporting the UPS DC bus.
State of Charge < 0 State of Charge > 0
0%
1
00%
99.5%
Note: UPS DC Bus Voltage ≥ Vcharge
State of Charge < 0 State of Charge > 0
0%
1
00%
99.5%
Note: UPS DC Bus
Voltage ≥ Vcharge