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System Overview
49
Following a User Command
In any mode, except OFF mode, the user may command the Liebert FS to transition in SHUTDOWN.
While in SHUTDOWN mode, the user will still be able to command the Liebert FS to transition into
CHARGE mode (if SOC > 0%) or STARTUP mode (if SOC < 0%), provided that the UPS System DC
bus voltage is greater than Vcharge.
Figure 52 SHUTDOWN mode diagram - user-initiated shutdown
5.3.8 COAST Mode
A transition into COAST mode can occur when the UPS System DC Bus voltage drops below Vcharge
while the Liebert FS is in STARTUP mode. While in COAST mode, the Liebert FS is in an idling con-
dition where it neither draws nor generates any power.
As soon as the UPS DC Bus Voltage rises above Vcharge, the Liebert FS will automatically exit
COAST mode and resume STARTUP mode.
After five minutes in COAST Mode, if the UPS DC Bus voltage has not risen above Vcharge, the
Liebert FS will automatically transition into SHUTDOWN Mode.
5.3.9 FAULT Mode
The Liebert FS includes self-test and diagnostic circuitry such that most systems malfunctions can be
identified. In case of a system malfunction, the Liebert FS will transition into FAULT mode.
While in FAULT mode, the Liebert FS is disabled—all power electronics are turned off. Most faults
are cleared automatically by the system without the need for user intervention. Some faults do
require user action to clear the fault or to notify Liebert Global Services. Refer to the 8.0 - Trouble-
shooting for more information).
The Liebert FS is programmed to operate in a variety of conditional modes. The modes and status for
each mode will be indicated on the control panel. The Liebert FS is set up to transition through the
various modes with no or minimal user intervention. Figure 53 illustrates the various modes of oper-
ation.
NOTE
Depending on the nature of the fault, the Liebert FS may still be capable of supporting the UPS
DC bus. Refer to 8.0 - Troubleshooting for more information.
State of Charge < 0 State of Charge > 0
0%
1
00%
99.5%