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UPS Status Messages
99
Unit Overload
The UPS is overloaded when the load arises above 105% nominal rating.
The alarm automatically resets once the overload condition is removed.
Confirm that the alarm is true by checking the load percent indicated on the LCD panel to
determine which phase is being overloaded.
If the alarm is true, measure the actual output current to verify that the indications are valid.
Disconnect unnecessary load. In a parallel system, a severe load sharing error can also lead to
the alarm.
Contact Liebert Services at 800-543-2378 for assistance.
System Overload
The UPS parallel system is overloaded when the total load arises above 105% nominal rating
for the set basic number of UPS units. The alarm resets automatically once the overload
condition is removed.
Confirm that the alarm is true by checking the system load percent indicated on the LCD panel
to determine which phase is being overloaded.
If the alarm is true, measure the actual output current to verify that the indications are valid.
Disconnect unnecessary load and ensure the safety. In a parallel system, a severe load sharing
error can also leads to the alarm.
Unit Overload Timeout
The UPS is overloaded and the overload times out.
Note 1: The highest loaded phase will indicate overload timing-out first.
Note 2: When the timer is active then alarm “unit overload” should also be active as the load is
above nominal.
Note 3: When the timer has expired, the inverter Static Switch is opened and the load
transferred to bypass. The inverter shutdown and will restart after 1 seconds.
Note 4: If the load decreases lower than 95% after 5 minutes, the system will transfer back to
inverter mode.
Confirm that the alarm is genuine by checking the load percent indicated on the LCD. If an
overload is indicated then check the load, and investigate any additional load connected prior to
the alarm (if applicable).
Inverter Overcurrent
The current of inverter IGBT is over limit. If the fault will not reset, contact Liebert Services at
800-543-2378 for assistance.
Bypass Phase Reversed
The phase sequence direction of bypass voltage is reversed.
Normally, the phase of Phase B lags 120 degrees behind Phase A, and the phase of Phase C
lags 120 degrees behind Phase B.
Verify that the phase rotation of the bypass supply presented to the UPS is correct, and rectify it
if it is found to be in error. Contact Liebert Services at 800-543-2378 for assistance.
Load Impact Transfer
A transfer to bypass occurred due to a large step load. The UPS should recover automatically.
Turn on connected equipment in sequential order to reduce the step loading of the inverter.
Transfer Timeout
The load is on bypass power due to excessive number of transfers that occurred within the last
hour.
The UPS will recover automatically and will transfer the load back to inverter power within an
hour.
Load Sharing Fault
UPS units working within a parallel system are not sharing load current correctly. Contact
Liebert Services at 800-543-2378 for assistance.
DC Bus Abnormal
Shut off inverter due to abnormal DC bus voltage.
Contact Liebert Services at 800-543-2378 for assistance.
System Transfer
The whole paralleled UPS system transferred to bypass at the same time. This message will
appear on the UPS which passive transfer to bypass.
Parallel Board Fault Parallel board is not working correctly. Contact Liebert Services at 800-543-2378 for assistance.
DC Bus Overvoltage
Rectifier, inverter and battery converter were shut down because DC bus voltage is too high.
Check whether there is a fault in rectifier side. If not, check whether overload occurs.
Restart the inverter after resetting the fault. If fault does not clear, contact Liebert Services at
800-543-2378 for assistance.
Parallel Connect Fault
The parallel cables are not connected correctly in a parallel system.
Reset the fault by pressing the Fault Clear button, then restart the inverter by pressing the
Inverter On button.
If the UPS does not resume normal operation, contact Liebert Services at
800-543-2378 for assistance.
Bypass Overcurrent
Bypass current is over limit above 135% rating. The UPS just alarms and does nothing. Refer to
your installation documentation or contact Liebert Services at 800-543-2378 for assistance.
Table 39 UPS status messages
Event Message Description / Suggested Action (if any)