Chapter 4 Operator Control And Display Panel 33
Liebert NXC 30kVA And 40kVA UPS User Manual
EOD event happened. Check the battery voltage
The adjacentbypass STS open circuit fault or shoet-circuit fault
The mains voltage is outside specifications and results in rectifier shutdown
At least one phase main input voltage is within 132V ~ 176V, thus the load should be derated
The mains frequency is outside specifications and results in rectifier shutdown
The AC input phase rotation is reversed
Battery voltage fed back to rectifier input
AC rectifier input neutral line not detected
Battery load sharing imbalance or rectifier input current abnormal
The bypass frequency is outside specifications. This alarm automatically resets once the bypass
voltage goes normal
Bypass abnormal
The amplitude or frequency of the bypass voltage exceeds the limit. This alarm automatically resets
once the bypass voltage returns to normal
At least one of the STSs at the bypass side is open or shorted. This fault is locked until power-off
Both the bypass and inverter voltages are abnormal, and the output is off
The phase rotation of the bypass voltage is reversed
The bypass current is outside the rated current
Bus voltage abnormal or battery SCR short circuit
The temperature of the rectifier radiator is so high that the inverter cannot operate normally
The rectifier, inverter and battery converter shut down because the DC bus voltage is too high. The load
The DC bus voltage is abnormal and results in inverter shutdown. The load transfers to bypass
The output voltage and bypass voltage are misaligned in phase. This alarm resets automatically once
the condition is no longer true
Inverter fault Inverter output voltage outside specifications. Load transfers to bypass
Inverter relay fail At least one of the inverter relays is opened or shorted. This fault is locked until mains power-off
Output fuse fail At least one of the inverter output fuses is blown
Output volt. abnormal At least one phase of the output voltages is abnormal
Unit overload
This alarm appears when the load arises above 105% of the nominal rating. The alarm automatically
resets once the overload condition is removed
System overload
This alarm appears when the total load rises above 105% of the nominal rating of the parallel system.
The alarm automatically resets once the overload condition is removed
Unit overload timeout
The UPS overload status continues and the overload times out.
When the time has expired, the load automatically transfers to the bypass
Load impact transfer
A transfer to bypass occurred due to a large step load. The UPS can recover automatically. Turn on the
load equipment in stages to reduce the load impact on the inverter
Transfer time-out
The load remains on bypass power owing to excessive number of transfers that occurred within the one
The UPSs in a parallel system are not sharing the load current correctly
All UPSs in the parallel system transfer to bypass at the same time when one of them needs to transfer
to bypass. This message appears on the LCD of the UPS with passive transfer to bypass
The auxiliary power failure or power-off
EPO button on operator control and display panel pressed or external EPO command received
At least one fan has fault
Maintenance bypass switch is off when the parallel system is on inverter, or output switch and
maintenance bypass switch are off when the inverter is on
The LBS setting is active
Maintenance bypass switch is open
Maintenance bypass switch is closed
Battery charger has failure
Discharge current is over limit, close the discharger
After UPS shutdown at EOD, the inverter automatically starts upon mains restoration
The battery is forced to be in boost charge state
Rectifier software being updated
Inverter software being updated
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