Chapter 4 Operation And Display Panel 45
Liebert
®
ITA 16kVA And 20kVA UPS User Manual
Alarm message
Description
Bypass protection
This alarm is triggered by an inverter software program when the amplitude or frequency of bypass
voltage is too high or too low. The amplitude threshold is fixed for ±10% rating. This alarm will
automatically recover when the bypass voltage is normal.
1. First check if there are some relevant alarms, such as ‘Bypass Phase Reverse’, ‘Input Disconnect
Fault’. If so, solve them first.
2. Then verify that the bypass voltage and frequency displayed on the LCD are within the selected
range. Note that the rated voltage and frequency are specified by the ‘Output Voltage Level’ and ‘Output
Frequency Level’ respectively.
3. If the displayed voltage is abnormal, please verify the actual bypass voltage and frequency presented
to the UPS. Check the external power if any fault is found. If the utility is likely to trigger this alarm
frequently, the bypass limit can be changed a little larger through the configuration software according to
the user backfeed
Inverter asynchronous
This alarm is triggered by an inverter software program when the inverter and bypass waveforms are
misaligned by more than 6 degrees in phase. The amplitude threshold is fixed for ±10% rating. This
alarm will recover automatically when the alarm condition disappears.
1. First check if the alarm ‘Bypass Unable To Trace’ or ‘Bypass Protection’ exits. If so, solve it first.
2. Verify the waveform of the bypass voltage. If too distorted, ask the user to verify it and seek any
possible measurement
Inverter fault
Inverter output voltage beyond limits. Load transfers to bypass
Inverter overtemp.
The temperature of the inverter heat sink is too high to keep the inverter running. This alarm is triggered
by the signal from a temperature monitoring thermostat on the inverter bridge heat sink. After the alarm
is cleared about 20 minutes, the inverter will start again automatically. The UPS will switch to bypass if
the alarm is triggered above one time in 2 hours, and power on the UPS manually and stwitch to inverter
working state after the alarm is cleared. Note: Wait for 20 minutes after the alarm is cleared, manual
power-on will be suceesful.
If the overtemperature condition is true, check the following items:
1. high ambient temperature.
2. blocked cooling airway.
3. any fan failure.
4. prolonged inverter overload
Fan fault
At least one of the cooling fans has failed
Inverter relay fail
At least one of the relays of inverter side is open or short circuit. This fault is locked until power off (for a
3-in 1-out system, possible causes for relay fault type: inverter fuse open, inverter IGBT open)
Bypass STS fail
At least one of the static switches of bypass side is open or short circuit. This fault is locked until power
off
Operation invalid
Incorrect operation
Neighbor bypass
SSTS fail
At least one of the static switches of UPS unit bypass side in parallel system is open or short circuit.
This fault is locked until power off
Output fuse fail
At least one inverter output fuse failure. The inverter shuts down, the load transfers to bypass
Unit over load
The UPS is confirmed to be overload when the load is above 105% nominal rating. The alarm
automatically recovers after the overload condition is removed.
1. Confirm that the alarm is true by checking the load percent indicated on the LCD to determine which
phase is being overloaded.
2. If the alarm is true, measure the actual output current to verify that the indications are valid.
Disconnect the unnecessary load and ensure the safety
Byp. abnormal
shutdown
Both bypass and inverter voltages are abnormal. Load interruption
Inverter over current
Inverter pulse width modulation module is over current
Bypass phase reverse
The phase sequence direction of the 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 the
fault is found
Load impact transfers
bypass
A transfer to bypass occurred due to a large step load. The UPS will recover automatically. Turn on the
load in sequential order for reducing the step load of the inverter
Transfer time-out
The load is on bypass power due to the excessive number of transfers that occurred within the last hour.
The UPS will recover automatically and will transfer the load to inverter power within an hour
Bus abnormal
DC bus voltage is abnormal. Inverter shuts down. Load transfers to bypass
DC bus over voltage
Rectifier and inverter are off because the DC bus voltage is too high. Check whether there is a fault in
rectifier side. If not, check whether there is an overload. After recovering the fault, restart the inverter
Bypass over current
Bypass current is over limit above 135% rating. The UPS just alarms without any action
