Chapter 4 Operator Control And Display Panel 35
Liebert APM 90 Integrated Modular UPS User Manual
Alarm
Explanation
Unit Over load Timeout
The UPS overload status continues and the overload times out.
Note that:
1. The highest loaded phase will indicate overload time-out first.
2. When the timer is active, then the alarm Unit Over load should also be active as the
load is above the nominal rating.
3. When the time has expired, the load transfers to static bypass. The inverter shuts down
and will restart after 10 seconds.
4. If the load decreases to lower than 95%, after five minutes, the system will transfer
back to the inverter. Check the load (%) displayed on the LCD to confirm if this alarm is
true. If the LCD tells that overload happens, then check the actual load and confirm if the
UPS has overload before the alarm happens
Byp. Abnormal Shutdown
Both the bypass and inverter voltages are abnormal, and the output is off
Inverter Over Current
The inverter has overcurrent fault
Bypass Phase Reversed
The phase rotation of the bypass voltage is reversed. Normally, phase B lags 120 degrees
behind phase A, and phase C lags 120 degrees behind phase B.
Check that the phase rotation of the UPS bypass supply is correct
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 last hour. The UPS can recover automatically and will transfer the load back to
inverter power within an hour
Load Sharing Fault
The UPSs in a parallel system are not sharing the load current correctly
DC Bus Abnormal
The DC bus voltage is abnormal and results in inverter shutdown. The load transfers to
bypass
DC Bus Over Voltage
The rectifier, inverter and battery converter shut down because the DC bus voltage is too
high.. Check if the rectifier has any fault. If no, check if an overload has occurred. Restart
the inverter after the fault is cleared
Bypass Over Current
The bypass current is above 135% of the rated current. The UPS alarms but has no action
LBS Active
The LBS setting is active. The UPS is acting as an LBS master or slave in a dual bus
configuration
Setting save error
The historical records are not saved (reserved)
Mains Neutral Lost
The neutral line of the AC input mains is not detected
Battery ground fault
The battery ground fault option has detected a battery ground fault. Contact the local
customer service center of Emerson to inspect the battery installation
Manual Turn On
INVERTER ON button activated on the operator control and display panel to turn on the
inverter
Manual Turn Off
INVERTER OFF button activated on the operator control and display panel to turn off the
inverter
EPO
The local or remote EPO has been activated
Interrupted Transfer
Confirm
A prompt for the user to decide whether to press the Enter key to acknowledge an
interrupted load transfer to bypass
Transfer Cancel
A prompt for the user to decide whether to press the ESC key to avoid an interrupted load
transfer to bypass
Fault Reset
FAULT CLEAR button pressed
Alarm Silence
SILENCE ON/OFF button pressed
Turn On Fail
The inverter failed to turn on when the INVERTER ON button is pressed. This may be the
result of an invalid operation (maintenance bypass on) or DC bus or rectifiers not ready
Audible Alarm Reset
FAULT CLEAR or SILENCE ON/OFF button pressed
Bypass Mode
The UPS is in bypass mode
Normal Mode
The UPS is in normal mode
Battery Mode
The UPS is in battery mode
