Maintenance
Liebert
®
eXM
™
78
Bypass Abnormal
This alarm is triggered by an inverter software routine when the amplitude or frequency of bypass
voltage exceeds the limit.
This alarm automatically resets once the bypass voltage goes normal.
First check if there are some relevant alarms such as “Bypass disconnect open”, “Bypass phase
reverse” and “Mains neutral lost”. If they appear, solve them first.
1. Then verify that the bypass voltage and frequency displayed on the panel is within the bypass
limit. Note here the rated voltage and frequency are specified by “Output voltage level” and
“Output frequency level” respectively.
2. If the displayed voltage is believed to be abnormal, then verify the bypass voltage and
frequency presented to the UPS. Check the external bypass supply if it is found to be faulty. 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 customer’s agreement.
Contact Liebert Services at 800-543-2378 for assistance.
Inverter Asynchronous
This alarm is triggered by an inverter software routine when the inverter and bypass waveforms
are misaligned by more than 6 degrees in phase. This alarm resets automatically once the
condition is no longer true.
1. First check if the alarm “Bypass unable to trace” or “Bypass abnormal” occurs. If so, solve it
first.
2. Verify the waveform of the bypass voltage. If it is too distorted, ask the customer to verify and
seek any possible measurements.
Contact Liebert Services at 800-543-2378 for assistance.
Inverter Fault
This alarm indicates a fault condition exists within the inverter.
Contact Liebert Services at 800-543-2378 for assistance.
Fan Fault At least one of the cooling fans failed. Contact Liebert Services at 800-543-2378 for assistance.
Inverter STS (relay) Fail
At least one of the static switches of inverter side is open or short circuit. This fault is locked until
power off. Contact Liebert Services for assistance at 800-543-2378 for assistance.
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.
Contact Liebert Services at 800-543-2378 for assistance.
Output Fuse Fail At least one of the output fuses is open. Contact Liebert Services at 800-543-2378 for assistance.
Control Power 2 Fail Control Power 2 is abnormal or lost. Contact Liebert Services at 800-543-2378 for assistance.
Unit Overload
The UPS is confirmed to be overload when the load arises above 105% nominal rating.
The alarm automatically resets once the overload condition is removed.
1. Confirm that the alarm is true by checking the load percent indicated on the LCD panel 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 unnecessary load and ensure the safety. In a parallel system, a severe load
sharing error can also leads to the alarm.
Contact Liebert Services at 800-543-2378 for assistance.
System Overload
The UPS parallel system is confirmed to overload when the total load arises above 105% nominal
rating for the set basic number of UPSs. The alarm automatically resets once the overload
condition is removed.
1. Confirm that the alarm is true by checking the system load percent indicated on the LCD
panel 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 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 confirmed to overload 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 10 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).
Table 38 UPS status messages (continued)
Event Message Description / Suggested Action (if any)
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