Liebert NX series Operation & Maintenance Manual page 38

Table 8 UPS status messages (continued)
No. Event Message
41 Control Power 2 Fail
42 Unit Over load
43 System Over load
44 Unit Over load Timeout
Description / Suggested Action (if any)
Control Power 2 is abnormal or lost. This alarm is triggered by a detection circuit on the M4
measure board, which monitors the second control power board.
Suggested Action
Confirm that the alarm is true by checking the output voltage of the second control power
board.
1. If the alarm is true, check and verify the input voltage and input cables of the control
power board. If they are OK, replace the second control power board.
2. If the alarm is false:
a. Check the fault signal from the second control power board to the M4 board and
which from the M4 measure board to the U1 control board.
b. Check the wiring from the second control power board to the M4 board and which
from the M4 board to the U1 board.
c. Replace the control power board, U1 and/or M4 board as required.
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.
Suggested Action
Confirm that the alarm is true by checking the load percent indicated on the LCD panel to
determine which phase is being overloaded.
1. 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.
2. If the alarm is not true:
a. Verify that the correct UPS kVA rating has been set via the configuration software.
b. Replace the U1 control board.
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.
Suggested Action
Confirm that the alarm is true by checking the system load percent indicated on the LCD
panel to determine which phase is being overloaded.
1. 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.
2. If the alarm is not true:
a. Verify that the correct UPS kVA rating has been set via the configuration software.
b. Check the setting of basic number of UPS via the configuration software. If it is
different from the actual system, power up the rest of the UPSs, or change the
setting number via the configuration software.
c. Check the M5 auxiliary power board and the parallel cables for output current
detection.
d. Replace the M5 and/ or U1 control board as required.
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 over load" 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.
Suggested Action
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).
1. If the alarm is genuine, check the load and rectify as necessary. Disconnect
unnecessary load and ensure the safety.
2. If the alarm is not genuine:
a. Verify that the correct UPS kVA rating has been set via the configuration software.
b. Replace the U1 control board as required.
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UPS Status Messages