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UPS Alarm and Status Messages
57
Low Power Factor
The output power factor is low.
The output power factor is less than 70% leading
or lagging. A simplified explanation of power
factor is the ratio of energy being supplied to
energy being used by the load. For a given load,
the current output of the UPS goes up as power
factor decreases.
This results in the UPS output being derated.
For example, study the following:
Load = 100 kw @ 480V
amps = kw X 1000 / volts X power factor X 1.73
(square root of 3)
100kw X 1000 = 100000
480volts X .9PF X 1.73 = 747.36
100000/747.36 = 133.8 amps
Now, replace the .9 power factor (typical
computer load power factor) with .7 power factor:
100kw X 1000 = 100000
480volts X .7PF X 1.73 = 581.28
100000/581.28 = 172 amps
The load remains the same, but the current
required to supply it is roughly 30% higher. The
extra current is wasted energy that can result in
nuisance trips of breakers, overheating of cables,
and other unwanted conditions. The UPS cannot
control the output power factor.
This alarm is notification to the
Press “SILENCE” to silence the audible alarm.
Evaluate the load on the UPS. For more
information, contact your factory-authorized service
provider.
Main Control Fault
The UPS has transferred to Bypass due to a loss
of communications with the Main Controller.
All Transfers, Startup, Shutdown, and Metering
screens are locked out.
The Controls attempt to reestablish
communications but will not return the load to
inverter automatically.
Press “SILENCE” to silence the audible alarm.
Contact your factory-authorized service provider.
If communications are reestablished, the One-Line
Display will be restored; however, Liebert does not
recommend attempting to return the load to inverter
until a service visit has been made and action taken
to determine why the fault occurred.
Action will involve resetting the UPS controls by
removing and then reapplying control power.
Therefore, it will be necessary to utilize
maintenance bypass, either by closing the optional
CB3 internal bypass breaker, or by closing the
optional external Maintenance Bypass Breaker
(MBB). Liebert does not recommend the user, or
operator, attempt this without first speaking with an
authorized service associate from Liebert.
Maintenance
Bypass Breaker
(MBB) Open
The maintenance bypass breaker indicates that it
is in the open position
Man Rexfer Inhibit
This summary event means the conditions
required to perform a manual transfer to Inverter
(online) are not met (Inverter must be in sync with
bypass).
This status message is self-clearing. When the
condition is no longer present, the message and
any control activity tied to the status event reverts
to normal.
The condition clears from the Active Event Window
when manual re-transfers are enabled.
A possible reason for this condition is an unstable
generator. If the generator frequency is not stable,
or not at 60 Hz, the Inverter may have difficulty
maintaining or acquiring synchronization with the
bypass source.
To check the synchronization of the Inverter to
bypass, click “Transfer” and observe the
synchroscope. A non-sync condition is indicated by
a varying phase angle error, rather than a stable “0”
degree indication.
If the unit is not on generator, and the bypass
voltage otherwise appears normal, contact your
factory-authorized service provider.
Table 7 Liebert NXL alarm and status messages (continued)
Event Message Event Definition Recommended Action