Emerson Liebert NXL 250 kVA, Operation And Maintenance Manual

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UPS Alarm and Status Messages
Liebert
®
NXL
™
92
Low Batt
Capacity
One or more battery circuit breakers are open.
This alarm applies if the system includes more
than one battery circuit breaker, and at least one
is closed, but one or more are open.
This alarm is self-clearing. When the condition is
no longer present, the alarm and any control
activity tied to the alarm reverts to normal.
Press “SILENCE” to silence the audible alarm.
To clear this alarm, verify all battery breakers are
closed. Investigate any open breakers.
Low Batt
Shutdown
The Battery has reached End of Discharge
(EOD).
There is no longer enough energy left in the
battery to run the Inverter with the current load.
If bypass is available, the UPS attempts to
transfer the load to bypass at EOD.
Press “SILENCE” to silence the audible alarm.
Once power is restored, attempt a normal restart of
the UPS.
If the restart fails, contact your factory-authorized
service provider.
Low Battery
Warning
The battery is nearly depleted, and the unit shuts
down very soon.
The Low Battery Warning setpoint is adjustable
under User Settings. This alarm means the
calculated time remaining on battery is now less
than the Low Battery Warning setpoint.
This alarm is self-clearing. When the condition is
no longer present, the alarm and any control
activity tied to the alarm reverts to normal.
Check to see if bypass is available by observing
the One-Line Display. Acceptable bypass voltage
is indicated by a green power line feeding the
Static Bypass Switch (BPSS) box.
If bypass is available, press “Transfer,” “Bypass” to
transfer to bypass. If the bypass is qualified, the
UPS transfers to the bypass source.
If bypass is not available, prepare to shut down
critical loads, or remove non-essential loads in
order to extend battery run time so that critical
loads may be shut down in an orderly manner.
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
480V X 0.9PF X 1.73 = 747.36
100000/747.36 = 133.8A
Now, replace the 0.9 power factor (typical
computer load power factor) with 0.7 power
factor:
100kW X 1000 = 100000
480V X 0.7PF X 1.73 = 581.28
100000/581.28 = 172A
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 user that the load
should be evaluated.
Press “SILENCE” to silence the audible alarm.
Evaluate the load on the UPS. For more
information, contact your factory-authorized
service provider
Table 10 Liebert NXL alarm and status messages (continued)
Event Message Event Definition Recommended Action