Emerson Liebert NX User Manual

Operating Procedures
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6.6 Emergency Shutdown With EPO
This circuit has been designed to switch off the UPS in emergency conditions (i.e., fire, flood, etc.). The
system will turn off the rectifier, inverter, static switch, battery circuit breaker and/or internal DC
bus disconnection device and stop powering the load immediately (including the inverter and bypass),
and the battery stops charging or discharging.
If the input utility is present, the UPS’s controls will remain active; however, the output will be
turned off. To remove all power from the UPS, the external power isolator should be opened.
6.7 Auto Restart
When the main and bypass sources fail, the UPS draws power from the battery system to supply the
load until the batteries are depleted. When the UPS reaches its end of discharge (EOD) threshold, it
will shut down.
The UPS will automatically restart and enable output power:
• After utility power is restored
• If “Auto Recovery after EOD Enabling” is enabled
• After the “Auto Recovery after EOD Delay Time” expires (the default delay is 10 minutes). During
the auto recovery delay, the NX will be charging its batteries to provide a safety margin for equip-
ment shutdown if input power fails again.
If the “Auto Recovery after EOD Enabling” feature is disabled, the user may restart the system man-
ually by pressing “Fault Clear” button.
6.8 Reset After Shutdown for Emergency Stop (EPO Action) or Other Conditions
Once all appropriate measures have been taken to correct the problem indicated by the alarm mes-
sage appearing on the operator control panel display, carry out this procedure to restore the UPS to
regular operation following an EPO action or for the following reasons: Inverter Overtemperature,
Cut-off Overload, Battery Overvoltage, excessive switching (BYP: XFER COUNT BLOCK), etc.
When the user confirms that the fault is cleared:
1. Press the FAULT CLEAR button to let the system exit the Emergency Off state.
2. Press the INVERTER ON button on the right side of the operator control panel for longer than
2 seconds.
After the EPO button is pressed, if the input utility is removed, the UPS will shut down completely.
When input utility is returned, if the rotary switch (SW1) is in either Bypass or in Normal position,
the UPS will start up on Bypass. There will be power at the output terminals of the UPS.
NOTE
The rectifier will start again, and the bypass will begin to power the load (for units with
internal battery contactor installed, the battery contactor will close). The Rectifier indicator
flashes while the rectifier is starting up. When the rectifier enters the normal operation state
(about 30 seconds), the rectifier indicator turns green.
NOTE
The rectifier will be turned On automatically when the overtemperature fault disappears at
5 minutes after the disappearance of overtemperature signals.
!
WARNING
If the rotary switch is in the Maint. position and input utility is present, there will be power at
the output terminals of the UPS.

Emerson Liebert NX Specifications

General

Brand	Emerson
Model	Liebert NX
Category	UPS
Language	English