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Operating Instructions
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9.4 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 Liebert NX will be charging its batteries to provide a safety
margin for equipment shutdown if input power fails again.
If the “Auto Recovery after EOD Enabling” feature is disabled, the user must restart the system man-
ually.
9.5 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 and inverter and will stop powering the load immediately (including
the inverter and bypass), and the battery stops charging or discharging. If a Liebert NX battery cabi-
net is connected, the circuit breaker in the battery cabinet will shunt trip open.
If input utility power is present, the UPS’s controls will remain active; however, the output will be
turned off. To remove all power from the UPS, open the external feeder breaker.
9.6 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 Bypass input circuit breaker (CB2) and UPS output circuit
breaker (CB5) are closed, the UPS will start up on Bypass. There will be power at the output termi-
nals of the UPS.
NOTE
The rectifier will start again, and the bypass will begin to power the load. 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 automatically turn on 5 minutes after the Inverter Overtemp alarm has
cleared.
!
WARNING
If the internal maintenance bypass circuit breaker (CB3) is closed and input utility is present,
there will be power at the output terminals of the UPS.