Liebert NXC 40kVA - EPO Procedures; UPS Reset Procedures after EPO; Automatic Restart

42 Chapter 5 UPS Operation Introduction
Liebert NXC 30kVA And 40kVA UPS User Manual
5.7 EPO Procedures
The EPO is designed to switch off the UPS in emergency conditions (that is, fire, flood, etc.). To carry out EPO, you
just need to press the EPO button, then the system will turn off the rectifier, inverter and stop powering the load
immediately (including the inverter and bypass), and the battery stops charging or discharging.
After EPO, if the input mains is present, the UPS’s control circuit will remain active; however, the output will be turned
off. To remove all power from the UPS, first disconnect the external power switch of the UPS, and then pull the battery
terminals (see Figure 5-3 for details).
5.8 UPS Reset Procedures After EPO
After shutting down the UPS through EPO or reasons of inverter overtemperature, overload, battery overvoltage and
DC bus voltage, clear the fault according to the alarm message displaying on LCD screen. Then carry out the following
reset procedures to make UPS resume normal operation.
After confirming the fault has been cleared and no remote EPO signal is received, the user can carry out the following
procedures:
1. Press the FAULT CLEAR key over two seconds, the system will exit the EPO state, and the alarm indicator (red) is
flashing.
2. Press and hold the ON key over two seconds, the inverter starts up, and the inverter indicator (green) is flashing.
After the inverter runs normally, the UPS will be transferred from the bypass to inverter, and then the inverter indicator
(green) is on.
Note
1. The rectifier will start and the bypass will begin to power the load. The rectifier indicator flashes while the rectifier is starting up.
When the rectifier enters normal operation (about 30 seconds later), the rectifier indicator turns solid green.
2. The rectifier will start automatically when the overtemperature fault disappears five minutes after the disappearance of
overtemperature signal.
3. After the EPO switch is pressed, if the mains input is cut off, the UPS will shut down completely. When the mains
input returns, the UPS will start up on bypass. There will be power at the output terminals of the UPS.
Warning
If the maintenance bypass switch Q3 is closed, and UPS has input power, it means UPS has outputs.
5.9 Automatic Restart
In the case of a mains failure, the UPS draws power from the battery system to supply the load until the batteries are
depleted. When the UPS reaches its EOD threshold, it will shut down.
The UPS will automatically restart and enable output power only when the following conditions are met:
1. If Auto Recovery after EOD Enabling is enabled.
2. After the Auto Recovery after EOD Delay Time expires (the default delay is 10 minutes), the UPS restarts bypass,
then inverter. During the automatic recovery delay, the UPS will charge its batteries to provide a safety margin for
equipment shutdown if input power fails again.
3. If the Auto Recovery after EOD Enabling feature is disabled, the user may restart the UPS manually by pressing the
FAULT CLEAR key first for two seconds and then ON key for two seconds.
Note
During the automatic restart process, manual startup is disabled. Automatic restart must be set by Emerson’s authorized service
engineer through Emerson setting software.