52 User Manual 10H52192UM60 - Rev. 1 - 09/2011
Liebert NX Operating Instructions
At this point, the other UPS modules report Parallel Comm. Fail, which is normal. The other UPS modules continue to supply the
load through the inverter.
3. Open the output switch QS4 on the UPS.
4. Wait for 10 minutes before carrying out maintenance or repair work on the UPS.
6.7 Insertion Procedure (for One UPS in a Parallel System)
This procedure is used to reintegrate a UPS that has previously been isolated from a parallel system. This procedure is based on the
assumption that the installation is complete and that the system has been commissioned by authorized personnel.
1. Close the output switch QS4 on the UPS to be reintegrated.
2. Close the input switches QS1 and QS2 on the UPS and connect the battery.
3. Press and hold the INVERTER ON button on the UPS for 2 seconds.
The inverter starts up and the inverter indicator starts flashing green. When the inverter is ready, the UPS transfers to parallel
operation with the other UPS modules, and the inverter indicator remains on (not flashing).
The UPS is in normal mode and the UPS indicator states are as listed in Table 6-3.
Table 6-3 UPS Indicator State
Indicator State
Rectifier indicator Green
Battery indicator Off
Bypass indicator Off
Inverter indicator Green
Output indicator Green
Status indicator Green
6.8 EPO Procedure
The EPO switch is designed to switch off the UPS in an emergency (i.e. fire, flood, etc.). The system will turn off the rectifier and
inverter, will stop supplying the load immediately (including the inverter and bypass), and the battery will stop charging or
discharging.
If the input mains is present, the UPS control circuit will remain active; however, the output will be turned off. To remove all power
from the UPS, open the external feeder breaker.
Note
In a parallel system, the EPO only isolates the UPS that has an EPO that has been activated.
6.9 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:
after the mains power is restored
if Auto Recovery after EOD Enabling is enabled
after the Auto Recovery once the EOD Delay Time expires (the default delay is 10 minutes); during the automatic
recovery delay, the UPS will charge 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 may restart the UPS manually by pressing the FAULT CLEAR
button.
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