Procedures For Transfer Between Operation Modes; Transfer From Normal Mode To Battery Mode; Transfer From Normal Mode To Bypass Mode; Transfer From Bypass Mode To Normal Mode - Liebert NXC 30kVA User Manual

38 Chapter 5 UPS Operation Introduction

5.3 Procedures For Transfer Between Operation Modes

5.3.1 Transfer From Normal Mode To Battery Mode

Open the external power switch to isolate the mains power and initiate the UPS on battery mode. To transfer the UPS
back to normal mode, wait for several seconds, and then close the external power switch to re-connect the mains
power to the UPS. 10 seconds later, the rectifier restarts automatically to feed power to the load by the inverter.

5.3.2 Transfer From Normal Mode To Bypass Mode

Press the OFF key for two seconds, the inverter indicator (green) is off, and the UPS will be transferred from normal
mode to bypass mode.
In bypass mode, the load is directly fed by the mains power instead of the pure AC power from the inverter.

5.3.3 Transfer From Bypass Mode To Normal Mode

When the UPS is in bypass mode, press the ON key for two seconds, the inverter starts up, and the inverter indicator
(green) is flashing till the inverter enters normal operation, then the UPS is transferred from bypass mode to normal
mode.

5.3.4 Transfer From Normal Mode To Maintenance Mode

The following procedures will transfer the UPS from inverter output mode to the maintenance bypass mode.
Before making this operation, read the information on the LCD to make sure that the bypass supply is normal and that the inverter
is synchronous with the bypass supply, so as not to risk a short interruption in power to the load.
1. Press the OFF key at least two seconds. At this point, the inverter indicator (green) turns off, accompanied by an
audible alarm. The load transfers to the static bypass, and the inverter shuts down.
Pressing the ALARM CLEAR key cancels the audible alarm but leaves the alarm message displayed until the alarm condition is
rectified.
2. Close the maintenance bypass switch Q3 when the UPS is in single module mode.
3. At the moment, the maintenance bypass parallels with the UPS static bypass.
4. The LCD displays 'Maint. sw. closed'.
5. Disconnect the output switch Q5 and neutral line switch Q6.
At the moment, the load is powered by the maintenance bypass directly.
When the UPS is in maintenance mode, the load is not protected against abnormal mains supply.
6. Pressing the EPO button stops the operation of rectifier, inverter, static switch and battery, but this action will not
affect the maintenance bypass power the load normally.
In maintenance mode, the load is directly fed by the mains power instead of the pure AC power from the inverter.
Caution: power supply interruption danger of the load
Liebert NXC 30kVA And 40kVA UPS User Manual
Note
Note
Caution
Note