Emerson 480V ユーザーズマニュアル

• Open CB1 to enter battery mode. This breaks the utility connection to the Liebert NX.

To return to normal mode, close CB1 after a few seconds. The rectifier will restart automatically 

after 10 seconds and resume feeding power to the inverter.

• Press the INVERTER OFF button to switch to bypass mode.

• In bypass mode, press the INVERTER ON button. When the inverter is ready, the UPS will 

switch to normal mode.

Follow the procedure below to transfer the load from the inverter output to the Maintenance Bypass 

line of the UPS.

This procedure assumes that the UPS is operating normally.
1. Press the INVERTER OFF button on the operator control panel for longer than 2 seconds.

The Inverter indicator will turn off and the status indicator will turn amber and an audible alarm 

will sound. The load will transfer to static bypass and the inverter will shut off.

2. Close maintenance breaker CB3.

The Maintenance Bypass supply is now in parallel with the UPS Static Switch supply.

3. Open output breaker CB5. This ends the bypass procedure. The load is now powered directly from 

the Maintenance Bypass supply.

4. Press the EPO (Emergency Power Off) button at the UPS front panel of this UPS module only. 

This will disable further Rectifier, Inverter, Static Switch and Battery operation. This will not 

affect the manual maintenance bypass power switch. If a Liebert NX battery cabinet is connected, 

the battery circuit breaker will shunt trip open.

5. Open the rectifier switch CB1 and bypass breaker CB2.

All operator indicators and messages will turn off as the utility-driven internal power supplies 

decay. The unit will power down, but the load will continue to be supplied by the manual Mainte-

nance bypass.

6. To return unit to normal operation, follow the steps in 9.2.1 - Startup Procedure.

NOTE
In bypass mode, the load is being powered by the utility and is not receiving conditioned power 

Before performing this operation, read the messages on the LCD to be sure that bypass supply 

is regular and the inverter is synchronous with it. If those conditions are not present, there is 

a risk of a short interruption in powering the load.

NOTE
Pressing the Alarm Silence Switch cancels the audible alarm, but leaves the warning message 

Wait 5 minutes for the internal DC busbar capacitors to discharge before attempting 

to remove the internal protective barriers.

Even with the UPS in maintenance bypass and “Off,” portions of the unit are still energized. 

Service is to be performed by qualified personnel only.

The load equipment is not protected from normal supply aberrations when operating in 

maintenance bypass mode.