56 Chapter 5 Operating Instructions
NX UPS Single Module And Parallel System 250kVA ~ 800kVA User Manual
2. When the rectifier start process is finished and the rectifier indicator goes solid green, close the external BCB.
3. Press the INVERTER ON key.
The inverter starts up, and the inverter indicator flashes in green color. When the inverter is ready, the UPS transfers
from bypass to inverter, the bypass indicator turns off, the inverter indicator and output indicator turn on.
The UPS is in normal mode, and the UPS indicator states are as listed in Table 5-2.
Table 5-2 UPS indicator state
Indicator
State
Rectifier indicator
Green
Battery indicator
Off
Bypass indicator
Off
Inverter indicator
Green
Output indicator
Green
Status indicator
Green
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, then close the external power switch to re-connect the mains power
to the UPS. 10 seconds (adjustable through background software) later, the rectifier restarts automatically to feed
power to the inverter.
5.3.2 Transfer From Normal Mode To Bypass Mode
When the UPS is in normal mode, pressing the INVERTER OFF key on the operator control and display panel
transfers the UPS from normal mode to bypass mode.
Note
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 INVERTER ON key on the operator control and display panel. After the
inverter enters normal operation, the UPS is transferred from bypass mode to normal mode.
5.3.4 Transfer From Normal Mode To Maintenance Mode
When the UPS is operating in normal mode, use the following procedures to transfer the load from the inverter output
to the maintenance bypass.
Caution
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 INVERTER OFF key on the operator control and display panel.
At this point, the inverter indicator turns off, the bypass indicator turns on, and the status indicator changes to amber,
accompanied by an audible alarm. The load transfers to the bypass, and the inverter shuts down.
Note
Pressing the SILENCE ON/OFF key cancels the audible alarm but leaves the alarm message displayed until the alarm condition
is rectified.
