48 Chapter 5 UPS Operation Instructions
Liebert
®
ITA 16kVA And 20kVA UPS User Manual
5.2.4 Transfer From Inverter Mode To Maintenance Bypass Mode
When the UPS is running in Normal mode, you can use this procedure to make the load transfer from inverter output
to maintenance bypass.
Caution
1. Before performing this procedure, you should check the LED information first, and make sure the bypass is normal and
synchronizes with the inverter. Otherwise, it may result in the load power interruption for a while.
2. You should select the single POD or prepare the maintenance bypass MCB by yourself to realize this function.
1. Press the OFF for two seconds.
The inverter indicators are off and the buzzer alarms. The load transfers to the static bypass, and the inverter shuts
down.
Note
Press the ALARM CLEAR button can silence the alarm, but the alarm message of the the LCD is not disappeared until the alarm
status is cleared.
2. Close the maintenance bypass MCB on the single POD front panel, and the maintenance bypass can supply
power to the load.
Warning
If you wish to maintain the UPS, wait ten minutes for the internal DC bus capacitance voltage discharging.
3. Disconnect the main/bypass input switch and output MCB.
Caution
1. When the UPS is in Maintenance Bypass mode, the load does not have the mains abnormal protection.
2. After the UPS transfers to the maintenance bypass, the UPS is not in operation, and the LCD is no display, and only the user
terminal block (silkprint: USER) of the single POD is electrified. Be careful when removes the UPS to be maintained.
5.2.5 Transfer From Maintenance Bypass Mode To Inverter Mode
After UPS maintenance, you can use this procedure to transfer the load from the maintenance bypass to the inverter.
Warning
As no auxiliary contact information of the maintenance bypass MCB is introduced into the UPS, UPS operation restoration after
maintenance must be done strictly following this procedure. Failure to observe this may cause damage to the equipment.
1. Close the output MCB on the front panel of the single POD.
2. Close the main input MCB and bypass input MCB on the front panel of the single POD.
3. Wait until the UPS starts to operate in Bypass mode, and open the maintenance bypass MCB on the front panel of
the single POD.
4. Press the ON button on the operation and display panel of the UPS, and the UPS transfers to Inverter mode.
5.3 UPS Complete Shutdown
For the UPS system with POD, if you need to shut down the UPS completely, transfer the UPS from Inverter mode to
Maintenance Bypass mode according to the procedures in 5.2.4 Transferring From Inverter Mode To Maintenance
Bypass Mode, so as to make no effect on the use of the load during the UPS power-off. Then if the power to the load
is not needed, open the maintenance bypass MCB directly, as shown in Figure 5-1.
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