Chapter 5 UPS Operation Introduction 39
Liebert NXC 30kVA And 40kVA UPS User Manual
7. If the UPS has internal battery, use the special tool to open the battery compartment door, then disconnect the three
terminals 'BAT+', 'BAT-' and 'BAT N' (see Figure 5-3 for details). If the UPS has external battery, disconnect the
corresponding switch of the external battery.
Figure 5-3 Disconnecting terminals of the internal battery
8. Disconnect the rectifier input switch Q1 and bypass input switch Q2.
At the moment, all the internal power supply is closed and the LCD does not display any more.
Warning
1. If the maintenance is required, wait 10 minutes for the internal DC bus capacitance discharging.
2. The parts of UPS circuits also have hazardous voltage, though the rectifier input switch, bypass input switch and battery switch
are disconnected. Therefore, the UPS maintenance is suitable for qualified personnel only.
5.3.5 Transfer From Maintenance Mode To Normal Mode
The following procedures will transfer the maintenance bypass supply mode of the UPS to the normal mode.
1. Open the front door, close the neutral line switch Q6.
2. Close the output switch Q5.
3. Close the bypass input switch Q2.
4. After the LCD startup, the system will transfer to the Event menu window till the system confirms that the record
displays 'Bypass mode'.
Warning
You must start the bypass first, and then disconnect the maintenance bypass switch; or it will cause output load power failure.
5. Disconnect the internal maintenance bypass switch Q3.
6. Close the rectifier input switch Q1, then the alarm indicator (red) is flashing.
7. Press the ON key for two seconds.
The inverter starts up, and the inverter indicator (green) is flashing. After the inverter runs normally, the UPS will be
transferred from the bypass to inverter, and then the inverter indicator (green) is on.
At the moment, the load has transferred to UPS normal mode.
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