NEC Express5800 User Manual page 59

NOTES:
To connect the power cord from the server to an uninterruptive
power supply (UPS), use service outlets on the rear of the UPS.
Refer to the manual that comes with the UPS for details.
When the power cord from the server is connected to a UPS, change
the BIOS SETUP utility of the server to link with power supply
from the UPS.
Change a parameter for "AC-LINK" of the Server menu of the
BIOS SETUP utility. See Chapter 4 for details.
Setting Up Your Server 3-9
Connect the battery
connector when using
UPS.
Disconnect the connector
when moving the UPS to
relocate it.