Emerson Liebert NX 10-30kVA - Manual (Page 86)

Operating Instructions
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9.5 Powering Down the UPS and Maintaining Power to Load
If the UPS needs to be shut down completely while maintaining power to the load, follow these steps:
1. Perform Steps 1 through 5 in 9.3 - Switching the UPS from Normal to Maintenance
Bypass.
2. Close the external maintenance bypass rotary switch to Maint postion.
On the primary input distribution panel, which is often located distant from the UPS area, a label
should be posted advising service personnel that the UPS circuit is under maintenance.
The UPS is now completely powered down.
The procedure can be performed only after the installation has been completed (which includes the
maintenance bypass cabinet), after the system has been placed in operation by authorized personnel.
See the reference drawing of Figure 59 for more information.
Figure 59 Typical configuration for single UPS with external maintenance bypass cabinet
NOTE
An external Maintenance Bypass Cabinet must be installed before attempting to perform the
following procedure.
!
WARNING
Wait 5 minutes for the internal DC busbar capacitors to discharge.
NOTE
The Maintenance Bypass Power switch may be operated at any time while the UPS is powered
down to connect the load to the maintenance bypass supply if required.