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Auxiliary Backup AC Power Supply
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APPENDIX F.0 A UXILIARY BACKUP AC POWER SUPPLY
Appendix F.1 Overview
The Liebert FS must be operated with a backup AC power supply to protect the unit’s mechanical
bearings if:
• the external DC supply is lost and
• the Liebert FS has developed a fault
If these two events occur simultaneously, the backup power supply will power the magnetic levitation
hardware to prevent the rotating group from running on the mechanical touchdown bearings.
This section details the function of the backup power supply and how it should be attached to the
Liebert FS. This is supplementary information—refer to appropriate sections of the user manual for
details on installation and operation.
Appendix F.2 Backup AC Power Supply Specification
Note: Connection to a 480VAC supply requires a 480 to 110 transformer, available from Liebert as an
option.
Appendix F.3 Recommended Backup Power Supply Configuration
Voltage: 110 to 230VAC, 400VA
Frequency: 50 to 60Hz
If the Liebert FS
is operating: Liebert recommends: For details, see:
In parallel
with batteries
Attaching the backup AC power supply to the output of the UPS. Figures 156 and 157
Without batteries
Feeding the backup AC supply from a separate, protected supply.
This may be the output of another UPS or a supply from a separate
feeder circuit.
Figures 158 and 159