Filter
Top Products
Auxiliary Backup AC Power Supply
153
Appendix F.4 Scenarios
This section describes five scenarios that might occur.
• Loss of backup AC supply at 0 RPM - This causes a fault message to appear on the control
panel to indicate there is a problem with the backup supply. The unit will not start until the
backup supply is reinstalled.
• Loss of backup AC supply at full speed - This causes a warning message to appear on the con-
trol panel to indicate there is a problem with the backup supply. This warning does not affect the
operation of the system.
• Loss of external DC supply - The Liebert FS will discharge normally until it reaches
25000 RPM. It will then change to shutdown mode and drive down to 3500 RPM, it will then coast
to a stop over a number of hours.
• Loss of external DC supply and loss of backup supply - The Liebert FS can support the
magnetic levitation hardware using energy from the flywheel. It will discharge normally until
25000 RPM, then change to shutdown mode and drive down to 3500 RPM. At this speed it can no
longer support itself, and the unit will turn off. The flywheel will safely drop onto the mechanical
touchdown bearings and will slowly come to a stop.
• Loss of external DC supply, loss of backup supply and a fault message appears on the
control panel - This unlikely combination of events will cause the flywheel to drop onto the
mechanical touchdown bearings without slowing to a safe rotation speed. The ceramic touchdown
bearings can withstand very high speeds. However, if the flywheel were to drop onto the ceramic
bearings at full speed, the bearings would last only a minute before starting to degrade. Although
the system has been designed to retain the rotor as it slows, internal damage will occur during
this period. The Liebert FS would require refurbishing at the factory before it could be used again.
Figure 160 Liebert FS connection
BACKUP AC
POWER SUPPLY
DC bus
Liebert FS
Flywheel
module
DISCONTINUED
PRODUCT