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10.0 OPERATION
10.1 Liebert
®
APM
™
Operating Modes
The Liebert APM can operate in any of three modes, as shown in Table 28. This section provides
instructions on switching between modes, resetting the UPS, switching the inverter On and Off and
performing other operations.
10.2 UPS Startup
The Liebert APM must be fully installed and commissioned before startup, and external power
isolators must be closed. Once those general conditions are met, the UPS may be started.
Table 28 UPS operating modes
Operating Mode Description
Normal
Operation
The UPS is powering the load.
On Maintenance
Bypass
The UPS is shut down but the load is connected to utility power via the Maintenance Bypass
Supply line.
NOTE: The load is not protected against disturbances in AC input power in this mode.
On Static Bypass
The load power is supplied through the static bypass line. This may be considered as a
temporary mode during load transfers between inverter and maintenance bypass or supply
under abnormal operating conditions.
NOTE
1. The user controls and indicators mentioned in these procedures are identified in 9.0 -
Operator Control and Display Panel.
2. The audible alarm may sound at various points during these procedures. It can be canceled
at any time by pressing the SILENCE ON/OFF push button.
NOTE
This unit refers to some modes and conditions that are set or adjusted using proprietary service
software. To take advantage of all the available features for the Liebert APM, the unit must be
commissioned by an Emerson-authorized engineer.
!
WARNING
Risk of electrical shock and arc flash. Can cause property damage, injury and death.
During this procedure the output terminals will become live.
If any load equipment is connected to the UPS output terminals, please check with the load
user and ascertain whether it is safe to apply power to the load. If the load is not ready to
receive power, then ensure that it is safely isolated from the UPS output terminals.