Emerson 15-90KVA Manuel D’Utilisation

The Liebert APM operates in the modes shown in Table 22. This section describes various kinds of 

operating procedures under each operating mode, including transfer between operating modes, UPS 

setting and procedures for turning on/off inverter.

As shown in Figure 48, the AC utility source is supplied through the input breaker, and the rectifier 

converts the alternating current into DC power. The inverter converts the AC power from the 

utility—or DC power from the batteries—into AC power for the load. The batteries power the load 

through the inverter in the event of a power failure. The utility source can also power the load 

through the static bypass.
If maintenance or repair of the UPS is necessary, the load can be switched without interruption in 

service using the Liebert BDC.

Risk of electrical shock and arc flash. Can cause property damage, injury and death.
The Liebert

®

 APM

™

 contains high voltages internally. Components that can only be accessed 

by opening the protective cover with tools cannot be serviced or replaced by the user.
Only properly trained and qualified service personnel are authorized to remove the protective 

covers.

Normal mode

NORMAL

UPS powers the load

Bypass mode

BYPASS

The load power supply is provided by the static bypass. This mode can be regarded 
as a temporary transition mode between the normal mode and maintenance bypass 
mode, or a temporary abnormal operating status.

Maintenance
Mode

MAINT

UPS shuts down, the load is connects to the mains through the Liebert BDC. In this 
mode the load is not protected against abnormal input utility power.