Operation
Liebert
®
APM
™
112
10.18 Operation
The Liebert APM operates in the modes shown in
. 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
, 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.
Figure 84 Single module block diagram—Single input configuration with three-breaker Liebert BDC
!
WARNING
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.
Table 31
UPS operating modes
Operating mode
Descriptions
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.
NOTES
1. Install in accordance with national and local electrical codes.
2. Input and bypass must share the same single source.
3. A neutral is required from the system AC input source. A full
capacity neutral conductor is recommended. Grounding
conductors are recommended.
4. UPS system input and output cables must be run in separate conduits.
5. Control wiring must be run in separate conduits.
6. Optional 54-pole, 225A for 45kVA frame only or optional 54-pole,
400A for 90kVA frame only.
BIB - Bypass Isolation Breaker
MBB - Maintenance Bypass Breaker
MIB - Maintenance Isolation Breaker
* External Overcurrent Protection
by others
Field-Supplied Wiring
UAM01003
Rev. 2
Bypass Distribution Cabinet
* System
AC Input
4-Wire + GND
BIB
MBB
MIB
Static Bypass
UPS Cabinet
Battery
Optional
54-Pole
See Note 6
AC Output
208V
4-Wire + GND