3--6
Powerware BPIV Parallel Cabinet Installation and Operation
164201409 REV. B
101503
3.2.3
Battery Mode
The UPMs transfer to Battery mode automatically if a utility power outage occurs,
or if the utility power does not conform to specified parameters. In Battery mode,
the battery provides emergency DC power that the inverter converts to AC power.
Figure 3---3 shows the path of electrical power through the Parallel System when
operating in Battery mode.
UPM1
UPM2
UPM3
UPM4
BATT
UPM
INPUT
BATT
BATT
BATT
OUTPUT TO
CRITICAL
LOAD
PARALLEL CABINET
CONTACTOR
BYPASS
K4
PATH OF ELECTRICAL POWER
UPM SWITCH 1
UPM SWITCH 2
UPM SWITCH 3
UPM SWITCH 4
BYPASS
INPUT
FROM
BYPASS
SOURCE
BYPASS
INPUT
OPEN
CLOSED
CONTACTORS
SWITCHES
Figure 3---3. Path of Current Through the Parallel System in Battery Mode
While in battery mode, the UPMs will enunciate an audible horn, light a visual
indicator lamp on the front panel (System Normal, On Battery), and make an entry
into the alarm event history. As the battery discharges, the boost converter and
inverter constantly make minute adjustments maintaining a steady output. The
UPMs will remain in this operating mode until the input power to the rectifier is
again within the specified voltage or frequency acceptance windows.
