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9.5
Battery Mode
The UPS transfers 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.
When the UPS switches to Battery mode, the alarm indications depend on the
cause and condition of the battery charge. The length of time the system can
operate in Battery mode depends on loading and the battery supply capacity.
Figure 9---4 shows the path of electrical power through the UPS system when
operating in Battery mode.
Bypass
Input
CB1
Rectifier
Input
(closed)
TRANSFORMER
Path of electrical power
Figure 9 ---4. Path of Current Through the UPS in Battery Mode
When the discharging battery voltage reaches the lower limit of UPS operation
capability, the critical load transfers to Bypass mode if it is available. If Bypass input
is not available, a "Shutdown Imminent" warning occurs. The warning time before
critical load loss occurs is approximately 2 minutes, depending on battery capacity
and the amount of loading.
If incoming power returns to within specified parameters, the UPS automatically
returns to Normal mode and alarm indications clear. However, the process of returning
to Normal mode is not instantaneous. The rectifier gradually draws increasing power
from the incoming utility until Normal mode is achieved.
Powerware 9315 (500 kVA- -750 kVA) Installation and Operation
164201244 REV. D 030101
STATIC SWITCH
FBP
(open)
RECTIFIER
INPUT
CB2
(closed)
CB4
(open)
BYPASS
INVERTER
DC
LINK
BATTERY
CB3
(closed)
OUTPUT
TRANSFORMER
Output
9--5
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