12 Powerware 9315 (200 kVA---300kVA) Opera tion
164201036 Rev.D 041500
Battery Mode
The UPS transfers to Battery mode automatically if a utility poweroutage occurs, o r
if the utility power does not conform to specifiedparameters. 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 indicationsdepend 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 capac ity.
Figure 5s hows the path of electrical power through the UPS when operatingin Bat tery
mode.
Path of electricalpower
Bypass
Rectifier
K4
Input
Input
K3
CB1
(closed)
BATTERY
RECTIFIER INVERTER
Output
TRANSFORMER
BYPASS
Figure 5. Path of Current Through the UPS in BatteryMode
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, theproces s ofreturning
to Normal mode is not instantaneous. The rectifier gradually draws increasing power
from the incoming utility until Normal mode is achieved.