Battery Backup Time And Discharge Process - Toshiba 5000 SERIES Installation And Operation Manual

13.7

Battery Backup Time and Discharge Process

The optional battery cabinet provides some period of back-up time depending on the UPS kVA rating
and system load. The exact length of these times will depend on the UPS model used, condition of the
batteries, amount and type of load, temperature and other variables.
Figure 13.1 graphically illustrates the battery discharge process under full load conditions.
The UPS battery voltage to drops as the battery discharges. The chart in Figure 13.1 lists the voltage level
at which each UPS low-voltage alarm will sound and at what level the low-voltage condition will cause the
unit to automatically shut down.
UPS Capacity
Nominal voltage (V
Alarm voltage (V
Shutdown voltage (V
CURRENT VOLTAGE
V
V
V
I
MAX
I
MIN
74
)
nom
)
low
)
min
NOM
LOW
MIN
100%
Battery Capacity
FIGURE 13.1: TYPICAL BATTERY DISCHARGE CURVE
5000 Series NEMA-3R 3-Phase UPS Installation and Operation Manual – 92975-000
20 kVA 30 kVA
288 Vdc 288 Vdc
246 Vdc 246 Vdc
230 Vdc 230 Vdc
Shutdown
Voltage
TIME
20% 0%