Battery Mode; Figure 6‐5. Path Of Current Through The Ups In Battery Mode - Eaton Power Xpert Plus 1 Installation And Operation Manual

6.2.6
Bypass Input
Input
Breaker
Rectifier
(CB1
Input
Rectifier
K1
Breakers Contactors
Closed
Open
NOTE On a UPS configured as an IOM, the bypass input, static switch, and K5 are not present.
Figure 6‐5. Path of Current Through the UPS in Battery Mode
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Power Xpert 9395 UPS (450–550 kVA) Installation and Operation Manual

Battery Mode

The UPS automatically transfers to Battery mode 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 6‐5 shows the path of electrical power through the UPS system when
operating in Battery mode.
Static
Switch
Battery
Converter
K2
Battery
Breaker
Battery
During a utility power failure, the rectifier no longer has an AC utility source from
which to supply the DC output current required to support the inverter. The input
contactor K1 opens and the battery instantaneously supplies energy to the battery
converter. The converter either bucks or boosts the voltage so that the inverter can
support the customer's load without interruption. If bypass is common with the
rectifier input, the backfeed protection contactor K5 also opens. The opening of
contactors K1 and K5 prevent system voltages from bleeding backwards through the
static switch and rectifier snubber components and re-entering the input source.
If the input power fails to return or is not within the acceptance windows required for
normal operation, the battery continues discharging until a DC voltage level is reached
where the inverter output can no longer support the connected loads. When this
event occurs, the UPS issues another set of audible and visual alarms indicating
SHUTDOWN IMMINENT. Unless the rectifier has a valid AC input soon, the output
can be supported for only two minutes before the output of the system shuts down.
If the bypass source is available, the UPS transfers to bypass instead of shutting
down.
UNDERSTANDING UPS OPERATION
K5
Inverter
Main Power Flow
Trickle Current
Energized
De-Energized
S
164201701 Rev 3 www.eaton.com/powerquality
Output
K3
6-7