Eaton Power Xpert 9395 UPS Installation and Operation Manual 164201716—Rev 13
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Figure 49. Path of Current Through the UPS in Online Mode
Static
Switch
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e
if
it
c
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R
K1
K3
Battery
Converter
Battery
Battery
Breaker
Main Power Flow
Trickle Current
Energized
De-Energized
Closed
Open
Breakers
Contactors
Static
Switch
K5
r
e
tr
e
v
n
I
r
e
if
it
c
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R
K1
K3
Main Power Flow
Trickle Current
Energized
De-Energized
Closed
Open
Breakers
Contactors
K2
Bypass Input
Rectifier
Input
Output
Input
Breaker
(CB1
NOTE
On a UPS configured as an IOM, the bypass input, static switch, and K5 are not present.
The inverter produces a three-phase AC output to a customer's load without the use of a transformer. The
inverter derives regulated DC from the rectifier and uses IGBT devices and pulse-width modulation (PWM) to
produce a regulated and filtered AC output. The AC output of the inverter is delivered to the system output
through the output contactor K3.
If the utility AC power is interrupted or is out of specification, the UPS automatically switches to Battery mode
to support the critical load without interruption. When utility power returns, the UPS returns to Online mode.
If the UPS becomes overloaded or unavailable, the UPS switches to Bypass mode. The UPS automatically
returns to Online mode when the overload condition is cleared and system operation is restored within
specified limits.
If the UPS suffers an internal failure, it switches automatically to Bypass mode and remains in that mode until
the failure is corrected and the UPS is back in service.
66..22..33
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NOTE
VMMS and ESS modes are mutually exclusive. If ESS mode is enabled, VMMS mode is
disabled.
When the UPS is operating in ESS mode, the bypass source supplies the commercial AC power to the load
directly through the static switch. Some power line filtering and spike protection is provided to the load but no
active power conditioning or battery support is available. All power converters are off and are in the ready state
(in case a forward transfer is needed). During this mode, the output contactor is closed and the link is
maintained through the diode bridge.
If commercial power voltage or frequency disturbances are detected, the system forward transfers to Battery
mode for minor disturbances and then to double-conversion mode for more severe disturbances. During a
