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Three-phase AC input power is converted to DC using a multilevel converter with IGBT devices to
produce a regulated DC voltage to the inverter. The UPS status indicated on the display is Unit Online
and the UPM status is Active.
The DC/DC converter derives its input from the regulated DC output of the rectifier and provides regulated
charge current to the battery. The battery is always connected to the UPS and ready to support the
inverter should the utility input become unavailable.
The inverter produces a three-phase AC output to the critical load. The inverter uses multilevel converter
technology with IGBT devices and pulse-width modulation (PWM) to produce a regulated and filtered AC
output.
If the utility AC power is interrupted or is out of specification, the UPS automatically switches to the stored
energy mode to support the critical load without interruption. When utility power returns, the UPS returns
automatically to the double conversion mode.
If the UPS becomes overloaded or unavailable, the UPS seamlessly switches to the bypass mode and
continues supplying the load through the static bypass. The UPS automatically returns to the double
conversion mode when the abnormal condition, such as an extended time overload, is cleared and the
system operation is restored within the specified limits.
If a UPM within the UPS suffers an internal failure, the remaining UPMs continue to support the load in the
double conversion mode. The UPS is automatically internally redundant when the UPS is not operating at
full load. However, if internal redundancy between the UPMs is not possible due to high load, the UPS
switches automatically to the bypass mode and remains in that mode until the failure is corrected and the
UPS is back in operation.
In an external parallel redundant system, each UPS can be isolated from the system for service while the
remaining UPSs support the load in the double conversion mode.
Each UPS in an external parallel system must be equipped with a dedicated UPS input feeder
NOTE:
circuit breaker, UPS bypass feeder circuit breaker, and UPS Module Output Breaker (MOB) to isolate the
UPS under service from the system.
3 3 . . 3 3 . . 1 1 . . 2 2
V V a a r r i i a a b b l l e e M M o o d d u u l l e e M M a a n n a a g g e e m m e e n n t t S S y y s s t t e e m m m m o o d d e e
When Variable Module Management System (VMMS) mode is enabled, the load is powered by UPMs in
double conversion mode. The UPS status indicated on the display is Unit Online VMMS and the UPM
status is Active.
UPS efficiency varies according to the load level at which the UPS operates. VMMS technology enables
achieving optimised system efficiency by automatically optimising the UPM load level. As an example,
when the load is very low, a minimum of one UPM is online. This enhances the UPS system efficiency by
several percentage points.
The remaining UPMs are ready to switch to online mode instantaneously, if the load increases. The load
will remain protected by double conversion UPS the entire time, even during and after a load step.
It is possible to configure VMMS mode to include power module redundancy at all times, so that a number
of additional redundant UPMs are always online.
When the UPMs are in ready state, the IGBT converters are constantly powered, since the rectifier input
and inverter output relays are closed. The DC link is also powered. Only the IGBT gate signals are
suspended. The only step needed to come out of ready state is to gate the IGBT switches. Since DC
voltage is constantly present, the inverter is able to start instantaneously: the 2 ms activation is practically
seamless.
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EATON 93PM G2 UPS
USER'S AND INSTALLATION GUIDE
P-164000956 - February 2021
www.eaton.eu
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