Eaton 91PS User And Installation Manual page 19

Eaton 91PS/93PS UPS 8-10 kW User's and installation guide
The inverter produces a single-/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 battery 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.
3.2.1.2 Energy Saver System mode
4
Figure shows the path of electrical power through the UPS system when the
UPS is operating in the Energy Saver System (ESS) mode.
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Eaton Corporation plc 2018. All rights reserved. Revision: 003 Document ID: P-164000672 19 (102)