Eaton 9395 UPS - Single UPS

UNDERSTANDING UPS OPERATION
Eaton 9395 UPS (450–825 kVA) Installation and Operation Manual S 164201725 Rev 4 www.eaton.com/powerquality
6-2
The emergency bypass consists of either a momentary static switch and wraparound
bypass breaker or a continuous static switch, and a backfeed protection contactor K5.
The bypass breaker (if installed) is located in parallel with the static switch. The
backfeed protection contactor is located in series with the static switch. The static
switch is armed and ready during normal operation.
On a UPS configured as an Input Output Module (IOM), bypass circuitry is not
installed. This configuration is primarily used in multiple UPS parallel systems that do
not need a bypass for each UPS and use a separate System Bypass Module (SBM) to
provide system bypass capabilities.
6.2 Single UPS
A single UPS operates independently to support an applied load from the inverter,
providing conditioned and uninterruptible AC power to the critical load from the output
of the module. During an outage, the inverter continues to operate, supporting power
to the load from the battery supply. If the unit requires service, applied loads are
transferred to the internal bypass either automatically or manually. With the exception
of a battery cabinet, no other cabinets or equipment are required for the single UPS to
successfully support its applied loads.
6.2.1 Modes
The Eaton 9395 UPS supports a critical load in five different modes of operation:
NOTE The Variable Module Management System and Energy Saver System modes are mutually exclusive.
S In Online mode, the critical load is supplied by the inverter, which derives its power
from rectified utility AC power. In this mode, the battery charger also provides
charging current for the battery, if needed.
S In Energy Saver System (ESS) mode, commercial AC power is supplied directly to
the critical load through the continuous static switch and transfers automatically to
Online mode if an abnormal condition is detected. The ESS mode requires a UPS
with a continuous static switch.
S In Variable Module Management System (VMMS) mode, the UPS operates as a
traditional double conversion UPS, but selectively shifts the load to fewer UPMs to
increase the efficiency of the UPS.
S In Bypass mode, the critical load is directly supported by utility power.
S In Battery mode, the battery provides DC power, which maintains inverter
operation. The battery supports the critical load.
The following paragraphs describe the differences in the UPS operating modes, using
block diagrams to show the power flow during each mode of operation.