Eaton 9395 550/275 UPS (225–550 kVA) Installation and Operation Manual
S
164201716 Rev 2
www.eaton.com/powerquality
6-1
Chapter 6
Understanding UPS Operation
6.1
UPS System Overview
The Eaton9395 UPS is a continuous-duty, solid‐state, transformerless (at 480 Vac),
three-phase, true online system that provides conditioned and uninterruptible AC
power to the UPS system's output and critical load.
The basic system consists of a rectifier, battery converter, inverter,
monitoring/operation control panel, integrated communication server, and digital
signal processor (DSP) logic. Figure 6‐1 shows the main elements of the UPS system.
Output
Contactor
K3
Battery
Battery
Breaker
Battery
Converter
Input
Contactor
K1
AC Input to
Rectifier/
Charger
AC Input to
Bypass
Backfeed
Protection
Contactor
K5
Power Module
Inverter
Rectifier
Digital
Metering
Static
Switch
AC Output
to Critical
Load
UPS Cabinet
Battery
Contactor
K2
Battery Cabinet or
Battery String
Input
Breaker
CB1
(optional)
Figure 6‐1. Main Elements of the UPS System
If utility power is interrupted or falls outside the parameters specified in Chapter 10,
“Product Specifications,” the UPS uses a
backup battery supply
to maintain power to
the critical load for a specified period of time or until the utility power returns. For
extended power outages, the UPS allows you to either transfer to an alternative
power system (such as a generator) or shut down your critical load in an orderly
manner.
The emergency bypass consists of a continuous-duty static switch and backfeed
protection contactor K5. The backfeed protection contactor is located in series with
the static switch. For manual transfers to bypass, the static switch is also used. The
static switch is armed and ready during both types of transfers.
Figure
