Understanding Ups Operation; Ups System Overview; Figure 6-1. Main Elements Of The Ups System - Eaton Power Xpert 9395 550/275 Installation And Operation Manual

Chapter 6

Understanding UPS Operation

6.1

UPS System Overview

The Power Xpert 9395 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.
AC Input to
Rectifier/
Charger
AC Input to
Bypass

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.
Power Xpert
Battery Cabinet or
Battery String
Input
Breaker
Input
CB1
Contactor
(optional)
K1
TM
9395 550/275 UPS (225–550 kVA) Installation and Operation Manual 164201716—Rev 8 www.eaton.com/powerquality
Battery
Battery
Breaker
Battery
Contactor
K2
Battery
Converter
Rectifier Inverter
Power Module
Digital
Metering
Static
Switch
Backfeed
Protection
Contactor
UPS Cabinet
Output
Contactor
K3
K5
AC Output
to Critical
Load
6-1