Understanding Ups Operation; Ups System Overview; Figure 5-1 Main Elements Of The Ups System - Eaton 9EHD-33-40/20 User's Installation And Operation Manual

Chapter 5

understanding uPS operation

5 1

uPS System overview

The Eaton 9EHD UPS is a continuous-duty, solid-state, transformer-free, 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 5-1 shows the main elements of the UPS
system.
If utility power is interrupted or falls outside the parameters specified in Chapter 9, "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.
AC Input to
Rectifer/
AC Input to
The emergency bypass consists of a continuous static switch, and an optional backfeed protection contactor. The
backfeed protection contactor (if fitted) is located in series with the static switch. The static switch is armed and
ready during normal operation.
42 Eaton 9EHD UPS (20-40 kVA, 380/400/415V) Installation and Operation Manual
Input Input
Breaker Contactor
Charger
(Optional)
Bypass Input Breaker
Bypass
External Battery cabinet
Battery
Contactor
Battery
Converter
Rectifer
Digital Metering
Backfeed
Contactor
Static
Switch
uPS Cabinet

figure 5-1 main elements of the uPS System

Output
Contactor
Inverter
Power Module
Maintenance Bypass Switch
Output Breaker
AC Output to
Critical Load