Eaton 9EHD Series, User'S Installation And Operation Manual

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Chapter 5 understanding uPS operation
5 1 uPS System overview
figure 5-1 main elements of the uPS System
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.
External Battery cabinet
Battery
Converter
Battery
Contactor
Output
Contactor
Input
Breaker
AC Input to
Rectifer/
Charger
Input
Contactor
(Optional)
Bypass Input Breaker
Backfeed
Contactor
Maintenance Bypass Switch
Output Breaker
AC Input to
Bypass
Static
Switch
Inverter Rectifer
Digital Metering
AC Output to
Critical Load
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.
uPS Cabinet
Power Module
Eaton 9EHD UPS (20-40 kVA, 380/400/415V) Installation and Operation Manual 42