Instruction manual

Eaton
®
9390 UPS (20–80 kVA) and 9390IT (20-40 kVA) Installation and Operation Manual S 164201603 Rev 4 www.eaton.com/powerquality
7-1
Chapter 7 Understanding UPS Operation
The Eaton 9390/9390IT UPS is a continuous-duty, solid‐state, transformerless (at 208,
380, 400, 414, and 480 Vac, three-phase, true online system that provides conditioned
and uninterruptible AC power to the UPS system's output. The 9390IT UPS model is
only available in 208V and 480V. The UPS supports process control, data processing,
telecommunications/PBX, research, and non-patient medical equipment. The Eaton
9390 UPS maintains power to the critical loads during commercial electrical power
brownout, blackout, overvoltage, undervoltage, and out‐of‐tolerance frequency
conditions.
The basic system consists of a rectifier, battery converter, inverter, monitoring/
operation control panel, integrated communication server, and digital signal processor
(DSP) logic.
In this manual, the power required by your equipment is called the critical load. The
UPS supplies the critical load with conditioned power that is synchronized with your
utility power. Figure 7‐1 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
InverterRectifier
Digital
Metering
Static
Switch
AC Output
to Critical
Load
UPS Cabinet
Ignore the dotted
lines for the
9390IT internal
battery
configuration.
External Battery Cabinet or
Internal Battery Compartment
Figure 7‐1. Main Elements of the UPS System
If utility power is interrupted or falls outside the parameters specified in Chapter 14,
“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.
Figure