Emerson 250-400kVA manual General Description, Modes of Operation, Normal Mode

Introduction

1.0INTRODUCTION

1.1General Description

The Liebert NXL UPS provides continuous, high-quality AC power to your business-critical equip- ment, such as telecommunications and data processing equipment. The Liebert NXL UPS supplies power that is free of the disturbances and variations in voltage and frequency common to utility power, which is subject to brownouts, blackouts, surges and sags.

The Liebert NXL utilizes the latest in high-frequency, double-conversion pulse-width modulation technology and fully digital controls to enhance its reliability and increase the ease of use.

As shown in Figure 1, the AC utility source is input at CB1 and the rectifier converts the AC utility into DC power. The inverter converts that DC power from the utility—or DC power from the batter- ies— into AC power for the load. The batteries power the load through the inverter in the event of a power failure. The utility source can also power the load through the static bypass.

If maintenance or repair of the UPS is necessary, the load can be switched without interruption in service to the maintenance bypass.

Figure 1 Typical UPS system one-line diagram

Bypass

BFB

Input

CB1

Battery

System

1.2Modes of Operation

1.2.1Normal Mode

DC Bus

CB2

MBD

Module Output

Operating in normal mode, the Liebert NXL’s rectifier derives power from a utility AC source and supplies regulated DC power to the inverter, which regenerates precise AC power to supply the con- nected equipment. The rectifier also uses the utility source power to charge the batteries.

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