Liebert 30-130kVA 1.3 Modes Of Operation

Introduction

ONLY qualified service personnel should perform maintenance on the UPS system. When performing

maintenance with any part of the equipment under power, service personnel and test equipment

should be standing on rubber mats. The service personnel should wear insulating shoes for isolation

from direct contact with the floor (earth ground).

Unless all power is removed from the equipment, one person should never work alone. A second per-

son should be standing by to assist and summon help in case an accident should occur. This is partic-

ularly true when work is performed on the battery.

Three types of messages are used throughout the manual to stress important text. Carefully read the

text below each Warning, Caution, and Note and use professional skills and prudent care when per-

forming the actions described by that text.

A Warning signals the presence of a possible serious, life-threatening condition. For example:

A Caution indicates a condition that could seriously damage equipment and possibly injure personnel.

For example:

A Note emphasizes important text. If the note is not followed, equipment could be damaged or may

not operate properly. For example:

1.3 Modes Of Operation

Refer to 2.0 - Theory of Operation and 3.0 - Operation for more details.

The utility AC source provides power to the rectifier/charger in the UPS module. The rectifier/charger

converts the utility AC power to DC and supplies DC power to the UPS module inverter while simul-

taneously float charging the battery plant. The UPS inverter converts DC to AC and furnishes AC

power to the critical bus.

If the utility source power fails or is outside the acceptable range, the battery plant becomes the pri-

mary supplier of DC power to the inverter.

After the utility source power is restored, or an alternate power source becomes available, the recti-

fier/charger slowly walks-in to once again power the inverters and recharge the battery plant.

Lethal voltages may be present within this unit even when it is apparently not operating.

Observe all cautions and warnings in this manual. Failure to do so could result in serious

injury or death. Do not work on or operate this equipment unless you are fully qualified to do

so! Never work alone.

Make sure you understand the proper sequence before operating any circuit breaker.

Operating a Maintenance Bypass circuit breaker out of sequence could cut off power to the

critical load.

NOTE

If the UPS system has a blown fuse, the cause should be determined before you replace the fuse.

Contact Liebert Global Services.