Emerson 250-400kVA Manuel D’Utilisation

This manual contains important instructions that should be followed during installation and mainte-

nance of your Liebert NXL UPS and batteries.

This equipment contains circuitry that is energized with high voltage. Only test equipment 

designated for troubleshooting should be used. This is particularly true for oscilloscopes. Always 

check with an AC and DC voltmeter to ensure safety before making contact or using tools. Even when 

the power is turned Off, dangerously high voltage may exist at the capacitor banks.
Observe all battery precautions when near the battery for any reason.
ONLY properly trained and qualified service personnel should perform maintenance on 

the UPS system. When performing maintenance on 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).
One person should never work alone. A second person should be standing by to assist and summon 

help in case an accident should occur. This is particularly true when work is performed on the bat-

tery.

Risk of electric shock. Can cause equipment damage, injury or death.
Exercise extreme care when handling UPS cabinets to avoid equipment damage or injury to 

personnel. Refer to separate installation manual for equipment handling information and 

installation procedures.
Follow all battery safety precautions in 3.0 - Maintenance when installing, charging or 

servicing batteries. In addition to the hazard of electric shock, gas produced by batteries can 

be explosive and sulfuric acid can cause severe burns.
In case of fire involving electrical equipment, use only carbon dioxide fire extinguishers or 

others approved for use in electrical fire fighting.
Extreme caution is required when performing maintenance. Service and maintenance work 

must be performed only by properly trained and qualified personnel and in accordance with 

applicable regulations as well as with manufacturers’ specifications.
Be constantly aware that the UPS system contains high DC as well as AC voltages. With 

input power off and the battery disconnected, high voltage at filter capacitors and power 

circuits should be discharged within 30 seconds. However, if a power circuit failure has 

occurred, assume that high voltage still exists after shutdown. Check with a voltmeter before 

making contact.
AC voltage will remain on the system bypass, the UPS output terminals and the static bypass 

switch, unless associated external circuit breakers are opened.
Check for voltage with both AC and DC voltmeters prior to making contact.
When the UPS system is under power, both the operator and any test equipment must be 

isolated from direct contact with earth ground and the UPS chassis frame by using rubber 

mats.
Some components within the cabinets are not connected to the chassis ground. Any contact 

between floating circuits and the chassis is a lethal shock hazard. Exercise caution that the 

test instrument exterior does not make contact, either physically or electrically, with earth 

ground.