Emerson NX Manuel D’Utilisation

Observe the safety precautions in Battery Cabinet Precautions on page 2.
Observe all of the warnings below before performing any maintenance on the UPS and associated 

equipment. Also observe the manufacturer’s safety precautions pertaining to the DC source, along 

with the DC source safety precautions in this section.

NOTE
Service and maintenance work must be performed only by properly trained and qualified 

Risk of electric shock and high short circuit current. Can cause equipment damage, personal 

injury and death.
• Extreme caution is required when performing maintenance.
• Be constantly aware that the UPS system contains high DC as well as AC voltages. With 

input power Off and the DC source disconnected, high voltage at filter capacitors and power 

circuits should be discharged within 5 minutes. However, if a power circuit failure has 

occurred, you should assume that high voltage may still exist after shutdown. Check with a 

voltmeter before making contact.

• AC voltage will remain on the bypass and output circuit breakers 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 chassis ground.
• Any contact between floating circuits and the chassis is a lethal shock hazard. Use 

differential oscilloscopes when measuring a floating circuit.

• Exercise caution that the test instrument exterior does not make contact, either physically 

or electrically, with earth ground.

• In case of fire involving electrical equipment, use only carbon dioxide fire extinguishers or 

others approved for use in fighting electrical fires.

Risk of electric shock and high short circuit current. Can cause equipment damage, personal 

injury and death.
• Always identify connecting wiring prior to disconnecting any wiring.
• Do not substitute parts except as authorized by Emerson

®

 Corporation.

• Maintain the UPS cabinets free of foreign materials such as solder, wire cuttings, etc.
• Contact Liebert Services if you are not sure of the procedures to follow or if you are 

unfamiliar with the circuitry.