Vertiv™ | Liebert® EXM
™
50-250kVA, 480V, 60Hz User Manual | 80
WARNING
Risk of electrical shock and arc flash. Can cause property damage, 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 optional battery cabinet disconnected, high voltage at filter
capacitors and power circuits should be discharged within 30 seconds. However, if a power
circuit failure has occurred, you should assume that high voltage still exists after shutdown.
Check with a voltmeter before making contact.
AC voltage will remain on the bypass and output contactors and the static bypass switch,
unless the associated external circuit breakers are opened.
Check for voltage with both AC and DC voltmeters before 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. The differential input should
have at least 800
vrms common mode input rating and a common mode rejection ratio of at
least 80 dB.
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 electrical fire fighting.
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