EC-fan Alarm Contact Tests
Check the alarm contact at KL2 to determine if there are any fault conditions present.
Condition No Fault Condition Fault Condition
NO - COM Open Closed
NC - COM Closed Open
NOTE: The table refers to conditions while the motor is actively energized. When the motor is de-
energized, it will be in a fault condition.
• Check EC Control to determine the fault condition.
9.2.4 Replacing EC Fans in Downflow Models
The EC-fan modules are removable for easier maintenance and replacement.
WARNING! Arc flash and electric shock hazard. Open all local and remote electric power-supply
disconnect switches, verify with a voltmeter that power is Off and wear appropriate,
OHSA-approved personal protective equipment (PPE) per NFPA 70E before working within the
electric control enclosure. Failure to comply can cause serious injury or death. Customer must
provide earth ground to unit, per NEC, CEC and local codes, as applicable. Before proceeding
with installation, read all instructions, verify that all the parts are included and check the
nameplate to be sure the voltage matches available utility power. The Liebert controller does
not isolate power from the unit, even in the “Unit Off” mode. Some internal components require
and receive power even during the “Unit Off” mode of the controller. The factory-supplied
disconnect switch is inside the unit. The line side of this switch contains live high-voltage. The
only way to ensure that there is NO voltage inside the unit is to install and open a remote
disconnect switch. Refer to unit electrical schematic. Follow all local codes.
WARNING! Risk of contact with high-speed, rotating fan impeller blades. Can cause injury or
death. Open all local and remote electric power-supply disconnect switches, verify with a
voltmeter that power is off, and verify that all fan impellers have stopped rotating before
working in the unit cabinet.
WARNING! Risk of very heavy fan module dropping downward suddenly. Can cause injury or
death. Only properly trained and qualified personnel should work on this equipment. The fan
module weighs approximately 100 lb. (45.4 kg).
Vertiv | Liebert® PDX™ and PCW™ Installer/User Guide | 67
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