Emerson Liebert iCOM, Manual

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Operation
Liebert
®
iCOM
®
for Liebert DSE
™
42
Dehum Operation with One Compressor Out on Alarm
This type of dehumidification operation will resemble DH Stage 2, except for the rules listed below.
If the compressor with the alarm resides in Tandem Bank 1 (C1A or C1B)…
• If Compressor 1B is out on alarm, operation will be identical to that of DH Stage 2, except that if
the CFC goes above the value on line DH02, C1B will not be restarted.
• If Compressor 1A is out on alarm operation will be similar to DH Stages 2 and 1, except
Compressor 1B will take the place of C1A.
• Operation of the compressors in Tandem Bank 2 will be the same as they are described in DH
Stages 2 and 1.
If the compressor with the alarm resides in Tandem Bank 2 (C2A or C2B)…
• If Compressor 2B is out on alarm, operation will be similar to that of DH Stages 2 and 1, except
that Compressor 1B will take the place of C2B: C1B will be turned Off if the reheat stage
indicated in the second column of line DH07 becomes active, or if the Low Limit sensor
temperature becomes less than or equal to the Low Limit 1 border. C1B can be restarted if the
CFC becomes greater than or equal to the value on line DH03 and the Low Limit sensor
temperature is greater than or equal to the Low Limit 1 reset border.
• If Compressor 2A is out on alarm, operation will be similar to that of DH Stages 2 and 1, except
Compressor 2B will take the place of C2A, and Compressor C1B will act like C2B.
• C1B will be turned Off if the reheat stage indicated in the second column of line DH07 becomes
active, or if the Low Limit sensor temperature becomes less than or equal to the Low Limit 1
border. C1B can be restarted if the CFC becomes greater than or equal to the value on line DH03
and the Low Limit sensor temperature is greater than or equal to the Low Limit 1 reset border.
Dehum Operation with Two Compressors Out on Alarm
When two of the four compressors are out on alarm, operation for all compressor combinations become
similar, and will be guided by the rules listed below.
• Both available compressors must be turned On and will operate like compressors C1A and C2A in
DH Stage 1.
• If Compressor 1A is operational, it will always be loaded at 100%.
• If Compressor 2A is operational, it will adjust its loading based on whether the Call for
Dehumidification is greater than the Call for Cooling: If the CFD is greater than or equal to the
CFC, C2A must use the ramp on line DH05 (“C2A CFC @ 0% / 100% Dehum Ramp”), with the
CFD used to determine ramp %. If the CFD is less than the CFC, then C2A must use the ramp on
line DH06 (“C2A CFC @ 0% / 100% Cooling Ramp”), with the CFC used to determine ramp %.
Dehumidification Deactivation with Three Compressors Out on Alarm
If three or four compressors are disabled from compressor-related alarms, no dehumidification
routines will be executed until at least two of the four compressors become operational.
Reheat During Dehumidification
The reheat activation rules in the preceding section may be altered, depending on which reheat mode
is selected on line A144:
• None : No reheats will ever be activated for dehumidification.
• Staged : The reheat rules in the preceding section will apply.
When a parameter on line DH07 (“Reheat Stage to Deactivate C1B / C2B”) is set to “None,” its
corresponding compressor will not be deactivated when reheats turn On.
!
WARNING
Risk of undersized electric power supply wiring. Can cause overheated wire resulting in
smoke, fire, activation of fire suppression systems, building evacuation, dispatching of
fire/rescue equipment and personnel, building damage, injury or death.
If the electrical service to the unit is not properly sized, it could trip the building circuit
breakers (or fuses) or, in extreme cases, damage the building wiring. This warning applies
only when the Dehumidification With Comp is set to BOTH and the Electric Reheat
Operation is set to Staged. Consult factory before making any changes to the default settings.