Fan Alarm/Fan Settings; High Pressure Cutout - Emerson Liebert iCOM Training And Service Manual

iCOM
Controls Training and Service Manual

Fan Alarm/Fan settings

The fan operation is controlled by two (2) digital devices: the Loss of Airflow
differential pressure switch and the Main fan overload motor protection. The time
delay at the unit start is always 5 seconds shorter than the control delay.

High Pressure Cutout

When the compressor is commanded to turn ON after being OFF for a period of 10
minutes, or if the power has been removed from the unit and then turned back on,
this sequence of operations happens:
During the first 10 minutes of the compressor being turned ON after the above
situation, if a high head pressure situation occurs, the compressor will be turned
OFF for 10 seconds and then turned back ON again "as long as the high head
pressure input has been reset". This will happen with no alarm indication. The
alarm will be "masked out". This can happen 3 times within the first 10 minutes of
compressor being turned on.
These HP situations will not be visible on the service menu screens lines S313 or
S314 counters, but will be counted on an internal counter, not shown on the
display. This internal counter increases by 1, regardless if 1, 2 or 3 HP alarms
were masked out within the first 10 minutes after compressor start.
If a high head pressure situation occurs a fourth time (or if the HP input remains in
alarm position continuously for 30 seconds) in the first 10 minutes of running, the
compressor will be Locked OFF, an alarm will happen, and the counter of the
affected circuit will show "1" alarm occurred. Reaching "1" will lockout the
compressor and it will not come back on until main power is reset or the S313 or
S314 counters are reset to 0. Setting the counter to 0 (zero) will auto-reset the
alarm without the need of pressing the reset button on the control display. Setting
the visible counter to 0 (zero) will also reset the internal counter to 0 (zero); the
internal counter also will be reset to 0 (zero) after a power cycle. This has in effect
masked out the first three high head pressure situations if they are within the first
10 minutes of starting.
Note: if the unit is equipped with manual reset high head pressure switches, or if
the auto reset high head pressure switches don't reset, the compressor will not be
turned back on in the above situation, but there will be a 30 second delay from
when the high head pressure situation occurs and when the alarm is enunciated.
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