Trane IntelliPak WEHE Series Installation, Operation And Maintenance Manual page 14

General Information
Compressor (DX) Cooling
Compressor control and protection schemes will function
identical to that of a traditional unit. Normal compressor
proving and disable input monitoring will remain in effect
as well as normal 3-minute minimum on, off, and inter-
stage timers. Also, all existing head pressure control
schemes will be in effect.
Cooling Sequence
If the control determines that there is a need for active
cooling capacity in order to meet the calculated discharge
air target setpoint, once supply fan proving has been
made, the unit will begin to stage compressors
accordingly. Note that the compressor staging order will
be based on unit configuration and compressor lead/lag
status.
Once the discharge air target setpoint calculation has
reached the Minimum Setpoint and compressors are
being utilized to meet the demand, as the discharge air
target setpoint value continues to calculate lower the
algorithm will begin to ramp the supply fan speed up
toward 100%. Note that the supply fan speed will remain
at the compressor stage's associated minimum value (as
described below) until the discharge air target setpoint
value is calculated below the discharge air temperature
Minimum Setpoint (limited discharge air target setpoint).
As the cooling load in the zone decreases the zone cooling
algorithm will reduce the speed of the fan down to
minimum per compressor stage and control the
compressors accordingly. As the compressors begin to
de-energize, the supply fan speed will fall back to the
Cooling Stage's associated minimum fan speed, but not
below. As the load in the zone continues to drop, cooling
capacity will be reduced in order to maintain the discharge
air within the ± ½ discharge air target deadband.
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