©2025 Copeland LP.
026-1803 R13 Supervisor I&O User Guide 9 - 57
The TD setpoint is the optimal difference between the
refrigerant drop leg temperature and the ambient (plenum)
temperature. When the TD (i.e., drop leg temp + drop leg
offset - plenum temp) begins to climb above this setpoint,
fans will be cycled ON to bring down the drop leg
temperature, thus lowering the TD measurement.
The TD deadband setpoint is a range of values around the TD
Setpoint within which the value of the TD calculation is
acceptable. When the TD rises above the setpoint plus 1/2
the deadband value, fans will begin cycling ON. When the TD
falls below the setpoint minus 1/2 the deadband value, fans
will cycle OFF.
For the Condenser Fan On Delay setpoint, fans are cycled ON
when the TD is above the setpoint at the rate set for
Condenser Fan On Delay. For example, if this field is set to 30
seconds, each fan is staged ON in 30-second intervals until all
fans are ON, or until the TD falls back below the setpoint.
For the Condenser Fan Off Delay setpoint, fans are cycled
OFF when the TD is below the setpoint at the rate set for
Condenser Fan Off Delay. In other words, if this field is set to
30 seconds, each fan is staged OFF in 30-second intervals
until all fans are OFF, or until the TD rises back above the
setpoint.
9.40.6 Inputs
The Drop Leg Temperature input is the current drop leg
temperature used for TD control.
The Plenum Temperature input provides the current value of
the ambient temperature used for TD calculation.
9.40.7 Alarms
For Drop Leg High alarm, the alarm setpoint is the drop leg
temperature that, if exceeded, will cause an alarm to be
generated. If you wish to generate an alarm for high drop leg
temperature, enter the desired setpoint. Otherwise, to disable
this alarm, leave the value set to NONE.
For Drop Leg Delay, if the drop leg alarming feature is used,
enter the amount of time the drop leg temperature must be
higher than the setpoint before an alarm will be generated
(HHH:MM).
For TD High alarm, the TD alarm setpoint is the value of the
TD calculation that, if exceeded, will cause an alarm to be
generated. If you wish to generate an alarm for high TD, enter
the desired setpoint. Otherwise, to disable this alarm, leave
the value set to NONE.
For TD Delay, if the TD alarming feature is used, enter the
amount of time the TD must be higher than the setpoint
before an alarm will be generated (HHH:MM)
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