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Therefore, the amount to add to the economizer's ECONOMIN
configuration is: (0.5/1.5) x (50-20) = 10%. In effect, for the posi-
tioning of the economizer, ECONOMIN would now be replaced
by ECONOMIN + 10%.
Static Pressure PID Config (S.PID)
Static pressure PID configuration can be accessed under this head-
ing in the Configuration
conditions, the control PID factors will not require any adjustment
and the factory defaults should be used. If persistent static pressure
fluctuations are detected, small changes to these factors may im-
prove performance. Decreasing the factors generally reduces the
responsiveness of the control loop, while increasing the factors in-
creases its responsiveness. Note the existing settings before
making changes, and seek technical assistance from Carrier before
making significant changes to these factors.
Static Pressure PID Run Rate (S.PID
This is the number of seconds between duct static pressure read-
ings taken by the ComfortLink PID routine.
Static Pressure Proportional Gain (S.PID
This is the proportional gain for the static pressure control PID
control loop.
Static Pressure Integral Gain (S.PID
This is the integral gain for the static pressure control PID control
loop.
Static Pressure Derivative Gain (S.PID
This is the derivative gain for the static pressure control PID con-
trol loop.
STATIC PRESSURE RESET
The configuration for Static Pressure Reset is found under Config-
uration
SP.
ITEM
EXPANSION
SP.RS Static Press. Reset Sensor Enable/Disable SPRSTSEN
Static Pressure Reset Sensor
If outdoor air quality sensor is not configured (Configuration
IAQ
AQ.CF
OQ.A.C=0), then it is possible to use the outdoor
air quality sensor location on the CEM board to perform static
pressure reset via an external 4 to 20 mA input. Enabling this sen-
sor will give the user the ability to reset from 0 to 3 in. wg of static
pressure. The reset will apply to the supply static pressure set point
(Configuration
SP
SP.SP), where 4 mA = 0 in. wg and
20 mA = 3 in. wg.
As an example, the static pressure reset input is measuring 6 mA,
and the input is resetting 2 mA of its 16 mA control range. The 4
to 20 mA range corresponds directly to the 0 to 3 in. wg of reset.
Therefore, 2 mA reset is 2/16 * 3 in. wg = 0.375 in. wg of reset. If
the static pressure set point (SP.SP) = 1.5 in. wg, then the static
pressure control point for the system will be reset 1.5 – 0.375 =
1.125 in. wg.
For third-party 4 to 20 mA SP reset, wire the input to TB202 ter-
minals 6 and 7.
For reset via a connected ComfortID™ system, the Linkage Coor-
dinator terminal monitors the primary-air damper position of all
the terminals in the system. It then calculates the amount of supply
static pressure reduction necessary to cause the most open damper
in the system to open more than the minimum value (60%) but not
more than the maximum value (90% or negligible static pressure
drop). This is a dynamic calculation, which occurs every two min-
utes whenever the system is operating. It ensures that the supply
static is sufficient to supply the required airflow at the worst case
terminal but not more than necessary, so that the air terminals do
not have to operate with a pressure drop greater than required to
maintain the airflow set point of each individual terminal in the
system. As the system operates, if the most open damper opens
more than 90%, the system recalculates the pressure reduction
SP submenu. Under most operating
SP.TM)
SP.P)
SP.I)
SP.D)
RANGE
CCN POINT DEFAULT
variable and Configuration
reduced. If the most open damper closes to less than 60%, the sys-
tem recalculates the pressure reduction variable and SP.RS is
increased.
With this system, one needs to enter as the static pressure set point
SP.SP either a maximum duct design pressure or maximum equip-
ment pressure, whichever is less. The system will determine the
actual set point required and deliver the required airflow to every
terminal under the current load conditions. As the conditions and
airflow requirements at each terminal change throughout the oper-
ating period, so will SP.RS and the unit's effective static pressure
set point.
In the unlikely chance that both static pressure reset control signals
are simultaneously present, the CCN signal will take precedence.
RELATED POINTS
These points represent static pressure control and static pressure
reset inputs and outputs. See Table 62.
Static Pressure mA (SP.M)
This variable reflects the value of the static pressure sensor signal
received by the ComfortLink controls. It may in some cases be
helpful in troubleshooting.
Static Pressure mA Trim (SP.M.T)
This input allows a modest amount of trim to the 4-20 mA static
pressure transducer signal and can be used to calibrate transducers.
Static Pressure Reset mA (SP.R.M)
This input reflects the value of a 4 to 20 mA static pressure reset
signal applied to TB202 terminals 6 and 7, from a third-party con-
trol system.
Static Pressure Reset (SP.RS)
This variable reflects the value of a static pressure reset signal ap-
plied from a CCN system. The means of applying this reset is by
forcing the value of the variable SPRESET through CCN.
Supply Fan VFD Speed (S.VFD)
Disable
This output can be used to check on the actual speed of the VFD.
This may be helpful in some cases for troubleshooting.
Fan Status Monitoring
GENERAL
The P Series ComfortLink controls offer the capability to detect a
failed supply fan through either a duct static pressure transducer or
an accessory discrete switch. The fan status switch accessory (part
no. CRFANSTATUS001A00) allows for the discrete monitoring
of the ON/OFF status of the unit supply fan. The switch closes
when the delta pressure across the switch rises above a configu-
rable threshold value. The switch connects to plug PL34, which is
located in the supply fan compartment. See Carrier accessory liter-
ature for more details. For any unit with a factory-installed duct
static pressure sensor, it is possible to measure duct pressure rise
directly, which removes the need for a differential switch. Any
unit with an installed supply fan VFD will have the duct static
pressure sensor as standard.
SETTING UP THE SYSTEM
The fan status monitoring configurations are located in Configu-
ration
UNIT. See Table 63.
Fan Stat Monitoring Type (SFS.M)
This configuration selects the type of fan status monitoring to be
performed.
0 - NONE — No switch or monitoring.
1 - SWITCH — Use of the fan status switch.
2 - SP RISE — Monitoring of the supply duct pressure.
74
SP
SP.RS, the amount of reset, is
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Troubleshooting
