Carrier WeatherExpert 48N2 Controls, Start-Up, Operation, Service, And Troubleshooting page 45

Unit Size (SIZE)
There are 6 unit sizes (tons) for the N Series control. Make sure
this configuration matches the size called out by the model
number of the unit. This is important, as the cooling stage ta-
bles are directly determined based on the SIZE configuration.
EDT Reset Configuration (RS.CF)
This configuration applies to several machine control types
(Configuration  UNIT  C.TYP = 1,2,3, and 4). See Table 27.
• 0 = NO RESET
No supply air reset is in effect
• 1 = SPT RESET
Space temperature will be used as the reset control vari-
able along with both RTIO and LIMT in the calculation of
the final amount of reset to be applied (Inputs  RSET
 SA.S.R).
• 2 = RAT RESET
Return-air temperature will be used as the reset control
variable along with both RTIO and LIMT in the calcula-
tion of the final amount of reset to be applied (Inputs 
RSET  SA.S.R).
• 3 = 3RD PARTY RESET
The reset value is determined by a 4 to 20 mA third party
input. An input of 4 mA would correspond to 0ºF reset. An
input of 20 mA would correspond to 20ºF reset. Configur-
ing the control for this option will cause RES.S to become
enabled automatically with the CEM board. To avoid
alarms make sure the CEM board and third party input are
connected first before enabling this option.
Reset Ratio (RTIO)
This configuration is used when RS.CF is set to 1 or 2. For ev-
ery degree that the controlling temperature (space/return) falls
below the occupied cooling set point (OCSP), the calculated
value of the supply air reset will rise by the number of degrees,
as specified by this parameter.
Reset Limit (LIMT)
This configuration is used when RS.CF is set to 1 or 2. This
configuration places a clamp on the amount of supply air reset
that can be applied.
EDT 4-20 mA Reset Input (RES.S)
This configuration is automatically enabled when Configura-
tion  EDT.R  RS.CF is set to 3 (third party reset).
COOLING CONFIGURATION
Relevant configurations for mechanical cooling are located at
the local display under Configuration  COOL. See Table 28.
Enable Compressor A1 (A1.EN)
This configuration is used to disable the A1 compressor in case
of failure for size 75 to 150-ton units.
Enable Compressor A2 (A2.EN)
This configuration is used to disable the A2 compressor in case
of failure for size 75 to 150-ton units.
Enable Compressor A3 (A3.EN)
This configuration is used to disable the A3 compressor in case
of failure for size 90 and 100-ton units. It is always disabled for
size 75-ton units.
Enable Compressor A4 (A4.EN)
This configuration is used to disable the A4 compressor in case
of failure for size 120 to 150-ton units. It is always disabled for
size 75 to 105-ton units.
Enable Compressor B1 (B1.EN)
This configuration is used to disable the B1 compressor in case
of failure for size 75 to 150-ton units.
Enable Compressor B2 (B2.EN)
This configuration is used to disable the B2 compressor in case
of failure for size 75 to 150-ton units.
Enable Compressor B3 (B3.EN)
This configuration is used to disable the B3 compressor in case
of failure for size 75 to 150-ton units.
Enable Compressor B4 (B4.EN)
This configuration is used to disable the B4 compressor in case
of failure for size 120 to 150-ton units. It is always disabled for
size 75 to 105-ton units.
CSB A1 Feedback Alarm (CS.A1)
This configuration is used to enable or disable compressor A1
feedback alarm. This configuration must be enabled whenever
A1.EN is enabled.
CSB A2 Feedback Alarm (CS.A2)
This configuration is used to enable or disable compressor A2
feedback alarm. This configuration must be enabled whenever
A2.EN is enabled.
CSB A3 Feedback Alarm (CS.A3)
This configuration is used to enable or disable compressor A3
feedback alarm. This configuration must be enabled whenever
A3.EN is enabled.
CSB A4 Feedback Alarm (CS.A4)
This configuration is used to enable or disable compressor A4
feedback alarm. This configuration must be enabled whenever
A4.EN is enabled.
CSB B1 Feedback Alarm (CS.B1)
This configuration is used to enable or disable compressor B1
feedback alarm. This configuration must be enabled whenever
B1.EN is enabled.
CSB B2 Feedback Alarm (CS.B2)
This configuration is used to enable or disable compressor B2
feedback alarm. This configuration must be enabled whenever
B2.EN is enabled.
CSB B3 Feedback Alarm (CS.B3)
This configuration is used to enable or disable the compressor
B3 feedback alarm. This configuration must be enabled when-
ever B3.EN is enabled.
CSB B4 Feedback Alarm (CS.B4)
This configuration is used to enable or disable the compressor
B4 feedback alarm. This configuration must be enabled when-
ever B4.EN is enabled.
SUMZ EDT Derivative Gain (DT.GN)
This is the derivative gain for the SUMZ EDT PID control loop.
Capacity Threshold Adjust (Z.GN)
This configuration provides an adjustment to the SUMZ Cool-
ing Algorithm for capacity control. The configuration affects
the cycling rate of the cooling stages by raising or lowering the
threshold that demand must build to in order to add or subtract
a stage of cooling.
Normally this configuration should not require any tuning or
adjustment. If there is an application where the unit may be
significantly oversized and there are indications of high com-
pressor cycles, then the Capacity Threshold Adjust (Z.GN) can
be used to adjust the overall logic gain. Normally this is set to
1.0, but it can be adjusted from 0.1 to 10. As the value of Z.GN
is increased, the cycling of cooling stages will be slowed.
Compressor Lockout Temperature (MC.LO)
This configuration defines the outdoor air temperature below
which mechanical cooling is locked out.
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