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70
Static Pressure Configuration (SP.CF)
This variable is used to configure the use of
Comfort
Link for
static pressure control. It has the following options:
• 0 (DISABLED) - No static pressure control by
Com
-
fort
Link controls. This would be used for a constant vol
-
ume (CV) application when static pressure control is not
required or for a VAV application if there will be third-par
-
ty control of the VFD. In this latter case, a suitable means
of control must be field-installed.
• 1 (ENABLED) - This will enable the use of
Comfort
Link
controls
Staged Air Volume Control (SP.SV)
This variable enabled the use of a CV unit with VFD for staged
air volume control.
Static Pressure Sensor (SP.S)
This variable enables the use of a supply duct static pressure
sensor. This must be enabled to use
Comfort
Link controls for
static pressure control. If using a third-party control for the
VFD, then this should be disabled.
Static Pressure Low Range (SP.LO)
This is the minimum static pressure that the sensor will mea
-
sure. For most sensors this will be 0 in. wg.
Comfort
Link con
-
trols will map this value to a 4 mA sensor output.
Static Pressure High Range (SP.HI)
This is the maximum static pressure that the sensor will mea
-
sure. Commonly this will be 5 in. wg. The
Comfort
Link con
-
trols will map this value to a 20 mA sensor output when the
signal is 20 mA.
Static Pressure Set Point (SP.SP)
This is the static pressure control point. It is the point against
which
Comfort
Link controls compares the actual measured
supply duct pressure for determination of the error that is used
for PID control. Adjust
SP.SP
to the minimum value necessary
for proper operation of air terminals in the conditioned space at
full load and part load. Too high a value will cause unnecessary
fan motor power consumption at part load conditions and/or
noise problems. Too low a value will result in insufficient air
-
flow.
VFD Minimum Speed (SP.MN)
This is the minimum speed for the supply fan VFD. Typically
the value is chosen to maintain a minimum level of ventilation.
NOTE: Most VFDs have a built-in minimum speed adjustment
that should be configured for 0% when using
Comfort
Link con
-
trols for static pressure control.
VFD Maximum Speed (SP.MX)
This is the maximum speed for the supply fan VFD. This is
usually set to 100%.
VFD Fire Speed Override (SP.FS)
This is the speed that the supply fan VFD will use during the
fire modes: pressurization, evacuation, and purge. This is usu
-
ally set to 100%.
Static Pressure Reset Configuration (SP.RS)
This option is used to configure the static pressure reset func
-
tion. When
SP.RS
= 0, there is no static pressure reset via an
analog input. When
SP.RS
= 1, there is static pressure reset
based on the CEM 4 to 20 mA input and ranged from 0 to 3 in.
wg. When
SP.RS
= 2, there is static pressure reset based on
RAT and defined by
SP.RT
and
SP.LM
. When
SP.RS
= 3, there
is static pressure reset based on SPT and defined by
SP.RT
and
SP.LM
. When
SP.RS
= 4, there is VFD speed control where
4 mA = 0% speed and 20 mA = 100% (
SP.MN
and
SP.MX
will
override).
Static Pressure Reset Ratio (SP.RT)
This option defines the reset ratio in terms of static pressure
versus temperature. The reset ratio determines how much the
static pressure is reduced for every degree below set point for
RAT or SPT.
Static Pressure Reset Limit (SP.LM)
This option defines the maximum amount of static pressure re
-
set that is allowed. This is sometimes called a “clamp.”
NOTE: Resetting static pressure via RAT and SPT is primarily
a constant volume application that utilizes a VFD. The reason
-
ing is that there are significant energy savings in slowing down
a supply fan as opposed to running full speed with supply air
reset. Maintaining the supply air set point and slowing down
the fan has the additional benefit of working around dehumidi
-
fication concerns.
Static Pressure PID Config (S.PID)
Static pressure PID configuration can be accessed under this
heading in the
Configuration
SP
submenu. Under most oper
-
ating conditions, the control PID factors will not require any
adjustment and the factory defaults should be used. If per
-
sistent static pressure fluctuations are detected, small changes
to these factors may improve performance. Decreasing the fac
-
tors generally reduce the responsiveness of the control loop,
while increasing the factors increase its responsiveness. Note
the existing settings before making changes, and seek technical
assistance from Carrier service personnel before making sig
-
nificant changes to these factors.
Static Pressure PID Run Rate (
S.PID
SP.TM
) —
This is the
number of seconds between duct static pressure readings taken
by the
Comfort
Link PID routine.
Static Pressure Proportional Gain (
S.PID
SP.P
) —
This is
the proportional gain for the static pressure control PID control
loop.
Static Pressure Integral Gain (
S.PID
SP.I
) —
This is the in
-
tegral gain for the static pressure control PID control loop.
Static Pressure Derivative Gain (
S.PID
SP.D
) —
This is the
derivative gain for the static pressure control PID control loop.
RELATED POINTS
These points represent static pressure control and static pres
-
sure reset inputs and outputs. See Table 47.
Table 47 —
Static Pressure Reset Related Points
ITEM
EXPANSION
RANGE
UNITS
CCN POINT
DEFAULT
Inputs
4-20
SP.M
Static Pressure mA
4 to 20
mA
SP_MA
4-20
SP.M.T
Static Pressure mA Trim
–2.0
+2.0
mA
SPMATRIM
RSET
SP.RS
Static Pressure Reset
0.0 to 3.0
in. wg
SPRESET
0.0
4-20
SP.M
Static Pressure Reset mA
4 to 20
mA
SP_MA
0.0
Outputs
FANS
S.VFD
Supply Fan VFD Speed
0 to 100
%
SFAN_VFD
Summary of Contents for WeatherExpert 48N2
Page 135: ...135 Fig 18 48 50N Typical Power Schematic Nominal 075 Ton Unit Shown ...
Page 136: ...136 Fig 19 48 50N Typical Power Schematic Nominal Ton 90 150 Units Shown ...
Page 137: ...137 Fig 20 48 50N Main Base Board Input Output Connections ...
Page 138: ...138 Fig 21 48 50N RXB EXB CEM Input Output Connections a48 9307 ...
Page 139: ...139 Fig 22 48 50N EXV SCB Input Output Connections a48 9308 ...
Page 140: ...140 Fig 23 48N Typical Modulating Gas Heat Unit Control Wiring ...
Page 141: ...141 Fig 24 50N Typical Electric Heat Unit Control Wiring ...
Page 144: ...144 Fig 27 48N Typical Gas Heat Section Wiring Nominal Ton 120 to 150 Units ...
Page 145: ...145 Fig 28 48 50N Typical Power Component Control Wiring 460 v ...
Page 146: ...146 Fig 29 48 50N Component Control Wiring 575 v Nominal Ton 075 to 150 Units ...
Page 147: ...147 Fig 30 48 50N Component Arrangement Power Box ...
Page 148: ...148 Fig 31 48 50N Component Arrangement Control Box ...
Page 240: ...240 APPENDIX D VFD INFORMATION CONT Fig G VFD Bypass Wiring Diagram WHEN USED ...