56
higher supply static pressure to meet the load conditions. For
example, a system design requirement may be 1.2 in. wg, the
equipment may be capable of providing 3.0 in. wg and the sup-
ply duct is designed for 5.0 in. wg. In this case, the installer
could enter 3.0 in. wg as the supply static pressure setpoint and
allow the air terminal system to dynamically adjust the supply
duct static pressure setpoint as required.
The system will determine the actual setpoint required de-
livering the required airflow at every terminal under the current
load conditions. The setpoint will always be the lowest value
under the given conditions. As the conditions and airflow set-
points at each terminal change throughout the operating period,
the equipment static pressure setpoint will also change.
The CCN system must have access to a CCN variable
(SPRESET which is part of the equipment controller). In the
algorithm for static pressure control, the SPRESET value is
always subtracted from the configured static pressure setpoint
by the equipment controller. The SPRESET variable is always
checked to be a positive value or zero only (negative values are
limited to zero). The result of the subtraction of the SPRESET
variable from the configured setpoint is limited so that it
cannot be less than zero. The result is that the system will
dynamically determine the required duct static pressure based
on the actual load conditions currently in the space. This elimi-
nates the need to calculate the design supply static pressure set-
point. This also saves the energy difference between the design
static pressure setpoint and the required static pressure.
Third Party 4 to 20 mA Input — It is also possible to perform
static pressure reset via an external 4 to 20 mA signal connect-
ed to the CEM board where 4 mA corresponds to 0 in. wg of
reset and 20 mA corresponds to 3 in. wg of reset. The static
pressure 4 to 20 mA input shares the same input as the analog
OAQ sensor. Therefore, both sensors cannot be used at the
same time. To enable the static pressure reset 4 to 20 mA
sensor, set (
Configuration
SP
SP.RS
) to Enabled.
RELATED POINTS — These points represent static pressure
control and static pressure reset inputs and outputs. See Table 61.
Static Pressure mA (
SP.M
) — This variable reflects the value
of the static pressure sensor signal received by the
Comfort
Link
controls. The value may be helpful in troubleshooting.
Static Pressure mA Trim (
SP.M.T
) — This input allows a
modest amount of trim to the 4 to 20 mA static pressure trans-
ducer signal, and can be used to calibrate a transducer.
Static Pressure Reset mA (
SP.R.M
) — This input reflects the
value of a 4 to 20 mA static pressure reset signal applied to TB6
terminals 11 and 12 on the CEM board, from a third party con-
trol system.
Static Pressure Reset (
SP.RS
) — This variable reflects the
value of a static pressure reset signal applied from a CCN sys-
tem. The means of applying this reset is by forcing the value of
the variable SPRESET through CCN.
Supply Fan VFD Speed (
S.VFD
) — This output can be used
to check on the actual speed of the VFD. This may be helpful
in some cases for troubleshooting.
Table 60 — Static Pressure Control Configuration
* Some defaults are model number dependent.
† 33-67 when
CV.FD
= Yes.
** 67 when
CV.FD
= Yes.
Table 61 — Static Pressure Reset Related Points
ITEM
EXPANSION
RANGE
UNITS
CCN POINT
DEFAULT
SP
SUPPLY STATIC PRESS.CFG.
SP.CF
Static Pres. VFD Control?
0, 1
STATICFG
0*
CV.FD
Constant VOL IDF is VFD
Yes/No
CVIDFVFD
No
SP.FN
Static Pres. Fan Control?
Yes/No
STATPFAN
Yes*
SP.S
Static Pressure Sensor
Enable/Disable
SPSENS
Disable*
SP.LO
Static Press. Low Range
–10 - 0
in. W.C.
SP_LOW
0
SP.HI
Static Press. High Range
0 - 10
in. W.C.
SP_HIGH
5
SP.SP
Static Pressure Setpoint
0 - 5
in. W.C.
SPSP
1.5
SP.MN
VFD Minimum Speed
0 - 100†
%
STATPMIN
20**
SP.MX
VFD Maximum Speed
0 - 100
%
STATPMAX
100
SP.FS
VFD Fire Speed Override
0 - 100
%
STATPFSO
100
HT.V.M
VFD Heating Minimum Speed
75-100
%
VFDHTMIN
75
SP.RS
Stat. Pres. Reset Config
0 - 4
SPRSTCFG
0
SP.RT
SP Reset Ratio (
/dF)
0 - 2.00
SPRRATIO
0.2
SP.LM
SP Reset Limit in iwc (
)
0 - 2.00
SPRLIMIT
0.75
SP.EC
SP Reset Econo.Position
0 - 100
%
ECONOSPR
5
S.PID
STAT.PRESS.PID CONFIGS
SP.TM
Static Press. PID Run Rate
1 - 200
sec
SPIDRATE
2
SP.P
Static Press. Prop. Gain
0 - 100
STATP_PG
20
SP.I
Static Press. Intg. Gain
0 - 50
STATP_IG
2
SP.D
Static Press. Derv. Gain
0 - 50
STATP_DG
0
SP.SG
Static Press. System Gain
0 - 50
STATP_SG
1.0
ITEM
EXPANSION
RANGE
UNITS
CCN POINT
DEFAULT
Inputs
4-20
SP.M
Static Pressure mA
4-20
mA
SP_MA
4-20
SP.M.T
Static Pressure mA Trim
-2.0 - +2.0
mA
SPMATRIM
4-20
SP.R.M
Static Pressure Reset mA
4-20
mA
SPRST_MA
0.0
RSET
SP.RS
Static Pressure Reset
0.0-3.0
in. wg
SPRESET
0.0
Outputs
Fans
S.VFD
Supply Fan VFD Speed
0-100
%
SFAN_VFD
Содержание Carrier Weathermaker 48A2
Страница 105: ...105 Fig 20 Typical Main Control Box Wiring Schematic 48 50A2 A3 A4 A5 Units...
Страница 106: ...106 Fig 21 Typical Auxiliary Control Box Wiring Schematic...
Страница 107: ...107 Fig 22 Typical 2 Stage Gas Heat Wiring Schematic Size 060 Units Shown a48 8357...
Страница 108: ...108 TO NEXT PAGE Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown A48 7296...
Страница 109: ...109 Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown cont A48 8358...
Страница 110: ...110 Fig 24 Typical Electric Heat Control Schematic 50 Series Size 060 Units Shown a50 8228...
Страница 111: ...111 Fig 25 Typical Power Schematic 48 50A2 A3 A4 A5 060 Unit Shown...
Страница 112: ...112 Fig 26 Typical Low Ambient Controls Option Wiring...
Страница 113: ...113 Fig 27 Typical Small Chassis Component Location Size 020 035 Units...
Страница 114: ...114 Fig 28 Typical Large Chassis Component Locations Size 040 060 Units...
Страница 118: ...118 Fig 30 Economizer Control Board ECB1 and VAV Control Board ECB2 A48 7706...
Страница 142: ...142 A48 3733 Fig 56 Main Burner Removal...
Страница 176: ...176 APPENDIX C VFD INFORMATION cont Fig F Internal Enclosure Fan Replacement A48 7716...
