Space Temperature Control Mode Response For C.typ=5 - Carrier 38APS025 Manual

For mechanical cooling, the unit's Control Method (Con-
figuration OPT2 CTRL) and inputs must allow the ma-
chine to run. See Control Methods on page 60 for additional
information.
On power up or changing from Off to Enabled, the machine
will remain off until Minutes Off Time Configuration
OPT2 DELY timer has expired. See Minutes Off Time on
page 128 for additional information. Liquid Line Solenoid
Valve operation is as described in Liquid Line Solenoid Valves
on page 40. Time Guard is honored for all compressors. For
specific information on Time Guard, see MDTG - Time Guard
Active on page 135.
In this Control Type, Space Temp Control Mode, Run
Status VIEW SPT.M=0 (Off Cool) as long as Run
Status VIEW STAT=1 (Off Local), 2 (Off CCN), 3 (Off
Time), or 4 (Off Emrgcy). When the Control Mode, STAT=5
(On Local), 6 (On CCN), or 7 (On Time), SPT.M=1 (Lo Cool)
if Y1 is closed (Inputs GEN.I Y.1=ON), SPT.M=2 High
Cool if Y2 is closed (Inputs GEN.I Y.2=ON), or SPT.M=0
(Off Cool) if Y1 and Y2 are both open, Y.1=OFF and
Y.2=OFF. With this Control Type, if the Indoor Fan Status
Switch opens, Inputs GEN.I ID.F.A=OFF, STAT will
change to 8 (IDFS Not On), the unit will remain with SPT.M=0
(Off Cool) if Y1 and Y2 are both open, Y.1=OFF and
Y.2=OFF. If Y1 or Y2 close, Y.1=ON or Y.2=ON the unit Con-
trol Mode will change from STAT=8 (IDFS Not On), to 4 (Off
Emrgcy) as an alarm is generated. Table 32 shows the space
temperature control mode response for C.TYP=5.
Table 32 — Space Temperature Control Mode
Response for C.TYP=5
SPACE
CONTROL
TEMPERATURE
MODE STAT
SPT
1 (Off Local) Not Applicable
2 (Off CCN) Not Applicable
3 (Off Time) Not Applicable
4 (Off Emrgcy) Not Applicable
SPS.P + LC.ON –
L.C.OF < SPT <
SPS.P + LC.ON
5 (On Local)
SPS.P + L.C.OF/2 <
SPT < SPS.P +
L.C.ON + H.C.ON
SPS.P + LC.ON –
L.C.OF < SPT <
SPS.P + LC.ON
6 (On CCN)
SPS.P + L.C.OF/2 <
SPT < SPS.P +
L.C.ON + H.C.ON
SPS.P + LC.ON –
L.C.OF < SPT <
SPS.P + LC.ON
7 (On Time)
SPS.P+L.C.OF/2 <
SPT < SPS.P +
L.C.ON + H.C.ON
8
Not Applicable
(IDFS Not On)
9 < SPS.P + LC.ON –
(SPT Satisfied) L.C.OF
*There is built-in overlap of the High Cool and Low Cool Operation.
Actual Space Temperature Control Mode depends on the direction
of space temperature change (positive or negative) and its starting
point.
38APD Units — On a call for cooling, the Indoor Fan Status
Cir A (Inputs GEN.I ID.F.A) is checked. The switch must
be closed before the capacity routine will start. The lead circuit
is determined. See Lead/Lag Determination on page 112. The
lead compressor will be determined and started. See Circuit
SPACE
INDOOR
TEMPER-
FAN
ATURE
STATUS
CONTROL
CIR A
MODE
ID.F.A
SPT.M
Off or On 0 (Off Cool)
Off or On 0 (Off Cool)
Off or On 0 (Off Cool)
Off or On 0 (Off Cool)
On 1 (Lo Cool)*
On 2 (Hi Cool)*
On 1 (Lo Cool)*
On 2 (Hi Cool)*
On 1 (Lo Cool)*
On 2 (Hi Cool)*
Off 0 (Cool Off)*
On 0 (Cool Off)*
75
Compressor Staging on page 112. If the lead compressor is a
digital compressor and is enabled, the compressor will start
fully loaded for 90 seconds prior to starting to cycle between
loaded and unloaded. Compressors will be staged until the
unit's supply air temperature meets the Control Point (CTPT)
as described in Supply Air Temperature Control on page 110.
If additional capacity requires the lag circuit to start, the lag
circuit's lead compressor will be determined and started. Dur-
ing operation, the controls will stage the condenser fans to
maintain head pressure.
page 117.
As part of normal operation, if a single compressor in a mul-
tiple compressor circuit (38APD040-130) operates for the cu-
mulative time of 60 minutes without an increase in circuit ca-
pacity, an oil recovery routine is initiated. When this routine is
initiated, a second compressor in the circuit is started. Once
started, the normal capacity control routine takes priority and
will turn off the compressor if needed.
As the capacity requirement begins to decrease, the ma-
chine controls will reduce the unit's capacity to maintain the
Control Point. If the unit is equipped with Minimum Load
Control, it will not be active until the unit is on its last stage of
capacity.
38APS — On a call for cooling, the Indoor Fan Status Cir A
(Inputs GEN.I ID.F.A) is checked. The switch must be
closed before the capacity routine will start. The lead compres-
sor will be determined and started. See Circuit Compressor
Staging on page 112. If the lead compressor is a digital com-
pressor and is enabled, the compressor will start fully loaded
for 90 seconds prior to starting to cycle between loaded and
unloaded. Compressors will be staged until the unit's supply
air temperature meets the Control Point (CTPT) as described
in Supply Air Temperature Control on page 110. During oper-
ation, the controls will stage the condenser fans to maintain
head pressure. See Head Pressure Control on page 117.
As part of normal operation, if a single compressor operates
for the cumulative time of 60 minutes without an increase in
circuit capacity, an oil recovery routine is initiated. When this
routine is initiated, a second compressor in the circuit is started.
Once started, the normal capacity control routine takes priority
and will turn off the compressor if needed.
As the capacity requirement begins to decrease, the ma-
chine controls will reduce the unit's capacity to maintain the
Control Point. If the unit is equipped with Minimum Load
Control, it will not be active until the unit is on its last stage of
capacity. The liquid line solenoid valve is de-energized 5 sec-
onds after the circuit stops.
C.TYP = 7 (PCT CAP) — This configuration will allow the
main base board (MBB) to monitor the 4-20 mA cooling
demand signal Inputs 4-20 CL.MA input to the energy
management module and translate this into desired percent
capacity for the unit.
Recommended Applications — This configuration is com-
patible with both standard and digital compressors. This appli-
cation is intended for direct capacity control by a third-party
control system. All safeties remain in effect (minimum run
time, time guard, low saturated suction, high condensing tem-
perature, low superheat, etc.).
Hardware Requirements — The following hardware is
required:
• energy management module
• 4 to 20 mA generator
Required Configurations — Table 33 lists the configurations
required for proper operation.
Wiring — See Fig. 85.
See Head Pressure Control on