Carrier Weathermaster 48P030-100 Controls, Start-Up, Operation, Service, And Troubleshooting page 56

ITEM
COOL COOLING INFORMATION
C.CAP Current Running Capacity
CUR.S Current Cool Stage
REQ.S Requested Cool Stage
MAX.S Maximum Cool Stages
DEM.L Active Demand Limit
SUMZ COOL CAP. STAGE CONTROL
SMZ Capacity Load Factor
ADD.R Next Stage EDT Decrease
SUB.R Next Stage EDT Increase
R.PCT Rise Per Percent Capacity
Y.MIN Cap Deadband Subtracting
Y.PLU Cap Deadband Adding
Z.MIN Cap Threshold Subtracting
Z.PLU Cap Threshold Adding
H.TMP High Temp Cap Override
L.TMP Low Temp Cap Override
PULL Pull Down Cap Override
SLOW Slow Change Cap Override
HMZR HUMIDIMIZER
CAPC Humidimizer Capacity
C.EXV Condenser EXV Position
B.EXV Bypass EXV Position
RHV Humidimizer 3-Way Valve
C.CPT Cooling Control Point
EDT Evaporator Discharge Tmp
H.CPT Heating Control Point
LAT Leaving Air Temperature
High Temp Cap Override (H.TMP)
If stages of mechanical cooling are on and the error is greater than
twice Y.PLU, and the rate of change of error is greater than 0.5F
per minute, then a stage of mechanical cooling will be added every
30 seconds. This override is intended to react to situations where
the load rapidly increases.
Low Temp Cap Override (L.TMP)
If the error is less than twice Y.MIN, and the rate of change of er-
ror is less than –0.5F per minute, then a mechanical stage will be
removed every 30 seconds. This override is intended to quickly re-
act to situations where the load is rapidly reduced.
Pull Down Cap Override (PULL)
If error from set point is above 4F and rate of change is less than
–1F per minute, then pulldown is in effect, and "SUM" is set to 0.
This keeps mechanical cooling stages from being added when the
error is very large but there is no load in the space. Pulldown for
units is expected to rarely occur, but is included for the rare situa-
tion when it is needed. Most likely, pulldown will occur when me-
chanical cooling first becomes available shortly after control goes
into an occupied mode (after a warm unoccupied mode).
Slow Change Cap Override (SLOW)
With a rooftop unit, the design rise at 100% total unit capacity is
generally around 30F. For a unit with 4 stages, each stage rep-
resents about 7.5F of change to EDT. If stages could reliably be
cycled at very fast rates, the set point could be maintained very
precisely. Since it is not desirable to cycle compressors more
than 6 cycles per hour, slow change override takes care of keep-
ing the PID under control when "relatively" close to set point.
Humidi-MiZer Capacity (CAPC)
This variable represents the total reheat capacity currently in use
during a Humidi-MiZer mode. A value of 100% indicates that all
of the discharge gas is being bypassed around the condenser and
into the Humidi-MiZer dehumidification/reheat coil (maximum
reheat). A value of 0% indicates that all of the flow is going
through the condenser before entering the Humidi-MiZer dehu-
midification/reheat coil (dehum/subcooling mode).
Condenser EXV Position (C.EXV)
This variable represents position of condenser EXV (percent
open).
Table 40 — Run Status Cool Display
EXPANSION RANGE UNITS
%
%
–100 to +100
^F
^F
Bypass EXV Position (B.EXV)
This variable represents position of bypass EXV (percent open).
Humidi-MiZer 3-Way Valve (RHV)
This variable represents the position of the 3-way valve used to
switch the unit into and out of a Humidi-MiZer mode. A value of
0 indicates that the unit is in a standard cooling mode. A value of 1
indicates that the unit has energized the 3-way valve and entered
into a Humidi-MiZer mode.
Cooling Control Point (C.CPT)
Displays current cooling control point (a target value for air tem-
perature leaving the evaporator coil location). During a Humidi-
MiZer mode, this variable will take on the value of the dehumidify
cool set point (Configuration
will stage up or down to meet this temperature.
Evaporator Discharge Temperature (EDT)
Displays the temperature measured between the evaporator coils
and the Humidi-MiZer dehumidification/reheat coil. Units config-
ured with Humidi-MiZer system have a thermistor grid installed
between these two coils to provide the measurement. This tem-
perature can also be read at Temperatures
Heating Control Point (H.CPT)
Displays the current heating control point for Humidi-MiZer coil.
During a Reheat mode, this temperature will be either an offset
subtracted from return air temperature (D.V.RA) or the Vent Re-
heat Set Point (D.V.HT). During a Dehumidification Mode, this
temperature will take on the value of the original cooling control
point so that the supply air is reheated just enough to meet the sen-
sible demand in the space. The Humidi-MiZer modulating valves
will adjust to meet this temperature set point.
Leaving Air Temperature (LAT)
Displays the leaving air temperature after the Humidi-MiZer re-
heat/dehumidification coil.
SumZ Operation
The SumZ algorithm is an adaptive PID style of control. The PID
(proportional, integral, derivative) is programmed within the con-
trol and the relative speed of staging can only be influenced by the
user through the adjustment of the Z.GN configuration, described
in the reference section. The capacity control algorithm uses a
modified PID algorithm, with a self adjusting gain which
56
CCN POINT WRITE STATUS
CAPTOTAL
COOL_STG
CL_STAGE
CLMAXSTG
DEM_LIM forcible
SMZ
ADDRISE
SUBRISE
RISE_PCT
Y_MINUS
Y_PLUS
Z_MINUS
Z_PLUS
HI_TEMP
LOW_TEMP
PULLDOWN
SLO_CHNG
HMZRCAPC
COND_EXV
BYP_EXV
HUM3WVAL
COOLCPNT
EDT
HEATCPNT
LAT
 
.
DEHU D.C.SP) Compressors
 
AIR.T CCT.