Carrier WeatherExpert 48N2, Controls, Start-Up, Operation, Service, And Troubleshooting, Page: 118 / 268

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Table 85 — Cooling Information Display Table
Cap Threshold Subtracting (Z.MIN)
This parameter is used in the calculation of SMZ and is calcu -
lated as follows:
Z.MIN = Configuration  COOL  Z.GN *
(–10 + (4* ( – SUB.R ))) * 0.6
Cap Threshold Adding (Z.PLU)
This parameter is used in the calculation of SMZ and is calcu -
lated as follows:
Z.PLU = Configuration  COOL  Z.GN *
(10 + (4* ( – ADD.R ))) * 0.6.
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, then a stage of mechanical cooling will be added
every 30 seconds. This override is intended to react to situa -
tions 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
error is less than –0.5  F, then a mechanical stage will be re -
moved every 30 seconds. This override is intended to quickly
react to situations where the load is rapidly reduced.
Pull Down Cap Override (PULL)
If the error from set point is above 4  F, and the 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 situation when it is needed. Most likely
pulldown will occur when mechanical cooling first becomes
available shortly after the 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
ITEM EXPANSION RANGE UNITS CCN POINT WRITE STATUS
COOL COOLING INFORMATION
C.CAP Current Running Capacity 0-100 % CAPTOTAL
CUR.S Current Cool Stage 0-20 COOL_STG
REQ.S Requested Cool Stage 0-20 CL_STAGE
MAX.S Maximum Cool Stages 0-20 CLMAXSTG
DEM.L Active Demand Limit 0-100 % DEM_LIM forcible
SUMZ COOL CAP. STAGE CONTROL
SMZ Capacity Load Factor –400-400 SMZ
ADD.R Next Stage EDT Decrease 0-30 ^F ADDRISE
SUB.R Next Stage EDT Increase 0-30 ^F SUBRISE
R.PCT Rise Per Percent Capacity 0-10 RISE_PCT
Y.MIN Cap Deadband Subtracting –40-0 Y_MINUS
Y.PLU Cap Deadband Adding 0-40 Y_PLUS
Z.MIN Cap Threshold Subtracting –99-0 Z_MINUS
Z.PLU Cap Threshold Adding 0-99 Z_PLUS
H.TMP High Temp Cap Override No/Yes HI_TEMP
L.TMP Low Temp Cap Override No/Yes LOW_TEMP
PULL Pull Down Cap Override No/Yes PULLDOWN
SLOW Slow Change Cap Override No/Yes SLO_CHNG
HMZR HUMIDIMIZER
CAPC Humidimizer Capacity 0-100 HMZRCAPC
C.EXV Condenser EXV Position 0-100 COND_EXV
B.EXV Bypass EXV Position 0-100 BYP_EXV
RHV Humidimizer 3-Way Valve No/Yes HUM3WVAL
C.CPT Cooling Control Point –20-140 COOLCPNT
EDT Evaporator Discharge Tmp –40-240 EDT
H.CPT Heating Control Point –20-140 HEATCPNT
LAT Leaving Air Temperature –40-240 LAT
EXVS EXVS INFORMATION
A1.EX Circuit A EXV 1 Position 0-100 % XV1APOSP
A2.EX Circuit A EXV 2 Position 0-100 % XV2APOSP
B1.EX Circuit B EXV 1 Position 0-100 % XV1BPOSP
B2.EX Circuit B EXV 2 Position 0-100 % XV2BPOSP
SH.A1 Cir A EXV1 Superheat Tmp –100-200 ^F SH_A1
SH.A2 Cir A EXV2 Superheat Tmp –100-200 ^F SH_A2
SH.B1 Cir B EXV1 Superheat Tmp –100-200 ^F SH_B1
SH.B2 Cir B EXV2 Superheat Tmp –100-200 ^F SH_B2
CTRL EXVS CONTROL INFORMATION
C.SHS EXV Superheat Ctrl SP 5-40 ^F SH_SP_CT
C.FLS EXV SH Flooding Ctrl SP 0-10 ^F FL_SP_CT
C.EXP EXV PID Ctrl Prop. Gain 0-5 EXV_PG_C
C.EXT EXV Ctrl Integrat. Time 0.5-60 EXV_TI_C
C.EXM Cir Strt EXV Mn Ctrl Pos 0-100 % EXCSMP_C