Controls, Start-Up, Operation, Service and ... - Climayoreo

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 0.5F, 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 error is less than
–0.5F, then a mechanical stage will be removed 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 4F, and the rate of change is less than –1F 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 represents about
7.5F of change to EDT. If stages could reliably be cycled at
Table 83 — Economizer Run Status Display Table
104
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 keeping the
PID under control when “relatively” close to set point.
VFD INFORMATION DISPLAY TABLE — The VFD information
display table provides information on the supply fan
VFD and exhaust fan VFD. See Table 85.
MODE TRIP HELPER — The Mode Trip Helper table provides
information on the unit modes and when the modes start
and stop. See Table 86. This information can be used to help
determine why the unit is in the current mode.
CCN/LINKAGE DISPLAY TABLE — The CCN/Linkage
display table provides information on unit linkage. See Table 87.
COMPRESSOR RUN HOURS DISPLAY TABLE — The
Compressor Run Hours Display Table displays the number of
run time hours for each compressor. See Table 88.
COMPRESSOR STARTS DISPLAY TABLE — The Compressor
Starts Display Table displays the number of starts for
each compressor. See Table 89.
SOFTWARE VERSION NUMBERS DISPLAY TABLE —
The Software Version Numbers Display Table displays the
software version numbers of the unit boards and devices. See
Table 90.
ITEM EXPANSION RANGE UNITS CCN POINT WRITE STATUS
ECON ECONOMIZER RUN STATUS
ECN.P Economizer Act.Curr.Pos. 0-100 % ECONOPOS
EC2.P Economzr2 Act.Curr.Pos. 0-100 % ECON2POS
ECN.C Economizer Act.Cmd.Pos. 0-100 % ECONOCMD forcible
ACTV Economizer Active ? YES/NO ECACTIVE
DISA ECON DISABLING CONDITIONS
UNV.1 Econ Act. Unavailable? YES/NO ECONUNAV
UNV.2 Econ2 Act. Unavailable? YES/NO ECN2UNAV
ENTH Enth. Switch Read High ? YES/NO ENTH
DBC DBC - OAT Lockout? YES/NO DBC_STAT
DEW DEW - OA Dewpt.Lockout? YES/NO DEW_STAT
DDBC DDBD- OAT > RAT Lockout? YES/NO DDBCSTAT
OAEC OAEC- OA Enth Lockout? YES/NO OAECSTAT
DEC DEC - Diff.Enth.Lockout? YES/NO DEC_STAT
EDT EDT Sensor Bad? YES/NO EDT_STAT
OAT OAT Sensor Bad ? YES/NO OAT_STAT
FORC Economizer Forced ? YES/NO ECONFORC
SFON Supply Fan Not On 30s ? YES/NO SFONSTAT
CLOF Cool Mode Not In Effect? YES/NO COOL_OFF
OAQL OAQ Lockout in Effect ? YES/NO OAQLOCKD
HELD Econ Recovery Hold Off? YES/NO ECONHELD
DH.DS Dehumid. Disabled Econ.? YES/NO DHDISABL
O.AIR OUTSIDE AIR INFORMATION
OAT Outside Air Temperature dF OAT forcible
OA.RH Outside Air Rel. Humidity % OARH forcible
OA.E Outside Air Enthalpy OAE
OA.D.T OutsideAir Dewpoint Temp dF OADEWTMP