York Millennium YCAJ150, Установка, эксплуатация и обслуживание, Страница: 44 / 116

44 YORK INTERNATIONAL
NOTE: It is required to first key in a “0” when program-
ming this cut-out (Example: 0395 PSIG).
More details on this safety are outlined in the SYSTEM
SAFETIES section.
OUTSIDE AIR TMP LOW CUT-OUT
The OUTSIDE AIR TMP LOW CUT-OUT allows the user
to select the chiller low ambient temperature cutout point.
If the ambient falls below this point the chiller will shut
down. Restart can occur, if demand allows, when tem-
perature rises above the cut-out. This only applies to
outdoor air-cooled chillers.
For normal ambient applications, the cut-out is set at
25.0°F (-3.9°C) and is NOT programmable. However, some
users may set the cut-out higher to shut down the chiller
and take advantage of other less costly cooling sources.
In this case, S1 Dip Switch #2 on the Micro Logic Board
must be in the CLOSED position for Low Ambient Control
to allow programming the cut-out above 25°F (-3.9°C).
Low ambient applications in ambients less than 25.0°F
(-3.9°C) require a low ambient kit to be installed. Other-
wise nuisance low pressure and low motor current trips
will result. If a low ambient kit is installed, the cut-out
may be lowered as needed below 25°F (-3.9°C). If opera-
tion is occasionally needed below 0°F (-17.8°C) the cut-
out should be set at 00.0°F (-17.8°C). This will allow
operation at any temperature since the micro is only
able to recognize temperatures above 1°F (-17.2°C), re-
gardless of the display.
NOTE: Operation below 0°F (-17.8°C) may cause other
types of nuisance safety shutdowns, but occa-
sional shutdowns can usually be tolerated since
the need for sustained operation at these tem-
peratures is unlikely and temperatures rarely sta-
bilize for any length of time below 0°F (-17.8°C).
The micro will accept a range of programmable values
between 00.0° - 50.0°F (-17.8 - 10°C) for this cut-out, if
S1 Dip Switch #2 on the Micro Logic Board is in the
CLOSED position. In the OPEN position, a fixed 25°F
(-3.9°C) cutout is recognized.
To program the OUTSIDE AlR TMP LOW CUT-OUT, key
in the desired value and press the ENTER key. The new
value will be entered into memory and the display will
advance to the next user programmable limit.
OUTSIDE AIR TMP HIGH CUT-OUT
The OUTSIDE AIR TMP HIGH CUT-OUT is selectable to
establish the high ambient cut-out point. If the ambient
rises above this point, the chiller will shut down. Restart
can occur when temperature drops below the cut-out.
This only applies to outdoor air-cooled chillers.
This cut-out is normally set at 130.0°F (54.4°C) to allow
operation to the absolute maximum temperature capa-
bility of the electro-mechanical components.
To program the OUTSIDE AIR TMP HIGH CUT-OUT, key
in the desired value and press the ENTER key. The new
value will be entered into memory and the display will
advance to the next user programmable limit.
The micro will accept a range of programmable values
between 100.0 - 130.0°F (37.8 - 54.4°C) for this cut-out.
DISCHARGE PRESSURE UNLOAD
The DISCHARGE PRESSURE UNLOAD point is a pro-
grammable limit to keep the system from faulting on the
high discharge pressure cut-out should a system prob-
lem or chiller problem occur. A typical problem would be
if the cooling tower would become dirty on a water-cooled
system. Pressure would rise and eventually cause the
chiller to fault causing total loss of cooling. By unloading
the compressors at high discharge pressures, the chiller
is allowed to continue to run automatically at reduced
capacity until the dirty cooling tower can be attended to.
When the unload point is reached, the micro will auto-
matically totally unload the affected compressor. Typi-
cal maximum programmed limits would be 375 PSIG
(2.6 mPa) for air-cooled chillers with 395 or 405 PSIG
(2.7 or 2.8 mPa) high pressure cut-outs and 255 PSIG
(1.8 mPa) water-cooled chillers with 275 PSIG (1.9 mPa)
cut-outs.
Reloading will occur when the discharge pressure drops
to 60 PSIG (413.7 kPa) below the programmed unload
pressure and will increment one stage at a time as dic-
tated by the loading timers.
To program the DISCHARGE PRESSURE UNLOAD, key
in the desired value and press the ENTER key. The new
value will be entered into memory and the display will
advance to the next user programmable limit.
The micro will accept a range of programmable values
between 200 - 390 PSIG (1.4 - 2.7 mPa) for the unload
point. For this feature to be functional, the Discharge
Pressure Readout Option must be installed.
NOTE: It is required to first key in a “0” when program-
ming this cut-out (Example: 0375 PSIG).
O U T S I D E A I R T M P L O W
C U T O U T = 2 5 . 0 F
O U T S I D E A I R T M P H I G H
C U T O U T = 1 3 0 . 0 F
D I S C H A R G E P R E S S U R E
U N L O A D = 3 6 0 P S I G