York YCAZ33BA3, Руководство пользователя, Страница: 36 / 88

YORK INTERNATIONAL
36
SUCTION PRESSURE UNLOAD
The SUCTION PRESSURE UNLOAD point is a pro-
grammable limit designed to assure that suction gas
returning to the compressor is cool enough to provide
adequate compressor cooling.
If the suction pressure rises to the suction pressure un-
load pressure, the micro will automatically totally unload
the affected compressor which reduces motor heating.
Reloading will occur when the suction pressure drops
to 10 PSIG below the programmed unload pressure
and will increment one stage at a time as dictated by
the loading timers.
This safety will only come into action on a very hot wa-
ter start with related high system suction pressure. It’s
sole purpose is to prolong motor life.
To program the SUCTION 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 80-105 PSIG for the unload point.
NOTE: When programming values from 80-99 PSIG, it
is required to first key in a “0”. Example: 085 PSIG.
RATE CONTROL TEMP
The RATE CONTROL TEMP establishes a tempera-
ture range over which the micro may override normal
system loading timers and react to the actual rate of
change of return and leaving water temperature. This
temperature range is slightly above the setpoint with
its band width being programmable. This control works
in conjunction with the RATE SENSITIVITY which is
also programmable.
These controls allow the chiller to adapt to a full range
of applications. Depending on how the controls are set
up, the chiller can be adapted to provide maximum re-
sponse, demand limiting/energy saving, or reduced
loader and compressor cycling. Typically, this value
should be programmed for 00.1°F. When program-
ming values like 00.1°F, it is first required to key in
“00”. Example: 00.1°F. Additional details for program-
ming this control will be discussed in the SELECTION
OF RETURN OR LEAVING CHILLED LIQUID CON-
TROL Section (Page 40).
ANTI RECYCLE TIME
The ANTI-RECYCLE TIME selection allows the user
to select the compressor anti-recycle time to best suit
his needs. Motor heating is a result of inrush current
when the motor is started. This heat must be dissipated
before another start takes place or motor damage may
result. The anti-recycle timer assures the motor has
sufficient time to cool before it is again restarted.
An adjustable timer allows for the motor cooling re-
quired, but gives the user the ability to extend the timer
to cut down on cycling. In some applications fast com-
pressor start response is necessary; in others, it is not.
These needs should be kept in mind and the timer
should be adjusted for the longest period of time toler-
able. Although 300 seconds is adequate motor cooling
time, longer periods will allow even more heat dissipa-
tion, reduce cycling, and possibly increase motor life.
To program the ANTI RECYCLE TIME, key in the de-
sired value and press the ENTER key. The new value
will be entered into memory and the display will ad-
vance to the next user programmable limit.
The micro will accept a range of programmable values
between 300-600 seconds for this operating control.
LEAVING WATER TEMP CUT-OUT
The LEAVING WATER TEMP CUT-OUT protects the
chiller from an evaporator freeze-up should the chilled
liquid temp drop below the freeze point. This situation
could occur under low flow conditions or if the micro
panel SETPOINT values are improperly programmed.
Anytime the leaving chilled liquid temperature (water
or glycol) drops to the cut-out point, the chiller will shut
down. Restart will occur when temperature rises above
the cut-out if the anti-recycle timers are satisfied.
For chilled water applications (comfort cooling, SW1
OPEN), the cut-out is automatically set at 36.0°F. This
covers applications where leaving water temperatures
are not designed to go below 40.0°F. If chilled liquid
(glycol) temperatures are required below 40°F, the cut-
out should be programmed for 4°F below the desired
leaving chilled liquid temperature.
To program the LEAVING WATER TEMP CUT-OUT the
BRINE & PROCESS MODE (SW1, CLOSED) must be
selected, 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 programmable limit.
S U C T I O N P R E S S U R E
U N L O A D = 0 9 0 P S I G
R A T E C O N T R O L T E M P
= 0 8 . 0 F
A N T I R E C Y C L E T I M E
= 6 0 0 S E C S
L E A V I N G W A T E R T E M P
C U T O U T = 3 6 . 0 F