FORM 150.60-NM4
YORK INTERNATIONAL
37
The micro will accept a range of programmable values
between 200-390 PSIG for the unload point. For this fea-
ture 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).
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 un-
load the affected compressor which reduces motor heat-
ing.
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 water
start with related high system suction pressure. Its 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 temperature
range over which the micro may override normal system
loading timers and react to actual rate of change of re-
turn 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 response,
demand limiting/energy saving, or reduced loader and
compressor cycling. Typically this value should be
programmed for 00.1°F. When programming values
like 00.1°F, it is first required to key in “00”. Example:
00.1°F. Additional details for programming this control will
be discussed in the SELECTION OF RETURN OR LEAV-
ING CHILLED LIQUID CONTROL Section (Page 41).
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 be-
fore another start takes place or motor damage may re-
sult. The anti-recycle timer assures the motor has suffi-
cient time to cool before it is again restarted.
An adjustable timer allows for the motor cooling required,
but gives the user the ability to extend the timer to cut
down on cycling. In some applications fast compressor
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 tolerable. Although
300 seconds is adequate motor cooling time, longer pe-
riods will allow even more heat dissipation, reduce cy-
cling, 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 advance 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.
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
