135
YORK INTERNATIONAL
FORM 150.52-NM2 (1001)
6.3 LOCAL COOLING SETPOINTS KEY
The Local Cooling Setpoints key is used to program the
required Leaving Chilled Liquid control temperatures
for the application. When the key is pressed, the fol-
lowing message will be displayed:
Key in the desired Chilled Liquid Setpoint and the al-
lowable deviation (Range). The micro will accept val-
ues from -12 to 11°C (10.0 - 52.0°F). For values below
4°C (40°F), Dip Switch S1, Switch #1 on the Micro-
processor Board must be properly programmed for
Brine Cooling (see Section 9 [3.7]). If unacceptable val-
ues are entered, or the switch is incorrectly selected
when setpoints below 4°C (40°F) are entered, the fol-
lowing message will be displayed before returning to
the Control Range message :
After the Setpoint is keyed in, the cursor will automati-
cally advance to the first digit of the Range as shown :
This value should be programmed for the maximum al-
lowable positive and negative chilled liquid temperature
deviation that is acceptable from setpoint in the system
application. A typical value would be +/- 1°C (2°F). The
micro will accept a range from 0.8-1.4°C (1.5-2.5 °F).
After the Setpoint and Range is keyed in, press the
ENTER Key to store the data in memory.
The default values for both water and glycol cooling
are:
Setpoint = 6.7°C (44.0°F)
Range = 1.1°C (2.0°F)
Failure to press the Enter key will
cause the newly programmed values
to be ignored and not entered into
memory.
After pressing the Enter key, the display will continue
to show the message until another key is pressed.
6.4 REMOTE COOLING SETPOINTS KEY
Remote Cooling Setpoints key allows resetting the
setpoint upward from the programmed value in memory
from a remote device. This feature is typically used for
demand limiting or ice storage applications. Reset is ac-
complished by timed closure of external contacts for a
defined period of time and allows reset of the setpoint
upward by up to 22°C (40°F) above the setpoint pro-
grammed in memory - see Section 9 (1.10).
The maximum allowable reset must be programmed into
memory and can be a value of 1 to 22°C (2 to 40°F)
depending on user requirements. To program the reset,
press the Remote Reset Temperature Range key. The
following message will appear:
The display indicates the Remote Setpoint which is al-
ways equal to the chilled liquid setpoint programmed by
the Chilled Liquid Temperature / Range key plus the
offset from the remote reset signal. The display will
also show the Range which is the programmed maxi-
mum deviation allowed for the application. This display
is not programmable, and will change the setpoint only
through a signal from a remote device.
Pressing the REM RESET TEMP RANGE Key again
scrolls the display to the MAX EMS-PWM REMOTE
TEMP RESET which is programmable. This should be
programmed to the maximum offset which is required
for the application. The maximum programmable value
is 22°C (40° F), while the minimum programmable
value is 1°C (2°F).
The cursor will stop beneath the first digit of the maxi-
mum reset. Key in the maximum reset allowed for the
application, remembering to use a leading "0" for values
less than 10°C (or 10°F ). Press the ENTER Key to
store the new value in memory.
6.5 CHILLED LIQUID TEMPERATURE CONTROL
The Microprocessor controls the chiller loading and un-
loading to maintain the leaving chilled liquid within the
programmed control range. A 60-second load timer and
30-second unload timer determines when the micro may
adjust the chiller capacity to keep the chilled liquid tem-
perature within the control range. A fuzzy logic load-
S E T P O I N T
=
6 . 7
° C
R A N G E
=
+ / - 1 . 1
° C
O U T
O F
R A N G E -
T R Y
A G A I N !
S E T P O I N T
=
6 . 7
° C
R A N G E
=
+ / - 1 . 1
° C
R E M
S E T P
=
6 . 7
° C
R A N G E
=
+ / -
1 . 1
° C
M A X
E M S - P W M
R E M O T E
T E M P
R E S E T
=
+ 4 . 4 ° C
9
