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1. INTRODUCTION & PHYSICAL DESCRIPTION
1.1
GENERAL
2
The YORK eco
Screw Chiller Control Panel is a mi-
croprocessor based control system fitted to YCAS liq-
uid chillers. It is capable of multi-refrigerant system
control to maintain chilled liquid temperature within pro-
grammed limits and to provide safety control of the
chiller. The microprocessor monitors leaving chilled liq-
uid temperature deviation from setpoint and the rate of
change of this temperature to start, stop, load and un-
load compressors as required.
User interface is via a touch keypad and a liquid crystal
display allowing access to operating and programmed
data. Information can be displayed in S.I. (Metric) units
or English (Imperial) units (Section 8.1). Conversion
tables are provided at the back of this manual.
A master ON / OFF rocker switch is provided on the
chiller control panel to activate or deactivate the com-
plete chiller, while switches to activate or deactivate
individual refrigerant systems are provided on the Mi-
croprocessor Board(s).
External interface is available for control of the chiller
via a YORK ISN System or YORK Remote Control
Center. In addition, EMS/BAS System connections are
provided for remote cycling, current limiting, remote tem-
perature setpoint reset and alarm annunciation.
YCAS chillers each have a single split circuit evapora-
tor serving 2 independent refrigerant systems. YCAS 2
system chillers are configured as a single self contained
section with a single control panel controlling the two
refrigerant systems.
YORK INTERNATIONAL
1.2
KEYPAD & DISPLAY
An operator keypad allows complete control of the chiller
from a central location. The keypad offers a multitude
of commands available to access displays, program
setpoints, and initiate system commands. Keys are
grouped and color coded for clarity and ease of use.
A 40 Character Liquid Crystal Display (2 lines of 20
characters) is used for displaying system parameters
and operator messages. The display has a lighted back-
ground for night viewing as well as a special feature
which intensifies the display for viewing in direct
sunlight.
Displays will be updated every two seconds by the mi-
croprocessor.
1.3
UNIT (CHILLER) ON / OFF SWITCH
A master UNIT (Chiller) ON / OFF switch is located
just below the keypad. This switch allows the operator
to turn the entire chiller OFF, if desired. The switch
must be placed in the ON position for the chiller to op-
erate. Any time the switch is in the OFF position, a
Status message indication will be displayed. See Page
93 for the location of this switch.
1.4
MICROPROCESSOR BOARD
The Microprocessor Board(s) controls and makes de-
cisions for the chiller. Information inputs from trans-
ducers and sensors around the chiller are either con-
nected directly to the Microprocessor Board or are con-
nected to the I/O Expansion Board and multiplexed be-
FORM 201.18-NM8
29023A
101
9
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