York MILLENIUM YCAS Series, Installation Operation & Maintenance, Page: 98 / 156

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YORK INTERNATIONAL
Micro Panel Contents
1. INTRODUCTION & PHYSICAL DESCRIPTION
29023A
1.1 GENERAL
The YORK Millennium Screw Chiller Control Panel is
a microprocessor based control system fitted to YCAS
liquid chillers. It is capable of multi-refrigerant system
control to maintain chilled liquid temperature within
programmed 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 English (Impe-
rial) units or S.I. (Metric) units (Section 8.1). Conver-
sion 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
temperature 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.
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.