Specifications

YORK INTERNATIONAL 7
FORM 160.48-O1
The system setpoints (see Fig. 4) are operator entered
on the front control center “Setpoints” keypad. These
set points can also be displayed on the 40 character
alphanumeric display. The system setpoints are:
• CHILLED LIQUID TEMPERATURE (LCWT)
• % CURRENT LIMIT
• PULLDOWN DEMAND LIMIT
• CLOCK (TIME-OF-DAY)
• DAILY SCHEDULE (7 DAY TIME-CLOCK
PROGRAMMING)
• HOLIDAY
• REMOTE RESET TEMPERATURE RANGE
• DATA LOGGER
The cause of all system shutdowns (safety or cycling)
is preserved (until the system is reset or restarts) in the
microcomputer’s memory for subsequent viewing on the
keypad display. The operator is continually advised of
system operating conditions by various background and
warning messages. The keypad contains special service
keys for use by the service technician when performing
system troubleshooting.
The MicroComputer Control Center is designed to be
compatible with most energy management systems
(EMS) in use today. The standard design allows for the
following EMS interface:
1. Remote Start
2. Remote Stop
3. Remote LCWT Setpoint (Pulse Width Modulated
signal)
4. Remote Current Limit Setpoint (Pulse Width Modu-
lated signal)
5. A “Remote Mode Ready to Start” Status Contacts
6. Safety Shutdown Status Contacts
7. Cycling Shutdown Status Contacts
As an enhancement to the standard EMS features, an
optional card file with plug-in printed circuit boards is
available. These optional cards will accept a remote
LCWT 0° to 10°F or 0° to 20°F setpoint offset and/or
remote current limit setpoint interface from three user
input choices:
1. 4-20 mA
2. 0-10 VDC
3. contact closures
CONTROL CENTER
The Control Center front panel layout consists of five
key groups, one switch, and a 1 line by 40 character
alphanumeric vacuum fluorescent display: (See Fig. 4)
CHARACTER DISPLAY - The alphanumeric vacuum
fluorescent display is located to the right of the “STA-
TUS” key. All messages, parameters, set points, and data
can be viewed at this location. The main communica-
tions between the operator or service technician and the
MicroComputer Control Center occurs on this display.
DISPLAY - Provide a direct read-out of each monitored
parameter on the alphanumeric display.
ENTRY - These keys are used to enter the values for
the operator programmed setpoints. These keys are
used in conjunction with the “SETPOINT” keys while in
program mode.
SETPOINTS - These keys are used as follows:
1. To view each setpoint, in any Mode, or
2. To select the individual setpoints that are programmed
by the operator in “Program” Mode only.
Pressing the appropriate key enables the operator to
program that setpoint pressing the “ENTRY” keys.
SERVICE - Included in this group of keys are those
functions that are only relevant to servicing the chiller.
Typically, these keys would not be used for daily chiller
operation.
ACCESS CODE - Permits operator to access the pro-
gram.
PROGRAM - Permits operator to program the Control
Center.
MODE - Permits operator to check what mode the Con-
trol Center is presently in (“LOCAL”, “REMOTE” or “SER-
VICE”).
1. Service - allows manual PRV control with visual dis-
play readout of PRV operation.
2. Local - allows manual compressor start from the
“COMPRESSOR” switch on control center front.
3. Program - allows operator programming of system
setpoints.
4. Remote - allows remote start, remote stop of com-
pressor and remote reset of LCWT and % current
limit.
COMPRESSOR - “START”, “RUN”, “STOP/RESET”
SWITCH - This 3 position rocker switch is used to start
(except in “REMOTE” mode), stop/run/reset the system.