Microcomputer Control Center - York YPC Engineering Manual

MicroComputer Control Center

The MicroComputer Control Center is designed for the
very best chiller protection and overall system efficiency.
As standard equipment on all Millennium YPC Two-Stage
Absorption chillers, the Control Center is a major develop-
ment in absorption chiller technology, providing the most
precise and reliable control available in the industry.
INFORMATION DISPLAY
Vital chiller operating information can be shown on the 40
character alphanumeric display. All information is in the
English language with numeric data provided in English
or metric units. Information provided standard on all units
includes:
• Chilled water temperatures, entering and leaving
• Tower water temperatures, entering and leaving
• First-stage generator pressure and temperature
• Refrigerant temperature
• Solution temperature
• Operating hours
• Number of starts
• Number of purge cycles (last 7 days and lifetime total)
• Steam valve position (in %)
• Indication of each pump's operation
In addition, all operating and setpoint information can
be transmitted to an optional remote printer through the
RS232 port to obtain data logs:
• At any time by pressing the PRINT button
• At set time intervals by programming the panel
• After a safety shutdown to list the cause of the shut-
down and the operational parameters just prior to
shutdown
• For a complete history printout of the last four shut-
downs and operational parameters just prior to shut-
down.
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CAPACITY CONTROL
When automatic capacity control is desired, the Micro-
Computer Control Center automatically varies the steam
flow rate to maintain the programmed leaving chilled water
set point for cooling loads ranging from 20% to 100% of
design.
• Digital keypad entry of setpoint to 0.1°F (0.1°C)
• Verify actual vs. setpoint temperature via alphanu meric
display
• Remote reset of setpoint (up to 20°F (or 11.1°C) range)
with a 1 to 11 second PWM signal (optional 4-20mA,
0-10VDC or contact closure).
When automatic control is not desired, the input steam
flow rate is also manually adjustable for the MicroComput-
er Control Center panel to any setting between minimum
and maximum, provided steam input is not inhibited by a
specific operating condition (e.g. safety).
STEAM LIMITING CONTROLS
• Manual limiting available from 20% to 100% of capac-
ity.
• Programmable pull down demand limiting to auto-mat-
ically limit steam source loading at start-up.
• Remote limiting of steam input form 30% to 100% with
a 1 to 11 second PWM signal.
SYSTEM CYCLING CONTROLS
• Programmable seven day time clock for automatic
start/stop of chiller and chilled condenser water pumps.
• Separate schedule input strictly for holidays
• Remote cycling contacts available for other field sup-
plied signals
• Multi-unit cycling contact input terminals for field sup-
plied signals
FORM 155.19-EG3 (1011)
JOHNSON CONTROLS