JOHNSON CONTROLS
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SECTION 1 - SYSTEM FUNDAMENTALS
FORM 161.01-OM1
ISSUE DATE: 6/8/2018
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Variable Speed Drive
The Variable Speed Drive is factory packaged with
the chiller. It is designed to vary the compressor motor
speed by controlling the frequency and voltage of the
electrical power to the motor. The control logic auto-
matically adjusts motor speed as required to suit lift
and capacity requirements. The VSD is connected to
an OptiView Control center. The VSD and OptiView
communicate using a Modbus communication proto-
col.
Optional Service Isolation Valves
If the chiller is equipped with optional service isolation
valves on the discharge and liquid line. These valves
are used for isolating the refrigerant charge in either
the evaporator or condenser to allow service access to
the system and must remain open during operation. A
refrigerant pump-out unit will be required to isolate the
refrigerant.
Isolation of the refrigerant in this system
must be performed by a qualied service
technician.
Optional Hot Gas Bypass
Hot gas bypass is optional and is used to provide great-
er turndown than otherwise available for load and head
conditions. The OptiView Control Center will auto-
matically modulate the hot gas valve open and closed
as required. Adjustment of the hot gas control valve
must only be performed by a qualified service techni-
cian.
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FIGURE 3 - OPTIVIEW CONTROL CENTER
OptiView Control Center
The YORK OptiView™ control center LCD graphic
display and keypad is the interface for starting, stop-
ping, configuring, monitoring, and commanding the
chiller. The control center is a microprocessor based
system designed for centrifugal chillers. It controls the
LCHLT (leaving chilled liquid temperature) and main-
tains safe operation of the chiller.
The display allows for the presentation of operating pa-
rameters and can trend data to present a graphical rep-
resentation of both present and historical operation of
the chiller. The locations of various chiller parameters
are clearly and intuitively marked. Instructions for spe-
cific operations are provided on many of the screens.
The screens and navigation are shown in "SECTION
3 - OPTIVIEW™ CONTROL CENTER FUNCTIONS
AND NAVIGATION".
Eight buttons are available on the right side of the pan-
el, which are primarily used for navigation between the
system screens. At the base of the display are 6 ad-
ditional buttons. The button functions are redefined
based on the currently displayed screen. The area to
the right of the keypad is used for data entry. A stan-
dard numeric keypad is provided for entry of system
setpoints and limits.
The Decimal key provides accurate entry of
setpoint values.
A +/- key has also been provided to allow entry
of negative values and AM/PM selection dur-
ing time entry.
In order to accept changes made to the chiller
setpoints, the Check key is provided as a uni-
versal ‘Enter’ key or ‘Accept’’ symbol.
In order to reject entry of a setpoint or dismiss
an entry form, the ‘X’ key is provided as a uni-
versal ‘Cancel’ symbol.
Cursor Arrow keys are provid-
ed to allow movement on
screens which contain a large
amount of entry data. In addi-
tion, these keys can be used to
scroll through history and event
logs.
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