Dunham-Bush WCFX-E Series, Manual

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UNIT FEATURES
ADVANCED CONTROLLER
Vision 2020i a flexible and advance programmable
electronic controller designed specifically for the
applications and precise control of Dunham-Bush Rotary
Screw compressor chillers.
The controller is provided with a set of terminals that
connected to various devices such as temperature
sensors, pressure and current transducers, solenoid
valves, compressors and fans contactors, control relays
and etc. Three sizes of controller are provided to handle
different number of input and output requirements: DB5-S
small board, DB5-M medium board and DB5-L large
board.
The unit algorithm program and operating parameters are
stored in FLASH-MEMORY that does not require a back-
up battery. The program can be loaded through PC or
programming key.
Vision2020i controller is equipped with a user friendly
terminal with 7” diagonal TFT 800 x 480 WVGA color
touch screen led back light graphical display, and
dedicated touch keys that provides easy access to the
unit operating conditions, control set points and alarm
history.
Each unit’s controller can be configured and connected to
the local DBLAN network that allows multiple units
sequencing control without additional hardware. The
DBLAN is local area network made up of several chillers’
controller.
Display and User Terminal
Vision 2020i controller is design to work with a user
friendly DBG5 7” graphical colour touch screen display
panel which connected with controller through shielded
twisted pair cable. The terminal allows carrying out all
program operations. The user terminal allows displaying
the unit working conditions, compressor run times, alarm
history and modifying the parameters. The display also
has an automatically self-test of the controller on system
start-up. Multiple messages will be displayed by
automatically scrolling from each message to the next. All
of these messages are spelled out in English language
on the display terminal.
There are touch keys enable user to access information,
base on the security level of the password. For more
detail operation of the Display Terminal, please refer to
the Unit Operation Manual.
Easily accessible measurements include:
D
Leaving chilled water temperature
D
Leaving chiller water temperature derivative
D
Evaporator Pressure
D
Condenser Pressure
D
Compressor amp draw of each compressor
D
Compressor elapsed run time of each compressor
D
Compressor starts status
D
Oil level sensor status
D
Water temperature reset value
D
Water flow switch status
D
External start/stop command status
D
Trend graph for leaving chilled water temperature
Optional entering chilled water temperature, leaving and
entering condenser water temperature are available. With
this option the operator can quickly and accurately read
all significant water temperatures and eliminate the need
for often-inaccurate thermometers. Voltage readout is
also offered as an optional feature.
Capacity Control
Leaving chilled water temperature control is
accomplished by entering the water temperature setpoint
and placing the controller in automatic control. The unit
will monitor all control functions and move the slide valve
to the required operating position. The compressor ramp
(loading) cycle is programmable and may be set for
specific building requirements. Remote adjustment of the
leaving chilled water setpoint is accomplished through
either direct connection of other Dunham-Bush control
packages to the controller through either the RS485 long
distance differential communications port, or from an
external Building Automation System supplying a simple
4 to 20mA signal. Remote reset of compressor current
limit may be accomplished in a similar fashion.
System Control
The unit may be started or stopped manually, or through
the use of an external signal from a Building Automation
System. In addition, the controller may be programmed
with seven-day operating cycle or other Dunham-Bush
control packages may start and stop the system through
inter-connecting wiring.
System Protection
The following system protection controls will automatically
act to insure system reliability:
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Low suction pressure
D
High discharge pressure
D
Freeze protection
D
Low differential pressure
D
Low oil level
D
Compressor run error
D
Power loss
D
Chilled water flow loss
D
Sensor error
D
Compressor over current
D
Compressor Anti-recycle
The controller can retains up to 99 alarm conditions
complete with time of failure together data stamping on
critical sensor readings in alarm history screens. This tool
will aid service technicians in troubleshooting tasks
enabling downtime and nuisance trip-outs to be
minimized.