Specifications

Catalog WSC/WDC-4 19
Starter Data Displayed
As standard, the percent of rated load amps (RLA) is displayed on the interface screen as a bar
chart. In addition, there are two options available to display additional starter data on screen. The
options are:
• Ammeter Display
, which displays phase amps and average amps
• Full Metering Display
, which displays phase and average amps, phase and average volts,
compressor kilowatts, power factor and unit kilowatt-hours.
These options, in particular the full metering option, give the owner/operator a great deal of
valuable electrical information in an easily accessed screen.
WDC Chiller Controls
Each model WDC dual compressor chiller comes complete with its own factory-mounted and
wired MicroTech II controller system featuring:
• 12-inch color touchscreen operator interface panel
• Microprocessor-based unit controller
• Microprocessor-based controller for each compressor
This distributed control scheme allows the operation of each compressor independently from the
other. Elapsed time, number of starts, percent RLA; are all monitored separately by each
MicroTech II control panel. In addition, individual compressor fault history, setpoint control,
loading functions, time of day starts, etc., can be controlled and monitored.
Compressor staging and the load balance function are a standard feature of each MicroTech II
control. Smart scheduling starts the compressor with the fewest number of starts first, and will
only start remaining compressors when proof of sufficient load has been established. The staging
function will stop the compressor with the most run-hours when the load decreases to single
compressor range. During two-compressor operation, the load balance function will equalize the
load between each compressor, providing optimum unit efficiency.
25% or greater annual kWh savings over the range of 5% to 60% design tons
The majority of comfort cooling systems operate at 60% or less of building design tons for most
of the year. A great number of those operating hours occur between 50% and 60% design cooling
capacity.
For that reason, the Model WDC chiller was designed to produce up to 60% unit capacity with a
single operating compressor, efficiently and reliably.
That performance is achieved by a combination of individual component features that include
compressor design, operating control, double heat transfer surface, and refrigerant flow control.
Versatile Communications Capabilities Give You Even More Control
For complete flexibility there are three ways to interface with the MicroTech II controller:
1. Direct entry and readout locally at the controller's operator interface panel on the unit.
2. Direct entry as above, plus digital and analog input/output signals for certain functions such as
enable run input, alarm signal output, 4-20ma or 0-5 VDC inputs for chilled water reset and
load limiting, outputs for pump and tower fan control, analog output for variable speed tower
fan and/or tower bypass valve.
3. Interface with a building automation system (BAS) with optional factory-installed Protocol
Selectability™ communication modules, eliminating additional gateways. The module can
also be field installed anytime after the unit is installed and operating.