Specifications

18 Catalog WSC/WDC-4
Trend Logging
Ever wonder how your chiller
performed last week? Were
you holding the correct
chilled water temperature?
What kind of cooling load did
the chiller have?
The McQuay MicroTech II
controller can provide the
answers, thanks to its huge
memory, and plot water
temperatures, refrigerant
pressures, and motor load
data. These values can also
be downloaded through a
convenient USB port, located
in the unit control panel, and
pasted into a spreadsheet for
archiving or further detailed
evaluation.
MicroTech II Controller Increases Chiller Operating Economy
Many standard features have been incorporated into MicroTech II control in order to maintain the
operating economy of McQuay centrifugal chillers. In addition to replacing normal relay logic
circuits, we’ve enhanced the controller's energy saving capabilities with the following features:
• Direct control of water pumps
. Optically isolated, digital output relays provide automatic
lead-lag of the evaporator and condenser pumps, permitting pump operation only when
required.
• User-programmable compressor soft loading
. Prevents excessive power draw during pull
down from high chilled water temperature conditions.
• Chilled-water reset
. Accomplished directly on the unit by resetting the leaving water
temperature based on the return water temperature, a remote 4-20 ma or a 1-5 VDC BAS
signal. Raising the chilled water setpoint during periods of light loads dramatically reduces
power consumption.
• Demand limit control
. Maximum motor current draw can be set on the panel, or can be
adjusted from a remote 4-20ma or 1-5 VDC BAS signal. This feature controls maximum
demand charges during high usage periods.
• Condenser water temperature control.
Capable of four stages of tower fan control, plus an
optional analog control of either a three-way tower-bypass valve or variable speed tower-fan
motor. Stages are controlled from condenser-water temperature. The three-way valve can be
controlled to a different water temperature or track the current tower stage. This allows
optimum chilled water plant performance based upon specific job requirements.
• Staging Options (Multiple Chiller Installations)
. The MicroTech II controller is capable of
compressor staging decisions and balancing compressor loads between McQuay chillers using
defaults or operator-defined staging.
• Plotting Historic Trends
. Past operation of the chiller can be plotted as trend lines and even
downloaded to spread sheets for evaluation - a valuable tool for optimizing efficiency.