Specifications

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:
• 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.
• 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.
• Staging Options (Multiple Chiller
• User-programmable compressor soft loading
.
Prevents excessive power draw during pull
down from high unoccupied chilled water
temperature conditions.
Installations). Lead-lag and load-balance: the
MicroTech II controller is capable of
compressor lead-lag decisions and balancing
compressor loads between two compressors on
one unit or two separate WMC chillers, using
defaults or operator defined staging. For
example, in the 30 to 60 percent load segment,
one compressor running on each of two
chillers will provide better efficiency than two
compressors running on one chiller.
• 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 1-5 VDC
BAS signal can also be used to reset the
leaving water. Raising the chilled water
setpoint during periods of light loads
dramatically reduces electrical consumption.
• 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.
• Demand limit control
. Maximum motor
current draw can be set on the panel, or can be
adjusted from a remote 4-20 ma or 1-5 VDC
BAS signal. This feature controls maximum
demand charges during high usage periods.
12 Catalog WMC-4