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Unit Controls
The control system is comprised of PLC, HMI and BMS
interface device. All unit controls and devices have been
factory installed and tested prior to shipment. The control
circuit incorporates all major safety devices and control
features for optimum performance and reliability. Display
screen will indicate status of all equipment and parameters.
Any fault in the system can be detected without any manual
intervention.
Chiller Controller
Mechanical chilling is controlled via T3C and Companion
Controller (both are Danfoss MCX products). This Danfoss
refrigeration controller is specifically designed to work with
the turbocor oil-less compressors in the most efficient
manner. All I/O and Setpoints are displayed on a Schneider
HMI.
Freeze Protection
The freeze control senses the temperature of the chilled
water outlet from the evaporator. It shuts down the module,
enables pumps, and opens any isolation valves under the
control of the module if abnormally low water temperature
is reached (factory set based on freezing point of chilled or
condenser fluid).
Flow Switch
A flow switch is a safety device which prevents the unit
from operating with little or no water flow.
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NOTICE
Proof of Flow Switch!
Failure to provide flow switches or jumping-out of
switches could result in severe equipment damage.
Evaporator water circuits require proof of flow
switches.
•
Failure to include the proof of flow devices and/or
jumping out these devices could cause the unit to
stop on a secondary level of protection.
•
Frequent cycling on these higher level diagnostic
devices could cause excessive thermal and pressure
cycling of unit components (O-rings, gaskets,
sensors, motors, controls, etc.) and/or freeze damage,
resulting in premature failure of the chiller.
Temperature Control
The temperature transducers sense the return chilled water
temperature, and the controller monitors this signal and
cycles the refrigeration system to maintain accurate
process water temperature. The set point can be changed
using HMI.
Electronic Expansion Valves
The Electronic Expansion Valve (EXV) is a metering device
that automatically controls the flow of refrigerant to the
evaporator based on superheat/sub-cooling. The EXV
allows operation at low condensing pressures/
temperatures and saves energy by increasing the
efficiency of the chiller through precise superheat/sub-
cooling control.
ARTC-SVX013A-EN
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