Carrier TOUCHPILOT 30KAV, Manual

Page: 7 / 44

7
3.6 - Temperature sensors
Temperature sensors constantly measure the temperature of
various components of the unit, ensuring the correct
operation of the system.
Evaporator entering and leaving water temperature sensors
The evaporator entering and leaving water temperature
sensors are installed in the entering and leaving side water
box. They are used for capacity control and safety purposes.
Suction gas temperature sensor
This sensor is used to control the suction gas temperature.
It is located at the suction line of the compressor.
Discharge gas temperature sensor
This sensor is used to control the discharge gas temperature,
and permits control of the discharge superheat temperature.
It is located at the discharge line of the compressor.
Motor temperature sensor
This sensor is used to control the motor temperature of each
compressor.
Temperature setpoint reset sensor (EMM)
This 4-20 mA space temperature sensor can be installed
remotely from the unit. It is used to reset the setpoint on the
unit.
Master/slave water sensor (optional)
The water temperature sensor is used for master/slave
assembly control.
Outdoor air temperature
The outdoor air temperature sensor is used for fan control.
3.7 - Actuators
Evaporator pumps
The controller can regulate one or two evaporator pumps
and takes care of the automatic changeover between these
pumps.
Electronic Expansion Valve
The electronic expansion valve (EXV) is used to adjust the
refrigerant flow to changes in the operating conditions of the
machine. To adjust the refrigerant flow, a piston moves
constantly up or down to vary the cross-section of the
refrigerant path. This piston is driven by an electronically
controlled linear stepper motor. The high degree of accuracy
with which the piston is positioned provides precise control
of the refrigerant flow.
Water flow switch
The water flow switch allows the control to ensure the
minimum water flow that is necessary for the proper
functioning of the unit. The configuration of its setpoint
depends on the unit size and is made automatically at the
start-up. If the measured water flow rate in the water loop is
lower than the configured flow rate, the alarm condition shuts
off the unit.