3.6 - Pressure transducers
Three types of transducers (high pressure, low pressure, air
differential pressure) are used to measure various pressures in
each circuit. These transducers deliver 0 to 5 VDC. They are
connected to the SIOB board.
■
Discharge pressure transducers (high pressure type)
These transducers measure the discharge pressure in each
circuit. They are used to control condensing pressure or high
pressure load shedding. Discharge pressure sensors are
mounted on the discharge line piping of each circuit.
■
Suction pressure transducers (low pressure type)
These transducers measure the suction pressure in each
circuit. They are used to control EXV, evaporating pressure
(in heating mode) and monitor suction pressure safeties
related to the compressor operating envelope. Suction
pressure sensors are located on the common suction piping
of each circuit.
■
Air differential pressure transducers
These tranducers are used to estimate the airflow or to
control the building pressure by measuring the differential
pressure.
3.7 - Temperature sensors
Temperature sensors constantly measure the temperature of
various components of the unit, ensuring the correct operation
of the system.
■
Space temperature sensors
Up to two sensors may be used. They take into account
either an average space temperature or minimum and
maximum space temperatures, depending on the
configuration.
•
Sensor T-55: This is a 10K sensor
•
Optional sensor T-56: This 10K sensor is fitted with
:
- an offset slider to adjust the temperature setpoint.
Moving the slider to the left (cold) allows the
temperature setpoint to be reduced by as much as
3K and moving it to the right (warm) allows it to be
increased by up to 3K (in steps of ± 1K). When the
slider is in its central position there is no offset.
- a button for extending the occupied period from
one to four hours depending on the occupied
period extension value entered in the configuration
menu (see GENCONF menu).
•
Optional sensor T-55: This 10K snesor is fitted with
a button for extending the occupied period.
•
Optional room-mate comfort controller (sensor T-59):
This 10K sensor is fitted with :
•
- a customised liquid crystal display (LLCD) that
indicates space temperature and setpoint offset.
•
- an on/off function to start and stop the unit using
remote contacts.
- temperature offset adjustement which allows the
temperature setpoint to be reduced by as much as 3K
and to be increased by as much as 3K.
- a button to extend the occupied period extension
value entered in the configuration menu (see
GENCONF menu).
■
Supply air temperature sensor
The control system uses this to maintain a constant space
temperature. This is a Carrier 10K sensor.
■
Return air temperature sensor
The control system uses this to calculate the fresh air rate
when using economizer with VAV option. This is a Carrier
10K sensor.
■
Outdoor air temperature sensor
This Carrier 5K system controls the economizer, allows the
gas heating stages to be used on the heat pumps and offsets
he space temperature setpoint where this is appropriate.
■
Water coil frost protection sensor
This Carrier 5K sensor is used on units fitted with hot-water
systems.
■
Defrost termination sensor
This sensor measures the common water temperature in the
master/slave system capacity control. It is installed only in the
case of master/slave units.
■
Defrost temperature sensors (heat pumps)
This Carrier 5K sensor is used by the defrost function on heat
pump units.
■
Air quality sensor
This sensor controls room air quality. It is an optional sensor
of the 0-10V d.c type.
3.8 – The controls
■
Electronic expansion valve (EXV)
The electronic expansion valve (EXV) is used to adjust the
refrigerant flow to changes in the operating conditions of the
machine. The high degree of accuracy with which the piston
is positioned provides precise control of the refrigerant flow
and suction superheat.
■
Indoor supply fan
The controller can start or stop the indoor fan thanks to the
time schedule. With VAV option, the indoor supply fan speed
is adjusted to fit the ventilation needs.
Two types of fan are compatible with the unit, sandard fan
or high static fan. They can be chhosen upon the field
environment.
■
Return fan
In some applications with high return duct ESP, a return fan
may be applied to help supply fan to maintain the airflow and
the buiding pressure.
■
Heaters
The controller can control additional heaters for cooling only
or heat pump unit. The additional heater can be electrical;
hot water coil or gas heater.
■
Pre-heaters
With the option, the unit can control 2 electrical pre-heaters,
if unit size < 125 and 3 if unit size >= 125.
■
Energy recovery module (ERM)
SmartVu can control an optional energy recovery module for
optimised energy management of the exhaust air.
■
High ambient fresh air option
With this option, the unit can control supply airflow% or
Fresh Air% according to OAT or SST values. It is working in
cooling mode, with economizer and without ERM.
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