Ingersol Rand Precedent TSC120F Series, Сервисные данные

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Sequence of Operation
16 RT-SVF28F-EN
cooling," the economizer will be used first to attempt to
satisfy the supply setpoint. On units with economizer, a
call for cooling will modulate the fresh air dampers open.
The rate of economizer modulation is based on deviation
of the discharge temperature from setpoint, i.e., the further
away from setpoint, the faster the fresh air damper will
open. Note that the economizer is only allowed to function
freely if ambient conditions are below the enthalpy control
setting or below the return air enthalpy if unit has
comparative enthalpy installed. If outside air is not
suitable for "economizing," the fresh air dampers drive to
the minimum open position. A field adjustable
potentiometer on the Economizer Actuator, or a remote
potentiometer can provide the input to establish the
minimum damper position. At outdoor air conditions
above the enthalpy control setting, primary cooling only is
used and the fresh air dampers remain at minimum
position. If the unit does not include an economizer,
primary cooling only is used to satisfy cooling
requirements.
Supply Air Setpoint Reset
Supply air reset can be used to adjust the supply air
temperature setpoint on the basis of a zone temperature,
return air temperature, or on outdoor air temperature.
Supply air reset adjustment is available on the unit
mounted VAV Setpoint Potentiometer for supply air
cooling control.
Reset Based on Outdoor Air Temperature.
Outdoor
air cooling reset is sometimes used in applications where
the outdoor temperature has a large effect on building
load. When the outside air temperature is low and the
building cooling load is low, the supply air setpoint can be
raised, thereby preventing subcooling of critical zones.
This reset can lower usage of primary cooling and result in
a reduction in primary cooling energy usageThere are two
user-defined parameters that are adjustable through the
VAV Setpoint Potentiometer: reset temperature setpoint
and reset amount. The amount of reset applied is
dependent upon how far the outdoor air temperature is
below the supply air reset setpoint. The amount is zero
where they are equal and increases linearly toward the
value set at the reset amount input. The maximum value
is 20°F. If the outdoor air temperature is more than 20°F
below the reset temperature setpoint the amount of reset
is equal to the reset amount setpoint.
Reset Based on Zone or Return Temperature.
Zone
or return reset is applied to the zone(s) in a building that
tend to overcool or overheat. The supply air temperature
setpoint is adjusted based on the temperature of the
critical zone(s) or the return air temperature.This can have
the effect of improving comfort and/or lowering energy
usage. The user-defined parameters are the same as for
outdoor air reset. Logic for zone or return reset control is
the same except that the origins of the temperature inputs
are the zone sensor or return sensor respectively. The
amount of reset applied is dependent upon how far the
zone or return air temperature is below the supply air reset
setpoint. The amount is zero where they are equal and
increases linearly toward the value set at the reset amount
potentiometer on the VAV Setpoint Potentiometer. The
maximum value is 3°F. If the return or zone temperature is
more than 3°F below the reset temperature setpoint the
amount of reset is equal to the reset amount setpoint.
Zone Temperature Control
Unoccupied Zone Cooling
During Unoccupied mode, the unit is operated as a CV
unit. VAV boxes are driven full open and the supply fan is
commanded to full speed. The unit controls zone
temperature to the Unoccupied zone cooling setpoints.
Daytime Warm-up
During occupied mode, if the zone temperature falls to a
temperature three degrees below the Morning Warm-up
setpoint, Daytime Warm-up is initiated. The system
changes to CV heating (full unit airflow), theVAV boxes are
fully opened and the CV heating algorithm is in control
until the Morning Warm-up setpoint is reached.The unit is
then returned to VAV cooling mode. The Morning Warm-
up setpoint is set at the unit mounted VAV Setpoint
potentiometer or at a remote panel.
Morning Warm-up (MWU)
Morning warm-up control (MWU) is activated whenever
the unit switches from unoccupied to occupied and the
zone temperature is at least 1.5°F below the MWU setpoint.
When MWU is activated the VAV box output will be
energized for at least 6 minutes to drive all boxes open, the
supply fan is commanded to full speed, and full heat (gas
or electric) is energized. When MWU is activated the
economizer damper is driven fully closed. When the zone
temperature meets or exceeds the MWU setpoint minus
1.5°F, the heat will be turned or staged down. When the
zone temperature meets or exceeds the MWU setpoint
then MWU will be terminated and the unit will switch over
to VAV cooling.
Electromechanical Controls
These units are offered with two control options,
electromechanical and ReliaTel controls. The ReliaTel
controls is a microelectronic control feature, which
provides operating functions that are significantly
different than conventional electromechanical units.
Electromechanical Control Cooling
without an Economizer
When the thermostat switch is set to the “Cool” position
and the zone temperature rises above the cooling setpoint,
the thermostat Y contacts close. The compressor
contactor (CC1) coil is energized provided the low pressure
control (LPC1), high pressure control (HPC1) and
discharge line thermostat (TDL 1) are closed. When the
(CC1) contacts close, compressor (CPR1) and the outdoor
fan motor (ODM) start. If the first stage of cooling can not