Carrier 50TCA04-A07 - Manual (Page 34)

34
C06053
Fig. 56 -- EconoMi$er IV Functional View
EconoMi$er IV
Table 11 provides a summary of Economizer IV.
Troubleshooting instructions are enclosed.
A functional view of the EconoMi$er is shown in 56.
Typical settings, sensor ranges, and jumper positions are
also shown. An EconoMi$er IV simulator program is
available from Carrier to help with EconoMi$er IV
training and troubleshooting.
EconoMi$er IV Standard Sensors
Outdoor Air Temperature (OAT) Sensor
The outdoor air temperature sensor (HH57AC074) is a 10
to 20 mA device used to measure the outdoor-air
temperature. The outdoor-air temperature is used to
determine when the EconoMi$er IV can be used for free
cooling. The sensor is factory-installed on the
EconoMi$er IV in the outdoor airstream. (See Fig. 55.)
The operating range of temperature measurement is 40_ to
100_F (4_ to 38_C). See Fig. 55.
Supply Air Temperature (SAT) Sensor
The supply air temperature sensor is a 3 K thermistor
located at the inlet of the indoor fan. (See Fig. 57.) This
sensor is factory installed. The operating range of
temperature measurement is 0° to 158_F (--18_ to 70_C).
See Table 5 for sensor temperature/resistance values.
SUPPLY AIR
TEMPERATURE
SENSOR
MOUNTING
LOCATION
SUPPLY AIR
TEMPERATURE
SENSOR
C06033
Fig. 57 -- Supply Air Sensor Location
The temperature sensor looks like an eyelet terminal with
wires running to it. The sensor is located in the “crimp
end” and is sealed from moisture.
Outdoor Air Lockout Sensor
The EconoMi$er IV is equipped with an ambient
temperature lockout switch located in the outdoor
airstream which is used to lock out the compressors below
a 42_F (6_C) ambient temperature. (See Fig. 52.)
EconoMi$er IV Control Modes
IMPORTANT: The optional EconoMi$er2 does not include
a controller. The EconoMi$er2 is operated by a 4 to 20
mA signal from an existing field-supplied controller (such
as PremierLink™ control). See Fig. 54 for wiring
information.
Determine the EconoMi$er IV control mode before set up
of the control. Some modes of operation may require
different sensors. (See Table 12.) The EconoMi$er IV is
supplied from the factory with a supply--air temperature
sensor and an outdoor-- air temperature sensor. This allows
for operation of the EconoMi$er IV with outdoor air dry
bulb changeover control. Additional accessories can be
added to allow for different types of changeover control
and operation of the EconoMi$er IV and unit.
Outdoor Dry Bulb Changeover
The standard controller is shipped from the factory
configured for outdoor dry bulb changeover control. The
outdoor air and supply air temperature sensors are
included as standard. For this control mode, the outdoor
temperature is compared to an adjustable setpoint selected
on the control. If the outdoor-air temperature is above the
setpoint, the EconoMi$er IV will adjust the outside air
dampers to minimum position. If the outdoor-air
temperature is below the setpoint, the position of the
outside air dampers will be controlled to provided free
cooling using outdoor air. When in this mode, the LED
next to the free cooling setpoint potentiometer will be on.
The changeover temperature setpoint is controlled by the
free cooling setpoint potentiometer located on the control.
(See Fig. 58.) The scale on the potentiometer is A, B, C,
50TC