35
7.0 COMPONENTS & CONTROLS
Components
7.11 Outdoor Fan Motor
All (-)A20 condensing units are equipped with a vari
-
able speed outdoor fan motor controlled by a pulse
width modulated signal (PWM) from the Variable
Speed Outdoor Control. The fan speed is selected to
optimize performance based on compressor speed.
7.12 Outdoor Fan Blade
All (-)A20 condensing units are equipped with a
swept fan blade design that provides improved
efficiency and quieter operation than conventional
fan blade designs.
7.13 Power Inverter
Compressor Control
(-)A20 condensing units are equipped with a power
inverter that varies the compressor speed from
900 RPM to 7000 RPM to match the changing
capacity needs of the conditioned space. The
inverter interfaces with the Variable Speed Outdoor
Control (VSODC) which communicates the level
of system capacity that is required to the inverter
based on input from the EcoNet
TM
Control Center
or conventional 24VAC 2-stage thermostat. The
inverter converts incoming single phase power to
simulated variable frequency 3-phase power that
is connected to the 3-phase compressor motor.
Each of the four (-)A20 models has a unique inverter
specifically designed and qualified for that specific
model to provide reliable operation under the most
extreme conditions. Each inverter is programmed
to monitor compressor power consumption, motor
torque, input current, input voltage, compressor dis
-
charge pressure, and compressor discharge
temperature. When the inverter identifies a condition
that could potentially result
in compressor or inverter damage, it automatically
reduces the compressor speed until a more reliable
operating condition is obtained or shuts the
compressor completely off if necessary. Once
safe operating conditions are attained, the inverter
will gradually increase the compressor speed in
an attempt to meet the capacity demand as long
as the operating conditions remain within the safe
operating range of the compressor and inverter.
1.
High voltage input (L1 – Black; L2 – Yellow)
2. Ground connection
3. Choke Connection
4.
High Pressure control connection (HPS) – with
automatic reset
5. Discharge line thermistor connection (Sensor)
6. Modbus communication connections (RS485)
7. Compressor connections (W-Black; V-Red;
U-Yellow)
3
2
1
6
5
4
1
