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7.0 COMPONENTS & CONTROLS
7.5 Compressor Sump
Thermistor
(-)A20 variable speed condensing units utilize a sump
thermistor to monitor the condition of the lower bearing
in the compressor sump. As environmental variables
change it is possible to have liquid refrigerant flood
back to the compressor.
Although the (-)A20 designs have been designed to
minimize floodback, on rare occasions floodback can
occur. During these conditions, the EcoNet™ Variable
Speed Outdoor Control has been programmed to slow
the compressor speed until all of the liquid
refrigerant exits the compressor shell.
The sump thermistor is also used to identify when
compressor stator heat is needed during off cycles
to warm the sump. See Section 8.4 for more details on
this operation.
Components
7.6 Discharge Line
Thermistor
(-)A20 condensing units are equipped with a discharge
line thermistor that is used to measure the
compressor discharge temperature. This sensor’s
leads connect directly to the inverter which
communicates with the Variable Speed Outdoor
Control (VSODC). The compressor discharge
temperature is continuously monitored by the
controls. The compressor speed is reduced
as needed to prevent excessive discharge
temperatures that would damage the compressor
under extreme environmental conditions. As the
discharge temperature returns to an acceptable
level, the controls will gradually increase the
compressor speed in an attempt to meet the
capacity demand as long as the discharge
temperature remains at a safe level.
7.4 Compressor
All (-)A20 condensing units are equipped with a
Copeland variable speed scroll compressor featuring
a brushless DC motor. The compressor is designed to
work in conjunction with the Power Inverter Compres
-
sor Control and the Variable Speed Outdoor Control to
provide capacity modulation.
