Carrier 69NT40-541-306, Операция и обслуживание

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5–9 T-354
5.10 SEQUENCE OF OPERATION
General operation sequences for cooling, heating, and defrost are provided in the following sub-paragraphs. Sche-
matic representation of controller action are provided in
Figure 5.3 and Figure 5.4 . Refer to Section 4 for detailed
descriptions of special events and timers that are incorporated by the controller in specific modes of operation.
5.10.1 Sequence of Operation - Perishable Mode Cooling
NOTE
In the conventional Perishable Mode of Operation, the evaporator motors run in high speed. In the
economy Perishable Mode, the fan speed is varied.
NOTE
In low temperature ambients, the condenser fan will be cycled by the controller to maintain proper con-
densing pressure.
1. With supply air temperature above set point and de creasing, the unit will be cooling with the condenser fan
motor (CF), compressor motor (CH), evaporator fan motors (EF) energized, and the COOL light illuminated
(see
Figure 5.5 ).
Figure 5.5 Perishable Mode Cooling
2. When the air temperature decreases to a predetermined tolerance above set point, the in-range light is illu-
minated.
3. As the air temperature continues to fall, modulating cooling starts at approximately 2.5

C (4.5

F) above set
point (see Figure 5.3 ).
4. The controller monitors the supply air. Once the sup ply air falls below set point and 0% SMV position is
reached, the controller periodically records the sup ply air temperature, set point, and time. A calculation is
then performed by subtracting the set point reading from the supply air and multiplying the result by the time
reading. The result is negative number.
CONTROL TRANSFORMER
POWER TO
CONTROLLER
SIGNAL TO
CONTROLLER
SIGNAL TO
CONTROLLER
ENERGIZED
DE--ENERGIZED
FOR FULL DIAGRAM AND
LEGEND, SEE SECTION 7
NOTE: HIGH SPEED EVAPORATOR FAN SHOWN. FOR LOW SPEED
CONTACT TE IS DE-ENERGIZED AND CONTACT TV IS ENERGIZED