Carrier PrimeLINE 69NT40-561-200, Руководство по эксплуатации и обслуживанию

Страница: 60 / 198

T-362 4–20
4.3.7 Perishable Heating
When it is necessary to raise the control temperature, the system will enter Perishable Heating mode. If the
temperature drops to 0.5°C (0.9°F) below setpoint, the unit will transition to Perishable Heating mode, and the
heaters will be energized. The unit will transition back to Perishable Idle mode when the temperature rises to 0.2°C
(0.4°F) below the setpoint, and the heaters will de-energize.
Figure 4.3 Controller Operation - Perishable Mode
4.3.8 Perishable Dehumidification
Dehumidification is provided to reduce the humidity levels inside the container. The dehumidification setpoint range
is from 50% to 95%. Dehumidification is activated when a humidity value is set at Cd33. The yellow SUPPLY LED
will flash ON and OFF every second to indicate that Dehumidification is active. Once Dehumidification is active and
the following conditions are satisfied, the controller will activate the heat relay to begin Dehumidification.
• The humidity sensor reading is above the humidity setpoint (Cd33).
• The unit is in Perishable Steady State and supply air temperature is less than 0.25°C (0.45°F) above setpoint.
• The heater debounce timer (three minutes) has timed out.
• Heater Termination Thermostat (HTT) is closed.
If the above conditions are true for at least one hour, the evaporator fans will switch from high speed to low speed.
Evaporator fan speed will then switch every hour, as long as the four conditions are met. See Bulb mode, Section
4.3.9 , for different evaporator fan speed options.
If any condition except item (1) becomes false OR if the relative humidity sensed is 2% below the dehumidification
setpoint, the high speed evaporator fans will be energized.
During dehumidification, power is applied to the defrost heaters. This added heat load causes the controller to open
the EEV to match the increased heat load while still holding the supply air temperature very close to the setpoint.
Opening the EEV reduces the temperature of the evaporator coil surface, which increases the rate at which water
is condensed and removes water from the passing air. Removing water from the air reduces the relative humidity.
When the relative humidity sensed is 2% below setpoint, the controller de-energizes the heat relay. The controller
Controller Set Point ABOVE -10 q C (+14 q F),
or -5
q
C (+23
q
F) optionally
Air Circulation
Air Circulation
Heating
Cooling,
Enconomized
Pull Down Perishable Mode
Set
Point
Set
Point
-0.20 q C -0.20 q C
-0.50 q C
+2.5 q C
(+4.5
q
F)
-0.50
q
C
+0.20
q
C
-0.25
q
C
Falling
Temperature
Rising
Temperature
Cooling,
Unloaded
Cooling,
Unloaded
(Only Applicable to Perishable Mode)
Controller Set Point ABOVE -10 q C (+14 q F),
or -5
q
C (+23
q
F) optionally
Air Circulation
Heating
-0.20 q C