Thermo King CRR-40 119, Руководство пользователя

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MP-3000a Controller
64
Defrost
The evaporator coil sensor temperature must be
below 18 C (65 F) to initiate a Demand Defrost or
Manual Defrost. The evaporator coil sensor
temperature must be below 10 C (50 F) to initiate
a Timed Defrost.
• Demand defrost function initiates defrost
immediately when:
- Temperature difference between the return
air sensor and defrost (evaporator coil) sensor
is too large
- Temperature difference between the left
hand and right hand supply air sensors is too
large and unit has operated for more than 90
minutes since last defrost
- Temperature difference between the supply
sensors and return air sensor is too large
• Manual Defrost may be initiated immediately
by pressing the Defrost key or by Refcon
Remote Monitoring Modem (RMM).
• A Timed Defrost always starts at 1 minute
past the hour immediately following a defrost
timer request for defrost. For example, if the
defrost timer requests a defrost cycle at 7:35,
the defrost cycle will start at 8:01. The
datalogger will record a Defrost event for each
log interval in which a Defrost cycle is
pending or active (i.e. both the 8:00 and 9:00
data logs on 1 hour logging interval).
- On Chill Loads (setpoints at -9.9 C [14.1 F]
and above), the initial time interval is:
• 8 hours of compressor operation at supply air
temperatures of 5.1 C (41.2 F) or above.
• 2.5 hours of compressor operation at supply
air temperatures of 5.0 C (41.0 F) or below.
One-half (0.5) hour is added to the time
interval each timed defrost interval. Defrost
synchronization creates step intervals of 3, 4,
4, 5, 5, 6, 6 and 7 hours. Maximum time
interval is 7 hours.
- On Frozen Loads, the initial time interval is
8 hours. Two (2) hours are added to the time
interval each timed defrost interval. Maximum
accumulated time interval is 24 hours.
- Defrost timer resets if the unit is Off more
than 12 hours, setpoint is changed more than 5
C (8.9 F) or PTI Pretrip test occurs.
NOTE: If unit operating conditions do not
allow the unit to enter a defrost cycle,
“Defrost Not Activated” appears on LCD
display when the DEFROST key is pressed.
When the defrost mode is initiated:
• The controller stops the compressor,
condenser fan and evaporator fans and
de-energizes the liquid line solenoid valve.
• When the compressor stops, the controller
turns ON the Defrost LED, Heat LED and
energizes the heater contactor, turning on the
electric heaters.
The controller terminates the defrost
mode when:
• Evaporator temperature:
- Chill mode: Evaporator coil sensor
temperature reaches 30 C (86 F); or exceeds
18 C (65 F) for 35 minutes.
- Frozen mode: Evaporator coil sensor
temperature reaches 18 C (65 F); or exceeds 8
C (46 F) for 35 minutes.
• Interval timer: Controller terminates defrost
after 90 minutes on 60 Hz power (120 on 50
Hz power). Alarm code 20 will be generated if
this occurs.
• Power OFF: Turning unit On/Off switch Off
terminates defrost.
When the defrost mode is terminated:
• The Heat and Defrost LEDs turn OFF and the
heater contactor is de-energized. The
controller starts the compressor and energizes
the liquid line solenoid to pre-cool the
evaporator coil. The condenser fan starts if
required.
• The controller pre-cools the evaporator coil to
the supply air temperature (or for 3 minutes
maximum) to minimize heat energy release
into the container. The controller then starts
the evaporator fans.