Thermo King 098916, Руководство по обслуживанию

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Operating Theory
107
Condenser Fan Control
The controller also uses a proportional-integral
derivative algorithm to control the condenser
temperature and ensure a constant liquid pressure
at the expansion valve. The condenser fan
operates continuously in high ambients. In low
ambient conditions, the controller pulses the
condenser fan on and off to maintain a minimum
condenser temperature. The controller maintains a
minimum 30 C (86 F) condenser temperature on
Chill loads and a minimum 20 C (68 F) condenser
temperature on Frozen loads.
Probe Test
The controller constantly monitors the left hand
and right hand supply sensors, return sensor and
defrost (evaporator coil) sensor to determine when
to initiate a demand defrost. If a demand defrost is
requested and defrost has occurred within last 90
minutes, the controller initiates a probe test to
check for a defective sensor.
During a Probe test, the LCD display shows
“PROBE TEST PLEASE WAIT”. The controller
operates the unit on high speed evaporator fans
only for 5 minutes. All sensor temperatures are
then compared:
• Sensors with large temperature differences are
discarded from the control algorithm. The
controller then activates the appropriate Alarm
codes to identify the defective sensor(s).
• If no sensors are found defective, controller
LCD display shows “RUNNING WITH
HIGH SUPPLY DIFFERENCE” message.
Sensor errors recorded during a probe test are
cleared when the next Defrost is initiated or
U
NIT
O
N
/O
FF
switch is turned O
FF
.
NOTE: A manual probe test can be performed
by a technician by selecting “SENSOR CHECK”
from the Manual Test Function menu.
Bulb Mode
The Bulb mode allows the shipper to control the
evaporator fan speed and defrost termination
temperature during Dehumidification. The Bulb
mode screen setting determines the evaporator fan
speed: Flow Cycle, Flow High or Flow Low.
Setting a Bulb mode fan speed automatically
activates the defrost termination temperature
setting and the Dehumidify mode (controller sets
Humidity control to DEHUM). The use of the
Bulb mode should be established by the shipper.
NOTE: If the Bulb mode is set to On, the
controller LCD display will show “BULB” and
current humidity setpoint.
Dehumidify Mode
During Chill mode operation, a dehumidification
system is available to reduce the relative humidity
in the container to the desired humidity setpoint.
The Dehumidify mode option is turned on from
Setpoint menu of the controller. The relative
humidity setpoint can be set from 60 to 99 percent
from the Setpoint menu.
NOTE: The use of the Dehumidify mode should
be established by the shipper.
Changing the humidity control from off to
DEHUM in the setpoint menu activates the
dehumidify control algorithm. When the
Dehumidify mode is on, the supply air
temperature must be in-range to activate
dehumidification:
• When the humidity level is 2 percent or more
above setpoint and the Digital Control valve
has reduced the unit cooling capacity to 85
percent, the controller pulses the electric
heaters on and off. This increases the cooling
load on the evaporator coil, thereby causing
the coil to become even colder and condense
more moisture from the container air.