Thermo King CRR-40 119, Руководство пользователя

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MP-3000a Controller
56
Temperature Control Accuracy and Frost
Protection
The PID algorithm generally minimizes container
temperature fluctuations to +/- 0.1 C (+/- 0.2 F).
Additional frost protections is provided by pulsing
the electric heaters ON and OFF to increase the
supply air temperature if the return air
temperature decreases to within 0.3 C (0.5 F) of
setpoint. The controller pulses the heater ON for 2
to 60 seconds every 60 seconds. The amount of
ON time depends on the amount of heat required
to provide frost protection.
Frozen Loads (Setpoint at -10 C
[14 F] and Below)
The unit operates on Full Cool and Null to
provide accurate control of frozen cargo. The
controller uses the return air sensor temperature
and setpoint temperature to regulate unit
operation.
If the return air sensor becomes disconnected or
fails, the controller uses the supply air sensors
plus an offset for temperature control.
KVQ Setting Value in Data Menu
The KVQ Setting value displayed in the Data
menu indicates the evaporating temperature the
KVQ valve uses to control refrigerant return to the
compressor. During maximum cooling capacity
operation, the KVQ Setting value may range
between -40 C and -60 C (-40 F and -76 F).
The temperature difference between the KVQ
valve setting and the return air temperature
determines the cooling capacity available. A
temperature difference of 5 C (8.9 F) or less
indicates very low cooling capacity.
Compressor Sequence Start
The controller performs a compressor sequence
start when the compressor has not operated for
more than 60 seconds within the last 18 hours. A
compressor sequence start cycles the compressor
ON 3 seconds, OFF 10 seconds, ON 5 seconds,
OFF 10 seconds, ON 7 seconds, OFF 10 seconds
and then ON continuously.
Compressor Liquid Injection
During compressor operation, a liquid injection
system injects refrigerant into the suction line to
protect the compressor for excessively high
operating temperatures.
Compressor Discharge Temperature
Control (Chill Mode Only)
• Liquid injection is activated at compressor
discharge temperatures between 115 C and
125 C (239 F and 257 F). The controller
pulses the liquid injection valve open for 2
to 60 seconds every 60 seconds. The
number of seconds the valve is energized
depends on the discharge temperature and
the KVQ valve setting.
• Liquid injection is activated when the
KVQ Setting is less than 5 C (8.9 F) below
the return air temperature. The controller
energizes liquid injection valve for 6
seconds every 60 seconds regardless of the
discharge temperature.
High Temperature Protection
• If the discharge gas temperature rises
above 130 C (266 F), the unit stops
immediately. The controller turns ON the
Alarm LED and records Alarm 56,
Compressor Temperature Too High. The
controller will restart the unit when the
sensor temperature is below 90 C (194 F).
Power Limit Mode
The controller uses the total unit current and the
condenser temperature to provide power limit
control in both the Chill and Frozen modes. When
the unit is on water-cooled operation, power limit
control is based on the total unit current draw
only.