Thermo King 098203, Руководство по обслуживанию

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Operating Theory
Chill Loads: (Setpoint at -9.9 C [14.1 F] and Above)
The unit operates on Cool with Modulation and Heat to provide accurate control of chill loads. During
Cool with Modulation, the controller uses a proportional-integral derivative (PID) algorithm, and a
Digital Control valve to provide accurate control of the container temperature in direct response to load
demand.
The Digital Control valve engages and disengages the compressor to control capacity. The valve opens
and closes in response to a controller voltage signal based on a control temperature differential. The
controller uses the setpoint temperature, supply air sensor temperature and pull-down rate for the last 10
seconds, last 20 seconds and last 180 seconds to calculate the control temperature differential.
Supply Air Sensor Control
Temperature control is provided by using a PT1000 temperature sensor to determine the supply
temperature used to calculate the control temperature.
If the supply air sensors fail, the controller uses the temperature of the return air sensor plus an offset for
temperature control.
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.
Cooling Capacity Display in main screen
The percent displayed in the main screen indicates the cool capacity that is currently provided. For
example, when controller display shows 70 percent, this means the Digital Control valve is operating to
reduce system cooling capacity from 100 percent to 70 percent (a 30 percent reduction).
Power Limit Management
Power Limit is active whenever the compressor is on in both the Chill and Frozen modes. When the total
current draw or the condenser temperature exceeds a predetermined threshold, the controller limits unit
power consumption by sending a voltage pulse to the Digital Control valve. The Digital Control valve
then operates to control the compressor. This reduces the cooling capacity load on the compressor,
thereby limiting the compressor motor current draw and the condenser temperature to a predetermined
threshold.
Additional power limit management flexibility is available. A maximum total current draw (17, 15 or 13
amps) and power management time interval can be selected from the Power Management feature of the
Commands menu. When the power management time interval expires, the unit returns to the standard
power limit control algorithm.
NOTE: Setting power management current at 13 amps can be used to provide slow pull-down of loads.
Compressor Vapor Injection
During compressor operation, a vapor injection system injects refrigerant into the center scroll of the
compressor to provide additional cooling capacity. When vapor injection is active, the controller
energizes the vapor injection valve continuously. The controller activates vapor injection when the: