Capacity Control And Limiter - Maersk Container Industry Star Cool SCI-20 Operating And Service Manual

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Chill mode
Defect sensor(s)
Tsup1 (2)
Tsup1 and Tsup2
Tsup1, Tsup2, and Tret
Tsup1, Tsup2, Tret, and Tevap
Frozen mode
Defective sensor(s)
Tret
Tret and Tevap
Tret, Tevap, and Tsup1
Tret, Tevap, Tsup1, and Tsup2
** = No more available sensors for substitution.

6.3 Capacity control and limiter

On the basis of requested capacity, this function determines operation mode and actions of the
individual system components (compressor, valves, heating elements) and ensures that compressor
minimum off time is observed. This function has 5 gears (modes). On the basis of requested
capacity, the gear is determined. Compressor frequency is directly dependent upon current mode.
Evaporator heater, on the other hand, is gear independent. There is overlap over the modes to
maintain slow mode shifting.
Gear Function
Off Everything is turned off.
Start up If cooling is required, the FC is starting at default frequency before shifting to
correct cooling mode.
PWM On/Off regulation of compressor.
CoolEco Maximum cooling capacity with use of economizer.
Heat Only the heaters are used.
Defrost Heaters are always used and hot gas valve is used if ambient temperature is above
5˚C (41˚F).
The capacity of the unit is controlled between maximum cooling capacity (-100% capacity) and
maximum heating capacity (+100% capacity). This is done by regulation of the compressor speed
by means of the FC or on/off regulation. In maximum capacity (+100% capacity) the unit uses the
heating elements, by means of Pulse Width Modulation, to control the capacity.
Operating and service manual
Substitution sensor/Action
Tact = Tsup2 (1)
Tact = Tret + constant
Tact = Tevap + constant
**
Substitution sensor/Action
Tact = Tevap + constant
Tact = Tsup1 + constant
Tact = Tsup2 + constant
**
Alarm
611, Too many sensor err
600, No control sensor
Alarm
611, Too many sensor err
600, No control sensor