Temperature Control; Temperature Monitoring; Thermostat Bands - Danfoss AK-CC55 Compact User Manual

Case/room controller (eev)

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AK-CC55 Compact

Temperature control

The temperature in the appliance is registered by one or two temperature sensors which are located in the return air

before the evaporator (S3) or after the evaporator (S4) respectively. A setting for the thermostat, night thermostat,

alarm thermostat and display reading determines how much the two sensor values should influence each individual

function, e.g. 50% of S4 will produce an equal value from both sensors.

The actual temperature control can take place in two ways:

As an ordinary ON/OFF regulation with a differential, or

As a modulating control where the temperature variation will not be nearly as high as in ON/OFF control.

There is, however, a limit to the use of a modulating control as it can only be used in remote cabinets. It is not

recommended to use modulating thermostat control in low temperature applications. In applications with one

evaporator and one compressor, the thermostat function with ON/OFF control should be selected. In remote

cabinets, the thermostat function may either be selected for ON/OFF control or modulating control.

Table 3: Control methods

Just as is possible for the thermostat, the alarm monitoring can be set with a weighting between S3 and S4 so that

you can decide how much the two sensor values should influence the alarm monitoring. Minimum and maximum

limits can be set for alarm temperature and time delays. A longer time delay can be set for high temperature alarm.

This time delay is active for pull-down, after defrosting, appliance cleaning and start-up.

Thermostat bands can be used beneficially for appliances where different product types are stored, which requires

different temperature conditions. It is possible to change between the two different thermostat bands via a contact

signal on a digital input. Separate thermostat and alarm limits can be set for each thermostat band.

For the defrost control, separate defrost stop temperature and max. defrost time can be set for each thermostat

band. For the compressor control it is possible to disable the second compressor in thermostat band 2 if required.

Figure 11: Thermostat band function with two different band settings

ON/OFF control

Modulating control

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