Digital Inputs; Forced Closing; Door Contact; Alarm Monitoring And Stop Of Refrigeration - Danfoss AK-CC55 User Manual

User Guide | Controller for appliance control, AK-CC55

Digital inputs

There are two digital inputs, DI1 and DI2, with dry contact
function, and one digital input DI3 with high voltage signal.
They can be used for the following functions:
- status readout of input signal (no action)
- door contact function with alarm
- starting a defrost
- main switch - start/stop of cooling
- night setback
- thermostat band's switch
- general alarm monitoring (DI1 and DI2 only)
- appliance cleaning
- case shutdown
- forced cooling
- override of night blinds
- allow operation with adaptive liquid control (ALC)
- coordinated defrost (DI2 only)
- forced closing of valve
- monitoring of refrigerant leakage

Forced closing

The AKV valves can be closed with an external signal ("Forced
closing").
The function must be used in connection with the compressor's
safety circuit, so that there will be no injection of liquid into the
evaporator when the compressor is stopped by the safety controls
and can't start again (However not at low pressure – LP).
Via a setting (see o90 Fan at forced closing) it is possible to define
whether an on-going defrost is allowed to continue at forced
closing or whether the defrost is put in standby position for a
period of up 10 minutes before it is cancelled - this feature can
be used to in CO2 systems to eliminate excessive heating while
compressors cannot run.
The signal can be received from the DI3-input or via the data
communication. During a forced closing, the fans can be defined
to be stopped or in operation.

Door contact

The door contact function can via the digital inputs be defined for
two different applications:
Alarm monitoring:
The controller monitors the door contact and delivers an alarm
message if the door has been opened for a longer period than the
set alarm delay.

Alarm monitoring and stop of refrigeration:

When the door is opened, the refrigeration is stopped, i.e. the
injection, the compressor and the fan are stopped and light
switches on.
If the door remains open for a longer time than the set restart time,
refrigeration will be resumed. This will ensure that refrigeration
is maintained even if the door is left open or if the door contact
should be defective. If the door remains open for a longer period
than the set alarm delay, an alarm will also be triggered.
Heating function (only with custom setup)
The heating function is used to prevent the temperature from
becoming too low, e.g. in a cold room, etc. The limit for when
the heating function cuts off is set as an offset value below the
current cut-out limit for the refrigeration thermostat. This ensures
that refrigeration and heating do not occur simultaneously. The
difference for the heating thermostat has the same value as for the
refrigeration thermostat. To prevent that the heating thermostat
cuts in during short-term drops in air temperature, a time delay
can be set for when to change from refrigeration to heating.
© Danfoss | DCS (vt) | 2019.09
Function
Not used
Follow DI status
Door contact function
Door alarm
Start defrost
Main switch
Night operation
Thermostat band
DI Alarm at closed
DI Alarm at open
Appliance cleaning
Forced cooling
Night blinds
Coordinated defrost
Forced closing
Appliance shutdown
Light
Refrigerant alarm
Allow fluid flow at short-circuit
Example
If DI1 is to be used to start a defrost, o02 must be set to 4.
Refrigeration
Neutral zone
Heat
Input / Settings menu Setting
DI1 DI2 DI3
o02 o37 o84
+ + + 0
+ + + 1
+ + + 2
+ + + 3
+ + + 4
+ + + 5
+ + + 6
+ + + 7
+ + 8
+ + 9
+ + + 10
+ + + 11
+ + + 12
+ 13
+ + + 14
+ + + 15
+ + + 16
+ + + 20
+ + + 21
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