Danfoss AK-CC 550 - Input;Output and System Integration; Digital Inputs and Door Contact

10 Manual RS8EN502 © Danfoss 02-2010 AK-CC 550
Refrigeration
Heat
Neutral zone
Digital inputs
TherearetwodigitalinputsDI1andDI2withcontactfunctionand
onedigitalinputDI3withhighvoltagesignal.
They can be used for the following functions:
-Retransmissionofcontactspositionviadatacommunication
- Door contact function with alarm
- Starting a defrost
-Mainswitch-start/stopofcooling
-Nightsetback
- Thermostat bands switch
-Generalalarmmonitoring
- Case cleaning
-Forcedcooling
-Overrideofnightblinds
-Coordinateddefrost(DI2only)
-Forcedclosingofvalve(DI3only)
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con-
trols.(Howevernotatlowpressure–LP).
Ifadefrostcycleisinprogress,theforcedclosingstatuswillnotbe
re-established until the defrost is completed.
ThesignalcanbereceivedfromtheDI3-inputorviathedatacom-
munication.
Duringaforcedclosingthefanscanbedenedtobestoppedor
in operation.
Door contact
Thedoorcontactfunctioncanviathedigitalinputsbedenedfor
twodierent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
switch 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
Theheatingfunctionisusedtopreventthetemperature
becoming too low, e.g. in a cutting room, etc. The limit for when
theheatingfunctioncutsoissetasanosetvalueunderthe
current cutout limit for the refrigeration thermostat. This ensures
that refrigeration and heating do not occur simultaneously.
Thedierence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.