Danfoss AKA 245 Specifications download pdf (Page 10)

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.

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Danfoss AKA 245 Specifications Page 10

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