Digital inputs
There are two digital inputs, DI1 and DI2, with dry contact function.
They can be used for the following functions:
• Status readout
• Door function with stop of cooling and door alarm
• Door alarm only
• Main switch (start/stop of cooling)
• Night setback
• Reference offset
• External alarm
• Defrost start
• Pulldown cycle
• Sc condenser sensor (only DI1)
Figure 8: Digital inputs
Danf
oss
84b2491
Door contact function
In cold rooms and frost rooms the door switch can switch the light on and off, start and stop the refrigeration and
give alarm if the door has remained open for too long.
Danf
oss
84B2460
Defrost
Depending on the application, you may choose between the following defrost methods:
•
Natural:
Here the fans are kept operating during defrost
•
Electric:
The heating element is activated during active defrost
•
Hot gas:
The defrost output is used to control a solenoid that lets the hot gas flow through the evaporator. The
compressor is kept running to generate hot gas.
Start of defrost
A defrost can be started in different ways:
•
Interval:
Defrost is started at fixed time intervals, e.g., every eighth hour
•
Compressor runtime:
Defrost is started at fixed compressor runtime intervals. In other words, a low need for
refrigeration will “postpone” the coming defrost.
•
Contact:
Defrost is started with a contact signal on a digital input.
•
Network:
The signal for defrost is received from a system unit via the data communication.
•
Defrost on demand
: In 1:1 system the efficiency of the evaporator can be followed. Icing-up will start a defrost.
•
Manual:
An extra defrost can be activated from the controller’s lower-most button (though not for application 4).
All the mentioned methods can be used at random – if just one of them is activated a defrost will be started.
Figure 9: Start of defrost
© Danfoss | Climate Solutions | 2023.05
BC432222569027en-000201 | 9
Case controller, type EKC 223 and EKC 224