Hussmann RDI-27 Installation & Operation Manual page 33

Digital inputs
There are two digital inputs both of which can be used for the
following functions:
- Case cleaning
- Door contact function with alarm
- Starting a defrost
- Coordinated defrost
- Change-over between two temperature reference
- Retransmission of a contact's position via data communication
Case cleaning function
This function makes it easy to steer the refrigeration appliance
through a cleaning phase. Via three pushes on a switch you
change from one phase to the next phase.
The rst push stops the refrigeration – the fans keep working
"Later": The next push stops the fans
"Still later": The next push restarts refrigeration
The di erent situations can be followed on the display.
On the network a cleaning alarm is transmitted to the system unit.
This alarm can be "logged" so that proof of the sequence of events
is provided.
Door contact function
In cold rooms and frost rooms the door switch can switch the light
on and o , start and stop the refrigeration and give alarm if the
door has remained open for too long.
Defrost
Depending on the application you may choose between the fol-
lowing defrost methods:
Natural: Here the fans are kept operating during the defrost
Electric: The heating element is activated
Brine: The valve is kept open so that the brine can ow
through the evaporator
Hotgas: Here the solenoid valves are controlled so that the
hotgas can ow through the evaporator
Start of defrost
A defrost can be started in di erent ways
Interval: Defrost is started at xed time intervals, say, every
eighth hour
Refrigeration time:
Defrost is started at xed refrigeration time inter-
vals, in other words, a low need for
refrigeration will "postpone" the coming defrost
Schedule: Here defrost can be started at xed times of the
day and night. However, max. 6 times
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
S5 temp In 1:1 systems the e ciency of the evaporator can
be followed. Icing-up will start a defrost.
Manual: An extra defrost can be activated from the control-
ler's lower-most button. (Though not for
application 4).
All the mentioned methods can be used at random – if just one
them is activated a defrost will be started.
4 Manual RS8EP502 © Danfoss
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Hot gas application
12-2015
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+ °C
+ Fan
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AK-CC 210