Specifications
RK0YG302 © Danfoss 04/2007 71
Sensors
Up to two thermostat sensors can be connected to the controller.
The relevant application determines how.
A sensor in the air before the evaporator:
This connection is primarily used when control is based on area.
A sensor in the air after the evaporator:
This connection is primarily used when refrigeration is controlled
and there is a risk of a too low temperature near the products.
A sensor before and after the evaporator:
This connection oers you the possibility of adapting the
thermostat, the alarm thermostat and the display to the relevant
application. The signal to the thermostat, the alarm thermostat
and the display is set as a weighted value between the two
temperatures, and 50% will for example give the same value from
both sensors.
The signal to the thermostat, the alarm thermostat and the display
can be set independently of one another.
Defrost sensor
The best signal concerning the evaporator’s temperature is ob-
tained from a defrost sensor mounted directly on the evaporator.
Here the signal may be used by the defrost function, so that the
shortest and most energy-saving defrost can take place.
If a defrost sensor is not required, defrost can be stopped based
on time, or S4 can be selected.
Control of two compressors
This control is used for controlling two compressors of the same
size. The principle of the control is that one compressor cuts in
and out based on the thermostat’s dierential and the other on
half the dierential. When the thermostat cuts in the compressor
with the fewest operating hours is started. The other compressor
will only start after a set time delay, so that the load will be divided
between them.
When the air temperature has dropped by half the dierential the
one compressor will stop, the other will continue working and not
stop until the required temperature is acheived.
The compressors used must be of a type that is capable of starting
up against a high pressure.
Change of temperature reference
In an impulse appliance, for example, used for various product
groups. Here the temperature reference is changed easily with
a contact signal on a digital input. The signal raises the normal
thermostat value by a predened amount. At the same time the
alarm limits with the same value are displaced accordingly.
AK-CC 210