Specifications

RK0YG302 © Danfoss 04/2007 107
EKC 514B1
On/O control
Modulating control
Demand-dependent defrosting
Liquid supply
The liquid supply is regulated based on signals from three sensors
(S1, S2 and an air sensor that may be placed before or after the
evaporator). The sensors register the dierence between the
temperature at the evaporator outlet (S2) and the temperature at
the evaporator inlet (S1). In combination with the air temperature
the sensors create a signal, so that superheat is continually kept at
a minimum whatever the operating conditions.
The placing of the S1 sensor is of paramount importance for a reliable
signal, and hence for a satisfactory regulation.
The AKV valve functions both as expansion valve and solenoid
valve. The valve opens and closes based on signals from the
controller.
Temperature control
The temperature is controlled on the basis of signals from one
or two temperature sensors. If there is only one sensor it may
optionally be placed in the air before or after the evaporator. If
there are two sensors, one must be placed before and one after
the evaporator. With a setting it is subsequently dened how
large an inuence the individual sensor is to have on the control.
The actual temperature control can take place in two ways: as an
ordinary ON/OFF regulation with a belonging dierential, or as
a modulating control there the temperature variation will not be
nearly as great as in ON/OFF control. There is however a limit to
the use of them as a modulating control can only be used in cen-
tral plant. In a decentralised plant the thermostat function with
ON/OFF control should be selected.
In a central plant the thermostat function may either be selected
for ON/OFF control or modulating control.
Defrost
With a simple function defrost can be started x times per day and
night. But the controller may also receive a signal from a defrost
clock or from another unit via the data communication, so that
defrost will take place at dened times of the day or night.
An on-going defrost can be stopped based on temperature, nor-
mally the one measured with the S5 sensor, or it may be stopped
based on time.
By means of a function the controller can itself determine whether
an approaching defrost will be necessary, or whether it may
be skipped. This function can only be used together with data
communication.