Danfoss EKC 414A Manual page 3

Function
Liquid supply
The supply of liquid is controlled on the basis of signals from the
pressure transmitter, temperature sensor S2 and the air tempera-
ture. The sensors create a signal so that the superheat is continu-
ously kept at a minimum whatever the operating conditions.
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 defined how
large an influence 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 differential, 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 defined 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. A combination with stop based on temperature
and with the time factor as a precautionary measure is also a pos-
sibility.
Clock module (accessory)
If the controller is mounted without data communication and
defrost has to be carried out at specific times, a clock module can
be mounted.
The controller comes prepared with plug and terminals so that the
module just has to be pushed in.
Subsequently, up to six defrosts per day can be set. The module
has battery back-up.
EKC 414A Manual RS8CK502 © Danfoss 05-2005
On / Off control
Modulating control
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