Function; Liquid Supply; Temperature Control; Defrost/Clock Module - Danfoss EKC 414A Manual

Function

Liquid supply

The supply of liquid is controlled on the basis of signals from
the pressure transmitter, temperature sensor S2 and the air
temperature. The sensors create a signal so that the
superheat is continuously 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 central 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,
normally 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 possibility.
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 RS.8C.K3.02 © Danfoss 09-2003
On / Off control
Modulating control
3