Danfoss EKC 361 User Manual page 4

Function
Very accurate temperature control
With this system where controller, pilot valve and main valve have
been adapted for optimum use in the refrigerating plant, the re-
frigerated products may be stored with temperature fluctuations
of less than ±0.25°C.
High air humidity
As the evaporating temperature is constantly adapted to the
refrigeration needs and will always be as high as possible with a
very small temperature fluctuation, the relative air humidity in the
room will be kept at a maximum.
Drying-out of the products will in this way be reduced to a mini-
mum.
Temperature is quickly attained
With the built-in PID control and the possibility of choosing be-
tween three transient phenomena, the controller can be adapted
to a kind of temperature performance that is optimum for this
particular refrigerating plant. See parameter (n07).
• Fastest possible cooling
• Cooling with less underswing
• Cooling where underswing is unwanted.
Regulation ICS/PM with CVQ
The controller receives signals from room sensor S
sensor must be placed at the air outlet from the evaporator to
obtain the best possible regulation. The controller sees to it that
the required room temperature is maintained.
Built-in between the controller and the actuator is a so-called
inner control loop which constantly checks the temperature (pres-
sure) in the actuator's pressure vessel. In this way a very stable
control system is obtained.
If there is a deviation between the required and the registered
temperature the controller will immediately send more or fewer
pulses to the actuator to counteract the error. A change of the
number of pulses will act on the temperature and hence the
pressure in the pressure vessel. As the charging pressure and the
evaporating pressure p follow each other, a changed charging
0
pressure will produce the effect that the valve's opening degree is
also changed. The ICS/PM with CVQ system maintains the pressure
in the evaporator whatever pressure changes there may be on the
suction side (on the ICS/PM valve's outlet).
Evaporating pressure limitation (p
The inner control loop mentioned above also causes the evapora-
ting pressure to stay within a fixed limit. In this way the system is
safeguarded against a too low supply air temperature.
It offers the following advantages:
- High-temperature systems can be connected to low-tempera ture
compressor units
- Protection against icing on evaporator
- Frost protection of liquid coolers
Regulation with ICM
When using ICM as selected valve the system will still control ICM
in order to maintain S according to entered setpoint.
air
This system does not inlude any inner control loop.
It is a direct operating and pressure independent valve for control-
ling media temperatur. (S ).
air
4
. This room
air
limitation)
0
Manual RS8AE802 © Danfoss 12-2009
The allowed temperature in the actuator determines the evapora ting pressure
Actuator temperature
EKC 361