4
Manual RS8AE802 © Danfoss 12-2009
EKC 361
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
air
. This room
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
0
follow each other, a changed charging
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
0
limitation)
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
air
according to entered setpoint.
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
).
The allowed temperature in the actuator determines the evapora ting pressure
Actuator temperature
