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8
Superheat control mode
There are two different control algorithms that can be selected: "standard" and "slow".
Standard is used for most applications, such as standard refrigeration. The EXV unit reacts quickly to changes
in superheat temperature. However, in some applications, the superheat inside the evaporator is volatile and
liquid refrigerant may contact the temperature sensor. The reaction of the controller may then be too fast and
the condenser control is getting unstable ("hunting")..
By using the "slow" parameter, this control behavior can be calmed down. This configuration is manly used in
some deep-freezing applications.
This function is only active if an electronic expansion valve is used.
9
Superheat setpoint
The controller calculates the current superheat value and compares it with the setpoint value based on
pressure transmitter and temperature sensor signals. The control valve is actuated in such a way that the
configured superheat is maintained in all operating conditions.
The setpoint value for superheat can be selected in a range from 3K to 30K.
This function is only active if an electronic expansion valve is used.
10
Alarm pause delay
If an alarm causes the compressor to deactivate, cooling can only start again after a certain delay period has
expired.
11
"High superheat" alarm setpoint
If the superheat temperature rises above the configured value, an alarm is triggered. This may happen in case
of:
▪
a lack of refrigerant
▪
a valve that is too small
▪
No subcooling
This function is only active if an electronic expansion valve is used.
12
"High superheat" alarm delay
If the temperature stays above the alarm level configured in
alarm is triggered.
13
"Low suction pressure " alarm threshold
An alarm is triggered if suction pressure falls below the configured value. The alarm is canceled when
suction pressure returns to the configured value + 0.5 bar.
This function is not active if no suction pressure sensor is used.
14
"Low suction pressure " alarm delay
If the pressure stays below the alarm level configured in
is triggered.
This function is not active if no suction pressure sensor is used.
15
Defrost minimum time (nighttime operation)
Minimum defrost time in nighttime operation. Prevents defrost being terminated too quickly in case of severe
icing due to inaccurate temperature measurements.
"High temperature" alarm delay (control temperature)
16
If the control temperature stays above the defined alarm value (17) for longer than the period defined by this
parameter, the alarm will be triggered.
"High temperature" alarm threshold (control temperature)
17
Relative alarm threshold to control temperature setpoint
+ this value an alarm is triggered.
T
= T
+ Parameter(17)
threshold
set-point
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Technical Information
11
for a period adjustable by this parameter an
13
for a period adjustable by this parameter an alarm
1
or 3. If the control temperature rises above setpoint
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