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Verfügbare Sprachen
Verfügbare Sprachen
Low-pressure application
Application (fig. 1)
For liquid level regulation on the low-pressure side.
The system can be used for regulation of the refrigerant level
in flooded evaporators, in pump recirculation tanks, etc.
The controller receives a signal from a liquid level measuring
unit that may be for example, a capacitive rod. The only
requirement is that the input signal to the controller must be
either 0-10 V or 4-20 mA.
Use type AKV and AKVA as expansion valve.
Connection (fig.3 )
- Connect a supply voltage of 24 V a.c. (the module and the
connected valve will together use 60 VA).
- Connect the valve (the coil must be 24 V a.c.).
- Connect either a current signal or a voltage signal.
- If it is required that the valve's forced-closing function is
used, a cutout switch will have to be connected. If it is not
used, terminals 1 and 2 must be shortcircuited.
- The three terminals "4", "5" and "8" have been reserved for
other purposes. They may not be used as loop terminals.
Front plate (fig. 5)
ALARM: The diode will flash, if one of the following situations
occurs:
- No input signal.
- The switch on the front plate is set to the right and
receives signals from the potentiometer.
- A forced-closing signal is received, so that the valve
is kept closed (connection between 1 and 2 is
interrupted).
ON:
The diode is lit when there is voltage on the control-
ler.
AKV:
The diode flashes in time with the opening signal for
the valve.
ENTER: This knob is only used for storing the lower and
upper values for the regulating range.
LEVEL SIGNAL: Switch. In "left position" an external signal is
received, in "right position" a signal is simulated with
the potentiometer.
MAX LEVEL: Used for adjustment of the upper value for the
liquid level.
MIN LEVEL: Used for adjustment of the lower value for the
liquid level.
TEST:
A voltmeter can be connected here. The voltmeter
will show the signal received by the regulation -
either from the signal input or from the potentiometer.
If one of the knobs, "MAX LEVEL" or "MIN LEVEL" is
pushed in, the stored value for this setting will be
shown (see adjustment).
Principle (fig. 6)
High-pressure application
The controller has been factory-set to regulate at low pressure,
but with a setting in the controller it can be changed to regulate
at high pressure. Fig. 2 shows a possible application and how
the setting is changed to high pressure (high pressure = HP).
Only the following points will now differ from the low-pressure
paragraph:
Principle (fig. 6a)
The controller will open the valve by rising input signal.
English
The controller will close the valve by rising input signal.
Adjustment (fig. 7)
The actual regulating range is set by storing two values in the
controller's memory.
- One value is the signal value when the valve closes,
corresponding to the liquid level "MAX LEVEL".
- The other is the signal value when the valve is 100% open,
corresponding to the liquid level "MIN LEVEL".
Either adjustment with a voltmeter: (fig. 8)
MAX LEVEL adjustment
1) Set the switch in right position
2) Connect a voltmeter to the "TEST" bushes
3) Keep adjusting the potentiometer until the voltmeter shows
the required level for MAX. LEVEL (cf. connection between
test voltage and input signal in fig. 4)
4) Push simultaneously the two knobs "MAX LEVEL" and
"ENTER". The value has now been stored.
MIN LEVEL adjustment
1) and 2) As above
3) Keep adjusting the potentiometer until the voltmeter shows
the required level for MIN. LEVEL
4) Push simultaneously the two knobs "MIN LEVEL" and
"ENTER". The value has now been stored.
When the adjustment has been completed, put the switch
back in left position, so that signals will be received from the
liquid level measuring unit (fig. 9).
Or visual adjustment: (fig. 10)
The two settings are made while a signal is being received
from the liquid level measuring unit, and no voltmeter is
required.
Here the values are stored with a pressure on the knobs,
when the level has been put in the required max. and min.
positions (cf. the two points 4 above).
Forced control (fig. 11)
- Push the switch over so a signal is received from the
potentiometer.
- Now turn the potentiometer to one of its extreme positions,
depending on whether the valve is to be opened or closed
("counter-clockwise" opens the valve and "clockwise" closes
the valve).
Adjustment (fig. 7a)
Adjustment must be performed as indicated in the low-
pressure paragraph, but since the function has been reversed,
the valve's opening/closing events will be the opposite.
Forced control
As described in the low-pressure paragraph, but the valve will
close when the potentiometer is turned "counter-clockwise".
96
(fig. 11)
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