Adjustment Of The Switching Points Kfa - Rechner Sensors LEVEL KFS-4 Série Manuel D'utilisation

Adjustment of the switching points KFA-5..

For the final operation each switching point has to be adjusted. For each switching point a 20-turn potentiometer
(no mechanical stop) is available. Each switching point is displayed with an LED indicating operating state.
Using the three-electrode principle measuring areas are created within the container, which form a measuring
volume like a cylindrical disc (the height of this cylindrical disc is about 15 mm). These measuring capaci-
tors have the lowest capacity value when the container is empty and the value increases when filling the
container dependent on the actual filling level and the DC (DC = dielectric constant) of the detected material.
The switching point is determined as a result of this capacity change. The „empty" capacity is constant; when
making the adjustment, first find the switching point of the capacity when empty.
For the vast majority of the products to be detected (non-conductive, not adhesive) this adjustment
with empty container is optimal.
„Empty" adjustment:
• Probe fixed in mounting position.
• Container empty or measuring volume free
• Find switching point (change switching state LED on/off)
Direction of activity: right-turn: on; left-turn: off
• From the switching point (LED just on) turn about ¼ - ½ turn to the left – in direction „off"- and keep it
on this position.
The unit is now ready for operation. No further adjustment is necessary as long as the mounting position of
the probe is not changed.
Normally there is a large switching safety, that means the change to the state „full" will be happen just when
a low filling degree of the measuring volume is reached. The switching points goes upward with further turn-
back of the adjustment potentiometer, but it cannot be changed by more then 15 mm of the height of the
measuring volume. This maximum switching point can be determined by the „full" adjustment.
The "full" adjustment is recommended when detecting materials that are highly viscous, adhesive
or conductive (e.g. hot-melt glue).
„Full" adjustment:
• Probe fixed in mounting position.
• Container or measuring volume is full
• Find switching point
• Without wire break control: from the switching point (LED just off) turn about ½ turn to the right –
in direction „on" – and keep it on this position.
• With wire break control: if the red LED is on, turn the potentiometer to the left until the green LED is
on. If the green LED is on, turn the potentiometer to the right until the switching state is indicated.
For the measuring systems with variable adjustment range (KFS-4... and KFA-4-...), please consider that the
change of the switching point is as follows: right turn of the potentiometer means higher filling level; left turn
means lower filling level. With wire break the green LED is flickering.
With this adjustment a safe switching-off will take place, even when some of the glue or the adhesive product
to be detected sticks to the probe.
One can determine the measuring safety, when empty and full adjustments are made in succession and
when the turns from one switching point to the other are counted.
If in doubt, the empty adjustment should be made, because this is independent of the characteristics of the
medium to be detected.
At full adjustment, which for example is recommended for the detection of glue, one has to take into account
that the measurement is dependent on the dielectric constant of the material to be detected. If the adjust-
ment is made on a material with a high dielectric constant and a change is made to a material with a lower
dielectric constant, then there is no switching safety. In such a case a switching point between empty and
full adjustment can be useful.
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