Instructions for Use SS 20.200
Page 8
6 Switching threshold
The switching output will trip at an adjustable flow velocity. There are two
basic types of setting the switching threshold:
Manual setting (order code L = P)
The switching threshold is set using the potentiometer mounted on the
front side of the
SS 20.200
. To increase the switching threshold, rotate
the potentiometer clockwise and visa-versa. The measuring range of the
sensor is correlated linearly with the 270 degrees of rotating, i.e., at the
upper end (clockwise) the switching threshold is 95 % of the measuring
range. At the lower end (zero point) the switching threshold is limited to
5 % of the measuring range.
The potentiometer has a slot size of 2.5 mm x 0.5 mm.
The maximum applicable torque at the potentiometer dead
stops is 3.5 Ncm.
With order code xx = 00, the potentiometer is set at about 50% (default).
At a distinct value xx > 00, the potentiometer is set ex works to the de-
sired switching threshold
(„xx“ % of measuring range).
The individual setting of the switching point is done by adjusting the flow
velocity to the desired threshold value. Then the potentiometer is rotated
from the zero point clockwise until the relay is switching. The release
point is then offset downward by the hysteresis (see also chapter:
Hyste-
resis of switching threshold
). For fine adjustment, the potentiometer can
now be rotated back a little bit.
Preprogramed switching threshold (order code L = F)
If the flow velocity to be monitored is already known at the time of order-
ing, the sensor can be ordered with a fixed, preprogramed switching
threshold. In this case, the potentiometer is put out of action and a stick-
er on the front side of the sensor informs about the programmed switch-
ing threshold.
Hysteresis of switching threshold
The hysteresis of the switching threshold is defined as the value that
separates the switching point (SP) from the release point (RP). It is im-
portant which switching logic (S) was selected.
For S = 1 and S = 2, the sensor switches directly at the defined SP. RP
is lower by 5 % of the measuring range.
For S = 3 and S = 4, SP is 5 % above the preset value. In this case, RP
coincides exactly with the preset value.
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