Siemens SIPART Series Compact Operating Instructions page 22

①
Pneumatic line
②
Pneumatic line for double-action actuators
③
Position sensing system (10 kΩ potentiometer, or NCS)
④
Electrical cable
⑤
Retrofittable EMC filter module (in the positioner)
⑥
Positioner
Figure 3-1 Separate installation of the NCS and positioner
3.2 Mode of operation
The NCS contains a magnetic field sensor. This sensor changes its electrical resistance in response to the immediate
presence of a permanent magnet. The sensor has a high signal-to-noise ratio to external magnetic fields due to the
measurement method used.
The following figure shows the mode of operation with a rotating magnet.
①
Magnet
②
Sensor
Figure 3-2 Relative resistance change depending on the angle of the magnet
The figure shows that a circular movement of the magnet generates a sinusoidal change of the resistance. The mechanical
stops of the fitting ensure that only one part (quadrant) of the sinusoidal curve is used at any one time. The principle-related
non-linearity of the curve is corrected by means of software based on a curve that is stored in the positioner.
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③
Resistance change
④
Angle
SIPART PS2 Non-Contacting Sensor (NCS)
A5E00097485-07, 01/2012