Mode Of Operation - Siemens SIPART PS2 Compact Operating Instructions

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.
A linear movement of the magnet in the sensor range also generates a resistance change that is used to identify the
position. The following figure highlights the principle:
①
Magnet
②
Sensor
Figure 3-3 Resistance change depending on the position of the magnet
Non-linearity is corrected automatically in the SIPART PS2 positioner by software.
The great advantage of this principle is the absence of wear. Moreover, vibration, dampness and temperature only have a
minor impact on the measurement result.
SIPART PS2 Non Contacting Sensor (NCS)
A5E00097485-09, 09/2014
③
Resistance change
④
Angle
③
Resistance change
④
Angle
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