The main element of the potentiometer consists of 2 linear tracks, with length equal to the maximumstroke of the displacement to be measured, made of a conductive material.
A mobile cursor with two brushes connected to each other serves as a bridge between the two tracksand measures the difference in potential between the first track (resistive) and the second track
(conductive).The cursor may be outside the device (and therefore connectable directly to the moving object whosedisplacement is to be measured) or inside. In this case, a rod is used as an actuator of the outsidemovement on the potentiometer cursor.The resistive track must be of high quality to guarantee highly precise measurement: only in this waycan an accurate and repeatable output voltage level correspond to the contact position on the track.Gefran produces all the resistive tracks for its potentiometric
transducers in-house, and thereforeguarantees reliable, precise measurement.Even if its tracks are developed and produced with the aim of guaranteeing accuracy, Gefran still runsa series of linearity tests.The relative simplicity of this technology allows it to be used in compact models. Gefran potentiometersrequire no control logic, and are therefore quick and easy to install.
Glossary:- linearity: the maximum percentage difference (error) between the straight line representing the theoretical outputcurve and the actual output curve of the transducer LT
Magnetostrictive technology
The new generation of potentiometric transducer is the magnetostrictive displacement transmitter, inwhich there is no contact between the transducer and the mobile cursor.The measurement element, a copper wire passing through a special alloy tube, measures the interaction
between mechanical waves and electromagnetic fields.A current pulse is transmitted along the tube from the sensor head; interaction between the currentpulse and the magnetic field generated by the displacement magnet creates torsion that is transmittedalong the wave-guide rod in the form of a mechanical wave. By measuring the time between transmission
of the first signal and detection of torsion on the rod, you can calculate the exact position of the magnet. There is no direct contact between moving parts, so the transducer is not subject to wear. This alsoguarantees greater precision and repeatability.
MK-4
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