Messotron MBI 46.51.39 Series, Руководство по эксплуатации

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Operating Instructions MBI 46.51.39
Version 0.9 en MBI 46.51.39 operating instructions.docx
Issue: 08/2022 page 6 from 29
4
Product
4.1 Terms and definitions
Term Definition
Carrier frequency
measuring amplifier Carrier frequency measuring amplifiers are used for LVDT/LVIT:
•
to provide the inductive sensor with the excitation voltage
•
to amplify the sensor output signal
•
to convert the sensor output into a normalized signal
Displacement
sensor In these instructions the term displacement transducer may also be
mentioned: sensor, transducers, or position sensors.
Differential
transformer
(LVDT)
Differential transformers consist of a primary coil and two secondary
coils placed around a movable magnetic core. The coils are coupled
based on the transformer principle.
LVDT stands for “Linear Variable
Differential Transformer”.
Inductive half-
bridge transducer
(LVIT)
Differential inductors represent a Wheatstone half-bridge with two
measuring coils. The impedance of the two measuring coils is
influenced in opposite directions by a movable magnetic core. They are
also referred to as LVIT (Linear Variable Inductance Transducer).
Long-stroke
sensors based on
the eddy current
principle Long-stroke sensors are inductive displacement sensors using a half-
bridge circuit, where only one coil is used for measuring. The second
coil is designed as a space-saving equivalent circuit. A movable tube
made of a conductive material changes the impedance of the measuring
coil based on the eddy current principle.
Symmetric sensor The measuring coils of differential transformers and inductors are built
in a symmetrically (mirrored) design. The electrical zero is at the center
of the nominal stroke.
Asymmetric sensor The space-saving equivalent circuit of the 2
nd
coil of the long-stroke
sensors results in an asymmetric design enabling a more favorable
stroke-to-length ratio. The electrical zero is at the start of the nominal
stroke, where the tube completely covers the measuring coil.
Core rod The core rod is a cylindrical part consisting of
•
a magnetic core
•
a core extension
Measuring tube The measuring tube is made of aluminum. In asymmetric displacement
sensors it is moved over the measuring coil drawing energy from the
coil field proportional to the tube’s position (eddy current effect).
Excitation voltage AC voltage (typically 1...5 Vpp), supplying the inductive sensor.
Carrier frequency Excitation frequency, usually 5 or 10 kHz, to drive the inductive
displacement sensor.