Linear position transducers

Linear position transducers with LVDT technology

Il inductive displacement transducer, Also known as LVDT extension, is an electromagnetic device used for the measurement of small displacements. The LVDT transducer has high precision and repeatability even in difficult working conditions and in the presence of contaminants.

Position and displacement transducers are robust and reliable, they ensure a long operational life. They offer measuring ranges from 0,2 mm to 10 mm in the high accuracy versions and up to 300 mm in the standard accuracy versions.

Economical, miniaturized, pressurized, spring-loaded, with or without built-in electronics versions are available. All LVDT transducers can be connected to amplifiers with analog, RS232, USB or fieldbus outputs.

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LVDT transducers GTL272A series

LVDT transducers GTL282A series

GT41 series LVDT transducers

GT42 series LVDT transducers

GT43 series LVDT transducers

GT44 series LVDT transducers

GT31 series LVDT transducers

LVDT transducers FMS100 series

LVDT transducers FMS102 series

LVDT transducers FMS130 series

LVDT transducers FMS132 series

LVDT transducers FMS100-P series

LVDT transducers FMS102-P series

LVDT transducers FMS130-P series

LVDT transducers FMS132-P series

TECHNICAL IN-DEPTH

The transducer is made by means of a tube composed of three windings arranged with parallel axes and with a movable ferromagnetic cylindrical core inside. The central winding is called packaging and the other two secondary: the primary one is connected to an AC voltage generator, the output voltage is measured at the ends of the secondary ones.

When the core is in the center, the voltage induced on the secondary windings, since these windings are wound in a discordant direction, is equal but opposite, so that the measured voltage signal is practically zero. As the core moves, however, the mutual inductances change, and depending on whether it moves to the left or to the right, the inductive coupling with the secondary respectively on the left or right will be greater. Consequently, the output signal will vary proportionally to the displacement of the core.

So-called is used to translate the LVDT output signal phase discriminating demodulators. These are electronic devices that allow you to extract the rms value of the voltage representing the displacement, and to interpret from which part of zero the displacement occurs. The best known of all uses a double Graetz bridge which rectifies the alternating signal coming from the secondary windings and makes the algebraic sum. Depending on the sign of the sum, it is possible to understand from which side of the zero the shift occurred.

LVDT is a very sensitive transducer capable of measuring displacements in the order of micrometer fractions. Depending on the power supply frequency of the primary and the mass of the core, there are cut-off frequencies of a few hundred hertz and therefore good dynamic responses to fast movements that vary over time.

Typical qualities of RODER inductive probes: excellent repeatability, durability and longevity • All RODER axially moving inductive probes are mounted on a ball bearing, with the exception of miniature models. • The ball bearing guide guarantees very low sensitivity to radial forces exerted on the measuring rod. An anti-rotation roller improves the movement of the mechanical guide. • The axial probe guides are highly protected against the penetration of liquids (oils) or solids (dust) by a high-quality elastomer protective bellows. • The measuring contacts can be replaced or changed. A wide range is available with different geometry, shape and size. • The measuring force can be adapted by changing the spring according to the probe type.

Axial movement RODER probes Standard execution Universal probes for classic applications and intense use. - Ø 8 mm fixing shank with the possibility of tightening over its entire length. - Measuring rod mounted on ball bearing. - Guide on ball bearing separate from the fixing shank in order not to negatively influence the movement of the measuring rod in case of inadequate tightening of the probe. - Degree of protection IP65 according to CEI 60529. - Wide range of accessories: measuring contacts, set of springs, etc. - LVDT executions and compatible with electronic instruments of other brands available on request.