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Classifying Parameters for Displacement Transducer

Displacement transducers consist of a variety of sensing devices used to measure the movement of an object. Different types of transducers suit specific applications. Some transducers have robust fabrication intended for use in extreme conditions.

Machine movement and displacement is a physical quantity converted into an electrical signal using a displacement transducer. The two primary purposes of a sensor are to sense physical motion and then change this information into a mechanical or electrical signal.

A displacement transducer comes in various categories. Categorising transducers depend on specific parameters. For example, transducers can measure different types of movement. A linear displacement transducer or more commonly referred to as LVDT, measures rectilinear motion.


Classifying according to transduction


A linear sensor or transducer can be classified according to the medium of transduction. The medium of transduction can either be resistive, capacitive, or inductive. An LVDT sensor converts the input signal into resistance, a capacitance, or inductance.


Classifying as either primary or secondary transducer


A primary transducer consists of both mechanical and electrical devices. The mechanical parts of the LVDT transducer are responsible for converting the mechanical movement of the object into mechanical signals. On the other hand, the components of the sensor converting the mechanical displacement into electrical data are called the secondary transducer.


Classifying as either passive or active transducer


Another classifying method for a linear sensor or lvdt displacement transducer is whether it is an active or a passive transducer.


• Passive transducer. A passive transducer will require an external power source to operate. Capacitive, resistive, and inductive transducers are all passive.


• Active transducer. When a sensor does not need an external power source to work, it is an active transducer. Active transducers are also known as self-generating transducers.


Examples of active transducers include photovoltaic cells and tacho generators. Active transducers induce specific physical quantities like light intensity, temperature, force, and velocity.


Classifying as either analogue or digital transducer


The output signal is another classifying parameter for transducers. Analogue transducers convert input quantity into continuous functions. An lvdt transducer is an excellent example of an analogue transducer. In comparison, a digital sensor changes input quantity into a pulse or digital signal.


Classifying as either transducer or inverse transducer


Sensors in general, convert input quantity into an electrical signal. An inverse transducer works by converting the electrical input quantity into a physical output.


Commonly used displacement transducers


Classifying displacement transducers into specific categories identity proper uses and applications. In addition to categorising transducers according to their characteristics, there are general classifications that identify each kind of displacement transducer and its underlying working principle.


• Linear variable displacement transducer. A type of electrical sensor designed to measure rectilinear motion. The resulting output signal of an LVDT comes from the measurement of the distance travelled by object. The unit of measurement is either in millimetres or inches. An example of a modern application for LVDTs includes automatic gauging in production lines.


• Resistive transducer. A resistive sensor works by converting a physical quantity into variable resistance measured in meters. A resistive transducer can also transform input into the electrical or mechanical signal as needed by the application. Resistance transducers have flexibility regarding measurement where AC, DC, current, or voltage, are all appropriate measurement options. Another advantage of a resistive sensor is high range resistance and fast response time.

• Hall-effect transducer. This type of transducer makes use of a magnetic field for measurement. The device converts the magnetic field into an electrical quantity which reads as either digital or analogue data.


• Capacitive transducer. This transducer is best for measuring physical quantities including pressure and displacement. Since it is a passive transducer, it does not need any external power to operate. The device consists of two metal plates separated by air, gas, liquid, or another material. Aside from not requiring external power input, capacitive transducers are very sensitive, thus providing a high-frequency response.


To conclude, the technology and mechanisms of displacement sensors have changed significantly over time. These days, more developments in the field of sensing technology pave the way for using transducers in applications unimaginable decades ago. For example, sensors are instrumental in innovations related to robotics and aerospace engineering.

Transducers are also becoming more compact and robust which allows for application in challenging and extreme conditions. With this, Positek remains to be ahead of the curve when it comes to developing transducers and sensors for various applications. Positek uses a patented contactless technology to manufacture robust and durable sensors applicable even in the most hazard

Article published on: 23/08/2018