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Published in Martin Novák, Introduction to Sensors for Electrical and Mechanical Engineers, 2020
The LVDT is a linear displacement position sensor. It transfers the movement of the transformer core into the output signal. The output signal is a voltage signal; in our case the used sensor has built-in electronics to transfer the voltage to current output. Sensors with current output (4 to 20 mA) have a limit of maximal resistance that can be connected to sensors’ output. The ideal load for a current output sensor is resistance zero; the maximal load is limited by the available voltage for output. When the output loop resistance is increasing, the output compensates by increasing output voltage so as to keep constant current. When the output is already on the maximal voltage, the output current starts to drop. The maximal resistance connected to the current output limits the wiring length between the sensor and gauge.
Sensors
Published in Bogdan M. Wilamowski, J. David Irwin, Control and Mechatronics, 2018
Tiantian Xie, Bogdan M. Wilamowski
Another displacement sensor is linear variable differential transformer (LVDT). The transformer comprises three coils: a primary center coil and two outer secondary coils. The transfer of current between the primary and the secondary coils of the transducer depends on the position of a magnetic core shown in Figure 21.3. At the center of the position measurement stroke, the two secondary voltages of the displacement transducer are equal; since they are connected oppositely, the output from the sensor is zero. As the core moves away from the center, the result is an increase position sensor in one of the secondary coils and a decrease in the other, which results in an output from the measurement sensor. The LVDT is used to measure displacement ranging from fractions of a millimeter to several centimeters. They can be manufactured to meet stringent accuracy and resolution requirements, for example, accuracy better than 0.2%.
Survey of Sensor Mechanisms
Published in Robert B. Northrop, Introduction to Instrumentation and Measurements, 2018
A schematic representation of an LVDT is shown in Figure 6.33B. Note that the two, series pickoff coils have opposite dot polarity, so that when the moveable magnetic core is at magnetic center (x = 0), the induced EMFs in each coil sum to zero at the output. The AC excitation of an LVDT can range in frequency from about 50 Hz to 20 kHz. Peak output response for a given displacement, δx > 0, is maximum at some frequency that may range from 400 Hz to over 2 kHz. Some LVDTs contain built-in oscillators and PSRs so one has only to supply a DC power source (e.g., 24 V) and observe a DC output that has a voltage/core-position relationship similar to that shown in Figure 6.34. Several electronic IC manufacturers offer oscillator/PSR chips (Signetics’ NE5520, Analog Devices’ AD630) to facilitate the use of LVDTs, which do not contain this signal processing circuit internally.
Experimental investigation of Gerber frames subjected to elastic lateral torsional buckling
Published in Australian Journal of Mechanical Engineering, 2022
Amit S. Chaudhary, K. B. Waghulde
Figure 7 illustrates arrangement of loading; a vertical point load is set on the top flange at the mid centre of beam length. The arrangement consists of An actuator is set below the load which is applied at the mid centre of the beam length, it consists cylinder with stroke distance 150 mm and collapsed height 250 mm and the capacity is 100 KN. By controlling the rate of fluid flow, the stroke is controlled.Linear variable differential transformer (LVDT) is used in experimentation of Gerber beam for the purpose of lateral displacement measure, to measure the rotational movement clinometers are used, and load cells are used to measure the load applied by actuator.An automatic data acquisition computerised system was arranged to collect data related to lateral displacement.
Microstructural analysis of the effects of compaction on fatigue properties of asphalt mixtures
Published in International Journal of Pavement Engineering, 2022
Tianshuai Li, Pengfei Liu, Cong Du, Marc Schnittcher, Jing Hu, Dawei Wang, Markus Oeser
A Universal Testing Machine UTM-250 equipped with a temperature control chamber was utilised for the indirect tensile fatigue test according to DIN EN 12697-26, as shown in Figure 4(a). The relative low-temperature value was chosen in accordance with the previous researches. Before the test, the specimens were stored at a constant temperature of 10°C for 6 h. In this study, a sinusoid loading was applied on the specimen until failure. The frequency of the repeated compressive load is 10 Hz and in a stress-controlled mode was chosen in the test. The range of the loading amplitude was between 0.035 and 0.5 MPa to ensure the peak value of the horizontal strain was between 0.05‰ and 0.3‰. Furthermore, the test time was set to 2 h in order to ensure that the same loading cycles were applied to each test specimen, and hence the fatigue damage of different internal structures can be compared. As can be seen from Figure 4(b), the loading device consists of two loading strips fixing the specimen in the vertical direction. For the measurement of the horizontal deformation, two Linear Variable Differential Transformer (LVDT) are used. They are positioned opposite to each other and secured onto the mounting frame with screws. The mounting frame itself is attached to the specimen with securing clamps. The range of one LVDT is 0.12 mm with an accuracy of 25 × 10−5 mm.
The alpha power Weibull transformation distribution applied to describe the behavior of electronic devices under voltage stress profile
Published in Quality Technology & Quantitative Management, 2022
Luis Carlos Méndez-González, Luis Alberto Rodríguez-Picón, Ivan Juan Carlos Pérez-Olguin, Luis Asunción Pérez-Domínguez, David Luviano Cruz
The second case study is based on a Linear Variable Differential Transformer (LVDT). An LVDT is a type of electrical transformer used for measuring linear displacement (position) in the industry. This device bases its operation on the movement of a core inside the sensor’s body with the windings wound; hence it is essentially a transformer with its moving core. The LVDT analyzed in this case study is located in test equipment that verifies the presence and depth at which a series of screws are located in an upper casing used in turbos of engines in the automotive sector. If there is an absence of these screws, liquid such as water can leak directly into the gear system causing general failure in the engine turbo system.