This residual voltage is low; it is due to In reality, there is a small residual voltage left due to factors like winding capacitance and variances in the magnetic materials. The LVDT consists of three solenoidal coils. At the centre of the position measurement stroke, the two secondary voltages of the displacement transducer are equal but because they are connected in opposition the resulting output from the sensor is zero. The induce voltages E1 and E2 in the two secondary windings are equal but opposite in direction as shown in figure. One of the most important features of an LVDT is its friction-free operation. An LVDT is, spelled out, a Linear Variable Differential Transformer. The primary winding is positioned between two identical secondary windings as shown in the figure below: The primary winding is energized with high-frequency AC voltages. When the core moves away from the center of the LVDT, known as the null point, the signal from the primary will be coupled to one secondary more than the other. [CDATA[// >. LVDT consist of one primary winding and two secondary windings, which are placed at either side of the primary winding on the same magnetic core as shown in figure. The effective voltage and LVDT output is the difference between each secondary. When the core is in center of secondary winding, S1 and S2, The induced e.m.f E1 and E2 will be equal but will be opposite in polarity, hence they cancel each other and the net voltage is become zero. The LVDT’s electrical output signal is determined by the relative differential AC voltage between the two secondary windings, which varies with the linear position of the core within the LVDT coil (Figure 3 center) . According to the AD598 datasheet, the input voltage range is 1~3Vrms. All rights reserved. It is used for the measurement of the weight on the highways. //--> When the core is centered, the voltages in the two secondary windings oppose each other, and the net output voltage is zero. The output voltage of secondary S 1 is ES 1 and that of secondary S 2 is ES 2. Construction of LVDT: LVDT consists of a cylindrical former where it is surrounded by one primary winding in the centre of the former and the two secondary windings at the sides. Within the coil assembly are three transformer windings. Applications of LVDT 3. LVDT Working Principle. Fig: LVDT cross-section (source: te.com ) Linear Variable Differential Transformer (LVDT) is an inductive transducer that we discussed in the previous article. I'll use AD598 for 5-wire LVDT signal conditioner. The circuit operates on the same principle as a transformer. An alternating current drives the primary and causes a voltage to be induced in each secondary proportional to the length of the core linking to the secondary. The two secondary winding are connected in series opposition. If E s1, E s2 and E 0 be the emf induced in the two secondary winding S1 & S2 and output voltage respectively then. Range of frequency is usually from 1 to 10 kHz. This mutual inductance, in turn, depends on the position of the core, with relation to each secondary coil. The secondary windings have an equal number of turns and are identically placed on either side of the primary winding. //-->