How does lvdt work

As the name suggests, many people get confused that it is a Transformer. But actually, it is a Transducer not a Transformer.

Because its working principle is same as Transformer i. It is categorized as an Inductive Transducer used to measure the speed or position of an object. Generally most Inductive Sensors work on the principle of Transformer. It is the most widely used Inductive Sensor due to its high accuracy level.

Its electrical output is obtained because of the difference of secondary voltages, hence it is called Differential Transformer. Hydrogen annealing is done on the Iron core to reduce harmonics, residual voltage of the core and thus provides high sensitivity.

The movable core also is laminated in order to reduce the eddy current losses. The displacement to be measured is attached to this movable soft iron core. And the way how the energy is getting converted is described in working of LVDT in a detailed manner.

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. The number of turns in both the secondary windings are equal, but they are connected in series opposition to each other, i. The two secondary coil is represented as S1 and S2. As the two secondary windings are positioned and connected in a set arrangement push-pull mode , when the core is positioned at the centre, a zero signal is derived.

Movement of the core from this point in either direction causes the signal to increase Fig C. As the windings are wound in a particular precise manner, the signal output has a linear relationship with the actual mechanical movement of the core. The secondary output signal is then processed by a phase-sensitive demodulator which is switched at the same frequency as the primary energising supply.

A LVDT is used to measure linear motion which is then converted to an electrical signal. The design of an LVDT is cylindrical consisting of primary and secondary windings. The primary windings produce a magnetic field in the center of the transducer signaling the secondary windings. Any movement from the core at this point causes the signal to increase or decrease. The LVDTs moving core is frictionless and does not come into contact with other electrical components giving it a distinct advantage over other types of sensors.

As mentioned, LVDTs are used in a variety of industries and for a variety of reasons.